WorldWideScience

Sample records for corneal topography

  1. Corneal topography

    DEFF Research Database (Denmark)

    Andersen, J.; Koch-Jensen, P.; Østerby, Ole

    1993-01-01

    The central corneal zone is depicted on keratoscope photographs using a small target aperture and a large object distance. Information on the peripheral area is included by employing a hemispherical target with a dense circular and radial pattern. On a 16 mm (R = 8 mm) reference steel sphere...

  2. Corneal Topography Analysis of Stromal Corneal Dystrophies

    OpenAIRE

    Kocluk, Yusuf; Yalniz-Akkaya, Zuleyha; Burcu, Ayse; Ornek, Firdevs

    2015-01-01

    Objective: The aim was to compare the corneal topography and tomography parameters of macular corneal dystrophy (MCD), granular corneal dystrophy (GCD) and lattice corneal dystrophy (LCD) patients obtained by Scheimpflug imaging system. Methods: The charts, photographs and topography images of patients were reviewed retrospectively. This study included 73 eyes of 73 patients (28 MCD, 20 GCG and 25 LCD patients). Topography images were obtained by Pentacam (Oculus Optikgerate, Wetzlar, Germany...

  3. Corneal topography measurements for biometric applications

    Science.gov (United States)

    Lewis, Nathan D.

    The term biometrics is used to describe the process of analyzing biological and behavioral traits that are unique to an individual in order to confirm or determine his or her identity. Many biometric modalities are currently being researched and implemented including, fingerprints, hand and facial geometry, iris recognition, vein structure recognition, gait, voice recognition, etc... This project explores the possibility of using corneal topography measurements as a trait for biometric identification. Two new corneal topographers were developed for this study. The first was designed to function as an operator-free device that will allow a user to approach the device and have his or her corneal topography measured. Human subject topography data were collected with this device and compared to measurements made with the commercially available Keratron Piccolo topographer (Optikon, Rome, Italy). A third topographer that departs from the standard Placido disk technology allows for arbitrary pattern illumination through the use of LCD monitors. This topographer was built and tested to be used in future research studies. Topography data was collected from 59 subjects and modeled using Zernike polynomials, which provide for a simple method of compressing topography data and comparing one topographical measurement with a database for biometric identification. The data were analyzed to determine the biometric error rates associated with corneal topography measurements. Reasonably accurate results, between three to eight percent simultaneous false match and false non-match rates, were achieved.

  4. Corneal topography and soft contact lens fit.

    Science.gov (United States)

    Young, Graeme; Schnider, Cristina; Hunt, Chris; Efron, Suzanne

    2010-05-01

    To determine which ocular topography variables affect soft contact lens fit. Fifty subjects each wore three pairs of soft lenses in random succession (Vistakon Acuvue 2, Vistakon Acuvue Advance, Ciba Vision Night & Day), and various aspects of lens fit were evaluated. The steeper base curves of each type were worn in one eye and the flatter base curves in the other eye. Corneal topography data were collected using a Medmont E300 corneal topographer (Camberwell, Australia). Corneal curvature, shape factor (SF), and corneal height were measured over a 10 mm chord and also over the maximum measurable diameter. These were measured in the horizontal, vertical, steepest, and flattest meridians. With each lens type, the steeper base curve provided the best fit on the greatest proportion of eyes and the significant differences in various aspects of fit were noted between base curves. For each lens type, there was no significant difference in mean K-reading between those eyes best fit with the steeper base curve and those eyes best fit with the flatter base curve. Two of the lenses showed a positive correlation between centration and horizontal corneal height (maximum), whereas one lens showed a negative correlation between centration and horizontal SF (SF = e). Several lenses showed a positive correlation between post-blink movement and horizontal or vertical corneal SF. The measurement of corneal topography using current Placido disc instrumentation allows a better prediction of soft lens fit than by keratometry, but it is not reliable enough to enable accurate selection of the best fitting base curve. Some correlations are evident between corneal measurements; however, trial fitting remains the method of choice for selection of soft lens base curve.

  5. Bessel Function Model for Corneal Topography

    CERN Document Server

    Okrasiński, Wojciech

    2011-01-01

    In this paper we consider a new nonlinear mathematical model for corneal topography formulated as two-point boudary value problem. We derive it from first physical principles and provide some mathematical analysis. The existence and uniqeness theorems are proved as well as various estimates on exact solution. At the end we fit the simplified model based on Modified Bessel Function of the First Kind with the real corneal data consisting of matrix of 123x123 points and obtain an error of order of 1%.

  6. Interferometer for measuring dynamic corneal topography

    Science.gov (United States)

    Micali, Jason Daniel

    The cornea is the anterior most surface of the eye and plays a critical role in vision. A thin fluid layer, the tear film, coats the outer surface of the cornea and serves to protect, nourish, and lubricate the cornea. At the same time, the tear film is responsible for creating a smooth continuous surface where the majority of refraction takes place in the eye. A significant component of vision quality is determined by the shape of the cornea and stability of the tear film. It is desirable to possess an instrument that can measure the corneal shape and tear film surface with the same accuracy and resolution that is currently performed on common optical elements. A dual interferometer system for measuring the dynamic corneal topography is designed, built, and verified. The completed system is validated by testing on human subjects. The system consists of two co-aligned polarization splitting Twyman-Green interferometers designed to measure phase instantaneously. The primary interferometer measures the surface of the tear film while the secondary interferometer simultaneously tracks the absolute position of the cornea. Eye motion, ocular variation, and a dynamic tear film surface will result in a non-null configuration of the surface with respect to the interferometer system. A non-null test results in significant interferometer induced errors that add to the measured phase. New algorithms are developed to recover the absolute surface topography of the tear film and corneal surface from the simultaneous interferometer measurements. The results are high-resolution and high-accuracy surface topography measurements of the in vivo cornea that are captured at standard camera frame rates. This dissertation will cover the development and construction of an interferometer system for measuring the dynamic corneal topography of the human eye. The discussion starts with the completion of an interferometer for measuring the tear film. The tear film interferometer is part of an

  7. New null screen design for corneal topography

    Science.gov (United States)

    Campos-García, Manuel; Estrada-Molina, Amilcar; Díaz-Uribe, Rufino

    2011-09-01

    In this work we report the design of a null screen for corneal topography. Here we assume that the corneal surface is an ellipsoid with a diameter of 12 mm and a curvature radius of 7.8 mm. To avoid the difficulties in the alignment of the test system due to the face contour (eyebrows, nose, or eyelids), we design a conical null-screen with spots (similar to ellipses) drawn on it in such a way that its image, which is formed by reflection on the test surface, becomes an exact radial array of circular spots if the surface is perfect. Additionally, we performed a numerical simulation introducing Gaussian random errors in the coordinates of the centroids of the spots on the image plane, and in the coordinates of the sources (spots on the null-screen) in order to obtain the conical null-screen that reduces the error in the evaluation of the topography.

  8. Determination of corneal image-forming properties from corneal topography.

    Science.gov (United States)

    Maloney, R K; Bogan, S J; Waring, G O

    1993-01-01

    Keratometry provides useful information about the cornea's image-forming properties, such as corneal astigmatism, but is inaccurate on irregular corneas. Quantitative corneal topographic information is now obtainable on irregular corneas, but is difficult for the clinician to interpret. We developed a method to determine the spherical power, astigmatism, and topographic irregularity of a cornea by finding the best-fit spherocylinder that was closest to its measured topography. Keratometric measurements and two videokeratographs were gathered prospectively on 262 normal and abnormal corneas. The best-fit measurements of spherical power, astigmatism, and topographic irregularity were reproducible with one standard deviation of 0.75 diopter or better; agreement with keratometric measurements in normal eyes was good (0.60 diopter or better). Topographic irregularity averaged 0.1 diopter on precision spheres, 0.4 diopter on 146 normal eyes, 0.8 diopter on 29 eyes after radial keratotomy, 2.0 diopters on 58 eyes after penetrating keratoplasty, and 3.0 diopters on 29 eyes with advanced keratoconus. We conclude the following: basic corneal image-forming properties can be measured from videokeratographs; the properties can be determined, by our methods, on irregular corneas in which keratometry is unreliable; and topographic irregularity provides a measure of irregular astigmatism.

  9. Corneal topography matching by iterative registration.

    Science.gov (United States)

    Wang, Junjie; Elsheikh, Ahmed; Davey, Pinakin G; Wang, Weizhuo; Bao, Fangjun; Mottershead, John E

    2014-11-01

    Videokeratography is used for the measurement of corneal topography in overlapping portions (or maps) which must later be joined together to form the overall topography of the cornea. The separate portions are measured from different viewpoints and therefore must be brought together by registration of measurement points in the regions of overlap. The central map is generally the most accurate, but all maps are measured with uncertainty that increases towards the periphery. It becomes the reference (or static) map, and the peripheral (or dynamic) maps must then be transformed by rotation and translation so that the overlapping portions are matched. The process known as registration, of determining the necessary transformation, is a well-understood procedure in image analysis and has been applied in several areas of science and engineering. In this article, direct search optimisation using the Nelder-Mead algorithm and several variants of the iterative closest/corresponding point routine are explained and applied to simulated and real clinical data. The measurement points on the static and dynamic maps are generally different so that it becomes necessary to interpolate, which is done using a truncated series of Zernike polynomials. The point-to-plane iterative closest/corresponding point variant has the advantage of releasing certain optimisation constraints that lead to persistent registration and alignment errors when other approaches are used. The point-to-plane iterative closest/corresponding point routine is found to be robust to measurement noise, insensitive to starting values of the transformation parameters and produces high-quality results when using real clinical data.

  10. On fractional Bessel equation and the description of corneal topography

    CERN Document Server

    Okrasiński, Wojciech

    2012-01-01

    In this note we apply a modified fractional Bessel differential equation to the problem of describing corneal topography. We find the solution in terms of the power series. This solution has an interesting behavior at infinity which is a generalization of the classical results for modified Bessel function of order 0. Our model fits the real corneal geometry data with an error of order of a few per cent.

  11. Using corneal topography design personalized cataract surgery programs

    Directory of Open Access Journals (Sweden)

    Jin-Ou Huang

    2014-08-01

    Full Text Available AIM:To investigate how to design personalized cataract surgery programs to achieve surgical correction of preoperative corneal astigmatism with surgical astigmatism under the guidance of corneal topography, improve postoperative visual quality and reduce the cost of treatment. METHODS: Totally 202 cases(226 eyescataract patients were divided into randomized treatment group and individualized treatment group. According to the method and location of the incision, randomized treatment group were divided into 8 groups. Surgical astigmatism after different incision were calculated with the use of preoperative and postoperative corneal astigmatism through vector analysis method. Individualized treatment groups were designed personably for surgical method with reference of every surgically induced astigmatism, the surgical method chooses the type of surgical incision based on close link between preoperative corneal astigmatism and surgically induced astigmatism, and the incision was located in the steep meridian. The postoperative corneal astigmatism of individualized treatment group was observed. RESULTS: Postoperative corneal astigmatism of individualized treatment group were lower than that of 3.0mm clear corneal tunnel incision in the randomized treatment group, there were statistically significance difference, while with 3.0mm sclera tunnel incision group there were no statistically significance difference. After 55.8% of patients with the use of individualized surgical plan could undergo the operation of extracapsular cataract extraction with relatively low cost and rigid intraocular lens implantation, the per capita cost of treatment could be reduced. CONCLUSION: Personalized cataract surgery programs are designed to achieve surgical correction of preoperative corneal astigmatism under the use of corneal topography, improve postoperative visual quality and reduce the cost of treatment.

  12. The Study of Corneal Topography in Myopic and Hyperopic Children

    Institute of Scientific and Technical Information of China (English)

    Lei Gao; Xuying Zhuo; Lusheng Ma; Ning Yu; Zhonghao Wang; Pengfei Jiang

    2005-01-01

    Purpose: To compare the differences of corneal topographies in myopic and hyperopic children and study the effect of Atropin on their changes.Methods: The refractive components of 136 eyes with different refractive conditions were measured with A-Scan and their corneal topographies with and without cycloplegia were obtained respectively.Results: The mean corneal power of zones 3mm (MD3, P=0.031 ) and minor keratometer K2 (P=0.003) of myopia are greater than those of hyperopia without cycloplegia. MD3 (P=0.009) and Keratometer K1 (P = 0.025) increased in hyperopic eyes, while MD3(P=0.033), K1 (P = 0.035) and K2 (P = 0.002) decreased in myopic eyes significantly after cycloplegia. Similarly, the mean corneal power of zones 5mm (MD5) and 7mm (MD7) in myopic eyes decreased dramatically (P ≤ 0.001 ).Conclusions: The corneal power was found to be greater in myopia than that in hyperopia. The effect of Atropin on corneal shape of myopia and hyperopia was in the opposite direction.

  13. Advances in corneal topography measurements with conical null-screens

    Science.gov (United States)

    Campos-García, Manuel; Cossio-Guerrero, Cesar; Huerta-Carranza, Oliver; Moreno-Oliva, Víctor I.

    2015-09-01

    In this work we report the design of a null-screen for corneal topography. To avoid the difficulties in the alignment of the test system due to the face contour (eyebrows, nose, or eyelids), we design a conical null-screen with a novel radial points distribution drawn on it in such a way that its image, which is formed by reflection on the test surface, becomes an exact array of circular spots if the surface is perfect. Additionally, an algorithm to compute the sagittal and meridional radii of curvature for the corneal surface is presented. The sagittal radius is obtained from the surface normal, and the meridional radius is calculated from a function fitted to the derivative of the sagittal curvature by using the surfacenormals raw data. Experimental results for the testing a calibration spherical surface are shown. Also, we perform some corneal topography measurements.

  14. Synchronous interferometric demodulation of Placido mires applied to corneal topography

    CERN Document Server

    Servin, Manuel

    2012-01-01

    This paper presents a novel digital interferometric method to demodulate Placido fringe patterns. This is a synchronous method which uses a computer-stored conic-wavefront as demodulating reference. Here we focuses on the experimental aspects to phase-demodulate Placido mires applied to corneal topography. This synchronous method is applied to two topographic Placido images and their de-modulated corneal-slope deformation is estimated. This conic-interferometric method is highly robust against typical "noisy" signals in Placido topography such as: reflected eyelashes and iris structures. That is because the eyelashes and the iris structure are high frequency "noisy" signals corrupting the reflected Placido mire, so they are filtered-out by this method. Digital synchronous interferometry is here applied for the first time to demodulate corneal topographic concentric-rings images (Patent pending at the USPTO).

  15. Curvature sensor for the measurement of the static corneal topography and the dynamic tear film topography in the human eye

    Science.gov (United States)

    Gruppetta, Steve; Koechlin, Laurent; Lacombe, François; Puget, Pascal

    2005-10-01

    A system to measure the topography of the first optical surface of the human eye noninvasively by using a curvature sensor is described. The static corneal topography and the dynamic topography of the tear film can both be measured, and the topographies obtained are presented. The system makes possible the study of the dynamic aberrations introduced by the tear film to determine their contribution to the overall ocular aberrations in healthy eyes, eyes with corneal pathologies, and eyes wearing contact lenses.

  16. Intraoperative raster photogrammetry--the PAR Corneal Topography System.

    Science.gov (United States)

    Belin, M W

    1993-01-01

    The PAR Corneal Topography System (CTS) is a computer-driven corneal imaging system that uses close-range raster photogrammetry to measure and produce a topographic map of the corneal surface. The CTS determines distortion in a projected two-dimensional grid. Unlike Placido-disc-based videokeratoscopes, the PAR CTS produces a true topographic map (elevation map) and requires neither a smooth reflective surface nor precise spatial alignment for accurate imaging. Because the system uses two noncoaxial optical paths, it can be integrated into other optical devices. A modified CTS was integrated into an experimental erbium: YAG photoablative laser. The CTS successfully imaged corneas before, after, and during laser photoablation. Its ability to image nonreflective surfaces and to be integrated into other optical systems may make it suitable for intraoperative refractive monitoring.

  17. Keratometry and corneal topography using multiple delay element OCT

    Science.gov (United States)

    Plesea, Lucian; Podoleanu, Adrian G.

    2008-02-01

    We have presented previously a novel method for the evaluation of the surface shape of an object, with immediate application to measurement of cornea shape. This method uses single shot C-scans obtained by using a multiple delay element (MDE) in the reference path of an OCT system. A calibrated MDE-OCT system can be used to measure the elevation of points on the cornea, in contrast to existing methods which are based on measurement of the cornea slope. The associated algorithm for extracting corneal topography data points from the MDE-OCT C-Scan image will be presented, data points which can then be used to calculate the Zernike coefficients for the cornea shape. The differences between the existing systems and the MDE-OCT method for keratometry and corneal topography are discussed.

  18. Measurement of the topography of human cadaver lenses using the PAR corneal topography system

    Science.gov (United States)

    Fernandez, Viviana; Manns, Fabrice; Zipper, Stanley; Sandadi, Samith; Hamaoui, Marie; Tahi, Hassan; Ho, Arthur; Parel, Jean-Marie A.

    2001-06-01

    To measure the radius of curvature and asphericity of the anterior and posterior surfaces of crystalline lenses of human Eye-Bank eyes using the PAR Corneal Topography System. The measured values will be used in an optical model of the eye for lens refilling procedures.

  19. Corneal modeling using conic section fits of PAR corneal topography system measurements

    Science.gov (United States)

    Zipper, Stanley; Manns, Fabrice; Fernandez, Viviana; Sandadi, Samith; Ho, Arthur; Parel, Jean-Marie A.

    2001-06-01

    The purpose of this study was to measure the average shape and variability of human corneas and to develop a tool for analyzing, height, curvature, and aberrations based on a conic section model. Fresh Eye Bank Eyes were placed in Dextran until the corneal thickness reached a physiological value. The eyes were placed in a custom made holder and measured using an intraoperative PAR Corneal Topography System (CTS) mounted on an operation microscope. Topography was measured before and after removal of the epithelium. A series of MATLAB functions were written to analyze the raw-z (height) data in polar coordinates. The functions fit conic sections to the PAR CTS data along hemi-meridians at 5 degree(s) intervals. The conic shape factor and apical radius were used to calculate and display the curvature. The dependence of these parameters with meridional position was examined.

  20. The effect of Gonioscopy on keratometry and corneal surface topography

    Directory of Open Access Journals (Sweden)

    DeBroff Brian M

    2006-06-01

    Full Text Available Abstract Background Biometric procedures such as keratometry performed shortly after contact procedures like gonioscopy and applanation tonometry could affect the validity of the measurement. This study was conducted to understand the short-term effect of gonioscopy on corneal curvature measurements and surface topography based Simulated Keratometry and whether this would alter the power of an intraocular lens implant calculated using post-gonioscopy measurements. We further compared the effect of the 2-mirror (Goldmann and the 4-mirror (Sussman Gonioscopes. Methods A prospective clinic-based self-controlled comparative study. 198 eyes of 99 patients, above 50 years of age, were studied. Exclusion criteria included documented dry eye, history of ocular surgery or trauma, diabetes mellitus and connective tissue disorders. Auto-Keratometry and corneal topography measurements were obtained at baseline and at three follow-up times – within the first 5 minutes, between the 10th-15th minute and between the 20th-25th minute after intervention. One eye was randomized for intervention with the 2-mirror gonioscope and the other underwent the 4-mirror after baseline measurements. t-tests were used to examine differences between interventions and between the measurement methods. The sample size was calculated using an estimate of clinically significant lens implant power changes based on the SRK-II formula. Results Clinically and statistically significant steepening was observed in the first 5 minutes and in the 10–15 minute interval using topography-based Sim K. These changes were not present with the Auto-Keratometer measurements. Although changes from baseline were noted between 20 and 25 minutes topographically, these were not clinically or statistically significant. There was no significant difference between the two types of gonioscopes. There was greater variability in the changes from baseline using the topography-based Sim K readings

  1. Data acquisition time constraints in elevation mapping corneal topography

    Science.gov (United States)

    Baron, William S.; Baron, Sandra F.

    1997-05-01

    Elevation mapping corneal topography instruments provide an array of x, y, z data points describing the corneal surface. An advantage of elevation mapping instruments is their ability to calculate the 3D data array strictly from the instrument's geometry and calibration data; no assumptions about the corneal surface itself are needed. However, uncompensated eye movements can affect accuracy. Longitudinal eye movements occur along the z axis, due to pulmonary and cardiac pulsations. Eye rotations due to saccades and drifts are normal occurrences, as are translational body movements. An analysis of eye and body movements at the cornea's surface indicates a nearly linear relationship between data acquisition times of less than 33 msec, and the possible change in elevation at a point referenced to an instrument axis. The proportionality constant is expected to vary by a factor of about six over the range of clinical patients, since eye and body movements are exaggerated in juvenile patients, geriatric patients, and patients with poor vision. The analysis estimates an elevation change due to rotation and longitudinal translation of the eye of up to +/- 285 micrometers in 33 msec within the clinical population. This analysis indicates that when a topographer's acquisition time is greater than 100 microsecond(s) ec (during which an apparent elevation change of up to 1.0 micrometers may occur) testing on static objects may not provide a realistic measure of an instrument's clinical performance.

  2. Corneal topography reinterpretation through separate analysis of the projected rings

    Science.gov (United States)

    Espinosa, Julian; Roig, Ana B.; Mas, David; Hernández, Consuelo; Illueca, Carlos

    2012-06-01

    We present a new algorithm to process captured images of reflected Placido rings. Up to our knowledge, conventional topographers transform from Cartesian to polar coordinates and vice-versa, thus extrapolating corneal data and introducing noise and image artefacts. Moreover, captured data are processed by the device according to proprietary algorithms and offering a final map of corneal curvature. Corneal topography images consists of concentric rings of approximately elliptical shape. Our proposal consists of considering the information that provides each separate ring. A snake-annealing-like method permits identifying the ring even with discontinuities due to eye-lashes and reflections. By analysing the geometrical parameters of rings (centre, semi-axis and orientation), one can obtain information about small morphological micro-fluctuations and local astigmatisms. These parameters can be obtained with sub-pixel accuracy so the method results of high precision. The method can be easily adapted to work on any topographer, so that it can provide additional information about the cornea at no additional cost.

  3. Accuracy of the PAR corneal topography system with spatial misalignment.

    Science.gov (United States)

    Belin, M W; Zloty, P

    1993-01-01

    The PAR Corneal Topography System is a computerized corneal imaging system which uses close-range raster photogrammetry to measure and produce a topographic map of the corneal surface. Raster photogrammetry is a standard method of extracting object information by projecting a known pattern onto an object and recording the distortion when viewed from an oblique angle. Unlike placido disc based videokeratoscopes, the PAR system requires neither a smooth reflective surface nor precise spatial alignment for accurate imaging. We studied both the accuracy of the system with purposeful misalignment (defocusing) of the test object and determined the ability to image freshly deepithelialized, keratectomized, and photoablated corneas. The PAR system was both accurate and reproducible in imaging calibrated spheres within a defined zone in space. Whole cadaver eyes were imaged both before and immediately after removal of the epithelium, lamellar keratectomy, and laser photoablation. The system demonstrated the ability to image irregular, deepithelialized, and keratectomized corneas. The ability to maintain accuracy without precise alignment and the facility to image freshly deepithelialized and keratectomized corneas may make the system suitable for intraoperative refractive monitoring.

  4. Comparison of Central Corneal Thickness Measurements by Ultrasonic Pachymetry and Orbscan II Corneal Topography and Evaluation of Ultrasonic Pachymetry Repeatability

    Directory of Open Access Journals (Sweden)

    Semra Tiryaki Demir

    2014-08-01

    Full Text Available Objectives: Comparison of central corneal thickness (CCT measurements by ultrasonic pachymetry and Orbscan II corneal topography and evaluation of ultrasonic pachymetry repeatability for same observer. Materials and Methods: The study included 132, 82, and 80 eyes of 66 patients with primary open-angle glaucoma (POAG, 41 patients with ocular hypertension (OHT, and 40 controls, respectively. All subjects were subjected to routine ophthalmic examination. Orbscan II (Bausch&Lomb corneal topography and ultrasonic pachymetry (Nidek Ultrasonic Pachymetry UP-1000 were used for measurement of CCT. ANOVA (Turkey test was used for variable distribution, paired sample t-test was used for repeated measurements, and the analyses were done by SPSS 20.0. Results: Mean CCT was 558.9±37.2 µm by ultrasonic pachymetry and 553.4±37 µm by corneal topography. There was a significant difference between the two measurements (p0.05. CCT was 555±39.2 µm, 564.3±28.4 µm, and 559.7±41.5 µm by ultrasonic pachymetry in POAG, OHT, and control subjects, respectively; CCT was 550.3±38.3 µm, 558.5±28 µm, and 553.2±42.5 µm by Orbscan II corneal topography in POAG, OHT, and control subjects, respectively. There was a significant linear correlation between Orbscan II corneal topography and ultrasonic pachymetry in CCT measurements (r=0.975, p<0.0001. Repeatability of ultrasonic pachymetry for same observer was (ICC value 0.990. Conclusion: There is a significant correlation between Orbscan II corneal topography and ultrasonic pachymetry in CCT measurements. These two methods of measurements should not be substituted for each other, since ultrasonic pachymetry measures CCT greater than Orbscan II corneal topography. Repeatability of ultrasonic pachymetry for same observer is very high. (Turk J Ophthalmol 2014; 44: 263-7

  5. Novel double path shearing interferometer in corneal topography measurements

    Science.gov (United States)

    Licznerski, Tomasz J.; Jaronski, Jaroslaw; Kosz, Dariusz

    2005-09-01

    The paper presents an approach for measurements of corneal topography by use of a patent pending double path shearing interferometer (DPSI). Laser light reflected from the surface of the cornea is divided and directed to the inputs of two interferometers. The interferometers use lateral shearing of wavefronts in two orthogonal directions. A tilt of one of the mirrors in each interferometric setup perpendicularly to the lateral shear introduces parallel carrier frequency fringes at the output of each interferometer. There is orthogonal linear polarization of the laser light used in two DPSI. Two images of fringe patters are recorded by a high resolution digital camera. The obtained fringe patterns are used for phase difference reconstruction. The phase of the wavefront was reconstructed by use of algorithms for a large grid based on discrete integration. The in vivo method can also be used for tear film stability measurement, artificial tears and contact lens tests.

  6. Dual interferometer for dynamic measurement of corneal topography

    Science.gov (United States)

    Micali, Jason D.; Greivenkamp, John E.

    2016-08-01

    The cornea is the anterior most surface of the eye and plays a critical role in vision. A thin fluid layer, the tear film, coats the outer surface of the cornea and serves to protect, nourish, and lubricate the cornea. At the same time, the tear film is responsible for creating a smooth continuous surface, where the majority of refraction takes place in the eye. A significant component of vision quality is determined by the shape of the cornea and stability of the tear film. A dual interferometer system for measuring the dynamic corneal topography is designed, built, verified, and qualified by testing on human subjects. The system consists of two coaligned simultaneous phase-shifting polarization-splitting Twyman-Green interferometers. The primary interferometer measures the surface of the tear film while the secondary interferometer tracks the absolute position of the cornea, which provides enough information to reconstruct the absolute shape of the cornea. The results are high-resolution and high-accuracy surface topography measurements of the in vivo tear film and cornea that are captured at standard camera frame rates.

  7. Measurement of fine dynamic changes of corneal topography by use of interferometry

    Science.gov (United States)

    Kasprzak, Henryk T.; Jaronski, Jaroslaw W.

    2002-06-01

    Paper presents results of in vivo measurements of dynamic variations of the corneal topography by use of the Twyman Green interferometer. Sequence of interferograms were recorded by the CCD camera and stored in the computer memory. Then the fringe tracking method was used separately to each interferogram giving the phase surface of the wave reflected from the cornea in the numerical form. Results from neighboring interferograms were subtracted giving new sequence of changes of the corneal topography within 40 ms. Obtained results show the complex space distribution of the corneal topography variations.

  8. Corneal topography measurement by means of radial shearing interference: Part II - experiment results

    Science.gov (United States)

    Garncarz, Beata E.; Kowalik, Waldemar W.; Kasprzak, Henryk T.

    The method of the measurement of the corneal topography was worked out. This measurement system uses an interferometer based on radial shearing. This paper presents the preliminary results of the experiments. The results are compared with other methods.

  9. Comparison of Central Corneal Thickness Measurements by Ultrasonic Pachymetry and Orbscan II Corneal Topography and Evaluation of Ultrasonic Pachymetry Repeatability

    OpenAIRE

    Semra Tiryaki Demir; Mahmut Odabaşı; Mehmet Ersin Oba; Ayşe Burcu Dirim; Efe Can; Orhan Kara

    2014-01-01

    Objectives: Comparison of central corneal thickness (CCT) measurements by ultrasonic pachymetry and Orbscan II corneal topography and evaluation of ultrasonic pachymetry repeatability for same observer. Materials and Methods: The study included 132, 82, and 80 eyes of 66 patients with primary open-angle glaucoma (POAG), 41 patients with ocular hypertension (OHT), and 40 controls, respectively. All subjects were subjected to routine ophthalmic examination. Orbscan II (Bausch&Lomb) ...

  10. Adaptive preprocessing algorithms of corneal topography in polar coordinate system

    Institute of Scientific and Technical Information of China (English)

    郭雁文

    2014-01-01

    New adaptive preprocessing algorithms based on the polar coordinate system were put forward to get high-precision corneal topography calculation results. Adaptive locating algorithms of concentric circle center were created to accurately capture the circle center of original Placido-based image, expand the image into matrix centered around the circle center, and convert the matrix into the polar coordinate system with the circle center as pole. Adaptive image smoothing treatment was followed and the characteristics of useful circles were extracted via horizontal edge detection, based on useful circles presenting approximate horizontal lines while noise signals presenting vertical lines or different angles. Effective combination of different operators of morphology were designed to remedy data loss caused by noise disturbances, get complete image about circle edge detection to satisfy the requests of precise calculation on follow-up parameters. The experimental data show that the algorithms meet the requirements of practical detection with characteristics of less data loss, higher data accuracy and easier availability.

  11. Time course of the effects of orthokeratology on peripheral refraction and corneal topography.

    Science.gov (United States)

    Kang, Pauline; Swarbrick, Helen

    2013-05-01

    To describe the time course of changes in both peripheral refraction and corneal topography in myopic adults wearing myopic orthokeratology (OK) lenses. Nineteen adult myopes were fitted with OK lenses in both eyes for overnight wear. Central and peripheral refraction and corneal topography were measured along the horizontal meridian at baseline and after 1, 4, 7 and 14 nights of lens wear. At baseline, refraction was myopic at all positions along the horizontal meridian. Two weeks of OK lens wear caused a significant change in refraction where the general trend was a hyperopic shift in spherical equivalent (M) except at 35° in the nasal visual field where there was instead a myopic shift in M. The most significant change in M occurred between baseline and after 1 night of OK lens wear and the effect became less dramatic across subsequent days of OK treatment. Similarly, OK caused significant change in corneal refractive power at all positions along the horizontal corneal chord. There was a reduction in corneal power or flattening of the cornea at all positions except at 2.4 mm and 2.8 mm on the nasal cornea where there was an increase in corneal refractive power or steepening of the cornea. This change was most apparent after 1 night of OK lens wear and, similar to changes in peripheral refraction, changes in corneal refractive power on subsequent days of OK treatment became less marked. Orthokeratology caused significant changes in both peripheral refraction and corneal topography. The greatest change in refraction and corneal refractive power across the horizontal corneal meridian occurred during the first night of OK lens wear. Subsequent changes in both peripheral refraction and corneal topography were less dramatic, in the same manner as reported changes in apical radius and central refraction after OK. This study confirms that with OK treatment, the peripheral retina experiences myopic defocus, which is conjectured to underlie the observed slowing of myopia

  12. OCT corneal topography within ¼ diopter in the presence of saccadic eye movements

    Science.gov (United States)

    Sayegh, Samir I.

    2013-03-01

    Refractive surgeons and cataract surgeons need accurate measurements of corneal curvature/power. Increased expectations of patients, the increasing number of patients having undergone prior surgeries and patients with corneal pathologies dictate the need for reliable curvature measurements to enhance the predictability and the quality of surgical outcomes. Eye movements can negatively influence these measurements. We present a model of eye movements based on peak saccade velocities and formulate criteria for obtaining OCT topography within ¼ of a diopter. Using these criteria we illustrate how next generation MHz systems will allow full corneal OCT topography in both healthy and pathological corneas

  13. Efficacy of axial and tangential corneal topography maps in detecting subclinical keratoconus.

    Science.gov (United States)

    Tummanapalli, Shyam Sunder; Potluri, Haresh; Vaddavalli, Pravin Krishna; Sangwan, Virender S

    2015-10-01

    To investigate and compare the efficacy of axial and tangential corneal topography maps obtained using the Orbscan IIz scanning-slit device to distinguish differences in eyes with subclinical keratoconus from normal eyes. LV Prasad Eye Institute, Hyderabad, India. Retrospective cross-sectional study. Axial and tangential maps of the anterior and posterior corneal surfaces were obtained in eyes of patients with subclinical keratoconus (normal fellow eye of an eye with clinically diagnosed keratoconus). The following measurements were obtained from each map and compared between the 2 groups: location of the corneal apex in millimeters relative to the corneal vertex, dioptric power at the corneal apex and corneal vertex, corneal irregularity indices at 3.0 mm and 5.0 mm, anterior-posterior apex ratio, and inferior-superior dioptric asymmetry value. Maps were obtained in 71 eyes (71 patients) with subclinical keratoconus and 76 normal eyes (76 patients). The tangential posterior apex curvature was significantly steeper than the axial posterior apex curvature in both groups (P keratoconus eyes from normal eyes. The anterior-posterior apex ratio on the tangential map and 5.0 mm irregularity index of the posterior corneal surface were highly sensitive and specific for early detection of subclinical keratoconus. Tangential corneal topography maps should be considered in preoperative subclinical keratoconus screening. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  14. Refractive improvements and safety with topography-guided corneal crosslinking for keratoconus: 1-year results.

    Science.gov (United States)

    Nordström, Maria; Schiller, Maria; Fredriksson, Anneli; Behndig, Anders

    2017-07-01

    To assess the refractive improvements and the corneal endothelial safety of an individualised topography-guided regimen for corneal crosslinking in progressive keratoconus. An open-label prospective randomised clinical trial was performed at the Department of Clinical Sciences, Ophthalmology, Umeå University Hospital, Umeå, Sweden. Thirty-seven patients (50 eyes) with progressive keratoconus planned for corneal crosslinking were included. The patients were randomised to topography-guided crosslinking (photorefractive intrastromal crosslinking (PiXL); n=25) or uniform 9 mm crosslinking (corneal collagen crosslinking (CXL); n=25). Visual acuity, refraction, keratometry (K1, K2 and Kmax) and corneal endothelial morphometry were assessed preoperatively and at 1, 3, 6 and 12 months postoperatively. The PiXL treatment involved an asymmetrical treatment zone centred on the area of maximum corneal steepness with treatment energies ranging from 7.2 to 15.0 J/cm(2); the CXL treatment was a uniform 9 mm 5.4 J/cm(2) pulsed crosslinking. The main outcome measures were changes in refractive errors and corneal endothelial cell density. The spherical refractive errors decreased (pkeratoconus with decreased spherical refractive errors and improved visual acuity, without damage to the corneal endothelium. NCT02514200, Results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  15. Substratum topography modulates corneal fibroblast to myofibroblast transformation.

    Science.gov (United States)

    Myrna, Kathern E; Mendonsa, Rima; Russell, Paul; Pot, Simon A; Liliensiek, Sara J; Jester, James V; Nealey, Paul F; Brown, Donald; Murphy, Christopher J

    2012-02-01

    The transition of corneal fibroblasts to the myofibroblast phenotype is known to be important in wound healing. The purpose of this study was to determine the effect of topographic cues on TGFβ-induced myofibroblast transformation of corneal cells. Rabbit corneal fibroblasts were cultured on nanopatterned surfaces having topographic features of varying sizes. Cells were cultured in media containing TGFβ at concentrations ranging from 0 to 10 ng/mL. RNA and protein were collected from cells cultured on topographically patterned and planar substrates and analyzed for the myofibroblast marker α-smooth muscle actin (αSMA) and Smad7 expression by quantitative real time PCR. Western blot and immunocytochemistry analysis for αSMA were also performed. Cells grown on patterned surfaces demonstrated significantly reduced levels of αSMA (P fibroblast phenotype while pathologic microenvironmental alterations may be permissive for increased myofibroblast differentiation and the development of fibrosis and corneal haze.

  16. Measurement of corneal topography through Hartmann-Shack wave-front sensor

    Science.gov (United States)

    Yang, Jinsheng; Rao, Xuejun; Rao, Changhui

    2008-12-01

    A corneal topography based on Hartmann-Shack Sensor is presented in this paper. In the system, the focus of an objective lens is precisely positioned on cornea's curve center. Wave-front of the reflecting beam can be measured by the Hartmann-Shack sensor which is conjugate to the cornea plane. If the corneal surface is a perfect sphere, wave-front detected by the Hartmann-Shack sensor is a plane. As a result, data measured by Hartmann-Shacks sensor is the deviation between the sphere and the real cornea surface. This paper describes a methodology for designing instrument based on Hartmann-Shack sensor. Then, applying this method, an instrument is developed for accurate measurement of corneal topography. In addition, measuring principle of Hartmann-Shack sensor which determined system parameters is also introduced. Repeatability is demonstrated by a series of data. The instrument was able to accurately measure simulative cornea's reflective aberrations, from which corneal topography and corneal refractive aberrations were derived.

  17. Corneal topography: Image processing and numerical analysis of keratoscopy

    DEFF Research Database (Denmark)

    Andersen, J.; Koch-Jensen, P.; Østerby, Ole

    1993-01-01

    . The average difference between observed and expected values was 0.2% and the average coefficient of variation was 0.1%. The standard deviations on observed ring means decreased inversely with ring number with an average coefficient of variation of 0.2%. Likewise, on a corneal surface SD also decreased...

  18. Corneal topography measurement by means of radial shearing interference: Part I - theoretical consideration

    Science.gov (United States)

    Kowalik, Waldemar W.; Garncarz, Beata E.; Kasprzak, Henryk T.

    The paper presents the principle of radial shearing interference; the build of a simple and stable device for interference measurement; the comparison of this structure with other types of interferometers; presents the results of the examination of corneal topography and discusses the prospects for its future uses.

  19. Customized schematic eye model for refraction correction design based on ocular wavefront and corneal topography measurements

    Science.gov (United States)

    Curatu, Eugene O.; Pettit, George H.; Campin, John A.

    2002-06-01

    The subject of this paper relates to the ocular optical design and vision analysis of refractive correction of the eye. After the purpose statement and the assumption list, the concept of the schematic eye matching a particular (measured) wavefront is introduced. This concept is based on the fact that the ocular wavefront, together with the corneal topography, can be seen as the mathematical global representation of the eye working in monochromatic light and having a foveal vision. The discussed design technique, including an iterative optimization method, could be applied in any ocular correction that utilizes cornea topography and/or ocular wavefront, e.g. contact lens or intra-corneal implant. However, the application this paper refers to is the ocular refractive correction by a procedure using the LADARVISION. It consists of surgical removal and subsequent replacement of a corneal flap on a stromal surface whose shape has been changed by laser ablation of the tissue. Subsequent sections of this paper are dedicated to establishing the limits of possible refractive correction, the influences of the flap and corneal topography into the refractive correction calculation. Finally a realistic evaluation of the results and a list of possible developments of this new optical design method are discussed.

  20. Effect of translation and rotation fitting on analysis of corneal topography.

    Science.gov (United States)

    Deng, Man Li; Li, Lin Na; Huang, Li Fang; Wang, Wenwen; Yu, A Yong; Huang, Jin Hai; Wang, Qin Mei; Bao, Fang Jun; Elsheikh, Ahmed

    2015-01-01

    The purpose was to assess the suitability of quadratic equations for the accurate representation of corneal topography and consider the effect of translation and rotation fitting on the quality of fit and the curvature results. Topography images were recorded for the anterior and posterior surfaces of 490 corneas of 490 myopic patients using Pentacam. Elevation data were fitted to four shape models, three of which considered translational and/or rotational fitting. Differences between the models in the estimates of radii of curvature (R) and asphericity coefficients (Q) and in the quality of fit (as measured by the root mean square (RMS) error and the structural similarity index (SSIM)) were statistically analysed. The general shape model that considered both translational and rotational misalignments provided the best fit for the anterior (RMS = 1.18 ± 0.56 µm, SSIM = 0.99 ± 0.01) and posterior (RMS 3.64 ± 1.23 µm, SSIM = 0.99 ± 0.01) corneal surfaces in all subjects. The quality of fit degraded significantly (with p corneal topography. The effects of misalignments on the estimates of corneal radius and asphericity are statistically significant and may in some cases be clinically significant.

  1. Corneal topography with conical null-screen for non-symmetric aspheric corneas

    Science.gov (United States)

    Armengol-Cruz, Victor de Emanuel; Osorio-Infante, Arturo I.; Campos-García, Manuel; Cossio-Guerrero, Cesar; Díaz-Uribe, José Rufino

    2016-09-01

    In this work, we will present some improvements to the conical null-screen based corneal topographer, for testing aspheric surfaces without rotational symmetry. We present the formulae to design the conical null-screen in such a way that the image on the CCD is a perfect array of spots; departures from this geometry are due to deformation or misalignment of the surface. Additionally, we will explain how to improve the algorithms to find the normals of corneal surface. Finally, we will evaluate the topography of a spherical surface.

  2. Changes in corneal topography and biomechanical properties after collagen cross linking for keratoconus: 1-year results

    Directory of Open Access Journals (Sweden)

    Mohammadreza Sedaghat

    2015-01-01

    Full Text Available Purpose: To evaluate changes in corneal topography and biomechanical properties after collagen cross-linking (CXL for progressive keratoconus. Patients and Methods: Collagen cross-linking was performed on 97 eyes. We assessed uncorrected visual acuity (UCVA and best corrected visual acuity (BCVA. Corneal topography indices were evaluated using placido disc topography, scanning slit anterior topography (Orbscan II, and rotating Scheimpflug topography (Pentacam. Specular microscopy and corneal biomechanics were evaluated. Results: A 1-year-follow-up results revealed that UCVA improved from 0.31 to 0.45 and BCVA changed from 0.78 to 0.84 (P < 0.001. The mean of average keratometry value decreased from 49.62 to 47.95 D (P < 0.001. Astigmatism decreased from 4.84 to 4.24 D (P < 0.001. Apex corneal thickness decreased from 458.11 to 444.46 mm. Corneal volume decreased from 56.66 to 55.97 mm 3 (P < 0.001. Posterior best fit sphere increased from 55.50 to 46.03 mm (P = 0.025. Posterior elevation increased from 99.2 to 112.22 mm (P < 0.001. Average progressive index increased from 2.26 to 2.56 (P < 0.001. A nonsignificant decrease was observed in mean endothelial count from 2996 to 2928 cell/mm 2 (P = 0.190. Endothelial coefficient of variation (CV increased nonsignificantly from 18.26 to 20.29 (P = 0.112. Corneal hysteresis changed from 8.18 to 8.36 (P = 0.552 and corneal resistance factor increased from 6.98 to 7.21(P = 0.202, so these changes were not significant. Conclusion: Visual acuity and K values improved after CXL. In spite of the nonsignificant increase in endothelial cell count and increase in the CV, CLX seems to be a safe treatment for keratoconus. Further studies with larger sample sizes and longer follow-up periods are recommended.

  3. PAR Corneal Topography System (PAR CTS): the clinical application of close-range photogrammetry.

    Science.gov (United States)

    Belin, M W; Cambier, J L; Nabors, J R; Ratliff, C D

    1995-11-01

    The PAR Corneal Topography System (CTS) is a computer-driven corneal imaging system which uses close-range photogrammetry (rasterphotogrammetry) to measure and produce a topographic map of the corneal surface. The PAR CTS makes direct point-by-point measurements of surface elevation using a stereo-triangulation technique. The CTS uses a grid pattern composed of horizontal and vertical lines spaced about 0.2 mm (200 microns) apart. Each grid intersection comprises a surface feature which can be located in multiple images and used to generate an (x,y,z) coordinate. Unlike placido disc-based videokeratoscopes, the PAR CTS requires neither a smooth reflective surface nor precise spatial alignment for accurate imaging. In addition to surface elevation, the PAR CTS computes axial and tangential curvatures and refractive power. Difference maps are available in all curvatures, refractive power, and in absolute elevation.

  4. Sustainability of orthokeratology as demonstrated by corneal topography.

    Science.gov (United States)

    Kang, Sung Yong; Kim, Bong Kyun; Byun, Young Ja

    2007-06-01

    To determine the sustaining effects of orthokeratology. This study enrolled 58 eyes with moderate myopia. LK-DM lenses (Lucid Korea Dream Lens) were fitted daily for at least eight hours on an overnight regimen. The effects of orthokeratology and it's sustainability throughout the day were recorded twice; immediately after removal in the morning and eight hours later. Sustainability was measured by comparing the changes from morning to afternoon for best uncorrected visual acuity, apical corneal power, keratometric values, spherical equivalent and induced astigmatism. UCVA demonstrated improved values at all follow up periods. Fluctuations during the day stabilized after 4 weeks of lens wear. K values averaged a mean of 42.4 mm at baseline, and reduced to 40.9 mm by week 12. Unaided logMAR visual acuity changed from 0.94+/-0.14 at baseline to -0.11+/-0.17 by week 12. The sustainability of orthokeratology, defined as the difference between morning and afternoon values of unaided logMAR visual acuity, increased from -0.82 on day 1 to -0.11 on week 12. UCVA and spherical refractive error did not change to a significant degree after 4 weeks. Although statistically insignificant minute fluctuations during the day were observed up to week 12, these fluctuations decreased to a statistically significant level after week 4.

  5. Forward ray tracing for image projection prediction and surface reconstruction in the evaluation of corneal topography systems

    NARCIS (Netherlands)

    Snellenburg, J.J.; Braaf, B.; Hermans, E.A.; Heijde, van der R.G.L.; Sicam, V.A.

    2010-01-01

    A forward ray tracing (FRT) model is presented to determine the exact image projection in a general corneal topography system. Consequently, the skew ray error in Placido-based topography is demonstrated. A quantitative analysis comparing FRT-based algorithms and Placido-based algorithms in reconstr

  6. Nanoscale topography-induced modulation of fundamental cell behaviors of rabbit corneal keratocytes, fibroblasts, and myofibroblasts.

    Science.gov (United States)

    Pot, Simon A; Liliensiek, Sara J; Myrna, Kathern E; Bentley, Ellison; Jester, James V; Nealey, Paul F; Murphy, Christopher J

    2010-03-01

    Keratocyte-to-myofibroblast differentiation is a key factor in corneal wound healing. The purpose of this study was to determine the influence of environmental nanoscale topography on keratocyte, fibroblast, and myofibroblast cell behavior. Primary rabbit corneal keratocytes, fibroblasts, and myofibroblasts were seeded onto planar polyurethane surfaces with six patterned areas, composed of anisotropically ordered grooves and ridges with a 400-, 800-, 1200-, 1600-, 2000-, and 4000-nm pitch (pitch = groove + ridge width). After 24 hours cells were fixed, stained, imaged, and analyzed for cell shape and orientation. For migration studies, cells on each patterned surface were imaged every 10 minutes for 12 hours, and individual cell trajectories and migration rates were calculated. Keratocytes, fibroblasts, and myofibroblasts aligned and elongated to pitch sizes larger than 1000 nm. A lower limit to the topographic feature sizes that the cells responded to was identified for all three phenotypes, with a transition zone around the 800- to 1200-nm pitch size. Fibroblasts and myofibroblasts migrated parallel to surface ridges larger than 1000 nm but lacked directional guidance on submicron and nanoscale topographic features and on planar surfaces. Keratocytes remained essentially immobile. Corneal stromal cells elongated, aligned, and migrated, differentially guided by substratum topographic features. All cell types failed to respond to topographic features approximating the dimensions of individual stromal fibers. These findings contribute to our understanding of corneal stromal cell biology in health and disease and their interaction with biomaterials and their native extracellular matrix.

  7. Anterior ciliary sclerotomy: effect on corneal topography, globe integrity, and the role of a novel antifibrotic gel

    Science.gov (United States)

    Lamar, Peggy; Fernandez, Viviana; Manns, Fabrice; Dubovy, Sander; Zipper, Stanley; Sandadi, Samith; Nakagawa, Natsushi; Weiser, Marc; Malecaze, Francois; Parel, Jean-Marie A.

    2002-06-01

    To (1) quantify changes in corneal topography induced by radial anterior sclerostomy for restoring accommodation and, (2) assess safety and ant fibrosis activity of cross-linked sodium hyaluronic acid (cSHA) based gels in ACS procedures. Methods (ex-vivo study): 6 fresh human Eye-Bank eyes were used. A 15% Dextran solution was injected in the anterior chamber and the vitreous cavity, the corneal epithelium was removed by scraping, and the whole eye was immersed in 15% Dextran solution until corneal thickness reached a physiological value. The conjunctiva and tenon capsule were removed and the eye was mounted on a custom-made holder. Preoperative corneal topography was measured with a PAR corneal topography system. Five to eight 3mm-long linear equidistant anterior radial incisions starting from the limbus were performed in the sclera at 90% depth with a diamond blade. Postoperative corneal topography was measured. The files providing the pre and postoperative tangential curvature along meridians separated by 5 degrees were exported. The axial curvature along the 0 and 90-degree meridians before and after surgery were compared. Methods (in-vivo study): Of 24 rabbits, 4 were operated following Thornton's (90% depth incision) and 20 following Fukasaku's (100% depth) techniques (total peritomy, four 4mm long radial scleral incisions starting 0.5 mm from the limbus).

  8. Stromal demarcation line induced by corneal cross-linking in eyes with keratoconus and nonkeratoconic asymmetric topography.

    Science.gov (United States)

    Malta, João B N; Renesto, Adimara C; Moscovici, Bernardo K; Soong, H K; Campos, Mauro

    2015-02-01

    To evaluate stromal demarcation lines following corneal cross-linking (CXL) using anterior segment optical coherence tomography in patients with keratoconus and nonkeratoconic asymmetric topography. Fifth-nine eyes of 59 patients were enrolled in a retrospective comparative case series, of which 19 eyes had keratoconus and 40 eyes had asymmetric topography. Eyes with asymmetric topography were treated in preparation for photorefractive keratectomy. One month after CXL, a stromal demarcation line was evaluated at 5 standardized corneal points using anterior segment optical coherence tomography. Mean stromal demarcation line depths were measured at 5 points on the cornea, namely, centrally, 3.0 mm temporally, 1.5 mm temporally, 3.0 mm nasally, and 1.5 mm nasally. For the keratoconus group, the values were 178 ± 47, 123 ± 15, 152 ± 47, 125 ± 23, and 160 ± 43 μm, respectively. For the asymmetric corneal topography group (without keratoconus), they were 305 ± 64, 235 ± 57, 294 ± 50, 214 ± 54, and 285 ± 58 μm, respectively. There was no correlation between central corneal pachymetry and stromal demarcation line depth in all 5 measured corneal points in both groups. CXL treatment profiles are similar in keratoconic and nonkeratoconic eyes with asymmetric topography.

  9. Investigating the Short-term Effect of Eyelid Massage on Corneal Topography.

    Science.gov (United States)

    Riede-Pult, Britta H; Evans, Katharine; Pult, Heiko

    2017-06-01

    The aim of this study was to evaluate the short-term effect of eyelid massage, after the use of warm compresses, on corneal topography. Corneal topography was evaluated on 20 subjects (mean age, 47.0 [SD ±17.3] years) using the Oculus Keratograph (Oculus, Wetzlar, Germany). Corneal eccentricity (Epsilon) was compared between topography measurements before eyelid warming (using warm compresses) (T1), after eyelid warming (T2), directly after eyelid massage (T3), and 30 minutes after eyelid massage (T4). Differences in corneal eccentricity between the enrolment measurement (T1) and consecutive measurements (T1-4) were analyzed. The contralateral eye-treated by warm compresses, but not by eyelid massage-was the control. Visual acuity (decimal), bulbar conjunctival hyperemia, and corneal staining (Cornea and Contact Lens Research Unit grading scale) were evaluated at T1 and T4 to assess clinical safety. No significant differences were found between consecutive eccentricity measurements overall and with the central radii (repeated-measures analysis of variance, P > .238 (massaged eyelid: Epsilon T1: 0.48 [95% confidence interval, ±0.07], T2: 0.49 [±0.05], T3: 0.49 [±0.06], T4: 0.48 [±0.06]; horizontal radii T1: 7.76 [±0.13] mm, T2: 7.74 [±0.13] mm, T3: 7.75 [±0.13] mm, T4: 7.76 [±0.13] mm; vertical radii T1: 7.56 [±0.12] mm, T2: 7.55 [±0.10] mm, T3: 7.54 [±0.10] mm, T4: 7.58 [±0.11] mm). Decimal visual acuity significantly improved at the end of the study (massaged eyelid: T1: 1.1 [±0.1]; T4: 1.3 [±0.1]; P .285). Redness was not significantly different between time points (repeated-measures analysis of variance; P = .187) in the colateral eyes. Hyperemia was significantly reduced in the massaged eyes (T1: 2.0 grade units [±0.3]; T4: 1.9 [±0.3]; P = .021). Eyelid warming followed by eyelid massage appears to be a safe procedure, without any clinically relevant short-term effects on the cornea.

  10. Influence of extracellular matrix proteins and substratum topography on corneal epithelial cell alignment and migration.

    Science.gov (United States)

    Raghunathan, Vijaykrishna; McKee, Clayton; Cheung, Wai; Naik, Rachel; Nealey, Paul F; Russell, Paul; Murphy, Christopher J

    2013-08-01

    The basement membrane (BM) of the corneal epithelium presents biophysical cues in the form of topography and compliance that can impact the phenotype and behaviors of cells and their nuclei through modulation of cytoskeletal dynamics. In addition, it is also well known that the intrinsic biochemical attributes of BMs can modulate cell behaviors. In this study, the influence of the combination of exogenous coating of extracellular matrix proteins (ECM) (fibronectin-collagen [FNC]) with substratum topography was investigated on cytoskeletal architecture as well as alignment and migration of immortalized corneal epithelial cells. In the absence of FNC coating, a significantly greater percentage of cells aligned parallel with the long axis of the underlying anisotropically ordered topographic features; however, their ability to migrate was impaired. Additionally, changes in the surface area, elongation, and orientation of cytoskeletal elements were differentially influenced by the presence or absence of FNC. These results suggest that the effects of topographic cues on cells are modulated by the presence of surface-associated ECM proteins. These findings have relevance to experiments using cell cultureware with biomimetic biophysical attributes as well as the integration of biophysical cues in tissue-engineering strategies and the development of improved prosthetics.

  11. Change in Tear Film Lipid Layer Thickness, Corneal Thickness, Volume and Topography after Superficial Cauterization for Conjunctivochalasis.

    Science.gov (United States)

    Chan, Tommy C Y; Ye, Cong; Ng, Paul K F; Li, Emmy Y M; Yuen, Hunter K L; Jhanji, Vishal

    2015-07-17

    We evaluated the change in tear film lipid layer thickness, corneal thickness, volume and topography after superficial cauterization of symptomatic conjunctivochalasis. Bilateral superficial conjunctival cauterization was performed in 36 eyes of 18 patients with symptomatic conjunctivochalasis. The mean age of patients (12 males, 6 females) was 68.6 ± 10.9 years (range: 44-83 years). Preoperatively, 28 eyes (77.8%) had grade 1 conjunctivochalasis, and 8 eyes (22.2%) had grade 2 conjunctivochalasis. At 1 month postoperatively, the severity of conjunctivochalasis decreased significantly (p corneal thickness, thinnest corneal thickness and corneal volume decreased significantly postoperatively (p corneal thickness and volume were observed after surgical correction of conjunctivochalasis.

  12. Comparison of corneal measurements in keratoconic eyes using rotating Scheimpflug camera and scanning-slit topography

    Institute of Scientific and Technical Information of China (English)

    Mohammad; Naderan; Saeed; Shoar; Morteza; Naderan; Mohammad; Amin; Kamaleddin; Mohammad; Taher; Rajabi

    2015-01-01

    AIM: To compare the anterior segment measurements obtained by rotating Scheimpflug camera(Pentacam) and Scanning-slit topography(Orbscan IIz) in keratoconic eyes.METHODS: A total of 121 patients, 71 males(58.7%)and 50 females(41.3%)(214 eyes) with the diagnosis of keratoconus(KC) were enrolled in this study. Following diagnosis of KC by slit-lamp biomicroscopic examination, central corneal thickness(CCT), thinnest corneal thickness(TCT), anterior chamber depth(ACD),and pupil diameter(PD) were measured by a single examiner using successive instrumentation by Pentacam and Orbscan.RESULTS: There was no significant difference between the two instruments for the measurement of CCT and TCT. In contrast, scanning-slit topography measured ACD(3.46±0.40 mm vs 3.38±0.33 mm, P =0.019) and PD(4.97 ±1.26 mm vs 4.08 ±1.19 mm, P <0.001) significantly larger than rotating Scheimpflug camera.The two devices made similar measurements for CCT(95% CI:-2.94 to5.06, P =0.602). However, the mean difference for TCT was-6.28(95% CI:-10.51 to-2.06, P =0.004) showing a thinner measurement by Orbscan than by Pentacam. In terms of the ACD, the mean difference was 0.08 mm(95%CI: 0.04 to 0.12, P <0.001) with Orbscan giving a slightly larger value than Pentacam. Similarly, Orbscan measurement for PD was longer than Pentacam(95% CI:0.68 to 1.08, P <0.001).CONCLUSION: A good agreement was found between Pentacam and Orbscan concerning CCT measurement while comparing scanning-slit topography and rotatingScheimpflug camera there was an underestimation for TCT and overestimation for ACD and PD.

  13. The influence of surface topography of a porous perfluoropolyether polymer on corneal epithelial tissue growth and adhesion.

    Science.gov (United States)

    Evans, Margaret D M; Chaouk, Hassan; Wilkie, John S; Dalton, Beatrice A; Taylor, Sarah; Xie, Ruo Zhong; Hughes, Timothy C; Johnson, Graham; McFarland, Gail A; Griesser, Hans H; Steele, John G; Meijs, Gordon F; Sweeney, Deborah F; McLean, Keith M

    2011-12-01

    Design principles for corneal implants are challenging and include permeability which inherently involves pore openings on the polymer surface. These topographical cues can be significant to a successful clinical outcome where a stratified epithelium is needed over the device surface, such as with a corneal onlay or corneal repair material. The impact of polymer surface topography on the growth and adhesion of corneal epithelial tissue was assessed using porous perfluoropolyether membranes with a range of surface topography. Surfaces were characterised by AFM and XPS, and the permeability and water content of membranes was measured. Biological testing of membranes involved a 21-day in vitro tissue assay to evaluate migration, stratification and adhesion of corneal epithelium. Similar parameters were monitored in vivo by surgically implanting membranes into feline corneas for up to 5 months. Data showed optimal growth and adhesion of epithelial tissue in vitro when polymer surface features were below a 150 nm RMS value. Normal processes of tissue growth and adhesion were disrupted when RMS values approached 300 nm. Data from the in vivo study confirmed these findings. Together, outcomes demonstrated the importance of surface topography in the design of implantable devices that depend on functional epithelial cover.

  14. Surface Topography and Mechanical Strain Promote Keratocyte Phenotype and Extracellular Matrix Formation in a Biomimetic 3D Corneal Model.

    Science.gov (United States)

    Zhang, Wei; Chen, Jialin; Backman, Ludvig J; Malm, Adam D; Danielson, Patrik

    2017-03-01

    The optimal functionality of the native corneal stroma is mainly dependent on the well-ordered arrangement of extracellular matrix (ECM) and the pressurized structure. In order to develop an in vitro corneal model, it is crucial to mimic the in vivo microenvironment of the cornea. In this study, the influence of surface topography and mechanical strain on keratocyte phenotype and ECM formation within a biomimetic 3D corneal model is studied. By modifying the surface topography of materials, it is found that patterned silk fibroin film with 600 grooves mm(-1) optimally supports cell alignment and ECM arrangement. Furthermore, treatment with 3% dome-shaped mechanical strain, which resembles the shape and mechanics of native cornea, significantly enhances the expression of keratocyte markers as compared to flat-shaped strain. Accordingly, a biomimetic 3D corneal model, in the form of a collagen-modified, silk fibroin-patterned construct subjected to 3% dome-shaped strain, is created. Compared to traditional 2D cultures, it supports a significantly higher expression of keratocyte and ECM markers, and in conclusion better maintains keratocyte phenotype, alignment, and fusiform cell shape. Therefore, the novel biomimetic 3D corneal model developed in this study serves as a useful in vitro 3D culture model to improve current 2D cultures for corneal studies.

  15. Analysis of pupil and corneal wave aberration data supplied by the SN CT 1000 topography system

    Science.gov (United States)

    Comastri, S. A.; Martin, G.; Pfortner, T.

    2006-11-01

    Ocular aberrations depend on pupil size and centring and the retinal image quality under natural conditions differs from that corresponding to laboratory ones. In the present article, pupil and wave aberration data supplied by the Shin Nippon CT 1000 (SN CT 1000) topography system are analysed. Two groups of eyes under natural viewing conditions are considered ((260+/-20) lux at the eye under study). The first group consists of 10 normal eyes (-1.25 to 3 D sphere; 0 to -1.75 D cylinder) of five young subjects (age between 18 and 33 years). For this group, five determinations per eye are performed and the repeatability of results is analysed. Pupil centre is displaced from corneal vertex towards the temporal region, the largest displacement being (0.5+/-0.1) mm. The variation of pupil diameter in each eye is less than 21% while the inter-subject variability is large since diameters are between (3+/-0.3) and (5.3+/-0.6) mm. Aberrations are evaluated for two different pupil sizes, the natural one and a fictitious one of 6 mm. The corneal higher-order root-mean square wavefront error (RMSHO) for a 6 mm pupil centred in the corneal vertex, averaged across all eyes, is (0.37+/-0.06) [mu]m while, considering the natural pupil diameter, the average in each eye is significantly lower, up to eight times smaller. The fourth-order spherical aberration is an important aberration in the considered eyes, its maximum value for a 6 mm pupil being (0.38+/-0.02) [mu]m. The second group consists of 24 eyes of 12 subjects (age between 25 and 68 years) such that four eyes are of normal adults (1.25 to +6 D sphere; 0 to -0.5 D cylinder), eight have astigmatisms (-5.5 to +3.25 D sphere; -1.5 to -4.5 D cylinder), six have post-refractive surgery (+0.5 to +3.5 D sphere; -0.5 to -4 D cylinder) and six have keratoconus (-9.5 to +1 D sphere; -1 to -4.5 D cylinder). For this group only one determination per eye is performed. Pupil centre is displaced from corneal vertex towards the temporal

  16. Effective spherical aberration of the cornea as a quantitative descriptor in corneal topography.

    Science.gov (United States)

    Seiler, T; Reckmann, W; Maloney, R K

    1993-01-01

    Following excimer laser photorefractive keratectomy and other refractive surgical procedures, complaints of halos, glare, and monocular diplopia are common. These procedures increase the asphericity of the cornea, which may cause the optical distortions. We used ray tracing techniques to estimate the longitudinal monochromatic aberration of the cornea from the measured corneal topography (effective spherical aberration) in 15 normal eyes with varying degrees of astigmatism and in ten eyes after photorefractive keratectomy. Best spherical corrected visual acuity in the astigmatic eyes was highly correlated with effective spherical aberration (r = -0.9527, P < .001). In the eyes that had photorefractive keratectomy, the effective spherical aberration was highly correlated with measured glare visual acuity (r = 0.875, P < .002). These results suggest that effective spherical aberration is a valuable topographic measure that provides information about the optical performance of aspheric corneas.

  17. Accuracy of optical biometry combined with Placido disc corneal topography for intraocular lens power calculation

    Science.gov (United States)

    Savini, Giacomo; Hoffer, Kenneth J.; Barboni, Piero; Balducci, Nicole; Schiano-Lomoriello, Domenico; Ducoli, Pietro

    2017-01-01

    Purpose To investigate the accuracy of a new optical biometer for intraocular lens (IOL) power calculation in eyes undergoing cataract surgery. Methods Consecutive eyes of patients undergoing cataract surgery with the same IOL model were enrolled in a prospective cohort study. Axial length (AL) and corneal power were measured with an optical biometer based on optical low-coherence interferometry and Placido-disc corneal topography. IOL power was calculated with the Hoffer Q, Holladay 1 and SRK/T formulas. For each formula the lens constant was optimized in retrospect in order to achieve a mean prediction error (PE) of zero (difference between the predicted and the postoperative refraction). Median absolute error (MedAE) and percentage of eyes with PE ±0.50 D were calculated. Results Seventy-four eyes of 74 cataract patients were enrolled. The MedAE was 0.25 D with all formulas. A PE within ±0.50 D was obtained in 89.04% of cases with the Hoffer Q and SRK/T formulas, and in 87.67% of cases with the Holladay 1 formula. Conclusions The optical biometer investigated in the present study provides accurate measurements for IOL power calculation. PMID:28231267

  18. Validity of autorefractor based screening method for irregular astigmatism compared to the corneal topography- a cross sectional study.

    Science.gov (United States)

    Galindo-Ferreiro, Alicia; De Miguel-Gutierrez, Julita; González-Sagrado, Manuel; Galvez-Ruiz, Alberto; Khandekar, Rajiv; Schellini, Silvana; Galindo-Alonso, Julio

    2017-01-01

    To present a method of screening for irregular astigmatism with an autorefractor and its determinants compared to corneal topography. This cross-sectional validity study was conducted in 2013 at an eye hospital in Spain. A tabletop autorefractor (test 1) was used to measure the refractive status of the anterior surface of the cornea at two corneal meridians of each eye. Then corneal topography (test 2) and Bogan's classification was used to group eyes into those with regular or no astigmatism (GRI) and irregular astigmatism (GRII). Test 1 provided a single absolute value for the greatest cylinder difference (Vr). The receiver operating characteristic (ROC) were plotted for the Vr values measured by test 1 for GRI and GRII eyes. On the basis a Vr value of 1.25 D as cut off, sensitivity, specificity were also calculated. The study sample was comprised of 260 eyes (135 patients). The prevalence of irregular astigmatism was 42% [95% confidence interval (CI): 36, 48]. Based on test 2, there were 151 eyes in GRI and 109 eyes in GRII. The median Vr was 0.75 D (25% quartile, 0.5 D) for GRI and 1.75 D (25% quartile, 1.25 D) for GRII. The area under curve was 0.171 for GRI and 0.83 for GRII. The sensitivity of test I was 78.1% and the specificity was 76.1%. A conventional autorefractor can be effective as a first level screening method to detect irregular corneal astigmatism in places where corneal topography facilities are not available.

  19. High-resolution corneal topography and tomography of fish eye using wide-field white light interference microscopy

    Science.gov (United States)

    Srivastava, Vishal; Nandy, Sreyankar; Singh Mehta, Dalip

    2013-04-01

    Topography and tomography of fish cornea is reconstructed using high resolution white light interference microscopy. White light interferograms at different depths were recorded by moving the object axially. For each depth position, five phase shifted interferograms were recorded and analyzed. From the reconstructed phase maps, the corneal topography and hence the refractive index was determined and from amplitude images the cross-sectional image of fish cornea was reconstructed. In the present method, we utilize a nearly common-path interference microscope and wide field illumination and hence do not require any mechanical B-scan. Therefore, the phase stability of the recorded data is improved.

  20. 远视与角膜地形图%Corneal topography and hyperopia

    Institute of Scientific and Technical Information of China (English)

    Masoud Reza Manaviat; Mohammad Reza Besharati; Maryam Kheirandish; Maryam Dehyadegari

    2009-01-01

    目的:运用Orbscan II测量远视者角膜地形图.方法:回顾性,观察性,连续性临床病例研究,进行LASIK术前评估的远视患者共295眼.回顾分析患者的年龄、性别以及Orbscan II所得角膜地形图.屈光度及以下参数由Orbscan II系统所得:角膜厚度、角膜直径、瞳孔直径和前房深度.结果:总的平均角膜厚度为546.3±35.5μm,17~29岁年龄组547.3±38.4μm,30~44岁年龄组553.4±38.3μm,45岁以上年龄组546.2±29.3μm.女性平均角膜厚度为551.5±35.9μm,男性为542.6±34.7μm.总的平均前房深度为2.57±0.40mm,17~29岁年龄组2.82±0.39mm,30~44岁年龄组 2.49±0.39mm,45岁以上年龄组2.37±0.40mm.女性平均前房深度2.53±0.40mm,男性为2.60±0.40mm.角膜厚度与角膜曲率之间存在显著负相关关系 (P=0.005,r=0.16),与瞳孔直径存在相关关系(P=0.013, r=0.144).屈光不正严重度与前房深度负相关,与角膜曲率负相关(P=0.061, r=0.108).结论:本研究提供并分析了远视患者的Orbscan II测量数据,远视患者的平均角膜厚度为546.3±35.5μm,平均前房深度为2.57±0.40mm.%AIM: To evaluate Orbscan II corneal topography in hyperopic cases.METHODS: A retrospective, observational, consecutive, clinical case series in two hundred and ninety five eyes of hyperopic patients who undergo a LASIK evaluation. The information that was reviewed included age and sex of the patients and the Orbscan II corneal topographic maps. Refractive powers and the following test indices produced by Orbscan II were analyzed: keratometry, corneal diameter, pupil diameter and anterior chamber depth. RESULTS: The total mean corneal thickness was 546.3±35.5μm.It was found ; 547.3±38.4μm in 17-29 years old, 553.4±38.3μm in 30-44 years old and 546.2±29.3μm in older than 45 years old .The mean corneal thickness was found 551.5±35.9μm in female, and 542.6±34.7μm in male. The total mean depth of anterior chamber was 2.57±0.40mm and in 17-29 years

  1. Biomimetic stochastic topography and electric fields synergistically enhance directional migration of corneal epithelial cells in a MMP-3-dependent manner.

    Science.gov (United States)

    Gao, Jing; Raghunathan, Vijay Krishna; Reid, Brian; Wei, Dongguang; Diaz, Rodney C; Russell, Paul; Murphy, Christopher J; Zhao, Min

    2015-01-01

    Directed migration of corneal epithelial cells (CECs) is critical for maintenance of corneal homeostasis as well as wound healing. Soluble cytoactive factors and the intrinsic chemical attributes of the underlying extracellular matrix (ECM) participate in stimulating and directing migration. The central importance of the intrinsic biophysical attributes of the microenvironment of the cell in modulating an array of fundamental epithelial behaviors including migration has been widely documented. Among the best measures of these attributes are the intrinsic topography and stiffness of the ECM and electric fields (EFs). How cells integrate these multiple simultaneous inputs is not well understood. Here, we present a method that combines the use of (i) topographically patterned substrates (mean pore diameter 800nm) possessing features that approximate those found in the native corneal basement membrane; and (ii) EFs (0-150mVmm(-1)) mimicking those at corneal epithelial wounds that the cells experience in vivo. We found that topographic cues and EFs synergistically regulated directional migration of human CECs and that this was associated with upregulation of matrix metalloproteinase-3 (MMP3). MMP3 expression and activity were significantly elevated with 150mVmm(-1) applied-EF while MMP2/9 remained unaltered. MMP3 expression was elevated in cells cultured on patterned surfaces against planar surfaces. The highest single-cell migration rate was observed with 150mVmm(-1) applied EF on patterned and planar surfaces. When cultured as a confluent sheet, EFs induced collective cell migration on stochastically patterned surfaces compared with dissociated single-cell migration on planar surfaces. These results suggest significant interaction of biophysical cues in regulating cell behaviors and will help define design parameters for corneal prosthetics and help to better understand corneal wound healing.

  2. [Pre- and postoperative corneal topography after combined single suture and running suture in ECCE. An analysis using the video keratoscope].

    Science.gov (United States)

    Schickel, B; Holschbach, A; Strobel, J

    1993-12-01

    In a prospective study with 45 patients undergoing extracapsular cataract extraction (ECCE) with implantation of posterior chamber lens, curvature measurements of the cornea by means of computerized videokeratoscope were taken postoperatively. Analysis of the corneal shape on color-coded topographic maps of astigmatism showed an hourglass-shaped formation in all patients with a main axis in the sense of general astigmatism. Within a 3-mm zone (optical zone) the steepest meridian in all eyes was 96.1 +/- 13.3 degrees with an astigmatism of +4.4 +/- 2.1 D (1st postoperative day). Postoperatively we found that 35.6% of the patients examined had irregular astigmatism that could not be corroborated by the readings from the Javal ophthalmometer. An irregular astigmatism, corneal topographic analysis reveals regions peripheral to the center with a peak corneal refractive power of +43.8 +/- 1.4 D. In contrast to the conventional methods (for example, Javal ophthalmometer, autokeratometer), computerized videokeratoscope analysis provides additional and useful information on the corneal topography after intraocular operations.

  3. Synchronous phase-demodulation of concentric-rings Placido mires in corneal topography and wavefront aberrometry (theoretical considerations)

    CERN Document Server

    Servin, Manuel

    2012-01-01

    This paper presents a digital interferometric method to demodulate Placido fringe patterns. This method uses a computer-stored conic-wavefront as reference carrier. Even though, Placido mires are widely used in corneal topographers. This is not however a paper on corneal topography and/or its clinical use. This paper focuses on the theoretical aspects to phase-demodulate Placido mires using synchronous interferometric techniques. Placido patterns may also be applied to test optical wavefronts using a Placido-Hartmann opaque plate with periodic annular apertures. This test is sensitive to the radial slope of the measuring wavefront. Another wavefront testing approach may use a Placido-Hartmann-Shack screen with a periodic array of toroidal lenslets. This periodic screen is sensitive to the wavefront's radial-slope at the focal plane of the lenslets. In brief, digital interferometric methods are herein applied for the first time to demodulate conic-carrier Placido images. Finally it should be mentioned that thi...

  4. Optical coherence tomography-based topography determination of corneal grafts in eye bank cultivation

    Science.gov (United States)

    Damian, Angela; Seitz, Berthold; Langenbucher, Achim; Eppig, Timo

    2017-01-01

    Vision loss due to corneal injuries or diseases can be treated by transplantation of human corneal grafts (keratoplasty). However, quality assurance in retrieving and cultivating the tissue transplants is confined to visual and microbiological testing. To identify previous refractive surgery or morphological alterations, an automatic, noncontact, sterile screening procedure is required. Twenty-three corneal grafts have been measured in organ culture with a clinical spectral-domain optical coherence tomographer. Employing a biconic surface fit with 10 degrees of freedom, the radii of curvature and conic constants could be estimated for the anterior and posterior corneal surfaces. Thereupon, central corneal thickness, refractive values, and astigmatism have been calculated. Clinical investigations are required to elaborate specific donor-host matching in the future.

  5. The effect of environmental factors on the response of human corneal epithelial cells to nanoscale substrate topography.

    Science.gov (United States)

    Teixeira, Ana I; McKie, George A; Foley, John D; Bertics, Paul J; Nealey, Paul F; Murphy, Christopher J

    2006-07-01

    We have previously shown that human corneal epithelial cells sense and react to nanoscale substrate topographic stimuli [Teixeira AI, Abrams GA, Bertics PJ, Murphy CJ, Nealey PF. Epithelial contact guidance on well-defined micro- and nanostructured substrates. J Cell Sci 2003;116(10):1881-92; Karuri NW, Liliensiek S, Teixeira AI, Abrams G, Campbell S, Nealey PF, et al. Biological length scale topography enhances cell-substratum adhesion of human corneal epithelial cells. J Cell Sci 2004;117(15):3153-64]. Here we demonstrate that cellular responses to nanoscale substrate topographies are modulated by the context in which these stimuli are presented to cells. In Epilife medium, cells aligned preferentially in the direction perpendicular to nanoscale grooves and ridges. This is in contrast to a previous study where cells cultured in DMEM/F12 medium aligned in the direction parallel to nanoscale topographic features [Teixeira AI, Abrams GA, Bertics PJ, Murphy CJ, Nealey PF. Epithelial contact guidance on well-defined micro- and nanostructured substrates. J Cell Sci 2003;116(10):1881-92]. Additionally, cell alignment in Epilife medium was dependent on pattern pitch. Cells switched from perpendicular to parallel alignment when the pitch was increased from 400 to 4,000 nm. There was a transition region (between 800 and 1,600 nm pitch) where both parallel and perpendicular alignments were favored compared to all other cellular orientations. Cells formed focal adhesions parallel to the substrate topographies in this transition region. On the nano- and microscale patterns, 400 and 4,000 nm pitch, focal adhesions were almost exclusively oriented obliquely to the topographic patterns.

  6. A New Clinical Instrument for The Early Detection of Cataract Using Dynamic Light Scattering and Corneal Topography

    Science.gov (United States)

    Ansari, Rafat R.; Datiles, Manuel B., III; King, James F.

    2000-01-01

    A growing cataract can be detected at the molecular level using the technique of dynamic light scattering (DLS). However, the success of this method in clinical use depends upon the precise control of the scattering volume inside a patient's eye and especially during patient's repeat visits. This is important because the scattering volume (cross-over region between the scattered fight and incident light) inside the eye in a high-quality DLS set-up is very small (few microns in dimension). This precise control holds the key for success in the longitudinal studies of cataract and during anti-cataract drug screening. We have circumvented these problems by fabricating a new DLS fiber optic probe with a working distance of 40 mm and by mounting it inside a cone of a corneal analyzer. This analyzer is frequently used in mapping the corneal topography during PRK (photorefractive keratectomy) and LASIK (laser in situ keratomileusis) procedures in shaping of the cornea to correct myopia. This new instrument and some preliminary clinical tests on one of us (RRA) showing the data reproducibility are described.

  7. 闭眼和睡眠对人角膜地形和散光的影响研究%lmpact study of closing eyes and sleep on corneal topography and corneal astigmatism

    Institute of Scientific and Technical Information of China (English)

    袁韬; 陆静

    2015-01-01

    目的:观察不同时间长度闭眼和睡眠后角膜地形图、角膜散光等的变化,研究闭眼以及睡眠造成的生理性缺氧对人眼角膜形态的影响。  方法:选取年龄22~33(26.19±3.95)岁的自愿者,排除屈光介质疾病及眼部其他疾病、无角膜接触镜配戴史等,共16例32眼,其中男10眼,女22眼。主要参数采用了Zeiss角膜地形图仪获取角膜模拟K值、角膜散光值、角膜表面不规则指数( CIM )和形状因子( SF ),测量时间点分别为:日间闭眼前、闭眼后10,20,30,60,120 min;夜间临睡前、超过6h 的睡眠结束后,开眼立即检测、开眼后10,20,60,120 min。  结果:闭眼过程中,人角膜地形图、角膜散光、CIM、SF等的变化差异无统计学意义。在超过6h的睡眠结束,开眼后过程中,人角膜地形图、角膜散光、CIM、SF等的变化差异无统计学意义。  结论:闭眼和睡眠没有构成对角膜实质性损伤,所以角膜地形和散光基本不变。%•AlM: To observe the changes of corneal topography and astigmatism et al with various duration of closing eyes and sleep;and study the impact of closing eye and sleep causing physiological hypoxia on corneal topography. • METHODS: Sixteen volunteers were selected ( 32 eyes), 22-33 (26. 19 ± 3. 95) years old, without refractive errors and other eye diseases, as well as never wearing corneal contact lens, including 10 male eyes and 22 female eyes. The main parameters received corneal simulation K value, corneal astigmatism, corneal irregular measure ( ClM ) and the shape factor ( SF ) by Zeiss corneal topographer. They were measured before and after closed eyes 10, 20, 30, 60, 120min; before sleep and after over 6h sleep, they were detected immediately as soon as they opened eyes after 10, 20, 60, 120min. • RESULTS: During closing eyes, there were no statistical significance on the changes of corneal topography, corneal astigmatism, and SF. After opening

  8. Revisiting corneal topography for the diagnosis of keratoconus: use of Rabinowitz's KISA% index

    Directory of Open Access Journals (Sweden)

    Sedghipour MR

    2012-01-01

    Full Text Available Mohammad Reza Sedghipour, Afshin Lotfi Sadigh, Behzad Fallahi MotlaghDepartment of Ophthalmology, Tabriz University of Medical Sciences, Tabriz, IranBackground: Numerous videokeratographic methods are used in the diagnosis of keratoconus.The purpose of this study was to compare the sensitivity and specificity of the KISA% index with the keratometry (K value, inferior-superior (I-S value, relative skewing of the steepest radial axes (SRAX, and keratometric astigmatism (AST indices in 25 patients presenting with bilateral keratoconus.Methods: Twenty-five patients presenting with bilateral keratoconus were enrolled. Fifty eyes from 25 healthy individuals without corneal abnormalities were used as controls. The clinical diagnosis of keratoconus was made by observation of scissors reflex at retinoscopy and characteristic slit lamp findings. Corneal topographic analysis was performed in each eye to calculate the K value, I-S value, AST, and SRAX indices.Results: The keratoconus percentage index (KISA% was significantly more sensitive and specific than the other indices examined. Furthermore, it was significantly better at predicting positive and negative results than the other indices included in the study.Conclusion: The current research suggests that KISA% could be used to detect/diagnose keratoconus but further studies are required to confirm the specificity and sensitivity of KISA% for the detection of early-stage disease and keratoconus suspects.Keywords: cornea, keratoconus, KISA% index

  9. 角膜地形图在准分子激光角膜屈光手术中的应用及研究进展%Application and research progress of corneal topography in excimer laser corneal refractive operation

    Institute of Scientific and Technical Information of China (English)

    邓晶; 孟欢; 李英俊; 金龙山

    2014-01-01

    In recent years,corneal topography has been widely applied in excimer laser surgery and it equipment update, especially the application of individual excimer laser corneal refractive operation guided by corneal topography,not only reduces postoperative low order aberrations,but also make up the problems such as correct postoperative glare and halo,night declining eyesight which were cannot fixed by the traditional operation,and it greatly improved the safety and stability,validity,and predictive of corneal refractive surgery.In this paper,we reviewed the current development of corneal topography and its application progressin excimer laser surgery.%近年来,角膜地形图在准分子激光手术及设备的更新中得到了广泛应用,尤其是角膜地形图引导的个体化准分子激光角膜屈光手术的开展,不但降低了术后低阶像差,而且弥补了传统术式无法矫正的术后光晕、眩光及夜间视力下降等问题,极大提高了角膜屈光手术的安全性、有效性、预测性和稳定性。本文就角膜地形图的发展现状及其在准分子激光手术中的应用进展等方面作一综述。

  10. The Analysis on Corneal Topography of Trabeculectomy%小梁切除术后角膜地形图分析

    Institute of Scientific and Technical Information of China (English)

    施小茹; 韩丽娜; 于洪泉; 徐杰; 夏静

    2001-01-01

    ObjectiveTo investigate the changes of corneal topography before and after trabeculectomy and analyze the cause of astigmatism after trabeculectomy.MethodsA standard trabeculectomy procedure(4mm×5mm scleral trap door)was performed at the 90 degree meridian in 30 eyes of 30 patients and followed up for 3 months.Computer assisted topographic analysis was performed preoperatively and on 3 months postoperatively.Additional data included axial length,intraocular pressure and visual acuity.ResultVariation of corneal topography indicated three types of astigmatic findings:a relative superior corneal steepening,perior flattening and complex regional changes.In the superior steepening and superior flattening groups there was the astigmatism with the rule.There was no correlation between the change of corneal topography and intraocular pressure.ConclusionChanges in corneal curvature are induced by filtering surgery,not by changing of intraocular pressure.Computer-assisted corneal topography is the best way to analyse the complex changes in corneal curvature.%目的 应用角膜地形图仪分析小梁切除术前术后角膜地形图改变,探讨术后引起散光的原因。方法 随机选择30例(30只眼)急性闭角型青光眼患者,作常规小梁切除术,分别于术前1天,术后3个月作角膜地形图,同时作视力眼轴及眼压测定。结果 角膜地形图改变分3种情况:16只眼角膜变陡峭5只眼角膜变平坦9只眼角膜地形图改变不规则,无论是角膜变陡峭还是变平坦均产生循规性散光。结论  滤过性手术可产生角膜曲率的改变

  11. Method and apparatus for white-light dispersed-fringe interferometric measurement of corneal topography

    Science.gov (United States)

    Hochberg, Eric B. (Inventor); Baroth, Edmund C. (Inventor)

    1994-01-01

    An novel interferometric apparatus and method for measuring the topography of aspheric surfaces, without requiring any form of scanning or phase shifting. The apparatus and method of the present invention utilize a white-light interferometer, such as a white-light Twyman-Green interferometer, combined with a means for dispersing a polychromatic interference pattern, using a fiber-optic bundle and a disperser such as a prism for determining the monochromatic spectral intensities of the polychromatic interference pattern which intensities uniquely define the optical path differences or OPD between the surface under test and a reference surface such as a reference sphere. Consequently, the present invention comprises a snapshot approach to measuring aspheric surface topographies such as the human cornea, thereby obviating vibration sensitive scanning which would otherwise reduce the accuracy of the measurement. The invention utilizes a polychromatic interference pattern in the pupil image plane, which is dispersed on a point-wise basis, by using a special area-to-line fiber-optic manifold, onto a CCD or other type detector comprising a plurality of columns of pixels. Each such column is dedicated to a single point of the fringe pattern for enabling determination of the spectral content of the pattern. The auto-correlation of the dispersed spectrum of the fringe pattern is uniquely characteristic of a particular optical path difference between the surface under test and a reference surface.

  12. 应用Pentacam与角膜地形图仪测量角膜曲率的比较%Differences of corneal curvature measured by Pentacam and corneal topography.

    Institute of Scientific and Technical Information of China (English)

    王红霞; 周奇志; 张鸣

    2012-01-01

    Objective To compare the differences of keratometry determined by Pentacam and corneal topography.Methods Preoperative measurement of corneal cuvature was prospectively obtained in 200eyes of 100 patients with ametropia by Pentacam and corneal topography.The ages of the patients were between 17 and 42 years old(average age:22.6 years old).The maximum,minimum and mean values of corneal curvature were recorded.Paired t test was used to analyze the difference of them.Results The maximum values of corneal curvature was(44.18 ± 1.49)D for Pentacam and(44.06 ± 1.35)D for corneal topography(P < 0.01),and the minimum values of corneal curvature was(43.01 ± 1.33)D for Pentacam and(43.17 ± 1.28)D for corneaI topograpby,(P <0.01),but the mean values of corneal curvature was (43.58 ± 1.38)D for Pentacam and(43.62 ± 1.30)D for cormeal topography(p > 0.05).Conclusion Both of Pentacam and corneal topography can be used for measuring keratometry,but Pentacam is more accurater.%目的 探讨Pentacam眼前段全景仪和角膜地形图仪测量角膜曲率结果的差异.方法 随机抽取准分子激光屈光性角膜手术前的近视100例(200眼),年龄17~42岁,平均(22.6±1.2)岁,分别应用Pentacam和角膜地形图仪对角膜曲率进行测量,记录角膜曲率的最大值(K1)、最小值(K2),平均角膜曲率(Km),并应用配对t检验对两种方法的K1、K2、Km分别进行统计学分析.结果 Pentacam测量的K1为(44.18±1.49)D、K2为(43.01±1.33)D、Km为(43.58±1.38)D;角膜地形图仪测量的K1为(44.06±1.35)D、K2为(43.17±1.28)D、Km为(43.62±1.30)D;经统计学分析,这两种方法的K1及K2差异具有统计学意义(P<0.01),Km差异无统计学意义(P>0.05).结论 Pentacam与角膜地形图仪均可用于测量角膜曲率,但Pentacam更精确、更全面.

  13. Corneal changes following collagen cross linking and simultaneous topography guided photoablation with collagen cross linking for keratoconus

    Directory of Open Access Journals (Sweden)

    Prema Padmanabhan

    2014-01-01

    Full Text Available Purpose: To compare the outcome of Collagen cross-linking (CXL with that following topography-guided customized ablation treatment (T-CAT with simultaneous CXL in eyes with progressive keratoconus. Materials and Methods: This was a prospective, non-randomized single centre study of 66 eyes with progressive keratoconus. Of these, 40 eyes underwent CXL and 26 eyes underwent T-CAT + CXL. The refractive, topographic, tomographic and aberrometric changes measured at baseline, 1, 3 and 6 months post-operatively were compared between both groups. Results: After a mean follow-up of 7.7 ± 1.3 months, the mean retinoscopic cylinder decreased by 1.02 ± 3.16 D in the CXL group ( P = 0.1 and 2.87 ± 3.22 D in the T-CAT + CXL group ( P = 0.04. The Best corrected visual acuity increased by 2 lines or more in 10% of eyes in the CXL group and in 23.3% of eyes in the T-CAT + CXL group. The mean steepest-K reduced by 0.40 ± 3.71 D ( P = 0.77 in the CXL group and by 2.91 ± 2.01D ( P = 0.03 in the T-CAT + CXL group. The sag factor and surface asymmetry index showed no significant change in the CXL group but reduced by 3.59 ± 5.94 D ( P = 0.01 and 0.72 ± 1.18 ( P = 0.02 respectively in the T-CAT + CXL group. There was a significant increase in the highest posterior corneal elevation in both groups (9.57 ± 14.93 μ in the CXL group and 7.85 ± 9.25 μ in the T-CAT + CXL group, P ≤ 0.001 for both. There was significantly greater reduction of mean coma ( P < 0.001 and mean higher-order aberrations ( P = 0.01 following T-CAT + CXL compared to CXL. Conclusions: CAT + CXL is an effective approach to confer biomechanical stability and to improve the corneal contour in eyes with keratoconus and results in better refractive, topographic and aberrometric outcomes than CXL alone.

  14. 圆锥角膜早期的角膜地形图改变%Corneal topography of early keratoconus

    Institute of Scientific and Technical Information of China (English)

    瞿小妹; 李梅

    2001-01-01

    目的 揭示早期圆锥角膜角膜地形图的特征,为早期诊断此病提供参考。方法 收集了本院门诊拟诊为早期圆锥角膜的患者27例52眼。所有患者均行TMS-1角膜地形图测定。结果 80.77%眼角膜最高屈光度部位在正下方或颞下方,最高屈光度在45D以上,散光在2D以上,所有眼平均最高屈光度在47.56D±5.80D,平均散光5.47D±3.80D;角膜非对称性指数(SAI)及角膜规则性指数(SRI)值大于0.5者分别为94%、98%,SAI值平均为2.6±1.9,SRI值平均为1.67±0.94。结论 早期圆锥角膜的测定须兼顾上述综合参数,SAI及SRI值的变化更敏感。%Objective To identify the significant findings of cornealtopography for early keratoconus.Methods Fifty-two eyes of 27 patients in whom the diagnosis of keratoconus were suspected and no slit-lamp evidence of the condition was enrolled. All eyes were evaluated by corneal topography analysis system.Results The highest corneal power of 80.76% eyes was over 45D, while the astigmatism was over 2D; The values of SAI and SRI were over 0.5 on 94% eyes and 98% eyes respectively.Conclusion The values of SAI and SRI were more sensitive to detecting the early keratoconus.

  15. Analysis of corneal thickness in myopia using the Orbscan corneal topography system%Orbscan测量近视眼角膜厚度

    Institute of Scientific and Technical Information of China (English)

    倪海龙; 王勤美; 许琛琛; 余野; 瞿佳

    2001-01-01

    目的:评价裂隙扫描角膜地形图/角膜测厚系统(Orbscan corneal topography system)在分析近视眼角膜厚度分布特征中的应用价值. 方法:应用Orbscan(Orbtek,Salt Lake City,UT,USA)测量206人404只近视眼角膜厚度;用超声测厚仪测定其中128人256只高度近视眼角膜中央厚度,对两种测量方法进行比较分析. 结果:高度近视眼与中低度近视眼在角膜中央区和距角膜中心3mm处上方、颞上、颞侧、颞下、下方、鼻下、鼻侧和鼻上等9个直径2mm区域的角膜厚度平均值,差异无统计学意义(P>0.05).两组角膜中央厚度最薄,分别为(554.4±35.3)μm与(555.1±33.8)μm;鼻上方角膜厚度最厚,分别为(661.3±39.2)μm与(661.4±36.1)μm.Orbscan系统测厚声速系数值设置为0.96,其与超声测厚法所得测量值之间,差异无统计学意义(P>0.05).结论:Orbscan能方便、准确、有效地测量近视眼全角膜厚度,当声速系数值为0.96,其与超声测厚仪所得的测量值之间具有相当高的一致性.

  16. 角膜地形图引导下白内障超乳手术对角膜散光的影响%Impact on corneal astigmatism during phacoemulsification guided by corneal Topography

    Institute of Scientific and Technical Information of China (English)

    陈艳; 张暹梅

    2009-01-01

    目的 观察角膜地形图引导白内障超声乳化术对角膜散光状态的影响.方法 对采用白内障超乳手术治疗的72例白内障患者进行观察,随机分为两组,34例角膜切口选择在角膜地形图垂直高曲率经线上,38例角膜切口选择在常规角膜12点左右方向,应用角膜地形图对手术前后角膜散光状态进行比较.结果根据角膜地形图曲率信息做角膜切口组散光度由术前的(1.11±0.36)D降低为术后3月的(0.96±0.32)D,常规12点左右方向角膜切口组散光度由术前的(1.08±0.54)D改变为术后3月的(1.36±0.43)D.根据角膜地形图曲率信息做角膜切口组术后1d和3月视力>0.5者27只眼(78.6%)和30只眼(87.4%),要多于常规12点左右方向角膜切口组27只眼(72.5%)和31只眼(80.4%).结论 根据角膜地形图的曲率信息在手术切口的方位和角度进行选择,可以减轻术后角膜的散光状态,对视力的恢复有益.%Objective To study the impact on corneal astigmatism during phacoemulsification guided by corneal topography.Methods The cohort consisted of 72 patients treated by phacoemulsification and intraocular lens implantation.All patients were divided into two groups randomly.Of 34 eyes were made corneal incision on the steepest meridian,while 38 eyes chose the line on the superior position.Corneal topography was used to compare the corneal astigmatism before and after operation.Results The group which made incision using curvature message in corneal topography had an astigmatism change from(1.11±0.36)D before operation to(0.96±0.32)D after operation.And in this group the vision of 27 eyes were above 0.5(78.6%)first day after operation and 30(87.4%)eyes 3 months after operation.The group which made incision on the superior position had an astigmatism change from(1.08±0.54)D before operation to(1.36±0.43)D after operation.In this group the vision of 27 eyes were above 0.5(72.5%)first day after operation and 31 eyes(80

  17. Micro- and nano-topography to enhance proliferation and sustain functional markers of donor-derived primary human corneal endothelial cells.

    Science.gov (United States)

    Muhammad, Rizwan; Peh, Gary S L; Adnan, Khadijah; Law, Jaslyn B K; Mehta, Jodhbir S; Yim, Evelyn K F

    2015-06-01

    One of the most common indications for corneal transplantation is corneal endothelium dysfunction, which can lead to corneal blindness. Due to a worldwide donor cornea shortage, alternative treatments are needed, but the development of new treatment strategies relies on the successful in vitro culture of primary human corneal endothelial cells (HCECs) because transformed cell lines and animal-derived corneal endothelial cells are not desirable for therapeutic applications. Primary HCECs are non-proliferative in vivo and challenging to expand in vitro while maintaining their characteristic cell morphology and critical markers. Biochemical cues such as growth factors and small molecules have been investigated to enhance the expansion of HCECs with a limited increase in proliferation. In this study, patterned tissue culture polystyrene (TCPS) was shown to significantly enhance the expansion of HCECs. The proliferation of HCECs increased up to 2.9-fold, and the expression amount and localization of cell-cell tight junction protein Zona Occludens-1 (ZO-1) was significantly enhanced when grown on 1 μm TCPS pillars. 250 nm pillars induced an optimal hexagonal morphology of HCEC cells. Furthermore, we demonstrated that the topographical effect on tight-junction expression and cell morphology could be maintained throughout each passage, and was effectively 'remembered' by the cells. Higher amount of tight-junction protein expression was maintained at cell junctions when topographic cues were removed in the successive seeding. This topographic memory suggested topography-exposed/induced cells would maintain the enhanced functional markers, which would be useful in cell-therapy based approaches to enable the in situ endothelial cell monolayer formation upon delivery. The development of patterned TCPS culture platforms could significantly benefit those researching human corneal endothelial cell cultivation for cell therapy, and tissue engineering applications.

  18. The study on the posterior corneal surface topography after LASIK%LASIK后角膜后表面形态的研究

    Institute of Scientific and Technical Information of China (English)

    许琛琛; 王勤美; 余野

    2001-01-01

    Objective:To investigate the changes in the posterior corneal surface topography after LASIK and the factors that influence the results.Methods:This study comprised 41 eyes of middle and high myopia(2 patients) that had undergone LASIK. Diopter and radius of curvature of posterior corneal surface were measured by Orbscan before operation, and at 3rd day, 3rd month post-operatiion. Eyes were divided into two groups(3mm area and 5mm area) according to the optical diameter of cornea.Results:Significant difference in posterior corneal surface topography existed between pre-operation and post-operation(P<0.05) in corneal center and peripheral(P<0.05). There is significant difference in 3 months and 3 days post operation in 3mm area(P<0.05). The change in radius of curvature of posterior corneal surface was correlated with corneal thickness after LASIK(r=-0.6,P<0.05), but irrelevant to IOP. The change of posterior corneal surface topography was more significant in the corneal thickness less than 350μm(P<0.01).Conclusion:LASIK can decrease the radius of curvature of the posterior corneal surface. The corneal thickness after LASIK is a major contributing factor.%目的:研究激光角膜原位磨镶术(LASIK)前后,角膜后表面屈光度及曲率半径的改变以及影响因素。 方法:随机选择停戴隐形眼镜一月以上的中高度近视41眼进行LASIK治疗,依角膜光学区直径的不同,分3mm区及5mm区两组,应用Orbscan分别观察分析其术前及术后3天、3月角膜后表面屈光度和曲率半径。 结果:各组术前与术后各期相比,角膜后表面屈光度和曲率半径的改变均有显著性意义(P<0.05),角膜中央变化较周边明显(P<0.05),角膜3mm区术后3月与3天相比差异有显著性意义(P<0.05),角膜后表面曲率半径的改变与患眼正常眼压无关,与术后角膜厚度存在统计学相关性(r=-0.6,P<0.05),厚度小于350μm时角膜后表

  19. Comparison of automatic keratometry and corneal topography on children' corneal power%自动角膜曲率计与角膜地形图仪测量儿童角膜屈光力的比较研究

    Institute of Scientific and Technical Information of China (English)

    王延飒; 王利华; 马鲁新

    2008-01-01

    目的 比较KR-8100自动角膜曲率计与TMs-4角膜地形图仪测量屈光不正儿童角膜屈光力及散光轴向的差异,并对两种测量方法进行一致性评价.方法 采用KR-8100自动角膜曲率计及TMS-4角膜地形图仪对53例(106只眼)屈光不正儿童进行测量,应用配对t检验对两种方法测量的陡峭 子午线角膜屈光力(Ks)、平坦子午线角膜屈光力(Kf)、角膜散光Ks-Kf大小及轴向进行比较,并应用Bland-Altmann分析对两种测量方法进行一致性评价.结果 角膜地形图仪测量的Ks、Kf、Ks-Kf值均高于角膜曲率计的测量值(P<0.01);角膜地形图仪与角膜曲率计的散光轴向测量值差异有统计学意义(P<0.01).两种仪器测量Ks的差值的均数为1.72D,测量Kf的差值的均数为1.37D,这种测量差别临床上不能接受,说明两种仪器测量角膜屈光力的一致性较差.结论 KR-8100自动角膜曲率计与TMS-4角膜地形图两种测量方法在临床上不能替代使用.%Objective To evaluate the agreement of measuring corneal power and astigmatism axis between automatic keratometry and corneal topography on ametropia' children.Methods Keratometric reading with Topcon KR-8100 automatic keratometry and corneal topography with the TMS-4 on 53 ametropia' children, 106 eyes were compared.Difference in measurements of steep meridian power magnitude Ks, flat meridian power magnitude Kf, astigmatism magnitude Ks-Kf and location as well between the two methods were assessed using paired t test.Bland-Altmann method was used to evaluate the agreement of the two methods.Results The Ks,Kf,Ks-Kf of the corneal topography were higher than that of the keratometry' (P<0.01).The difference of the astigmatism axis between the corneal topography and the keratometry was significant (P<0.01).Of the two instruments,the mean difference of Ks was 1.72D,Kf was 1.37D,the difference of the measurement cannot be acceptable, so it showed incomparable results for them to

  20. Effect of 3.0mm corneal incision guided by corneal topography on corneal astigmatism in cataract surgery%角膜地形图引导下3.0mm角膜切口对白内障术后角膜散光的影响

    Institute of Scientific and Technical Information of China (English)

    陆士恒; 张忆; 吕骄

    2013-01-01

    AIM: To compare preoperative and postoperative corneal astigmatism using 3.0mm corneal incision guided by corneal topography system in phacoemulsification.METHODS: Phacoemulsification was performed on 144 cases 156 eyes with 3.0mm corneal clear incision at the steepest corneal meridian. Preoperative corneal astigmatism and the data 3 months postoperatively were observed by the corneal topography system. Statistical analysis included sample Student's t - test, one way ANOVA test, Kruskal-Wallis test and Pearson correlation test.RESULTS: According to analysis, the postoperative corneal astigmatism correlated negatively with the preoperative corneal astigmatism (r=-0. 69, P<0. 01). The corneal cylinder changed significantly in each grade after the surgery (P< 0. 05). When the preoperative corneal cylinder was between 0. 12D and 0. 25D, the postoperative corneal cylinder was higher than before. Whereas, the postoperative corneal cylinder became lower than before when the preoperative cylinder ranged from 0.37D to 1.0D.CONCLUSION: The incision located at the steepest corneal meridian under the guidance of corneal topography changes the preoperative astigmatism. For astigmatic correction, 3.0mm on - axis clear corneal incision phacoemusification is recommended with preoperative corneal astigmatism between 0.37 and 1.0D.%目的:观察角膜地形图引导下3.0mm透明角膜切口白内障超声乳化手术前后患者角膜散光的变化.方法:在角膜最大曲率子午线上做3.0mm切口行白内障超声乳化手术,对术前散光度数≤1.0D的144例156眼术前、术后3mo的资料进行回顾性分析,统计手术前后角膜地形图散光的变化.采用t检验、单因素方差分析、Pearson相关分析对数据进行统计学处理.结果:3.0mm角膜透明手术切口的术源性散光为0.77±0.53D.患者手术前后的散光对比有统计学意义(P<0.05),散光变化具有相关性(r=-0.69,P<0.01).术前角膜散光≤0.25D者术后散光增大,其

  1. Examination and management of corneal topography before laser in situ keratomileusis surgery%LASIK术前角膜地形图检查及处理

    Institute of Scientific and Technical Information of China (English)

    汤明霞

    2012-01-01

    Objective To explore the significance of corneal topography before laser in situ keratomileusis (LAS1K) surgery. Methods The comeal topography examination was performed to 500 patients (920 eyes) with myopia or with astigmatism. Before surgery the patients were grouped and handled according to Rabirtowitz standard. The intraoperative conditions, the number of kerato-conus, refractive regression cases and time were observed. Results Intraoperative corneal flap making accidents were not seen, keratoconus was not founded after surgery, and most refrative regressions occurred in 1 year after operation. In patients with higher K value, higher myopia and older age, refrative regression occurred easily after surgery. Conclusion Preoperative corneal topography examination before LASIK surgery is of clinical importance.%目的 探讨角膜地形图检查在准分子激光原位磨镶术(LASIK)术前的重要意义.方法 对欲行LASIK治疗的近视或伴散光的500例(920只眼)进行术前角膜地形图检查,术前根据Rabinowitz标准将患者进行分组并处理,观察各组手术病例术中情况,术后1年内发生圆锥角膜和屈光回退的例数、时间.结果 术中未出现制作角膜瓣意外,术后未发现圆锥角膜,术后回退时间多发生在1年后,K值较高、高度近视、年龄偏大的患者较易发生回退.结论 术前角膜地形图检查对LASIK 术有重要的检查意义.

  2. Corneal topography and pachymetry in normal eyes%正常人角膜前后表面地形及全角膜厚度的研究

    Institute of Scientific and Technical Information of China (English)

    刘祖国; 张梅; 谢玉环

    2001-01-01

    目的 了解正常人的角膜前后表面形态及全角膜厚度,为诊断异常角膜提供参考依据。方法 应用Orbscan角膜地形图仪对46例正常人(46只眼)的角膜进行检测,建立其正常参数。结果 正常人角膜最薄处为(0.55±0.33) mm,平均位于距视轴(0.90±0.51) mm处。32例(70%)角膜最薄点位于颞下方,11例(24%)位于颞上方,2例(4%)位于鼻下,1例(2%)位于鼻上方。角膜厚度以角膜中央最薄(0.56±0.03) mm,角膜上方最厚(0.64±0.03) mm。模拟角膜屈率(Sim K)为(44.24±1.61/43.31±1.66)D, 散光度为(0.90±0.41)D。角膜前表面高度地形图的图形中,岛形最多,其次为不完全嵴形。角膜后表面高度地形图的图形中,岛形最多,其次为规则嵴形及不完全嵴形。在前表面角膜屈率地形图的图形中,对称蝴蝶结形最多,其次为椭圆形及不对称蝴蝶结形。在角膜厚度彩色地形图中,椭圆形最多,其次为圆形。结论 了解正常人全角膜厚度、角膜高度形态及角膜前表面角膜屈率地形图将为诊断异常角膜提供依据。Orbscan 角膜地形图仪是一种测量角膜地形及全角膜厚度的有用工具,在角膜屈光手术中将具有重要的应用价值。%Objective To evaluate the corneal topography and pachymetry on normal eyes. Methods The Orbscan corneal topography system was used to investigate corneal topography and pachymetry on 46 normal subjects. Results In normal eyes, island-shape was the most common type in the elevation topography of anterior corneal surface, followed by incomplete ridge, regular ridge, irregular ridge and unclassified type. For the elevation topography of posterior corneal surface, the most common type was also the island-shape, followed by regular ridge, incomplete ridge and irregular ridge. The thinnest point of cornea in normal eyes was located (0.90±0.51) mm away from the visual

  3. 瞬目后不同注视时间的角膜地形图变化%Corneal topography changes at different time of fixation after blinking

    Institute of Scientific and Technical Information of China (English)

    王若洁; 郑穗联; 苏小夏; 邱梭; 施明光

    2010-01-01

    目的 分析比较非干眼与干眼瞬目后不同注视时间的角膜地形图变化,以探讨最后一次瞬目后进行角膜地形图摄影的最佳时间.方法 应用角膜地形图仪检测非于眼(30只眼)和干眼(30只眼),其中非干眼在最后一次完整瞬目后的5s、15s、30s时进行摄影,干眼在正常瞬目情况下,其中一次完整瞬目后的5s进行摄影,分别记录角膜不规则指数(CIM)、形态系数(SF).结果 非干眼瞬目后5s、15s、30s的CIM值明显增大(P<O.05),而SF差异无统计学意义.干眼患者瞬目后5s的CIM、SF值分别1.15±0.55、0.28±0.14.与非干眼相比,平均CIM值明显大于非干眼瞬目后5s的CIM值(P<0.01),且大于非干眼瞬目后15s的平均CIM值,小于瞬目后30s的平均CIM值.SF平均值两者无统计学意义(P>0.05).结论 (1)角膜地形图测量准确性与测量时注视时间密切相关,建议在最后一次瞬目后5s内进行摄影.(2)角膜表面规则性与泪膜的均匀涂布有关.%Objective To analyze and compare the changes of corneal topographic parameters at different time of fixation after blinking between non-dry eyes and dry eyes and to investigate the optimal time between the last blink and the acquisition of topographic image. Methods Thirty non-dry eyes and 30 dry eyes were examined using corneal topography system. Photographs were taken at 5, 15 and 30 seconds after a complete blinking in non-dry eyes and were taken at 5 seconds after the last blinking in dry eyes. The main outcome measures were corneal irregularity measure (CIM) and shape factor (SF). Results The mean values of CIM increased significantly during the 30 seconds pause in blinking in non-dry eyes (P <0.05). The mean of CIM and SF values were 1.15± 0.55, 0.28± 0.14 at 5 seconds after the last blink in dry eyes, respectively. The mean values of CIM was significantly greater than that at 5S after a complete blinking in non-eyes (P<0.01). Conclusions The accuracy of the

  4. One-Year Results of Simultaneous Topography-Guided Photorefractive Keratectomy and Corneal Collagen Cross-Linking in Keratoconus Utilizing a Modern Ablation Software

    Directory of Open Access Journals (Sweden)

    A. M. Sherif

    2015-01-01

    Full Text Available Purpose. To evaluate effectiveness of simultaneous topography-guided photorefractive keratectomy and corneal collagen cross-linking in mild and moderate keratoconus. Methods. Prospective nonrandomized interventional study including 20 eyes of 14 patients with grade 1-2 keratoconus that underwent topography-guided PRK using a Custom Ablation Transition Zone (CATz profile with 0.02% MMC application immediately followed by standard 3 mw/cm2 UVA collagen cross-linking. Maximum ablation depth did not exceed 58 μm. Follow-up period: 12 months. Results. Progressive statistically significant improvement of UCVA from 0.83±0.37 logMAR preoperative, reaching 0.25±0.26 logMAR at 12 months (P<0.001. Preoperative BCVA (0.27±0.31 logMAR showed a progressive improvement reaching 0.08±0.12 logMAR at 12 months (P=0.02. Mean Kmax reduced from 48.9±2.8 to 45.4±3.1 D at 12 months (P<0.001, mean Kmin reduced from 45.9±2.8 D to 44.1±3.2 D at 12 months (P<0.003, mean keratometric asymmetry reduced from 3.01±2.03 D to 1.25±1.2 D at 12 months (P<0.001. The safety index was 1.39 at 12 months and efficacy index 0.97 at 12 months. Conclusion. Combined topography-guided PRK and corneal collagen cross-linking are a safe and effective option in the management of mild and moderate keratoconus. Precis. To our knowledge, this is the first published study on the use of the CATz ablation system on the Nidek Quest excimer laser platform combined with conventional cross-linking in the management of mild keratoconus.

  5. Using corneal topography design personalized cataract surgery programs%应用角膜地形图设计个性化白内障手术方案

    Institute of Scientific and Technical Information of China (English)

    黄金鸥; 陈金邦; 陈炜江; 裘义松; 魏肖红

    2014-01-01

    AIM:To investigate how to design personalized cataract surgery programs to achieve surgical correction of preoperative corneal astigmatism with surgical astigmatism under the guidance of corneal topography, improve postoperative visual quality and reduce the cost of treatment. METHODS: Totally 202 cases ( 226 eyes ) cataract patients were divided into randomized treatment group and individualized treatment group. According to the method and location of the incision, randomized treatment group were divided into 8 groups. Surgical astigmatism after different incision were calculated with the use of preoperative and postoperative corneal astigmatism through vector analysis method. Individualized treatment groups were designed personably for surgical method with reference of every surgically induced astigmatism, the surgical method chooses the type of surgical incision based on close link between preoperative corneal astigmatism and surgically induced astigmatism, and the incision was located in the steep meridian. The postoperative corneal astigmatism of individualized treatment group was observed. RESULTS: Postoperative corneal astigmatism of individualized treatment group were lower than that of 3.0mm clear corneal tunnel incision in the randomized treatment group, there were statistically significance difference, while with 3. 0mm sclera tunnel incision group there were no statistically significance difference. After 55. 8% of patients with the use of individualized surgical plan could undergo the operation of extracapsular cataract extraction with relatively low cost and rigid intraocular lens implantation, the per capita cost of treatment could be reduced. CONCLUSION: Personalized cataract surgery programs are designed to achieve surgical correction of preoperative corneal astigmatism under the use of corneal topography, improve postoperative visual quality and reduce the cost of treatment.%目的:探讨如何在角膜地形图的指导下,设计个性化

  6. The research and realization of data acquisition based on corneal topography system%基于角膜地形图仪系统的数据获取研究与实现

    Institute of Scientific and Technical Information of China (English)

    岑琴; 谢忠好; 黄学平

    2015-01-01

    Objective To acquire the corneal data automatically by designing and developing corneal data analysis software with the Orbscan Ⅱ corneal topography system,providing automatic analysis function for corneal clinical diagnosis.Methods Based on the existing corneal topography system,the corneal data analysis software hooked the process of the Orbscan using API Hook.During the measurement of the cornea,the program acquired the corneal data in real time,and through sharing memory file,took the data into the program process of the corneal data analysis software to realize collection,acquisition and analysis of the corneal data.Results The acquired data were carried out partial differential analysis and regression to calculate and produce Q-value of the 360 semi-meridian.It used OpenGL graphics technology to vividly demonstrate aspheric properties and morphological images of individual corneal surface in VC ++ 6.0 development environment.Conclusion The corneal data of the Orbscan Ⅱ corneal topography system could be obtained automatically by the analysis program,which achieved seamless connection of software development,provided the actual three-dimensional corneal morphology and Q-value distribution curve for patients,better extended the function of the corneal topography system,and provided the data foundation and automatic analysis function for the further study of cornea.%目的 应用Orbscan Ⅱ角膜地形图仪系统,设计开发角膜数据分析软件来自动获取角膜数据,为角膜的临床诊断提供自动分析功能.方法 实验研究.在现有的角膜地形图仪系统的基础上,角膜数据分析软件通过API Hook挂接到Orbscan进程,在检查测量角膜过程中,由程序即时获取数据,并通过共享内存文件的方式,将数据读取到角膜数据分析软件的程序进程当中,实现角膜数据的采集、获取及分析.结果 对获取的数据进行偏微分分析和拟合回归处理,计算产生360

  7. Quantitative evaluation of keratoconus patients' corneal topography%圆锥角膜患者角膜地形图量化参数分析

    Institute of Scientific and Technical Information of China (English)

    郝永娜; 魏瑞华; 王海燕; 赵少贞

    2012-01-01

    Objective To evaluate corneal topography of keratoconus,and evaluate characteristics of the quantitative parameters.Methods Sixty-three keratoconus patients (Rabinowitz diagnosis standards) were examined on both eyes with Obscan Ⅱ topography.The recorded quantitative parameters were analyzed statistically.Sixty-four patients (64 eyes) with moderate or high myopia were selected as normal control and comparison analysis were made between them.Results The maximum keratometry of clinical keratoconus had significantly correlation with maximum posterior elevation,thinnest pachymetry,3-mm irregularity,5-mm irregularity (P <0.0001).Clinical and subclinical keratoconus eyes had higher maximum posterior elevation,3-mm irregularity,5-mm irregularity and thinner corneas compared with normal eyes.The distance from the thinnest point to the corneal center of clinical keratoconus group,subclinical keratoconus group and normal group was (0.76±0.42)mm,(0.66±0.38)mm and (0.61±0.29)mm,respectively.Most of the corneal thinnest point of clinical/subclinical keratoconus eyes was in the inferior tempus,the normal group was in the lmm ring region.Conclusions Obscan Ⅱ topography can make fully evaluation on comeal anterior and posterior face.Keratoconus can be diagnosed earlier by analyzing the quantitative index statistically.%目的 对圆锥角膜(KC)患者双眼的角膜地形图进行分析,对各量化参数进行特点评估.方法 临床病例研究.对2008年1月至2010年3月在天津医科大学眼科中心就诊符合诊断标准的KC患者63例(108只眼),使用Obscan Ⅱ角膜地形图仪检测双眼角膜,统计分析获得的数量指标,并与作为正常对照眼的64例中高度近视患者(64只眼)进行比较分析.结果 临床期KC组的最大角膜曲率值与最高角膜后表面高度、角膜最薄厚度、3 mm区域不规则值、5 mm区域不规则值差异有统计学意义(P<0.01).与正常对照组相比,临床期KC眼和亚临床期KC眼均具

  8. Dynamic changes in corneal topography and its influence on the point-spread function of the eye

    Science.gov (United States)

    Siedlecki, Damian; Kasprzak, Henryk; Pierscionek, Barbara K.

    2007-03-01

    The dynamic changes of the anterior surface of the eye are investigated. A Twyman-Green interferometer is used to record topographic images at 40 ms intervals. A method of analysis of the dynamic changes in topography by use of Zernike polynomials enables a general distinction to be made between dynamic alterations in the shape of the cornea itself and the changes in the layer of the tears. The influence of deviations in the shape of the anterior surface of the eye on the retinal image is estimated.

  9. 角膜地形图引导下白内障手术切口构建的变异对角膜散光影响%The Effect of the Corneal Astigmatism in Changed Cataract Surgery Incision with the Corneal Topography

    Institute of Scientific and Technical Information of China (English)

    刘文慧; 施彦; 李一壮

    2010-01-01

    Objective To observe the effect of the corneal astigmatism in cataract surgery incision which selected according to corneal topography to further reduce the preoperative corneal astigmatism. Meth-ods Computer-assisted corneal topography was used to examine the 126 eyes of 123 patients preoperatively.The cases were divided into 5 groups randomly. Group A: Manual small incision cataract surgery (MSICS) Group: Superior anti-bow sclera tunnel incision was made on 22 eyes of Group A. Group B: MSICS Group: The anti-bow sclera tunnel incision was made on the steepest meridian according to the corneal topography ex-amined preoperatively on 28 eyes. Group C: Phacoemulsification Group: Superior clear corneal incision was made on 24 eyes of group C. Group D: Phacoemulsification Group: The clear corneal incision was made on the steepest meridian according to the corneal topography examined preoperatively on 26 eyes. Group E: MSICS Group: incision was made on the steepest meridian according to the corneal topography The straight sclera tun-nel examined preoperatively on 26 eyes. The corneal topography at 1 day and 7 days after surgery was ob-served and recorded except for visual acuity and so on. Results ①Visual acuity: The differences were not sta-tistically significant among these groups which Visual acuity was above 0.5 after 1 day and 7 days except the one between Group B and Group E after 7 days. ②Astigmatism axis conversion: The conversions were not sig-nificant from Group A to Group D. There were 12 cases changed in Group E. ③Corneal astigmatism: In Group A, the differences were not statistically significant among pre-operation, 1 day and 7 days. In Group B, the val-ues of corneal astigmatism in 1 day after surgery were a little more decreased than pre-existing ones, but were statistically significant 7 days later. The values of Group C and D were a little greater in 1 day after surgery and reduced 7 days later, however the values of Group C were higher. In group E

  10. Assessment of the effects of LASIK on astigmatism of-2.0D or above by corneal topography%LASIK手术治疗-2.0D以上散光的角膜地形图分析

    Institute of Scientific and Technical Information of China (English)

    周少博; 路晓明; 洪海烽; 苏小波; 黎健菁; 胡群英

    2010-01-01

    目的 利用角膜地形图评价LASIK治疗-2.0D以上散光疗效的准确性.方法 对25例(36只眼)散光度在-2.0D以上的近视散光患者于LASIK手术前后行角膜地形图和主觉验光检查,并将主觉验光测得的散光值换算成角膜平面的散光值,随访6月以上,比较手术前后角膜地形图测得的角膜散光的改变情况以及主觉验光所得的散光改变.结果 手术前后平均角膜地形图散光大小分别为(-2.29±0.61)D和(-1.91±0.68)D,主觉验光手术前后平均角膜平面的散光大小分别为(-2.22±0.61)D和(-0.46±0.43)D,两者手术前后差异均有统计学意义(P0.05),散光轴位平均差异为(6.53±14.19)度,而术后角膜地形图散光和术后显然验光角膜平面的散光大小差异有统计学意义(P=0.00).结论 角膜地形图测量术前-2.0D以上散光与主觉验光结果基本一致,但LASIK术后,角膜地形图往往高估术后的散光值.%Objective To investigate the accuracy of the effects of laser in situ keratomileusis (LASIK) on astigmatism of -2.0D or above assessed by corneal topography.Methods Thirty-six eyes of 25 patients with astigmatism of-2.0D or above who underwent LASIK were included in this retrospective study. Corneal topography and subjective refraction examination were performed before and at least 6 months after surgery.The astigmatism of subjective refraction was translated to cylinder diopter of corneal plane.Astigmatism measured with corneal topography and that of subjective refraction was compared before and after the surgery. Results The mean astigmatism measured by corneal topography was (-2.29±0.61) D and (-1.91±0.68) D pre- and postoperative respectively.The meaa astigmatism in corneal plane measured by manifest refraction was (-2.22±0.61) D and (-0.46±0.43) D pro- and postoperative respectively.The differences between pre- and post-operation were both statistically significant (P<0.05).The mean difference between pre- and post

  11. Placido disk-based topography versus high-resolution rotating Scheimpflug camera for corneal power measurements in keratoconic and post-LASIK eyes: reliability and agreement

    Science.gov (United States)

    Penna, Rachele R.; de Sanctis, Ugo; Catalano, Martina; Brusasco, Luca; Grignolo, Federico M.

    2017-01-01

    AIM To compare the repeatability/reproducibility of measurement by high-resolution Placido disk-based topography with that of a high-resolution rotating Scheimpflug camera and assess the agreement between the two instruments in measuring corneal power in eyes with keratoconus and post-laser in situ keratomileusis (LASIK). METHODS One eye each of 36 keratoconic patients and 20 subjects who had undergone LASIK was included in this prospective observational study. Two independent examiners worked in a random order to take three measurements of each eye with both instruments. Four parameters were measured on the anterior cornea: steep keratometry (Ks), flat keratometry (Kf), mean keratometry (Km), and astigmatism (Ks-Kf). Intra-examiner repeatability and inter-examiner reproducibility were evaluated by calculating the within-subject standard deviation (Sw) the coefficient of repeatability (R), the coefficient of variation (CoV), and the intraclass correlation coefficient (ICC). Agreement between instruments was tested with the Bland-Altman method by calculating the 95% limits of agreement (95% LoA). RESULTS In keratoconic eyes, the intra-examiner and inter-examiner ICC were >0.95. As compared with measurement by high-resolution Placido disk-based topography, the intra-examiner R of the high-resolution rotating Scheimpflug camera was lower for Kf (0.32 vs 0.88), Ks (0.61 vs 0.88), and Km (0.32 vs 0.84) but higher for Ks-Kf (0.70 vs 0.57). Inter-examiner R values were lower for all parameters measured using the high-resolution rotating Scheimpflug camera. The 95% LoA were -1.28 to +0.55 for Kf, -1.36 to +0.99 for Ks, -1.08 to +0.50 for Km, and -1.11 to +1.48 for Ks-Kf. In the post-LASIK eyes, the intra-examiner and inter-examiner ICC were >0.87 for all parameters. The intra-examiner and inter-examiner R were lower for all parameters measured using the high-resolution rotating Scheimpflug camera. The intra-examiner R was 0.17 vs 0.88 for Kf, 0.21 vs 0.88 for Ks, 0.17 vs 0

  12. Comparison of corneal topography measurement with two different instruments%两种仪器测量近视患者角膜地形图的对比研究

    Institute of Scientific and Technical Information of China (English)

    王虎杰; 栗静; 刘磊; 李新宇; 黎冬平; 王恒

    2013-01-01

    目的 对比OrbscanⅡ和Pentacam跟前节分析仪测量近视患者角膜地形图的差异.方法 分别使用OrbscanⅡ和Pentacam眼前节分析仪测量119例近视患者角膜地形图,并对测量结果进行方差分析、配对t检验和Pearson相关分析.结果 OrbscanⅡ和Pentacam测得CCT平均值分别为(515.67 ±36.06)μm、(539.67 ±31.41)μm,差异有统计学意义(P<0.05);OrbscanⅡ测得角膜前后表面曲率、前后表面高度和瞳孔直径均显著高于Pentacam;两种仪器测得角膜散光和前房深度无差异.结论 两种仪器测得角膜地形图存在一定差异,在临床工作中不能将二者测量结果简单替代.%Objective To compare the differences in measurements of corneal topography using Orbscan Ⅱ and Pentacam anterior segment analysis system.Methods Corneal topography of 119 patients were obtained with Orbscan Ⅱ and Pentscam,analysis of variance,paired t-test and Pearson correlation analysis were used to analyze the difference and oorrelation between these measurements.Results The mean CCT measured by OrbscanⅡ and Pentacam were (515.67 ±36.06) um and (539.67 ±31.41)um respectively,there were statistical differences(P <0.05) ; the anterior and posterior comeal curvature,the anterior and posterior corneal elevation and the corneal diameter obtained by Orbscan Ⅱ were higher significantly than those by Pentacam; there were no statistical differences between Sim K and anterior chamber depth ob-tained by Orbscan Ⅱ and Pentacam.Conclusion The corneal topographies measured by Orbscan Ⅱ and Pentacam have differences,so the two measurments should not be used interchangeably in clinic.

  13. Clinical study on astigmatism of phacoemulsification incision decided by corneal topography%角膜地形图引导下的角膜切口白内障手术矫正角膜散光的研究

    Institute of Scientific and Technical Information of China (English)

    张欣; 王颖; 卢山; 何伟

    2010-01-01

    Objective To observe preoperative and postoperative astigmatism of corneal incision decided by the corneal topography. Methods A total of 240 eyes underwent phacoemulsification with corneal incision were randomly divided into three groups. Group A (80 eyes), incision at the steepest corneal meridian decided by corneal topography; group B (80 eyes), incision at 90 °; group C (80 eyes), incision at 180 °. Corneal astigmatism, visual changes of preoperative and 1 week, 1 month and 3 months postoperative were observed. Results Uncorrected visual acuity (>0.7) of group A were better than group B and C (P0.6) were the same in all three groups of the patients. Astigmatism of group A were significantly reduced (P 0.05). Astigmatism of group A were significantly reduced (P <0.05) 1 week, 1 month and 3 months postoperative compared with group B and group C (P <0.05). Conclusions The incision which located at the steepest corneal meridian under the guidance of corneal topography reduces the preoperative and postoperative astigmatism, and attains better uncorrected visual acuity postoperative.%目的 观察角膜地形图引导下的透明角膜切口白内障手术对术前及术后散光度的影响.方法 透明角膜切口晶状体超声乳化术240只眼,随机分成三组,每组80只眼.A组:切口位于角膜最大屈光轴方向;B组:切口位于90°方向;C组:切口位于180°方向.观察术前、术后1周、1月、3月角膜散光度和视力变化.结果 (1)A组术后1周、1月和3月裸眼视力> 0. 7者多于B组和C组(P < 0. 05);三组患者术后最佳矫正视力> 0. 6者基本相同.(2)A组患者术后1周、1月及3月与术前相比,散光度明显减小(P<0.01);术后1周与术后1月、3月相比,散光度也减小(P<0.05);而术后1月与3月相比,散光度基本相似(P>0.05).(3)A组与B组相比,术后1周、1月及3月时的散光度均明显减小(P<0.05);A组与C组相比,术后1周、1月及3月时

  14. Corneal Topographic Changes After Eyelid Ptosis Surgery.

    Science.gov (United States)

    Savino, Gustavo; Battendieri, Remo; Riso, Monica; Traina, Salvatore; Poscia, Andrea; DʼAmico, Giovanni; Caporossi, Aldo

    2016-04-01

    To evaluate the corneal topography and the topographic changes after ptosis surgery on patients affected by congenital and acquired blepharoptosis. Twenty eyes of 17 patients affected by acquired and congenital ptosis underwent surgical correction through anterior levator complex tightening. Computerized tomography (Syrius Sistem; CSO) was used to analyze any change in corneal astigmatism (CYL), simulated keratometry, anterior corneal symmetry index front, apical keratometry front, and central corneal thickness. Visual acuity, margin reflex distance, and levator function were also measured. After surgical ptosis repair, corneal topography demonstrated a reduction in average keratometry of 0.15 ± 0.47 diopters (D) and in corneal astigmatism of 0.26 ± 1.12 D. Significant differences were found in apical keratometry front (-1.84 ± 1.76 D) and in best-corrected visual acuity (-0.18 ± 0.06 logMAR) in the postoperative examinations. Central corneal thickness did not show significant differences between preoperative and postoperative examinations. Postoperative topographic maps showed a reduction of symmetry index front (0.10 ± 0.64 D). Eyelid ptosis modifies anterior corneal surface inducing refractive errors and modifying corneal astigmatism in patients, thus affecting the quality of vision. The surgical correction of blepharoptosis induces anterior corneal surface modification, restoring corneal symmetry and regular corneal astigmatism. Postoperative corneal topography showed normal corneal contours.

  15. Toward optical coherence topography

    Science.gov (United States)

    Sayegh, Samir; Jiang, Yanshui

    2012-03-01

    Commercial OCT systems provide pachymetry measurements. Full corneal topographic information of anterior and posterior corneal surfaces for use in cataract surgery and refractive procedures is a desirable goal and would add to the usefulness of anterior and posterior segment evaluation. While substantial progress has been made towards obtaining "average" central corneal power (D Huang), power in different meridians and topography are still missing. This is usually reported to be due to eye movement. We analyze the role of centration, eye movements and develop a model that allows for the formulation of criteria for obtaining reliable topographic data within ¼ diopter.

  16. An analysis of changes in the posterior corneal surface using Sirius topography after LASIK and LASEK%Sirius角膜地形图仪测量LASIK和LASEK术后角膜后表面的研究

    Institute of Scientific and Technical Information of China (English)

    施彦; 俞存

    2014-01-01

    目的 通过Sirius角膜地形图仪测量LASIK和LASEK术后角膜后表面,分析其变化特点,评价各因素对角膜后表面变化的影响.方法 前瞻性临床研究.入选2012年5月至2013年7月在宁波第一医院行准分子激光屈光手术患者,其中LASIK手术37例(74眼),LASEK手术26例(52眼),术前应用Sirius角膜地形图仪测量每眼,并完善术前常规检查,记录相关数值.记录患者术中的切削深度、切削比例、残留基质厚度,术后1周、1个月、3个月复查.各时间点之间数据比较应用重复测量资料方差分析,各变量与角膜后表面高度变化量之间的影响程度应用多元线性回归.结果 LASIK与LASEK术后1周、1个月和3个月角膜后表面高度与术前比较稍增高,差异有统计学意义(F=43.58、7.51,P<0.01);残留基质对LASIK术后1周、1个月和3个月后表面高度变化量有影响(t=-3.421、-3.376、-3.116,P<0.01),对LASEK术后1个月和3个月后表面高度变化量有影响(t=-3.077、-2.872,P<0.01).结论 Sirius角膜地形图仪测定显示LASIK、LASEK术后均表现为角膜后表面微量前移.残留基质厚度对角膜后表面变化影响较大.%Objective To discuss the relationship between changes in the posterior corneal surface and refractive surgery using Sirius 3D topography; to further analyze and evaluate factors that affect the posterior corneal surface.Methods This was a prospective clinical study.Myopic patients who underwent excimer laser refractive surgery from May 2012 to July 2013 in Ningbo First Hospital were chosen (74 eyes of 37 LASIK patients and 52 eyes of 26 LASEK patients).Sirius 3D topography was used to reveal the corneal topography of the posterior corneal surfaces preoperatively.Ablation depth (AD),ablation ratio (ablation depth/corneal thickness,AD/CT) and residual bed thickness (RBT) were recorded for every patient during surgery and again at 1 week,1 month and 3 months postoperatively.Data were compared

  17. Sirius角膜地形图仪与角膜曲率仪测量LASIK术前患者角膜曲率的一致性研究%Consistency in measuring corneal curvature with Sirius corneal topography and a keratometer

    Institute of Scientific and Technical Information of China (English)

    罗素荣; 陈伟; 李昉; 张伟岗

    2013-01-01

    Objective To explore the differences and agreements between Sirius corneal topography and a keratometer in the measurement of corneal curvature before laser in situ keratomileusis (LASIK) in patients with myopia.Methods This was a prospective control study.One hundred and seventy eyes of 85 patients with myopia were selected at The People's Hospital of Shaoxing.Measurements of corneal curvature were taken with both Sirius corneal topography and a keratometer.A paired samples t-test and Pearson linear correlation were used for statistical analysis,and a BlandAltman analysis was used to evaluate the consistency of the two methods of measurement.Results The corneal curvature K1 values measured by Sirius corneal topography and a keratometer were 42.41±1.25 D and 42.33±1.28 D,K2 values were 43.36±1.38 D and 43.56±1.38 D,and (K1+K2)/2 values were 42.88±1.28 D and 42.92±1.29 D,respectively,indicating significant differences (t1=5.241,P<0.01; t2=-9.936,P<0.01; taverage=-3.021,P<0.01) and significant linear correlations between K1 and K2 (r1=0.989,P<0.01 ;r2=0.981,P<0.01; raverage=0.990,P<0.01).The differences between Sirius corneal topography and keratometry measurements of corneal curvature for K1 and K2 values and the differences in average corneal curvature (K1+K2)/2 were 0.08 D,-0.20 D and-0.04 D,respectively.The differences between standard deviations were 0.1897 D,0.2644 D and 0.1790 D and the 95% limits of agreement were (0.45 D,-0.30 D),(0.32 D,-0.72 D) and (0.31 D,-0.39 D).There were 2.4%(4/170),3.5(6/170) and 4.7%(8/170) points for the 95% limits of agreement,and consistency within the bounds of the maximum differences were 0.44 D, 0.68 D and 0.38 D, respectively. Conclusion Sirius corneal topography and keratometry show good agreement in the measurement of corneal curvature in patients with myopia. The values can be used interchangeably.%目的 研究Sirius角膜地形图仪和角膜曲率仪测量准分子激光原位角膜磨镶

  18. Clinical study on postoperative astigmatism of phacoemulsification guided by Astramax corneal topography%Astramax角膜综合检查站引导白内障手术术后屈光状态的临床研究

    Institute of Scientific and Technical Information of China (English)

    郑艳霞; 杨卫国; 魏宝丰; 高亚玲; 穆金卫

    2012-01-01

    目的 观察Astramax三维角膜综合检查站引导白内障超声乳化手术5.5mm透明角膜切口对术后屈光状态的影响.方法 对89例(100眼)老年性白内障患者随机分为观察组51眼及对照组49眼.观察组透明角膜切口位于角膜曲率最大子午线方向,对照组透明角膜切口位于10点位方向,2组行白内障超声乳化,植入5.5mm非折叠人工晶体.于术后1周、1个月及3个月时对患者进行视力、裂隙灯、眼底、角膜地形图检查,观察患者屈光状态的变化.结果 术后1个月及3个月观察组裸眼视力≥0.5者分别为42眼(82%)和43眼(84%),对照组分别为31眼(63%)和33眼(67%),2组比较有显著性差异(P均<0.05).观察组术后1个月、3个月角膜散光度明显减小(P<0.01);对照组术后3个月角膜散光度明显减小(P<0.05).结论 Astramax三维角膜综合检查站引导白内障超声乳化5.5mm角膜透明切口手术可以减少手术性散光、矫正角膜散光、提高术后视觉效果.%Objective It is to observe the influence of phacoemulsification guided by Astramax corneal topography system on postoperative astigmatism. Methods One hundred eyes with cataract were randomly divided into treatment groups (51 eyes, incision at the steepest corneal meridian ) and control group ( 49 eyes, incision at 10 o' clock ). The 5. 5 mm non-folded artificial lens was imbeded after phacoemulsification. The refraction state was observed after operation by sight, slit lamp, eye ground and corneal topography and compared. Results There were 42 eyes ( 82% ) and 43 eyes ( 84% ) which sight & 0. 5 at 1 and 3 month after operation in treatment group and 31 eyes ( 63% ) and 33 eyes ( 67% ) in control group with significant difference ( all P < 0.05 ). The corneal astigmatism degree was extremely significant smaller ( P < 0. 01 ) at 1 and 3 month after operation in treatment group, and was significant smaller ( P <0.05 ) at 3 month after operation in control group

  19. Comparative Study on the Changes in Corneal Topography before and after Pterygium Resection%翼状胬肉切除术前后角膜地形图变化对比研究

    Institute of Scientific and Technical Information of China (English)

    韩嵩

    2014-01-01

    目的:探讨利用角膜地形图来研究翼状胬肉切除术前后角膜表面屈光度的变化。方法:选取2012年6-10月在本院眼科就诊的40例(44眼)原发性翼状胬肉患者,按照随机数字表法将其分为A、B两组,A组行胬肉切除联合术中应用丝裂霉素C,B组行胬肉切除联合角膜缘干细胞,手术前后分别行角膜地形图仪检查,记录主要参数,并比较手术前后角膜地形图变化,进行统计学分析。结果:翼状胬肉切除术后,A、B两组各参数均明显低于术前,且A组各参数均明显低于B组,差异均有统计学意义(P<0.05)。结论:翼状胬肉切除术能够解除翼状胬肉对角膜的机械牵拉及压迫作用,降低散光,提高视力,术中使用丝裂霉素C可降低复发率,有利于角膜屈光状况的恢复。%Objective:To investigate the pterygium excision changes in corneal surface refraction using corneal topography before and after operation.Method:40 patients(44 eyes)with primary pterygium were selected in our ophthalmology from June 2012 to October 2012,they were randomly divided into the group A and the group B.The group A was given mitomycin C pterygium excision combined with intraoperative,and the group B was given pterygium excision with limbal stem cell.Corneal topography examinations were performed before and after operation,the main parameters were recorded,and the changes of corneal topography were compared before and after operation,the results were statistically analyzed.Result:After excision of pterygium,the parameters of two groups were significantly lower than preoperative,and the parameters of group A were significantly lower than the group B,the differences were statistically significant(P<0.05 or P<0.01).Conclusion:Pterygium resection can remove pterygium mechanical pull and compression of the cornea,reduce the astigmatism and improve eyesight,intraoperative use of mitomycin C can reduce the recurrence

  20. 裂隙扫描角膜地形图角膜测厚系统的临床与科研应用%Clinical and scientific research applications of Orbscan corneal topography system

    Institute of Scientific and Technical Information of China (English)

    倪海龙; 王勤美; 瞿佳

    2002-01-01

    90年代中期发展起来的裂隙扫描角膜地形图/角膜测厚系统(Orbscan corneal topography system)基于光学裂隙扫描原理,能一次性测量角膜前后表面曲率、角膜前后表面隆起度和角膜厚度.目前研究已经显示其在角膜屈光手术、接触镜验配、干眼症和圆锥角膜的诊断及眼库眼球角膜的筛选等诸多领域的应用价值.本综述结合新近相关文献,概述了Orbscan在上述领域的应用.

  1. [Methods for sealing of corneal perforations].

    Science.gov (United States)

    Samoilă, O; Totu, Lăcrămioara; Călugăru, M

    2012-01-01

    A variety of corneal pathology can lead to corneal ulcers and perforations. A deep corneal ulcer may need surgical treatment to allow good volume restoration and reepithelisation. Corneal perforation must be sealed and when the perforation is large, the task of repairing the defect can be underwhelming. The elegant solution is the corneal transplant, but this is not always readily available, especially in undeveloped countries. We present here two cases with different solutions to seal the perforated cornea: the first one has a large peripheral defect and it is successfully sealed with scleral patch and the second one is central with small perforation and is successfully sealed with multilayered amniotic membrane. Both cases are followed for over 12 months and demonstrate good corneal restoration (both on clinical examination and corneal topography). Sclera and amniotic membrane can be used to seal corneal defects when corneal transplant is not readily available.

  2. Corneal Laceration

    Medline Plus

    Full Text Available ... Laceration? Corneal Laceration Diagnosis Corneal Laceration Treatment What Is Corneal Laceration? Written By: Daniel Porter Reviewed By: ... A Harrison MD Sep. 01, 2016 The cornea is the clear front window of the eye . A ...

  3. Corneal Ectasis among Wrestlers: Report of Two Cases

    OpenAIRE

    Mohammad Ali Zare Mehrjardi; Hadi Zare Mehrjardi; Abasali Gaeeni; Elham Ashrafi; Homa Naderifar

    2014-01-01

    Report keratoconus in two patients with a long history of wrestling without any risk factor for corneal ectasia and reviewing the possible pathogenesis. To confirm suspicion of keratoconus, corneal topography was performed using scanning slit topography system and Orbscan. In two wrestlers with the complaint of visual loss in their eyes and IOP raising, corneal topography was performed and development of keratoconus (KCN) was detected. Athletes involved in sports with high strenuous exercises...

  4. Analysis on tear film after LASIK by femtosecond laser with Oculus corneal topography%Oculus角膜地形图仪对飞秒激光LASIK术后泪膜的分析

    Institute of Scientific and Technical Information of China (English)

    张媛; 贾冰冰; 张岩; 高冬梅; 庞玉珍

    2014-01-01

    AIM:To observe the changes of tear film on the patients after laser in situ keratomileusis ( LASIK) with corneal flap created by femtosecond laser with Oculus corneal topography. METHODS:Totally 120 myopic patients (240 eyes) were collected who underwent femtosecond laser surgery LASIK from August to September 2013, and these patients can be followed up for 3mo. Tear break-up time ( BUT) and tear meniscus height ( TMH ) with Oculus corneal topography were recorded preoperatively and postoperatively at 1wk;1, 2 and 3mo. RESULTS: Oculus BUT: there existed obvious differences (P=0. 012, 0. 000, 0. 023 0. 05 ) existed in 3mo compared with the preoperative level. TMH:there existed obvious differences (P=0. 025, 0. 019, 0. 0260. 05 ) existed in 3mo compared with the preoperative level. CONCLUSION: Femtosecond laser surgery affects the stability of the tear film at a certain time and a certain extent. The mechanism related to many factors. It is temporary and lighted.%目的:观察Oculus角膜地形图仪检查飞秒激光制瓣准分子激光原位角膜磨镶术( laser in situ keratomileusis, LASIK)术后泪膜的变化。  方法:收集2013-08/09于我院行飞秒激光制瓣LASIK并随访3 mo的患者120例240眼,观察术前、术后1 wk;1,2,3 mo患者的 Oculus 角膜地形图仪检查的泪膜破裂时间( tear break-up time,BUT)、Oculus角膜地形图仪检查的泪河高度( tear meniscus height,TMH)。  结果:Oculus BUT:术后1 wk;1,2 mo与术前相比有显著差异( P=0.012,0.000,0.0230.05)。泪河高度:术后1wk;1,2mo与术前相比有显著差异( P=0.025,0.019,0.0260-05)。  结论:飞秒激光制瓣准分子激光原位角膜磨镶术在一定时间和一定程度上影响泪膜的稳定性,发生机制与多种因素有关,持续时间比较短,症状比较轻。

  5. Polar Value Analysis of Corneal Astigmatism in Intrastromal Corneal Ring Segment Implantation

    OpenAIRE

    Chang Rae Rho; Min-Ji Kim; Choun-Ki Joo

    2016-01-01

    Purpose. To evaluate surgically induced astigmatism (SIA) and the average corneal power change in symmetric intrastromal corneal ring segment (ICRS) implantation. Methods. The study included 34 eyes of 34 keratoconus patients who underwent symmetric Intacs SK ICRS implantation. The corneal pocket incision meridian was the preoperative steep meridian. Corneal power data were obtained before and 3 months after Intacs SK ICRS implantation using scanning-slit topography. Polar value analysis was ...

  6. The management of cornea blindness from severe corneal scarring, with the Athens Protocol (transepithelial topography-guided PRK therapeutic remodeling, combined with same-day, collagen cross-linking

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2012-02-01

    Full Text Available Anastasios John KanellopoulosLaservision.gr Institute, Athens, Greece; Manhattan Eye, Ear and Throat Hospital, New York, NY, USA; New York University Medical School, New York, NY, USAPurpose: To evaluate the safety and efficacy of combined transepithelial topography-guided photorefractive keratectomy (PRK therapeutic remodeling, combined with same-day, collagen cross-linking (CXL. This protocol was used for the management of cornea blindness due to severe corneal scarring.Methods: A 57-year-old man had severe corneal blindness in both eyes. Both corneas had significant central scars attributed to a firework explosion 45 years ago, when the patient was 12 years old. Corrected distance visual acuity (CDVA was 20/100 both eyes (OU with refraction: +4.00, –4.50 at 135° in the right eye and +3.50, –1.00 at 55° in the left. Respective keratometries were: 42.3, 60.4 at 17° and 35.8, 39.1 at 151.3°. Cornea transplantation was the recommendation by multiple cornea specialists as the treatment of choice. We decided prior to considering a transplant to employ the Athens Protocol (combined topography-guided partial PRK and CXL in the right eye in February 2010 and in the left eye in September 2010. The treatment plan for both eyes was designed on the topography-guided wavelight excimer laser platform.Results: Fifteen months after the right eye treatment, the right cornea had improved translucency and was topographically stable with uncorrected distance visual acuity (UDVA 20/50 and CDVA 20/40 with refraction +0.50, –2.00 at 5°. We noted a similar outcome after similar treatment applied in the left eye with UDVA 20/50 and CDVA 20/40 with –0.50, –2.00 at 170° at the 8-month follow-up.Conclusion: In this case, the introduction of successful management of severe cornea abnormalities and scarring with the Athens Protocol may provide an effective alternative to other existing surgical or medical options.Keywords: Athens Protocol, collagen cross

  7. Asphericity analysis using corneal wavefront and topographic meridional fits

    Science.gov (United States)

    Arba-Mosquera, Samuel; Merayo-Lloves, Jesús; de Ortueta, Diego

    2010-03-01

    The calculation of corneal asphericity as a 3-D fit renders more accurate results when it is based on the corneal wavefront aberrations rather than on the corneal topography of the principal meridians. A more accurate prediction could be obtained for hyperopic treatments compared to myopic treatments. We evaluate a method to calculate corneal asphericity and asphericity changes after refractive surgery. Sixty eyes of 15 consecutive myopic patients and 15 consecutive hyperopic patients (n=30 each) are retrospectively evaluated. Preoperative and 3-month-postoperative topographic and corneal wavefront analyses are performed using corneal topography. Ablations are performed using a laser with an aberration-free profile. Topographic changes in asphericity and corneal aberrations are evaluated for a 6-mm corneal diameter. The induction of corneal spherical aberrations and asphericity changes correlates with the achieved defocus correction. Preoperatively as well as postoperatively, asphericity calculated from the topography meridians correlates with asphericity calculated from the corneal wavefront in myopic and hyperopic treatments. A stronger correlation between postoperative asphericity and the ideally expected/predicted asphericity is obtained based on aberration-free assumptions calculated from corneal wavefront values rather than from the meridians. In hyperopic treatments, a better correlation can be obtained compared to the correlation in myopic treatments. Corneal asphericity calculated from corneal wavefront aberrations represents a 3-D fit of the corneal surface; asphericity calculated from the main topographic meridians represents a 2-D fit of the principal corneal meridians. Postoperative corneal asphericity can be calculated from corneal wavefront aberrations with higher fidelity than from corneal topography of the principal meridians. Hyperopic treatments show a greater accuracy than myopic treatments.

  8. 角膜塑形镜治疗青少年近视眼角膜地形图参数分析%Assessment of corneal topography indices after orthokeratology correction for pediatric myopia

    Institute of Scientific and Technical Information of China (English)

    刘兵; 茹海霞; 王华; 陈威; 杨春燕

    2014-01-01

    Objective To analysis anterior corneal surface shape changes in pediatric myopic overnight or-thokeratology. Methods Retrospective observational case series were observed. Tomey TMS -4 was used to receive corneal topographic data before and after overnight orthokeratology lens wear. Seventy-five pediatric myopic patients (150 eyes, age range: 9~17 years) were included. The myopia was -4.23±1.82 (range:-8.75~-0.75) D, the astigmatism was -0.3±0.47 (range: -2~0) D, and spherical equivalent refraction was -4.34±1.88 (range: -9.13~-0.75) D. Topog-raphy data was collected and analyzed when uncorrected visual acuity (UCVA) was 1.0. Results After normative or-thokeratology lens correction, UCVAs of one hundred and fifty eyes reached 1.0, and no severe complications were ob-served. The topography parameters showed that mean Ks:41.19±1.73D,Kf:39.67±1.67D,AveK:40.43±1.61D, PVA:-0.01±0.09~0.11±0.08 (LogMAR), Es:-0.14±0.47,Em:-0.39±0.34,SRI:0.49±0.33,SAI:0.84±0.60, and were significantly different from no lens wear. No significant change was observed in Cyl (1.48±0.96D) before and after lens wear. The fluctuation range above parameters’ means were ks:0.82±0.83 (0~3.88) D,Kf:0.69±0.75 (0.01~4.54) D,Avek:0.71±0.75 (0.01~3.51) D,Cyl:0.45±0.48 (0.01~2.70) D,Es:0.27±0.31 (0~1.14),Em:0.18±0.24 (0~1.51),Sri:0.19±0.20 (0~1.02),Sai:0.40±0.55 (0~3.65) . Conclusions Improved visual acuity after overnight wear of orthokeratology lens can be attributed to changes in anterior corneal curvature and E value. Corneal regular astigmatism remained unchanged, but corneal PVA reduced and corneal irregularity increased. Improved UCVA can be maintained within a certain fluctuation of topography parameters.%目的:分析青少年近视眼经角膜塑形镜矫正后角膜前表面的变化。方法回顾性分析青少年近视患者共75人150眼,年龄9~17岁,屈光状态:-4.23±1.82(-8.75~-0.75) Ds/-0.3±0.47(-2~0)Dc,等效球镜度数:-4.34±1.88(-9

  9. Comparison of corneal topography after topography-guided FS-LASIK and wavefront-optimized FS-LASIK%角膜地形图引导与波前像差优化的飞秒LASIK术后角膜地形图比较

    Institute of Scientific and Technical Information of China (English)

    张丽; 周跃华; 徐雯; 李颖; 王玥; 张秋露; 柳静; 胡雅斌

    2016-01-01

    Objective To compare the outcomes of topography-guided LASIK and wavefront-optimized LASIK in eyes of patients undergoing femtosecond laser LASIK (FS-LASIK) for myopia with astigmatism.Methods In this prospective clinical study,44 eyes of 22 patients underwent topography-guided LASIK (topography group) and 43 eyes of 22 patients underwent wavefront-optimized LASIK (wavefront group).The topography treatment was based on data generated by a networked diagnostic device:Wavelight Topolyzer.Visual acuity,refractive error,the index of corneal surface variance (ISV),corneal wavefront aberrations and ablation decentration were evaluated 6 months postoperatively.Data were analyzed using independent t test.Results Six months postoperatively,there were no significant differences in UCVA or BCVA (t=-1.553,-1.570,P>0.05) between the groups.No eyes lost a line of BCVA in either group.There were no statistically significant differences in postoperative average sphere,cylinder refraction or spherical equivalent (SE) between the groups.The postoperative value of ISV increased compared to baseline for both groups (t=5.216,7.870,P<0.05).The mean postoperative ISV in the topography group (39.9±13.0) was significantly lower than that in the wavefront group (44.9±12.2) (t=-2.296,P<0.05).The postoperative mean decentration in the topography group (0.24± 0.29 mm) was less than that in the wavefront group (0.29±±0.31 mm),but the difference was not statistically significant (t=-1.005,P>0.05).There were significant differences in postoperative coma aberrations (Z31) [-0.166 ±0.357 m vs.-0.362±±0.353 m,t=2.325,P<0.05] and spherical aberrations (Z40) [0.390± 0.263 μm vs.0.486±±0.164 μm,t=-2.096,P<0.05] between the two groups.Conclusion Both topography-guided ablation and wavefront-optimized ablation provide good visual acuity and refractive results,but the former treatment results in a better index of corneal surface variance and induces fewer corneal aberrations

  10. Correlations between corneal and total wavefront aberrations

    Science.gov (United States)

    Mrochen, Michael; Jankov, Mirko; Bueeler, Michael; Seiler, Theo

    2002-06-01

    Purpose: Corneal topography data expressed as corneal aberrations are frequently used to report corneal laser surgery results. However, the optical image quality at the retina depends on all optical elements of the eye such as the human lens. Thus, the aim of this study was to investigate the correlations between the corneal and total wavefront aberrations and to discuss the importance of corneal aberrations for representing corneal laser surgery results. Methods: Thirty three eyes of 22 myopic subjects were measured with a corneal topography system and a Tschernig-type wavefront analyzer after the pupils were dilated to at least 6 mm in diameter. All measurements were centered with respect to the line of sight. Corneal and total wavefront aberrations were calculated up to the 6th Zernike order in the same reference plane. Results: Statistically significant correlations (p corneal and total wavefront aberrations were found for the astigmatism (C3,C5) and all 3rd Zernike order coefficients such as coma (C7,C8). No statistically significant correlations were found for all 4th to 6th order Zernike coefficients except for the 5th order horizontal coma C18 (p equals 0.003). On average, all Zernike coefficients for the corneal aberrations were found to be larger compared to Zernike coefficients for the total wavefront aberrations. Conclusions: Corneal aberrations are only of limited use for representing the optical quality of the human eye after corneal laser surgery. This is due to the lack of correlation between corneal and total wavefront aberrations in most of the higher order aberrations. Besides this, the data present in this study yield towards an aberration balancing between corneal aberrations and the optical elements within the eye that reduces the aberration from the cornea by a certain degree. Consequently, ideal customized ablations have to take both, corneal and total wavefront aberrations, into consideration.

  11. Corneal Laceration

    Medline Plus

    Full Text Available ... your vision. Privacy Policy Related People with Advanced Keratoconus May Have A Future Alternative to Full Corneal ... 2016 Corneal Collagen Cross-linking Approved to Treat Keratoconus in U.S. Aug 01, 2016 Firework Blinds Teenager, ...

  12. Corneal Laceration

    Medline Plus

    Full Text Available ... lost sight from a corneal scar as a child. Now that I’m older, will a corneal transplant help me? May 15, 2015 Why Do My Eyes Burn After Inserting My Contacts? Feb 27, 2015 Dark ...

  13. Study of the clinical characteristics of corneal topography in patients with keratoconus%圆锥角膜患者角膜地形图形态学特征

    Institute of Scientific and Technical Information of China (English)

    隋文婕; 宋鹏; 刘明娜; 李素霞; 贾艳妮; 高华

    2014-01-01

    目的 观察圆锥角膜患者角膜地形图形态学特征,为临床早期诊断和筛查圆锥角膜及分析圆锥角膜发病机制提供依据.方法 回顾性病例对照研究.选取临床完成期圆锥角膜患者62例(66眼)、初期圆锥角膜患者57例(57眼)及正常对照者35例(70眼)行三维眼前节分析仪(ALLEGROOculyzer)检查.角膜后表面高度图形态分为岛型、不完全岛型、桥型递增型、桥型递减型、不完全桥型及不规则型6种.分析各组角膜后表面高度图形态学特点及角膜最薄点与顶点及瞳孔中心之间位置关系,数据采用单因素方差分析和非参数秩和检验进行分析.结果 正常对照组角膜后表面高度图形态以不完全桥型(61%)和桥型递减型(26%)为主,初期圆锥角膜组以桥型递增型(40%)和不完全岛型(25%)为主,完成期圆锥角膜组以不完全岛型(33%)和岛型(56%)为主.正常对照组、初期圆锥角膜组、完成期圆锥角膜组角膜最薄点位于顶点颞下方比例分别为81%、86%、76%,最薄点与顶点距离分别为(0.59±0.20)mm、(0.77±0.27)mm、(0.66±0.32)mm,3组比较差异有统计学意义(F=6.903,P<0.01);最薄点偏离顶点颞下方角度分别为:(41.96±17.30)°、(49.14±18.83)°、(49.40±16.77)°,3组比较差异有统计学意义(F=3.112,P<0.05).结论 可疑圆锥角膜患者角膜后表面由不完全桥型向桥型递增型发展,角膜最薄点偏离顶点距离增加要警惕圆锥角膜的可能.%Objective To observe the morphological characteristics of corneal topography in patients with keratoconus using the ALLEGRO Oculyzer for measurements; to provide data for early diagnosis and screening of keratoconus and an analysis of the pathogenesis of keratoconus.Methods This was a retrospective case control study.Sixty-two clinical keratoconus patients (66 eyes),57 subclinical keratoconus patients (57 eyes) and 35 healthy people (70 eyes) were enrolled in this research

  14. Comparative analysis of corneal topography characteristics in primary keratoconus and secondary keratoconus after LASIK%LASIK术后继发圆锥角膜与原发圆锥角膜地形图特征比较

    Institute of Scientific and Technical Information of China (English)

    张阳阳; 隋文婕; 宋鹏; 刘明娜; 陈敏; 高华

    2015-01-01

    目的 分析LASIK术后继发圆锥角膜与原发圆锥角膜的角膜地形图形态学差异,为临床诊断及分析继发圆锥角膜的危险因素提供参考.方法 回顾性病例研究.选取1997年1月至2012年12月在山东省眼科研究所确诊的LASIK术后继发圆锥角膜完成期患者13例(20眼)为继发组,随机选取相同时期某一时间段内确诊的原发圆锥角膜完成期患者18例(25眼)为原发组.原发组与继发组患者的年龄分别为(18.9±2.8)岁(15~28岁)和(24.3±9.1)岁(19~48岁);眼轴平均长度分别为(25.39±1.33)mm(23.3~27.8 mm)和(27.09±2.43)mm(25.3~30.1 mm)(t=3.942,P<0.01).对2组患者的OrbscanⅡ角膜地形图形态学特征进行分析,主要比较2组角膜最溥点位置,角膜前表面最大模拟曲率(Kmax),角膜模拟散光度,角膜中央3 mm区平均曲率及3 mm区散光度,角膜前、后表面距最佳拟合球面距离(Diff值),角膜后表面形态等.对数据进行独立样本t检验、单因素方差分析和Pearson相关分析.结果 原发组角膜最薄点在4个象限的分布为颞下18眼(72%)、颞上4眼(16%)、鼻下1眼(4%)和鼻上2眼(8%),继发组为颞下8眼(40%)、颞上4眼(20%)、鼻下4眼(20%)、鼻上4眼(20%).原发组和继发组角膜模拟散光度分别为(5.85±3.26)D和(3.95±2.51)D(t=-2.142,P<0.05);3 mm区散光度分别为(4.12±2.11)D和(2.82±1.50)D(t=-2.187,P<0.05);2组患者后表面形态差异无统计学意义(P>0.05).结论 继发圆锥角膜地形图形态较原发圆锥角膜相对规则,角膜散光度小.角膜最薄点分布均匀且靠近角膜中央,提示角膜中央过多切削可能是继发圆锥角膜发生的危险因素.%Objective To analyze the difference in corneal topography between primary keratoconus and secondary keratoconus after LASIK; to provide a reference for the clinical diagnosis and analysis of risk factors in secondary keratoconus.Methods In this retrospective case analysis,13

  15. Corneal Abrasions

    Science.gov (United States)

    ... and lead to a serious condition called a corneal ulcer . That's why it's important to see a doctor to get a corneal abrasion checked out. What Causes a Corneal ... and land on your cornea, tears help to wash the particles away. Sometimes, ...

  16. 角膜塑形术前后角膜地形图与角膜曲率计一致性研究%Consistency study between corneal topography and keratometer during orthokeratology

    Institute of Scientific and Technical Information of China (English)

    朱梦钧; 瞿小妹; 冯浩雁

    2012-01-01

    目的 比较角膜塑形术前后EyeSys角膜地形图系统与角膜曲率计测量角膜屈光力与散光轴向的差异.方法 对进行角膜塑形术治疗的321例患者在术前及术后1d、术后1个月分别进行角膜地形图及角膜曲率计的检查,对两种方法所测得的水平子午线角膜屈光力(HK)、垂直子午线屈光力(VK)、角膜散光及轴向进行比较.结果 角膜塑形术前、术后1d、术后1个月,角膜地形图仪测量的HK值分别为(43.25±1.16)D、(42.88±1.18)D、(42.79±1.87)D,较角膜曲率计测量的HK值分别高0.20D、0.39 D、0.40D,差异均有显著统计学意义(均为P<0.01).角膜地形图仪测量的VK值分别为(44.39±1.33)D、(43.96±1.33)D、(43.02±1.64)D,较角膜曲率计测量的VK值高0.13D、0.32 D、0.73 D,差异均有显著统计学意义(均为P<0.01).角膜地形图仪测得角膜散光值均较角膜曲率计小,术前、术后1d、术后1个月分别小0.06D、0.10D、0.40D.术后两种方法测量HK、VK、角膜散光及散光轴向之间的差异逐渐增大(P<0.01),并且两种方法的轴向差异朝着逐渐变大的方向分布.但两种方法对顺规及非顺规散光的检出率差异均无统计学意义(均为P>0.05).结论 EyeSys角膜地形图系统可以更全面及准确地了解角膜塑形术过程中的角膜情况,故临床上应以角膜地形图的结果作为主要依据,角膜曲率计的结果仅可以作为参考.%Objective To evaluate the difference of comeal power and astigmatism axis measured by EyeSys corneal topography and keratometer during orthokeratology. Methods Three hundreds and twenty-one cases underwent orthokeratology performed the examination of comeal topography and keratometer at pre-operation and postoperative 1 day, 1 month, the horizontal meridian power magnitude ( HK), vertical meridian power magnitude (VK), corneal astigmatism magnitude and its axis measured by two instruments were compared. Results At pre-operation and

  17. A novel Hartman Shack-based topography system: repeatability and agreement for corneal power with Scheimpflug+Placido topographer and rotating prism auto-keratorefractor.

    Science.gov (United States)

    Prakash, Gaurav; Srivastava, Dhruv; Choudhuri, Sounak

    2015-12-01

    The purpose of this study is to analyze the repeatability and agreement of corneal power using a new Hartman type topographer in comparison to Scheimpflug+Placido and autorefractor devices. In this cross sectional, observational study performed at the cornea services of a specialty hospital, 100 normal eyes (100 consecutive candidates) without any previous ocular surgery or morbidity except refractive error were evaluated. All candidates underwent three measurements each on a Full gradient, Hartman type topographer (FG) (iDesign, AMO), Scheimpflug+Placido topographer (SP) (Sirius, CSO) and rotating prism auto-keratorefractor (AR) (KR1, Nidek). The parameters assessed were flat keratometry (K1), steep keratometry (K2), steep axis (K2 axis), mean K, J 0 and J 45. Intra-device repeatability and inter-device agreement were evaluated. On repeatability analysis, the intra-device means were not significantly different (ANOVA, p > 0.05). Intraclass correlations (ICC) were >0.98 except for J 0 and J 45. In terms of intra-measurement standard deviation (Sw), the SP and FG groups fared better than AR group (p 0.05, R (2) 0.05). ICC ranged from 0.92 to 0.99 (p < 0.001). Regression fits on Bland-Altman plots suggested no clinically significant effect of average values over difference in means. The repeatability of Hartman type topographer in normal eyes is comparable to SP combination device and better than AR. The agreement between the three devices is good. However, we recommend against interchanging these devices between follow-ups or pooling their data.

  18. Central Corneal Thickness Measurement Using Ultrasonic Pachymetry, Rotating Scheimpflug Camera, and Scanning-slit Topography Exclusively in Thin Non-keratoconic Corneas

    Science.gov (United States)

    Mohammadpour, Mehrdad; Mohammad, Kazem; Karimi, Nasser

    2016-01-01

    Purpose: To evaluate the agreement among Pentacam, Orbscan and ultrasound (US) pachymetry for measurement of central corneal thickness (CCT) in thin corneas with normal topographic pattern. Methods: We included 88 eyes of 44 refractive surgery candidates with thinnest pachymetric readings of 500 micrometers (μm) or less on Orbscan, a normal topographic pattern, no sign of keratoconus, and best corrected visual acuity (BCVA) of 20/20. Pentacam, Orbscan and US were performed in one session by the same examiner. Exclusion criteria were history of ocular surgery, topographic abnormalities suggesting forme fruste keratoconus or keratectasia, and recent contact lens wear. Results: The difference in CCT measurements by US pachymetry and Orbscan II [using an acoustic factor (AF) of 0.92] ranged from −34 to +34 μm. The difference between the thinnest point and central readings measured by US reached 16 μm with Orbscan II (AF: 0.92) and 2 μm with Pentacam. Mean differences between the employed devices were 0.2 μm for Pentacam versus US (P = 0.727), 30.1 μm for uncorrected Orbscan versus US (P < 0.001), 10.4 μm for Orbscan II (AF = 0.92) versus US (P < 0.001), and 0.2 μm for Orbscan II (AF = 0.94) versus US (P = 0.851). Conclusion: In normal thin corneas, Pentacam demonstrated better agreement with US pachymetry as compared to corrected Orbscan readings. Results achieved by Orbscan were better consistent with US pachymetry using an AF of 0.94. We speculate that a dynamically graded AF in reverse proportion to CCT constitutes a better approach for correcting Orbscan measurements. PMID:27621779

  19. A comparison of the differences in astigmatism used by corneal topography,retinoscopy and subjective refraction%角膜地形图和主客观验光测量散光度数及轴位的对比观察

    Institute of Scientific and Technical Information of China (English)

    杨培星; 刘才远; 丁连娥; 郑纯; 吴静

    2016-01-01

    Objective To compare the differences in astigmatism obtained by corneal topography,retinoscopy and subjective refraction in the preoperative examination of excimer laser surgery.Methods A comparison was made through the methods of corneal topography by SCHWIN,cycloplegic retinoscopy and subjective refraction in 123 patients with 195 eyes with simple and compound astigmatism.Re-sults The value of corneal astigmatism measured by corneal topography,retinoscopy and subjective refraction was mainly between-0.5 and -2.0 D.Between the corneal topography method and retinoscopy there was a statistically significant difference in the power of astigmatism (P =0.000)while there was no significant difference in the axis of astigmatism (P =0.459).The corneal topography, compared with subjective refraction,showed statistically significant difference in the power of astigmatism (P =0.000)and no signifi-cant difference in the axis (P =0.355).The retinoscopy,compared with subjective refraction,did not show statistically significant differences in the power of astigmatism and its axis (P =0.144,P =0.653,respectively).Conclusions Examination of corneal topog-raphy in the preoperative refractive surgery with excimer laser is decisive in calculating the axis of corneal astigmatism,and combined with retinoscopy and subjective refraction it can determine the final value.%目的:比较分析角膜地形图、检影验光及主觉验光三种方法在准分子激光术前检查测得散光度数和轴位的差异与关系。方法采用计算机辅助的角膜地形图法、带状光散瞳检影验光及主觉验光三种测量方法对123例195只非混合性散光进行检查并比较。结果(1)检影验光、主觉验光和角膜地形图法测得散光主要分布在-0.5~-2.0 D,三种方法测得散光主要为顺规散光。(2)角膜地形图法与检影验光相比,散光度数差异有统计学意义(P =0.000),轴向差异无统计学意义(P =0

  20. Técnicas para facilitar o diagnóstico da topografia da córnea in vivo Techniques for facilitating in vivo corneal topography diagnosis

    Directory of Open Access Journals (Sweden)

    Luis Alberto Vieira de Carvalho

    2005-04-01

    videokeratograph developed in our laboratory was used to collect in vivo data. The cornea of a patient with keratoconus was used as input data for all implemented visualization methods. RESULTS: The various methods of visualization were compared between each other for the same cornea and it was observed that for each method the corneal anomalies appear differently. DISCUSSION: The aspects related to the scientific visualization of the cornea have been a subject of very little attention both by the Brazilian and international community. Nevertheless, with the results presented in this first study, we believe it is not only important to extend the scope of these studies but also to apply these techniques to other medical areas. CONCLUSION: A simple choice of the visualization method can make the difference between a simple and correct diagnosis and a completely dramatic error in an apparently simple case. Therefore, the results obtained in this study make clear the importance of making the correct choice of the scientific visualization method for this kind of medical instrument.

  1. 超声角膜测厚仪和角膜地形图测量LASIK前后的角膜厚度%A comparison of ultrasonic corneal thickness measurement and corneal topography in the measurement of central corneal thickness before and after LASIK

    Institute of Scientific and Technical Information of China (English)

    刘磊; 李新宇

    2001-01-01

    Objective:To compare corneal thickenss value before and after LASIK operation with two different measurement.Methods:JEMED/EGH 4000 ultrosonic corneal thickness measurement and Orbscan-Ⅱ anterior system were used to measure the central corneal thickness one month before and after LASIK.Results:There was no significant difference between the two methods before LASIK(P>0.05),but they had significant difference(P0.05)。术后Orbscan-Ⅱ眼前节分析诊断系统测量中心角膜厚度值低于超声角膜测厚仪,两者比较差异有显著性意义(P<0.05)。结论:LASIK术后,角膜弯曲度、球面性的改变及其设计理论,可能影响角膜地形图的测定结果。对于欠矫病例再手术时,应用两种方法测量角膜厚度,互相参照,为再次手术提供保障。

  2. The comparative study of IOL Master and A ultrasound combined with corneal topography measurement for IOL power%IOLMaster和A超联合角膜地形图测量对人工晶体度数影响的对比分析

    Institute of Scientific and Technical Information of China (English)

    王科华; 王建洲; 蒋剑; 江海波; 夏晓波

    2014-01-01

    Objective To investigate the difference of IOL Master and A-ultrasound combined with corneal topography meas-urement in intraocular lens ( IOL) power calculation .Methods A total of 84 eyes of 60 cataract patients received phacoemulsification and intraocular lens implantation surgery were selected in Xiangya Hospital from March 2010 to September 2011.There were 57 eyes of 42 age-related cataract patients and 27 eyes of 18 complicated cataract patients .The patients were divided into IOL Master group and A ultrasound combined with corneal topography measurement group .Before surgery , in IOL Master group , axial length ( AL) and corneal curvature were measured with IOL Master , IOL power was calculated according to the Haigis , SRK/T formula and so on.At the same time the axial length ( AL) and corneal curvature were measured with A ultrasound combined with corneal topography respectively and IOL power was calculated by SRK/Ⅱ formula.In A ultrasound combined with corneal topography measurement group , axial length ( AL) and corneal curvature were measured with A ultrasound combined with corneal topography respectively , IOL power was calculat-ed according to the SRK/Ⅱformula.3 months postoperatively , all the patients were conducted refractive outcome and calculating mean absolute refractive error(MAE).Finally the data were analysed.Results ⑴In IOL Master group, before operation there was no sig-nificant difference in mean axial length between IOL Master and A-ultrasound measurement ( P >0.05 ) , while in the patients with AL>26 mm the axial length was (28.53 ±0.57)mm and (29.42 ±0.64)mm using IOL Master and A-ultrasound measurement respec-tively ( P <0.05).The mean corneal curvature was (42.12 ±0.31)D and (43.09 ±0.27)D using IOL Master and corneal topogra-phy measurement respectively ( P <0.01).The mean IOL power were (17.06 ±0.48)D and (16.37 ±0.56)D in IOL Master group and A ultrasound combined with corneal topography measurement group respectively

  3. Corneal Laceration

    Science.gov (United States)

    ... drugs. These drugs thin the blood and may increase bleeding. After you have finished protecting the eye, see a physician immediately. Next Corneal Laceration Symptoms Related Ask an Ophthalmologist Answers I lost sight from a corneal scar as a child. Now that I’m older, ...

  4. Corneal Laceration

    Medline Plus

    Full Text Available ... Tips & Prevention News Ask an Ophthalmologist Patient Stories Español Eye Health / Eye Health A-Z Corneal Laceration ... Laceration Treatment What Is Corneal Laceration? Leer en Español: ¿Qué Es una Laceración de la Córnea? Written ...

  5. Corneal Laceration

    Medline Plus

    Full Text Available ... Health Find an Ophthalmologist Academy Store Eye Health A-Z Symptoms Glasses & Contacts Tips & Prevention News Ask ... Ophthalmologist Patient Stories Español Eye Health / Eye Health A-Z Corneal Laceration Sections What Is Corneal Laceration? ...

  6. Corneal Laceration

    Medline Plus

    Full Text Available ... Health Find an Ophthalmologist Academy Store Eye Health A-Z Symptoms Glasses & Contacts Tips & Prevention News Ask ... Ophthalmologist Patient Stories Español Eye Health / Eye Health A-Z Corneal Laceration Sections What Is Corneal Laceration? ...

  7. Resultados preliminares de um sistema de topografia de grande-ângulo usando videoceratógrafo com discos de Plácido Preliminary results of a wide-angle corneal topography system for Placido-based videokeratographers

    Directory of Open Access Journals (Sweden)

    Luis Alberto Vieira de Carvalho

    2008-04-01

    Full Text Available OBJETIVO: Desenvolver a instrumentação e o "software" para topografia de córnea de grande-ângulo usando o tradicional disco de Plácido. O objetivo é permitir o mapeamento de uma região maior da córnea para topógrafos de córnea que usem a técnica de Plácido, fazendo-se uma adaptação simples na mira. MÉTODOS: Utilizando o tradicional disco de Plácido de um topógrafo de córnea tradicional, 9 LEDs (Light Emitting Diodes foram adaptados no anteparo cônico para que o paciente voluntário pudesse fixar o olhar em diferentes direções. Para cada direção imagens de Plácido foram digitalizadas e processadas para formar, por meio de algoritmo envolvendo elementos sofisticados de computação gráfica, um mapa tridimensional completo da córnea toda. RESULTADOS: Resultados apresentados neste trabalho mostram que uma região de até 100% maior pode ser mapeada usando esta técnica, permitindo que o clínico mapeie até próximo ao limbo da córnea. São apresentados aqui os resultados para uma superfície esférica de calibração e também para uma córnea in vivo com alto grau de astigmatismo, mostrando a curvatura e elevação. CONCLUSÃO: Acredita-se que esta nova técnica pode propiciar a melhoria de alguns processos, como por exemplo: adaptação de lentes de contato, algoritmos para ablações costumizadas para hipermetropia, entre outros.PURPOSE: To develop the instrumentation and software for wide-angle corneal topography using a Placido-based videokeratographer. The objective is to allow the measurement of a greater area of the cornea using a simple adaptation to the Placido mire. METHODS: Using the traditional Placido disc of a commercial corneal topographer, 9 LEDs (Light Emitting Diodes were installed on the conic mire so that the voluntary patient could gaze in different directions. For each direction Placido images were acquired and processed to form, using a sophisticated computer graphics algorithm, a tridimensional

  8. Changes on the corneal thickness and curvature after orthokeratology

    Science.gov (United States)

    Mitsui, Iwane; Yamada, Yoshiya

    2004-07-01

    To evaluate the corneal thickness and curvature changes after Orthokeratology contact lens wear, using the ORBSCAN II corneal topography system, corneal thickness and corneal curvature were measured on one hundred and twenty eyes of sixty patients before and after wearing the custom rigid gas permeable contact lenses for Orthokeratology. The contact lenses were specially designed for each eye. The subjects wore the orthokeratology lenses for approximately Four hours with their eyes closed. The corneal thickness of the subjects was increased on fifty-five eyes at not only the peripheral zone but also the center of the cornea. The average increase of central and peripheral corneal thickness was 18 micrometer and 22micrometer, respectively. The mean anterior curvature of corneal surface changed 1.25D. The mean posterior curvature of corneal endothelium side changed 0.75D.

  9. The Study of Corneal Topography Feature Extraction Method Based on Morphology%基于形态学的角膜地形图特征提取方法研究

    Institute of Scientific and Technical Information of China (English)

    郭雁文

    2015-01-01

    This paper puts forward a new retrieval algorithm of corneal topography features based on morphology .Firstly ,eccentricity is calculated by use of regional image to self‐adapt and locate the center of concentric circles ,with which as polar point the image is transferred into po‐lar coordinates ,where morphological small scale square structure operator and black TOP‐HAT T ransformation are used to get rid of noises and get filtered image .Secondly ,corrosion images of point pairs with fixed distance in a given direction are used to figure out main directions of fabric texture lines according to direction strength ,in which effective linear features are extracted by o‐pening operation .Finally ,closing operation is used to make up for the lost data caused by inner eyelashes ,obtaining a complete image for ring edge detection .Experiments show that the algo‐rithms meet the needs of precisely calculating parameters ,with the characteristics of less data loss ,higher data accuracy and easier availability .%提出了一种新的角膜地形图像特征提取算法。首先利用区域图像计算偏心率,用自适应确定同心圆的圆心,以此为极点将图像转至极坐标域,利用形态学的小尺度方形结构算子及图像的黑TOP‐HAT 变换补得到去除噪声后的滤波图像;其次利用给定方向上相距固定距离的点对腐蚀图像,按照方向强度确定出纹理直线的主要方向,利用开运算提取有效的线形特征;最后利用闭运算,对因内睫毛影响而损失的数据进行有效弥补,获得圆环边缘检测完整的结果图像。经多幅实验数据证明,该算法满足后续参数精确计算的要求,具有数据损失小,数据精度高,算法易实现的特点。

  10. Corneal collagen cross-linking

    Directory of Open Access Journals (Sweden)

    Jankov II Mirko

    2010-01-01

    Full Text Available Corneal collagen cross-linking (CXL with riboflavin and ultraviolet-A (UVA is a new technique of corneal tissue strengthening by using riboflavin as a photosensitizer and UVA to increase the formation of intra- and interfibrillar covalent bonds by photosensitized oxidation. Keratocyte apoptosis in the anterior segment of the corneal stroma all the way down to a depth of about 300 microns has been described and a demarcation line between the treated and untreated cornea has been clearly shown. It is important to ensure that the cytotoxic threshold for the endothelium has not been exceeded by strictly respecting the minimal corneal thickness. Confocal microscopy studies show that repopulation of keratocytes is already visible 1 month after the treatment, reaching its pre-operative quantity and quality in terms of functional morphology within 6 months after the treatment. The major indication for the use of CXL is to inhibit the progression of corneal ectasias, such as keratoconus and pellucid marginal degeneration. CXL may also be effective in the treatment and prophylaxis of iatrogenic keratectasia, resulting from excessively aggressive photoablation. This treatment has also been used to treat infectious corneal ulcers with apparent favorable results. Combination with other treatments, such as intracorneal ring segment implantation, limited topography-guided photoablation and conductive keratoplasty have been used with different levels of success.

  11. Differences between real and predicted corneal shapes after aspherical corneal ablation

    Science.gov (United States)

    Anera, Rosario G.; Villa, César; Jiménez, José R.; Gutiérrez, Ramón; Jiménez del Barco, Luis

    2005-07-01

    We study the differences between real and expected corneal shapes, using an aspherical ablation algorithm with a known equation and avoiding the limitation imposed by most studies of refractive surgery in which the ablation equations are not known. We have calculated the theoretical corneal shape predicted by this algorithm, comparing this shape with the real corneal topography. The results indicate that the deviations that appear in the corneal shape are significant for visual performance and for the correction of eye aberrations. If we include in this analysis the effect of reflection losses and nonnormal incidence on the cornea, we can reduce corneal differences, but they will remain significant. These results confirm that it is essential to minimize corneal differences to achieve effective correction in refractive surgery.

  12. Corneal Laceration

    Medline Plus

    Full Text Available ... from Laundry Packets On the Rise Jun 30, 2017 People with Advanced Keratoconus May Have A Future Alternative to Full Corneal Transplantation Nov 29, 2016 Combating Eye Injuries from Air Guns Aug 30, ...

  13. Corneal transplant

    Science.gov (United States)

    ... lenses to achieve the best vision. Laser vision correction may be an option if you have nearsightedness, ... Editorial team. Related MedlinePlus Health Topics Corneal Disorders Refractive Errors Browse the Encyclopedia A.D.A.M., Inc. ...

  14. Corneal Laceration

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    Full Text Available ... Pediatric Ophthalmology Education Center Oculofacial Plastic Surgery Center Laser Surgery Education Center Redmond Ethics Center Global Ophthalmology Guide ... What Is Corneal Laceration? Leer en Español: ¿Qué ...

  15. Corneal Laceration

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    Full Text Available ... itself. A corneal laceration is a very serious injury and requires immediate medical attention to avoid severe ... Dangerous for Your Eyes Sep 20, 2017 Eye Injuries from Laundry Packets On the Rise Jun 30, ...

  16. Corneal Laceration

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    Full Text Available ... itself. A corneal laceration is a very serious injury and requires immediate medical attention to avoid severe ... 27, 2015 Dark Spot in Vision After Blunt Trauma Dec 21, 2014 Pain a Year After Eyelid ...

  17. Corneal Laceration

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    Full Text Available ... itself. A corneal laceration is a very serious injury and requires immediate medical attention to avoid severe ... and preserving your vision. Privacy Policy Related Eye Injuries from Laundry Packets On the Rise Jun 30, ...

  18. Corneal Laceration

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    Full Text Available ... 2017 People with Advanced Keratoconus May Have A Future Alternative to Full Corneal Transplantation Nov 29, 2016 Combating Eye Injuries from Air Guns Aug 30, ... Public & Patients: Contact Us About ...

  19. Corneal Laceration

    Medline Plus

    Full Text Available ... by something sharp flying into the eye. It can also be caused by something striking the eye ... If the corneal laceration is deep enough it can cause a full thickness laceration. This is when ...

  20. Corneal Laceration

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    Full Text Available ... Pediatric Ophthalmology Education Center Oculofacial Plastic Surgery Center Laser Surgery Education Center Redmond Ethics Center Global Ophthalmology Guide ... What Is Corneal Laceration? Written By: Daniel Porter ...

  1. Corneal Laceration

    Medline Plus

    Full Text Available ... By: Devin A Harrison MD Sep. 01, 2017 The cornea is the clear front window of the eye . A corneal laceration is a cut on the cornea. It is usually caused by something sharp ...

  2. Corneal Laceration

    Medline Plus

    Full Text Available ... itself. A corneal laceration is a very serious injury and requires immediate medical attention to avoid severe ... 27, 2015 Dark Spot in Vision After Blunt Trauma Dec 21, 2014 Pain a Year After Eyelid ...

  3. 角膜地形图引导和非球面切削LASIK术后视觉质量问卷分析%Questionnaire analysis of visual quality after corneal topography guided and aspherical cutting laser in situ keratomileusis

    Institute of Scientific and Technical Information of China (English)

    闻华明; 李海祥

    2011-01-01

    Objective To analyze the questionnaire of visual quality after com puter assisted corneal topography guide optimized refractive keratectomy ( ORK-CAT) and the comeal aspherical cutting optimized refractive keratectomy( ORK-Aph) excimer laser in situ keratomileusis ( LASIK) . Methods One hundred and thirty-three patients ( 257 eyes) from the myopia laser treatment center of the Affiliated Hospital of Zunyi Medical College were measured and randomly divided into three groups,in which 35 ca ses( 69 eyes) were received routine LASIK ( convention group) ,51 cases(98 eyes) re ceived ORK-CAT personality LASIK( ORK-CAT group) , another 47 cases ( 90 eyes) re ccived ORK-Aph personality LASIK ( ORK-Aph group). The subjective visual quality questionnaire ( SVQ) was designed and carried out at 1 week,1 month and 3 months af ter operation,the svo included the night vision satisfaction and visual quality complaint scores( visual vague, glare, halation, diplopia, blurred night vision) . Results SVQ showed there was statistical difference in night vision satisfaction among three groups at 1 week , 1 month and 3 months after operation( all P < 0. 05 ) , and there was also sta tistical difference in visual quality complaint scores among three groups at 1 month and 3 months after operation( all P< 0. 05 ) , the ORK-CAT group and ORK-Aph group were better than the convention group ( both P < 0. 05 ) , the night vision satisfaction and visual quality complaint scores of ORK-CAT group at 3 months after operation were 79. 14 and 50. 62 , which were better than 69. 20 and 65. 28 0f ORK-Aph group ( both P < 0. 05 ) . At lower myopia , there was no statistical difference in the mean rank of visual quality complaint scores and night vision satisfaction among three goups( P > 0. 05 ) ; At medium myopia,the mean rank of ORK-CAT group( 25 cases) were superior than that of ORK-Aph group ( 23 cases) and conventional group ( 1 3 cases) in visual quality complaint, scores and night vision

  4. Corneal Topographical Changes Flollowing Strabismus Surgery

    Institute of Scientific and Technical Information of China (English)

    MaiGH; WangZ

    1999-01-01

    Purpose:To study corneal topographical changes after strabismus surgery.Methods:Computer-aided corneal topography was used in 43 strabismus patients(45 eyes)one or two days prior to and six or seven ays after strabismus surgery.The spherical and cylindrical equivalents were calculated based on the simulated keratometry.Results:After the surgery,only the changes at 3mm in the inferior quadrant were statistically significant.The changes at 3mm in the rest quadrants and the changes at 7mm were no significant.Significant changes in spherical equivalent were found post-operatively.neither the horizontal nor the verical meridional equivalent showed significant changes after surgery.Conclusions:The results of corneal topographical changes following strabismus surgery in our preliminary study indicated the little effect of strabismus surgery on corneal curvature and corneal astigmatism.

  5. Analysis of corneal morphologic and pathologic changes in early-stage congenital aniridic keratopathy

    Science.gov (United States)

    Du, Juan; Liu, Rong-Qiang; Ye, Lei; Li, Zhi-Hui; Zhao, Feng-Tu; Jiang, Nan; Ye, Lin-Hong; Shao, Yi

    2017-01-01

    AIM To determine typical corneal changes of congenital aniridic keratopathy (CAK) using corneal topography and confocal systems, and to identify characteristics that might assist in early diagnosis. METHODS Patients with CAK and healthy control subjects underwent detailed ophthalmic examinations including axial length, corneal thickness, tear film condition, corneal topography, and laser-scanning in vivo confocal microscopy (IVCM). RESULTS In early stage aniridic keratopathy, Schirmer I test (SIT), break-up time (BUT), mean keratometry (mean K) and simulated keratometry (sim K) were reduced relative to controls (Pcorneal astigmatism (sim A) and corneal thickness were increased (Pcorneal morphology in borderline situations can be useful to confirm the diagnosis of CAK. PMID:28393028

  6. LASIK for correcting irregular astigmatism and asymmetrical astigmatism guided by corneal topography%角膜地形图引导下准分子激光矫正角膜不规则散光及不对称性散光

    Institute of Scientific and Technical Information of China (English)

    吴震; 荆翠红; 韩九娥; 蔡娟娟; 李水仙; 王运红; 吴化宇

    2012-01-01

    目的 探讨角膜地形图引导下准分子激光个性化切削手术矫正角膜不规则散光及不对称性散光的效果和优缺点.方法 应用MEL - 70准分子激光仪及配套TOMEY -Ⅲ角膜地形图引导个性化切削系统进行准分子激光原位角膜磨镶术(LASIK)矫正不对称性或不规则角膜散光复性近视散光58例108眼.其中49例97眼为初次手术;另9例11眼为二次手术,系由不均匀切削、偏心切削或中央岛而形成的不规则散光.术前最佳矫正视力均值0.98±0.32;屈光度:球镜平均(-4.59±1.68)D,柱镜平均(-1.62±0.78)D.结果 108眼手术均顺利完成,无术中或术后并发症.术后角膜地形图显示:角膜中央3 mm切削深度平整、均匀,术后1周平均裸眼视力1.03 ±0.29.屈光度:球镜-0.50~+0.75D,平均(-0.35 ±0.29)D,柱镜0~- 0.75D,平均(-0.38 ±0.24)D.结论 TOMEY -Ⅲ角膜地形图捕捉角膜曲率信息准确,引导准分子激光个性化切削程序设计合理,系统安全可靠.用它来进行个性化LASIK可较为精确地矫正角膜不规则及不对称散光.%Objective To discuss the effect of laser in situ keratomileusis (LASIK) for correcting irregular astigmatism and asymmetrical astigmatism guided by corneal topographic map.Methods There were 58 cases( 108 eyes) with compound myopic astigmatism,asymmetric or irregular corneal astigmatism accepted LASIK under MEL- 70 excimer laser that guided by TOMEY-Ⅲ corneal topography.49 patients (97 eyes) received their first operation on the eye.9 patients ( 11 eyes) with irregular astigmatism due to uneven cutting,eccentric cutting or central island received the second operation on the same eye.The preoperative best corrected visual acuity was on average of 0.98 ± 0.32,Sphere ( - 4.59 ± 1.68 ) D,Cylinder ( - 1.62 ± 0.78) D.Results 108 operations were successfully finished without intraoperative or postoperative complications.Corneal topography showed the centra 3 mm cutting was depth uniform

  7. Polar Value Analysis of Corneal Astigmatism in Intrastromal Corneal Ring Segment Implantation

    Science.gov (United States)

    Rho, Chang Rae; Kim, Min-Ji

    2016-01-01

    Purpose. To evaluate surgically induced astigmatism (SIA) and the average corneal power change in symmetric intrastromal corneal ring segment (ICRS) implantation. Methods. The study included 34 eyes of 34 keratoconus patients who underwent symmetric Intacs SK ICRS implantation. The corneal pocket incision meridian was the preoperative steep meridian. Corneal power data were obtained before and 3 months after Intacs SK ICRS implantation using scanning-slit topography. Polar value analysis was used to evaluate the SIA. Hotelling's trace test was used to compare intraindividual changes. Results. Three months postoperatively, the combined mean polar value for SIA changed significantly (Hotelling's T2 = 0.375; P = 0.006). The SIA was 1.54 D at 99° and the average corneal power decreased significantly by 3.8 D. Conclusion. Intacs SK ICRS placement decreased the average corneal power and corneal astigmatism compared to the preoperative corneal power and astigmatism when the corneal pocket incision was made at the preoperative steep meridian. PMID:27795856

  8. Polar Value Analysis of Corneal Astigmatism in Intrastromal Corneal Ring Segment Implantation

    Directory of Open Access Journals (Sweden)

    Chang Rae Rho

    2016-01-01

    Full Text Available Purpose. To evaluate surgically induced astigmatism (SIA and the average corneal power change in symmetric intrastromal corneal ring segment (ICRS implantation. Methods. The study included 34 eyes of 34 keratoconus patients who underwent symmetric Intacs SK ICRS implantation. The corneal pocket incision meridian was the preoperative steep meridian. Corneal power data were obtained before and 3 months after Intacs SK ICRS implantation using scanning-slit topography. Polar value analysis was used to evaluate the SIA. Hotelling’s trace test was used to compare intraindividual changes. Results. Three months postoperatively, the combined mean polar value for SIA changed significantly (Hotelling’s T2=0.375; P=0.006. The SIA was 1.54 D at 99° and the average corneal power decreased significantly by 3.8 D. Conclusion. Intacs SK ICRS placement decreased the average corneal power and corneal astigmatism compared to the preoperative corneal power and astigmatism when the corneal pocket incision was made at the preoperative steep meridian.

  9. Corneal Transplantation

    DEFF Research Database (Denmark)

    Hjortdal, Jesper Østergaard

    Corneal transplantation has been performed for more than 100 years. Until 15 years ago the state-of-the art type of transplantation was penetrating keratoplasty, but since the start of this millennium, newly designed surgical techniques have developed considerably. Today, the vast majority of ker...

  10. Corneal Laceration

    Medline Plus

    Full Text Available ... Tips & Prevention News Ask an Ophthalmologist Patient Stories Español Eye Health / Eye Health A-Z Corneal Laceration ... After Eyelid Scratch Jul 28, 2014 Leer en Español: ¿Qué Es una Laceración de la Córnea? Find ...

  11. Corneal chromoblastomycosis.

    Science.gov (United States)

    Barton, K; Miller, D; Pflugfelder, S C

    1997-03-01

    We sought to illustrate the difficulty in managing uncommon, pigmented mold-related corneal ulceration and to highlight the role of itraconazole in treating these patients. We describe the management and clinical course of a patient with a recurring corneal infection caused by Fonsecaea pedrosoi and discuss this experience in the light of existing literature on management of cutaneous chromoblastomycosis. A corneal ulcer caused by this organism healed initially on treatment with topical and systemic antifungal medication, but infection recurred in the deep stroma 4 months after cessation of therapy. After failure to respond to a further period of medical therapy, a small therapeutic penetrating keratoplasty was performed. Culture of a fibrinous membrane from the anterior iris surface demonstrated intraocular fungal infection, and postoperatively, an episode of marked fibrinous uveitis developed, suggesting the presence of viable intraocular fungal elements. A large penetrating keratoplasty was therefore performed with excision of involved iris in combination with extracapsular cataract extraction. F. pedrosoi was again cultured from the fibrinous membrane adherent to the iris and from the anterior lens capsule. Postoperatively the patient received a 5-month course of systemic itraconazole, and no further recurrences have been encountered after a further 2 months. F. pedrosoi is the organism most commonly isolated from the chronic cutaneous mycosis, chromoblastomycosis, and is relatively resistant to medical therapy. As has been reported for cutaneous disease, surgery in combination with systemic itraconazole may provide the best chance of cure in corneal chromoblastomycosis.

  12. Topography Grid

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC builds and distributes high-resolution, coastal digital elevation models (DEMs) that integrate ocean bathymetry and land topography to support NOAA's mission to...

  13. Topography-guided steep corneal cuts and Toric intraocular lens implantation for correcting astigmatism in cataract patients%角膜地形图引导的陡轴切口和 Toric晶状体治疗白内障合并角膜散光

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    Objective To evaluate the clinical efficacy of topography-guided steep corneal cuts and Toric intraocu-lar lens implantation for the treatment of corneal astigmatism in cataract patients.Methods This is a retrospective obser-vational study.Author enrolled 52 patients (66 eyes) who had cataract and corneal astigmatism.Patients received either to-pography-guided steep corneal cut ( group A;40 patients, 50 eyes) or standard corneal cut with AcrySof Toric IOL implan-tation ( group B;12 patients, 16 eyes) .Uncorrected visual acuity, astigmatism and Toric IOL rotational stability were eval-uated.Results In both groups, postoperative uncorrected visual acuity improved significantly at 1 week, 1 month, and 3 months after surgery ( P <0.05).Astigmatism also significantly reduced in both groups after the surgery ( P <0.05).In group B patients, the largest IOL rotation did not exceed 4°.Conclusion The topography-guided steep corneal cuts and Toric IOL implantation for cataract patients with astigmatism is an easy, safe, and effective treatment.%目的:评估角膜地形图引导的陡轴切口和Toric晶状体对白内障合并角膜散光治疗的临床疗效。方法回顾分析对2013年1月至2014年12月白内障合并角膜散光患者52例(66只眼)A术式术后的裸眼视力、角膜散光情况,B术式术后的裸眼视力、总合散光及Toric晶状体在囊袋内的稳定性。结果 A术式术后各时间点裸眼视力与术前比较提高,术后1周、1个月、3个月与术前相比,散光度均明显减小( P <0);B术式后各时间点裸眼视力均显著高于术前,术后1周、1个月、3个月全部眼总合散光明显改善( P <0),最大IOL旋转度未超过4°。结论角膜地形图引导的陡轴切口和Toric晶状体植入是治疗白内障合并角膜散光易行、安全、有效的治疗方法。

  14. Analysis of corneal topography after Q-value adjusted customize laser in situ keratomileusis for myopia%Q值引导的个体化准分子激光原位角膜磨镶术后角膜地形图分析

    Institute of Scientific and Technical Information of China (English)

    赵向阳; 刘军; 李卫平; 刘晓芳

    2010-01-01

    目的 分析Q值引导的个体化准分子激光原位角膜磨镶术后角膜地形图的动态变化.方法 将94例188只眼接受准分子激光原位角膜磨镶术治疗的近视患者分为两组,47例94只眼行非球面个体化切削作为Ⅰ组;另47例94只眼行标准切削作为Ⅱ组,采用Orbscan Ⅱ角膜地形图仪随访6个月.结果 术后各时间点切削区形态、平均偏中心距离和SimK的变化,两组比较差异无统计学意义(P>0.05),各时间点Q值差异两组比较有统计学意义(P0.05). The significant difference was seen in Q-value between two groups in different time points in post-operation (P<0.05). Q-value was lower in the aspheric group than the standard group. Postoperative average corneal thickness and ablated depth were statistically significant differences (P<0.05). Conclusions Q-value adjusted customize LASIK is safety, efficacy, stable and the physiology of the corneal surface is better maintained than standard treatment. Corneal topography provides a objective method to evaluate the result of operation.

  15. Corneal topographic changes following retinal surgery

    Directory of Open Access Journals (Sweden)

    Pandey RM

    2004-08-01

    Full Text Available Abstract Background To study the effect of retinal/ vitreoretinal surgeries on corneal elevations. Methods Patients who underwent retinal/ vitreoretinal surgeries were divided into 3 groups. Scleral buckling was performed in 11 eyes (Group 1. In 8 (25% eyes, vitreoretinal surgery was performed along with scleral buckling (Group 2. In 12 eyes, pars plana vitrectomy was performed for vitreous hemorrhage (Group 3. An encircling element was used in all the eyes. The parameters evaluated were best-corrected visual acuity (BCVA, change in axial length, and corneal topographic changes on Orbscan topography system II, preoperative and at 12 weeks following surgery. Results There was a statistically significant increase in anterior corneal elevation in all the three groups after surgery (p = 0.003, p = 0.008 & p = 0.003 respectively. The increase in posterior corneal elevation was highly significant in all the three groups after surgery (p = 0.0000, p = 0.0001 & p = 0.0001 respectively. The increase in the posterior corneal elevation was more than the increase in the anterior elevation and was significant statistically in all the three groups (group I: p = 0.02; group II: p = 0.01; group III: p = 0.008. Conclusions Retinal/ vitreoretinal surgeries cause a significant increase in the corneal elevations and have a greater effect on the posterior corneal surface.

  16. RTVue傅里叶光学相干断层扫描仪测量角膜参数的重复性和准确性评价%Repeatability and accuracy of corneal parameters measured by RTVue Fourier-domain optical coherence topography

    Institute of Scientific and Technical Information of China (English)

    华焱军; 黄锦海; 潘超; 王勤美

    2013-01-01

    膜地形图仪略大;RTVue FD-OCT获得的Rposterior/Ranterior比Gullstrand模型眼小,可能为建立更准确的标准化模型眼提供依据.%Background Corneal parameters (such as curvature,thickness,etc) are essential to the diagnosis of corneal related diseases,contact lenses fitting and corneal refractive surgery.Objective The aim of this study was to assess the repeatability and accuracy of corneal parameters obtained by RTVue Fourier-domain optical coherence topography (FD-OCT).Methods In this prospective study,77 eyes of 43 subjects with the refraction from-1.25 D to-10.00 D and astigmatism <2 D were enrolled in keratorefractive surgery center,Eye Hospital of Wenzhou Medical College.The anterior and posterior corneal curvature in 3 mm central zone (Ranterior and Rposterior),the ratio of posterior and anterior curvature (Rposterior/Ranterior),corneal central thickness (CCT),total corneal power(Knet),the simulated corneal power (Sim K),the anterior and posterior corneal power (Kanterior,Kposterior)were measured by FD-OCT.Corneal power (Km) was obtained by Topolyzer topography based on Placido ring.Three consecutive scans were acquired in every tested eye.Repeatability of FD-OCT measurement was assessed using the coefficient of variation CV),Cronbach Alpha and intra-class correlation coefficient (ICC).Repeated measure ANOVA was used to analyze the differences among SimK,Knet and Km.Pearson correlation analysis was used to analysis the correlation between SimK and K Knet and Km,SimK and Km.The agreement between Sim K and K Knet and Km,SimK and Km was assessed by Bland-Altman plots analysis.All the subjects understood the purpose of this investigation and written informed consent was obtained prior to the medical examination.Results The Ranterior,Rposterior,Rposterior/Ranterior,Kanterior,Kposterior,Sim K,Knet and CCT were (7.691 ±0.302) mm,(6.532±0.276) mm,0.849±0.014,(48.97±1.92)D,(-6.13±0.26)D,(43.95±1.72) D,(42.95±1.68) D and (545.20± 35.04) μm,respectively.The CV of all

  17. Feline corneal disease.

    Science.gov (United States)

    Moore, Phillip Anthony

    2005-05-01

    The cornea is naturally transparent. Anything that interferes with the cornea's stromal architecture, contributes to blood vessel migration, increases corneal pigmentation, or predisposes to corneal edema, disrupts the corneas transparency and indicates corneal disease. The color, location, and shape and pattern of a corneal lesion can help in determining the underlying cause for the disease. Corneal disease is typically divided into congenital or acquired disorders. Congenital disorders, such as corneal dermoids are rare in cats, whereas acquired corneal disease associated with nonulcerative or ulcerative keratitis is common. Primary ocular disease, such as tear film instability, adenexal disease (medial canthal entropion, lagophthalmus, eyelid agenesis), and herpes keratitis are associated with the majority of acquired corneal disease in cats. Proliferative/eosinophilic keratitis, acute bullous keratopathy, and Florida keratopathy are common feline nonulcerative disorders. Nonprogressive ulcerative disease in cats, such as chronic corneal epithelial defects and corneal sequestration are more common than progressive corneal ulcerations.

  18. 角膜地形图对准分子激光屈光性手术后屈光回退的预测作用%The Prediction of regression after laser refractive surgery from corneal topography

    Institute of Scientific and Technical Information of China (English)

    陆培荣; 李龙标; 潘承思; 张济明; 张晓峰

    2001-01-01

    ObjectiveTo develop a method to predict the regression after laser refractive surgery from corneal topography.MethodsThe database of 327 eyes(176 patients)who had laser in situ keratomileusis(LASIK)or photorefractive k-eratectomy(PRK)was reviewed.There was correlation between the ratio of the clinical refractive reduction to the corneal refractive reduction(A)and the corneal refractive reduction(X):A=0.0627 X+1.153 4,r=0.602 9,P<0.001.The relationship between clinical refractive change(Y)and corneal refractive change(X)between pre- and post-operation was Y=0.062 7 X2+1.153 4 X.The relation was used to predict the regression in the follow-up.The eye was predicted to be of regression if 0.062 7 X2+1.153 4 X+0.5<the attempt refraction in any time of the follow-up.The results were compared with that of actual regression.Results309 eyes were followed up for more than 6 months,101 eyes were predicted to have regression from corneal topography,and 47 eyes of them were actual regression.There were 59 eyes of regression among 309 eyes.The predictive sensitivity was 79.66%,and the specificity was 78.40%.ConclusionIt may be clinically useful in the prediction of regression after laser refractive surgery from corneal topography.%目的建立根据角膜地形图前表面曲率变化预测准分子激光术后屈光回退的一种方法。方法根据准分子激光术后327眼手术前后角膜地形图角膜前表面曲率变化值X与临床屈光度变化值Y得出两者关系Y=0.062 7 X2+1.153 4 X,随访过程中根据X算出所矫屈光度,若预矫屈光度大于0.062 7 X2+1.153 4 X+0.5,则作为屈光回退患者,与术后实际屈光回退情况进行比较。结果随访观测309眼,实际屈光回退59眼,依本方法预测出回退的101眼中日后实际回退47眼,预测灵敏度79.66%,预测特异度78.40%。结论角膜地形图在准分子激光术后

  19. Equine corneal stromal abscesses

    DEFF Research Database (Denmark)

    Henriksen, M. D. L.; Andersen, P. H.; Plummer, C. E.

    2013-01-01

    The last 30 years have seen many changes in the understanding of the pathogenesis and treatment of equine corneal stromal abscesses (SAs). Stromal abscesses were previously considered an eye problem related to corneal bacterial infection, equine recurrent uveitis, corneal microtrauma and corneal...

  20. Corneal Topographic Analysis in Patients with Cataract

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    We studied the corneal curvature of 161 eyes in 101 patients, aged from 50 to 80 years (mean: 63 years), with senile cataract using the Topographic Modeling System (IMS) preoperatively. The results revealed that mean surface asymmetry index (SAD was 0. 36 and mean surface regularity index (SRI) 0. 79. Simulated keratometry reading (Sim K) was 44. 46 D, and 43. 56 D. Minimun K reading was 42. 60 D. The same patterns of corneal topography in both eyes were 50% in 60 patients who had binocular examination....

  1. Corneal heat scar caused by photodynamic therapy performed through an implanted corneal inlay.

    Science.gov (United States)

    Mita, Mariko; Kanamori, Tomomi; Tomita, Minoru

    2013-11-01

    A 60-year-old man had a combination of laser in situ keratomileusis and Kamra corneal inlay implantation to correct presbyopia. Although the outcome was favorable postoperatively, central serous chorioretinopathy was observed in the left eye along with a decrease in the uncorrected (UDVA) and corrected (CDVA) distance visual acuities and the corrected near visual acuity (CNVA). Photodynamic therapy (PDT) was later performed in a university hospital. After PDT, the patient experienced a decline in the visual acuity and came to our clinic a month after the PDT. Degeneration and a scar were observed at the location of the inlay due to the heat and burning. Flattening of the corneal topography was also observed where the corneal scar was located, along with a significant decrease in CDVA in the left eye. Prior to any surgery in which the corneal inlay is an impediment, surgeons should take advantage of the reversibility of the Kamra inlay by explanting the inlay.

  2. ROLE OF CORNEAL COLLAGEN CROSS LINKING IN KERATOCONUS

    OpenAIRE

    Atul; Superna; Bhimasankar; Vijayleela

    2015-01-01

    To evaluate the outcome of collagen cross linkage using riboflavin 0.1% and ultraviolet A radiation of a wavelength 370nm . PURPOSE : To determine the effect of collagen cross linking for keratoconus on pachymetry , corneal topography, uncorrected visual acuity, specular count, IOP at 1, 3, 6 months . METHODS : The current study was designed as a prospective interventional trial of corneal collagen cross - linking in subjects w...

  3. Uso da topografia de córnea na adaptação de lente de contato rígida gás-permeável em pacientes portadores de ceratocone: descrição de técnica e resultados preliminares Corneal topography for rigid gas permeable lens fitting in keratoconus: technique and preliminary results

    Directory of Open Access Journals (Sweden)

    José Álvaro Pereira Gomes

    2002-09-01

    Full Text Available Objetivo: Apresentar um método prático baseado nos valores topográficos para adaptação de lente de contato rígida gás-permeável (LCRGP em pacientes com ceratocone. Método: Foram estudados 33 olhos de 17 pacientes consecutivos portadores de ceratocone, no período de julho de 1997 a abril de 1999. O exame inicial consistiu de medida da acuidade visual, refração, biomicroscopia e topografia de córnea com o topógrafo computadorizado Eye Sys. As sessões de adaptação foram feitas com lentes de contato de teste, com curva-base selecionada a partir da topografia de córnea. Foi considerada como referência inicial o valor médio de K 1,5 mm superior ao centro óptico de cada olho a 90º. Resultados: A adaptação de lente de contato rígida gás-permeável foi bem sucedida em 30 olhos (91%. Em todos esses casos houve melhora significativa da acuidade visual, que no final variou de 20/20 a 20/60. Para a adaptação inicial, foram necessárias, em média, 3 ± 1 tentativas. Foi realizada readaptação com sucesso em 3 casos (10%. Na maioria dos casos (57%, as lentes pedidas possuíam curva-base com valor mais próximo de K 1,5 mm a 90º em relação a K. Esse achado foi comprovado por análise estatística das medidas individualmente e das médias das diferenças entre as duas medidas topográficas e a curva-base final de lente pedida. Conclusão: A adaptação baseada na topografia de córnea 1,5mm superiormente 90º ao centro óptico mostrou-se rápida e eficaz nos casos de ceratocone.Purpose: To introduce a practical method based on the topographic values for rigid gas-permeable contact lens (RGPCL fitting in keratoconus patients. Methods: Thirty-three eyes of 17 consecutive patients with keratoconus were studied between July 1997 and April 1999. The initial ophthalmologic examination consisted of visual acuity examination, refraction, biomicroscopy, corneal topography with Eye Sys system. The tested contact lenses were selected based

  4. Acute Corneal Hydrops 3 Years after Intra-corneal Ring Segments and Corneal Collagen Cross-linking

    Science.gov (United States)

    Antonios, Rafic; Dirani, Ali; Fadlallah, Ali; Chelala, Elias; Hamadeh, Adib; Jarade, Elias

    2016-01-01

    This case report describes a 15-year-old male with allergic conjunctivitis and keratoconus, who underwent uneventful intra-corneal ring segment (ICRS) implantation and corneal collagen cross-linking (CXL) in the right eye. During the follow-up periods, the patient was noted to have several episodes of allergic conjunctivitis that were treated accordingly. At the 2 years postoperatively, he presented with another episode of allergic conjunctivitis and progression of keratoconus was suspected on topography. However, the patient was lost to follow-up, until he presented with acute hydrops at 3 years postoperatively. There are no reported cases of acute corneal hydrops in cross-linked corneas. We suspect the young age, allergic conjunctivitis and eye rubbing may be a risk factors associated with possible progression of keratoconus after CXL. Prolonged follow-up and aggressive control of the allergy might be necessary in similar cases. PMID:26957859

  5. Analysis of correlation between corneal topographical data and visual performance

    Science.gov (United States)

    Zhou, Chuanqing; Yu, Lei; Ren, Qiushi

    2007-02-01

    Purpose: To study correlation among corneal asphericity, higher-order aberrations and visual performance for eyes of virgin myopia and postoperative laser in situ keratomileusis (LASIK). Methods: There were 320 candidates 590 eyes for LASIK treatment included in this study. The mean preoperative spherical equivalence was -4.35+/-1.51D (-1.25 to -9.75), with astigmatism less than 2.5 D. Corneal topography maps and contrast sensitivity were measured and analyzed for every eye before and one year after LASIK for the analysis of corneal asphericity and wavefront aberrations. Results: Preoperatively, only 4th and 6th order aberration had significant correlation with corneal asphericity and apical radius of curvature (pcorneal asphericity (pcorneal aberrations had no significant correlation with visual acuity and area under the log contrast sensitivity (AULCSF) (P>0.05). Postoperatively, corneal aberrations still didn't have significant correlation with visual acuity (P>0.05), but had significantly negative correlation with AULCSF (PCorneal asphericity had no significant correlation with AULCSF before and after the treatment (P>0.05). Conclusions: Corneal aberrations had different correlation with corneal profile and visual performance for eyes of virgin myopia and postoperative LASIK, which may be due to changed corneal profile and limitation of metrics of corneal aberrations.

  6. Corneal ulcers in horses.

    Science.gov (United States)

    Williams, Lynn B; Pinard, Chantale L

    2013-01-01

    Corneal ulceration is commonly diagnosed by equine veterinarians. A complete ophthalmic examination as well as fluorescein staining, corneal cytology, and corneal bacterial (aerobic) and fungal culture and sensitivity testing are necessary for all infected corneal ulcers. Appropriate topical antibiotics, topical atropine, and systemic NSAIDs are indicated for all corneal ulcers. If keratomalacia (melting) is observed, anticollagenase/antiprotease therapy, such as autologous serum, is indicated. If fungal infection is suspected, antifungal therapy is a necessity. Subpalpebral lavage systems allow convenient, frequent, and potentially long-term therapy. Referral corneal surgeries provide additional therapeutic options when the globe's integrity is threatened or when improvement has not been detected after appropriate therapy.

  7. Acute corneal hydrops during pregnancy with spontaneous resolution after corneal cross-linking for keratoconus: a case report.

    Science.gov (United States)

    Stock, Ricardo Alexandre; Thumé, Thaís; Bonamigo, Elcio Luiz

    2017-02-25

    Keratoconus may progress to acute corneal hydrops even after cross-linking. In some cases, keratoconus progresses during pregnancy. In this report, we present a case of a patient with increased anterior stromal resistance after cross-linking that would favor nonprogression of keratoconus during pregnancy. We report that cross-linking is likely to have had a protective effect in a white pregnant patient with acute corneal hydrops who showed rapid improvement, as documented by corneal topography. Improvement occurred within 8 days, whereas up to 250 days are reported in the literature. No keratoconus progression occurred in the 20-month follow-up period. Cross-linking failed to prevent the occurrence of acute corneal hydrops after rupture of Descemet's membrane but most likely helped to accelerate the resolution of the condition. Corneal hardening resulting from cross-linking may have also contributed to stabilizing keratoconus during pregnancy.

  8. Corneal transplant - discharge

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000243.htm Corneal transplant - discharge To use the sharing features on this page, please enable JavaScript. You had a corneal transplant. Most of the tissue of your cornea (the ...

  9. Comparison and analysis of Orbscan II corneal topography between early keratoconus and myopic%早期圆锥角膜与近视的Orbscan II角膜地形图对比分析

    Institute of Scientific and Technical Information of China (English)

    门洁; 张晓辉; 黄丹; 陈章明

    2015-01-01

    Objective To investigate the cornea topographic characteristics and sensitive indexes of Orbscan II of early keratoconus.Methods By using Orbscan II,a prospective study was performed in 23 cases (43eyes) early kerato-conus and 25 cases (50 eyes) myopia.The results were evaluated and analysed.Results There is no statistically sig-nificance between the two groups of early keratoconus and myopia in age, degree of myopia and astigmatism ( P>0.05).The study discover that there are statistically significance in the thinnest thickness of cornea、diff values of cor-nea anterior surface、diff values of cornea posterior surface、3.0mm Zone Irreg and 5.0mm Zone Irreg between early kera-toconus and myopia ( P<0.05).Co ncluis ons All thinnest corneal thickness,diff values of cornea anterior surface、diff values of cornea posterior surface、3.0mm Zone Irreg appear to be sensitive indexes for diagnosing early keratoconus.%目的:探讨早期圆锥角膜的Orbscan II角膜地形图特点及敏感指标。方法应用Orbscan II研究23例(43只眼)早期圆锥角膜患者和25例(50只眼)近视患者角膜地形图的参数改变特点,并进行统计分析。结果患者年龄、近视度数、散光度数均无统计学差异(P >0.05)。角膜地形图参数中:角膜最薄点厚度、角膜前表面高度、角膜后表面高度、3.0 mm区不规则性(3.0 mm Zone Irreg)、5.0 mm区不规则性(5.0 mm Zone Irreg)在两组之间均有统计学差异( P<0.05)。结论角膜最薄点厚度、角膜前表面高度、角膜后表面高度、3.0 mm区不规则性有助于区分早期圆锥角膜和近视患者,是诊断早期圆锥角膜的敏感地形图指标。

  10. Corneal topographic changes after 20-gauge pars plana vitrectomy associated with scleral buckling for the treatment of rhegmatogenous retinal detachment

    Directory of Open Access Journals (Sweden)

    Alexandre Achille Grandinetti

    2013-04-01

    Full Text Available PURPOSE: To evaluate the changes in corneal topography after 20-gauge pars plana vitrectomy associated with scleral buckling for the repair of rhegmatogenous retinal detachment. METHODS: Twenty-five eyes of 25 patients with rhegmatogenous retinal detachment were included in this study. 20-gauge pars plana vitrectomy associated with scleral buckling was performed in all patients. The corneal topography of each was measured before surgery and one week, one month, and three months after surgery by computer-assisted videokeratoscopy. RESULTS: A statistically significant central corneal steepening (average, 0,9 D , p<0,001 was noted one week after surgery. The total corneal astigmatism had a significant increase in the first postoperative month (p=0,007. All these topographic changes persisted for the first month but returned to preoperative values three months after the surgery. CONCLUSION: Pars plana vitrectomy with scleral buckling was found to induce transient changes in corneal topography.

  11. Assessment of refractive astigmatism and simulated therapeutic refractive surgery strategies in coma-like-aberrations-dominant corneal optics

    National Research Council Canada - National Science Library

    Zhou, Wen; Stojanovic, Aleksandar; Utheim, Tor Paaske

    2016-01-01

    ...) on power and orientation of refractive astigmatism (RA) and to explore how to account for that influence in the planning of topography-guided refractive surgery in eyes with coma-like-aberrations-dominant corneal optics...

  12. Corneal mucus plaques.

    Science.gov (United States)

    Fraunfelder, F T; Wright, P; Tripathi, R C

    1977-02-01

    Corneal mucus plaques adhered to the anterior corneal surface in 17 of 67 advanced cases of keratoconjunctivitis sicca. The plaques were translucent to opaque and varied in size and shape, from multiple isolated islands to bizarre patterns involving more than half the corneal surface. Ultrastructurally, they consisted of mucus mixed with desquamated degenerating epithelial cells and proteinaceous and lipoidal material. The condition may be symptomatic but can be controlled and prevented in most cases by topical ocular application of 10% acetylcysteine.

  13. 2-YEAR EXPERIENCE OF CORNEAL COLLAGEN CROSSLINKING IN KERATOCONUS TREATMENT

    Directory of Open Access Journals (Sweden)

    D. D. Dement’ev

    2015-01-01

    Full Text Available Aim. To assess reliability, efficacy, and stability of corneal collagen crosslinking (CXL results for stage I‑II keratoconus.Patients and methods. 2‑year (2012-2014 results of CXL were analyzed. CXL was performed on 20 eyes of 15 patients (13 men and 2 women, mean age 31 years. Stage 1 keratoconus was diagnosed in 13 eyes, stage 2 keratoconus was diagnosed in 2 eyes. Primary stage 1‑2 keratoconus was diagnosed in 17 eyes, keratoconus after corneal refractive surgery (LASIK, radial keratotomy was diagnosed in 3 eyes. Preoperative and postoperative examination included uncorrected (UCVA and best-corrected (BCVA visual acuity measurement, pachymetry, corneal topography (total astigmatism measurement, and biomicroscopy. Follow-up period varied from 1 to 24 months.Results. All patients reported on vision improvement. Preoperatively, mean UCVA and BCVA were 0.4 and 0.64, respectively. Postoperatively, mean UCVA and BCVA were 0.49 and 0.66, respectively. Preoperatively and postoperatively, total astigmatism was 2.1 D and 2.0 D, respectively, while mean central corneal thickness was 454 μm and 447 μm, respectively.Conclusions. Corneal collagen crosslinking for stage 1‑2 keratoconus provides mild UCVA and BCVA improvement, decrease in total astigmatism and central corneal thickness. CXL provides stable results of treatment of primary stage 1‑2 keratoconus and keratoconus after corneal refractive surgery. 

  14. Silk film topography directs collective epithelial cell migration.

    Directory of Open Access Journals (Sweden)

    Brian D Lawrence

    Full Text Available The following study provides new insight into how surface topography dictates directed collective epithelial cell sheet growth through the guidance of individual cell movement. Collective cell behavior of migrating human corneal limbal-epithelial cell sheets were studied on highly biocompatible flat and micro-patterned silk film surfaces. The silk film edge topography guided the migratory direction of individual cells making up the collective epithelial sheet, which resulted in a 75% increase in total culture elongation. This was due to a 3-fold decrease in cell sheet migration rate efficiency for movement perpendicular to the topography edge. Individual cell migration direction is preferred in the parallel approach to the edge topography where localization of cytoskeletal proteins to the topography's edge region is reduced, which results in the directed growth of the collective epithelial sheet. Findings indicate customized biomaterial surfaces may be created to direct both the migration rate and direction of tissue epithelialization.

  15. Characterization of Corneal Indentation Hysteresis.

    Science.gov (United States)

    Ko, Match W L; Dongming Wei; Leung, Christopher K S

    2015-01-01

    Corneal indentation is adapted for the design and development of a characterization method for corneal hysteresis behavior - Corneal Indentation Hysteresis (CIH). Fourteen porcine eyes were tested using the corneal indentation method. The CIH measured in enucleated porcine eyes showed indentation rate and intraocular pressure (IOP) dependences. The CIH increased with indentation rate at lower IOP ( 25 mmHg). The CIH was linear proportional to the IOP within an individual eye. The CIH was positively correlated with the IOP, corneal in-plane tensile stress and corneal tangent modulus (E). A new method based on corneal indentation for the measurement of Corneal Indentation Hysteresis in vivo is developed. To our knowledge, this is the first study to introduce the corneal indentation hysteresis and correlate the corneal indentation hysteresis and corneal tangent modulus.

  16. Application of corneal tomography before keratorefractive procedure for laser vision correction.

    Science.gov (United States)

    Luz, Allan; Lopes, Bernardo; Salomão, Marcela; Ambrósio, Renato

    2016-05-01

    Ectasia after refractive surgery represents a major concern among refractive surgeons. Corneal abnormalities and preexisting corneal ectasia are the most important risk factors. Corneal topography and central corneal thickness are the factors traditionally screening for in refractive surgery candidates. Study of the anterior surface by Placido topography allows for identification of keratoconus before biomicroscopy. However, this is insufficient for the evaluation of pre-operative refractive surgery. There are cases of ectasia after laser in situ keratomilusis (LASIK) without identifiable risk factors such that there is a need to go beyond the corneal surface. A key requirement is quantifying susceptibility to corneal biomechanical instability and progression to ectasia. Tomographic indices derived from elevation maps and pachymetry spatial variation produce a Belin Ambrosio display final D index (BAD-D index), which has shown better results compared to surface curvature indices for detecting very mild forms of ectasia. A logistic regression formula, integrating age, residual stromal bed, and BAD-D (Ectasia Susceptibility Score, ESS) resulted in a significant improvement in accuracy, leading to 100% sensitivity and 94% specificity for detecting susceptible cases. A comprehensive corneal structural analysis based on corneal segmental tomography can detect susceptible corneas, which increases safety for refractive surgery patients.

  17. Induced astigmatism after diamond burr superficial keratectomy for recurrent corneal erosion.

    Science.gov (United States)

    Yoo, Janie H; Choi, David M

    2009-11-01

    To report a case of induced astigmatism after diamond burr superficial keratectomy (DBSK) for recurrent corneal erosion (RCE). Case report. Review of clinical findings in a 54-year-old women with ocular history of a scleral buckling procedure for a retinal detachment from blunt trauma and phacoemulsification with intraocular lens placement. The patient presented with RCE after trauma with a mascara brush to the OD and was treated with DBSK. Postoperatively, she developed significant astigmatism. In the third postoperative week after the DBSK procedure, the patient reported of worsening vision. On corneal topography, the patient was found to have 4 diopters of induced astigmatism. The astigmatic error was followed closely by serial corneal topography; a gradual decrease in the amount of astigmatism occurred over the course of 30 weeks. Forme fruste keratoconus was suspected in the patient's contralateral eye, based on corneal topographic analysis. Induced corneal astigmatism is a previously undescribed complication that can occur after DBSK. It is unclear whether the induced astigmatism in our patient was caused by the DBSK procedure alone or whether the patient had decompensated structural integrity from forme fruste keratoconus or blunt corneal trauma or both. The authors recommend that corneal topographic analysis be appropriately considered before DBSK for RCE and that corneal astigmatism be seen as a potential complication of the procedure.

  18. Current status of corneal xenotransplantation.

    Science.gov (United States)

    Kim, Mee Kum; Hara, Hidetaka

    2015-11-01

    Corneal allo-transplantation is a well-established technique to treat corneal blindness. However, the limited availability of human donors demands the exploration of alternative treatments such as corneal xenotransplantation (e.g., pigs as donors) and bioengineered corneas. Since the first attempt of corneal xenotransplantation using a donor pig cornea in 1844, great advances have been made in the development of genetically-engineered pigs, effective immunosuppressive protocols and the establishment of guidelines for the conduction of clinical trials. We highlight immunological and physio-anatomical barriers of corneal xenotransplantation, recent progress of corneal xenotransplantation in non-human-primates studies, and regulatory guidelines to conduct clinical trials for corneal xenotransplantation.

  19. Corneal blindness and xenotransplantation.

    Science.gov (United States)

    Lamm, Vladimir; Hara, Hidetaka; Mammen, Alex; Dhaliwal, Deepinder; Cooper, David K C

    2014-01-01

    Approximately 39 million people are blind worldwide, with an estimated 285 million visually impaired. The developing world shoulders 90% of the world's blindness, with 80% of causative diseases being preventable or treatable. Blindness has a major detrimental impact on the patient, community, and healthcare spending. Corneal diseases are significant causes of blindness, affecting at least 4 million people worldwide. The prevalence of corneal disease varies between parts of the world. Trachoma, for instance, is the second leading cause of blindness in Africa, after cataracts, but is rarely found today in developed nations. When preventive strategies have failed, corneal transplantation is the most effective treatment for advanced corneal disease. The major surgical techniques for corneal transplantation include penetrating keratoplasty (PK), anterior lamellar keratoplasty, and endothelial keratoplasty (EK). Indications for corneal transplantation vary between countries, with Fuchs' dystrophy being the leading indication in the USA and keratoconus in Australia. With the exception of the USA, where EK will soon overtake PK as the most common surgical procedure, PK is the overwhelming procedure of choice. Success using corneal grafts in developing nations, such as Nepal, demonstrates the feasibility of corneal transplantation on a global scale. The number of suitable corneas from deceased human donors that becomes available will never be sufficient, and so research into various alternatives, for example stem cells, amniotic membrane transplantation, synthetic and biosynthetic corneas, and xenotransplantation, is progressing. While each of these has potential, we suggest that xenotransplantation holds the greatest potential for a corneal replacement. With the increasing availability of genetically engineered pigs, pig corneas may alleviate the global shortage of corneas in the near future.

  20. Refractive corneal surgery - discharge

    Science.gov (United States)

    Nearsightedness surgery - discharge; Refractive surgery - discharge; LASIK - discharge; PRK - discharge ... You had refractive corneal surgery to help improve your vision. This surgery uses a laser to reshape your cornea. It corrects mild-to-moderate nearsightedness, ...

  1. Equine corneal surgery and transplantation.

    Science.gov (United States)

    Denis, Heidi M

    2004-08-01

    Corneal disease is common in equine ophthalmology and requires vigilant monitoring and appropriate therapy to optimize the outcome. Many equine corneal diseases, particularly those that progress rapidly, may benefit from surgical intervention. These include descemetoceles, deep corneal lacerations and ulcers, corneal perforation/iris prolapse, ulcerative keratitis, corneal stromal abscesses, and corneoscleral neoplasia. Indications for corneal transplantation include optical, tectonic, therapeutic, and cosmetic purposes. Corneal transplantation is most often implemented in equine patients for tectonic and therapeutic reasons when a cornea is compromised by corneal stromal abscess, iris prolapse, or neoplasia. This article provides an outline of when to consider surgical intervention for corneal disease, the procedures available and expected outcomes, and how appropriate early surgical intervention can dramatically improve the end result.

  2. Pilot Study of Corneal Sensitivity and Its Association in Keratoconus.

    Science.gov (United States)

    Mandathara, Preeji S; Stapleton, Fiona J; Kokkinakis, Jim; Willcox, Mark D P

    2017-02-01

    To evaluate corneal sensitivity and its association with other clinical parameters in keratoconus. Twenty-four subjects with keratoconus aged between 18 and 65 years were recruited in this cross-sectional study. Ocular symptoms, corneal topography, tear variables such as tear osmolarity, volume and lower tear meniscus height, ocular surface staining, central sensitivity threshold (CST), and corneal subepithelial nerve mapping were obtained. Association between central CST and other clinical variables was examined using the Spearman correlation coefficient. Partial correlation was performed to control for effects of confounding factors. Data from the most severe eye of each subject were included in analyses. Based on the maximum simulated keratometry (Kmax) reading, subjects were graded as having mild (N = 11; K max ≤ 52 D) or severe (N = 13; K max > 52 D) keratoconus. Central corneal sensitivity was lower (ie, increased CST) in the severe keratoconus group compared with that in the mild keratoconus group (median, interquartile range: 1.09; 0.60-19.66 vs. 0.51; 0.39-1.51 g/mm, P = 0.035). In bivariate correlations, reduced corneal sensitivity in keratoconus was associated with age (ρ = 0.42, P = 0.040), disease duration (ρ = 0.49, P = 0.015) and severity (ρ = 0.44; P = 0.032), lower central nerve fiber density (ρ = -0.68, P = 0.014), contact lens wear (ρ = 0.44; P = 0.025), and contact lens tolerance (ρ = 0.46; P = 0.033). After adjusting for contact lens wear, reduced corneal sensitivity was negatively associated with ocular symptoms (ρ = -0.426, P = 0.048) and pain sensitivity (ρ = -0.423, P = 0.045) and positively associated with corneal staining (ρ = 0.52, P = 0.011). Altered corneal sensitivity in keratoconus affected ocular symptoms and ocular surface health, which may have significant impact on the success of management options for keratoconus.

  3. Central corneal abscess.

    Science.gov (United States)

    van Bijsterveld, O P

    1976-05-01

    Central corneal abscess developed in the experimental animal after inoculation of biologically active staphylococcal strains in a paracentral epithelial lesion of the cornea. These abscesses did not ulcerate, developed only with high inocula, occurred more frequently in immunized rabbits. A serpiginous type of ulceration did not develop at the site of the initial epithelial lesion nor at any other place in the cornea. Histologically, the lesions consisted of densely packed polymorphonuclear leukocytes between the corneal lamellae.

  4. Effects of diabetic keratopathy on corneal optical density, central corneal thickness, and corneal endothelial cell counts.

    Science.gov (United States)

    Gao, Feng; Lin, Tao; Pan, Yingzhe

    2016-09-01

    Diabetic keratopathy is an ocular complication that occurs with diabetes. In the present study, the effect of diabetic keratopathy on corneal optical density, central corneal thickness, and corneal endothelial cell count was investigated. One hundred and eighty diabetic patients (360 eyes) were enrolled in the study during the period from March, 2012 to March, 2013. The patients were divided into three age groups: 10 years, with 60 patients per group (120 eyes). During the same period, 60 healthy cases (120 eyes) were selected and labeled as the normal control group. The Pentacam was used to measure the corneal optical density, and central corneal thickness. Specular microscopy was used to examine the corneal endothelial cell density. The coefficient of partial correlation was used to control age and correlate the analysis between the corneal optical density, corneal endothelial cell density, and central corneal thickness. The stage of the disease, the medial and intimal corneal optical density and central corneal thickness was analyzed in the diabetes group. The corneal optical density in the diabetes group increased compared with that of the normal control group. The medial and intimal corneal optical density and central corneal thickness were positively correlated with the course of the disease. However, the corneal endothelial cell density was not associated with the course of diabetes. There was a positive association between the medial and intimal corneal optical density and central corneal thickness of the diabetic patients. In conclusion, the results of the present study show that medial and intimal corneal optical density and central corneal thickness were sensitive indicators for early diabetic keratopathy.

  5. Determining the efficacy of corneal crosslinking in progressive keratoconus

    Science.gov (United States)

    Malik, Sidra; Humayun, Sadia; Nayyar, Shahzad; Ishaq, Mazhar

    2017-01-01

    Objective: To determine the Efficacy of Corneal Crosslinkage (CXL), using Corneal Topography, in eyes with progressive Keratoconus. Methods: This randomized control trial was conducted at Armed Forces Institute of Ophthalmology, Rawalpindi, Pakistan from October 2013 to April 2014. A total of 60 eyes of 30 patients were included who presented with bilateral progressive Keratoconus. Each eye of the patient was randomized either to a treatment group (Group-A) or control untreated group (Group-B) of 30 eyes each. A written informed consent was obtained from each patient, following which corneal crosslinkage (CXL) with topical riboflavin eye drops was performed. Follow up visit was done at three months post operatively, Corneal topography was repeated and recorded. Results: The mean age of the patients was 23.13±7.62 years (range 13 to 39 years). There were 26 males and 34 females patients. The mean simK value at the start of study was 50.94±4.84 diopters in Group-A and 49.73±5.24 diopters in Group-B. At three months follow-up, the mean simK value was significantly lower in Group-A (48.28±4.47) as compared to Group-B (51.11±4.85). Keratoconus improved/ remained stable in 34 (56.7%) eyes while progressive disease was noted in 26 (43.3%) eyes. When compared between the groups, the frequency of efficacy was significantly higher in Group-A (86.7% vs. 26.7%; p=.000) as compared to Group-B. Conclusion: Corneal Crosslinking was found effective in causing regression or halting the progression of disease in patients with progressive Keratoconus at three months follow-up, however, the efficacy of corneal crosslinking was unaffected by patient’s age and gender. PMID:28523043

  6. A corneal mold to restore normal corneal dimensions.

    Science.gov (United States)

    Swinger, C A; Kornmehl, E W; York, S; Forman, J S

    1986-01-01

    A corneal mold is described that provides an MK corneal button of normal thickness and curvature from an edematous, post-mortem button. The uniform, processed tissue can then be used for experimental refractive surgery.

  7. Intrastromal corneal ring segments for management of keratoconus

    Directory of Open Access Journals (Sweden)

    Sri Ganesh

    2013-01-01

    Full Text Available Keratoconus is a progressive corneal ectasia, which can be managed both by conservative measures like glasses or contact lenses in non-progressive cases or surgical procedures like collagen crosslinking (CXL with or without adjuvant measures like intrastromal corneal rings segments (ICRS or topography guided ablation. Various kinds of ICRS are available to the surgeon, but it is most essential to be able to plan the implantation of the ring to optimize outcomes. Aims: The aim of this study is to evaluate the visual outcome and progression in patients of keratoconus implanted with ICRS. Materials and Methods: Two different types of ICRS-Intacs (Addition Technology and Kerarings (Mediphacos Inc. were implanted in 2 different cohorts of patients and were followed-up to evaluate the outcome of the procedure. All patients underwent a complete ocular examination including best spectacle corrected visual acuity, slit lamp examination fundus examination, corneal topography and pachymetry. The ICRS implantation is done with CXL to stop the progression of the disease. Improvement in uncorrected visual acuity (UCVA, best spectacle corrected visual acuity and topographic changes were analyzed. Results: A significant improvement in keratometry and vision was seen in both groups. Conclusion: ICRS have been found to reduce corneal irregularity and flatten keratometry with improvement in UCVA and best corrected visual acuity.

  8. Intrastromal corneal ring segments delay corneal grafting in patients with keratoconus

    Directory of Open Access Journals (Sweden)

    Luiz Arthur F. Beniz

    2016-02-01

    Full Text Available ABSTRACT Purpose: To assess the impact of intrastromal corneal ring segments (ICRS as a surgical alternative to corneal grafting in patients with keratoconus who were scheduled for a corneal transplant. Methods: This single-surgeon, single-center, retrospective, observational case series study included 19 eyes of 18 patients (mean age, 23.36 ± 6.22 years with a confirmed diagnosis of keratoconus. These patients were enrolled from the State of Goiás, Brazil corneal graft waiting list. Following extensive pre-operative testing, including the measurement of best-corrected visual acuity (BCVA, applanation tonometry, biomicroscopy, funduscopy, pachymetry, and corneal topography, patients were implanted with Keraring® ICRS. Patients underwent clinical examination at postoperative days 1, 7, 30, 90, and 180 and were examined again 2 years following surgery. Results: At the 2-year cut-off following ICRS implantation (mean follow-up, 28.72 ± 4.71 months, there was a statistically significant improvement in BCVA (logMAR from 0.59 ± 0.35 preoperatively to 0.35 ± 0.45 postoperatively ( p <0.01. Three of 19 eyes (15.8% still required keratoplasty. In the remaining patients (84.2%, BCVA was managed with spectacles (52.6% or contact lenses (31.6%. One patient developed infectious keratitis, requiring removal of ICR at the first postoperative visit. Conclusion: ICRS implantation may be a surgical alternative to keratoplasty in patients with keratoconus. This procedure may delay or even eliminate the need for keratoplasty in such patients.

  9. [Corneal sensibility following epikeratophakia].

    Science.gov (United States)

    Biermann, H; Grabner, G; Baumgartner, I; Reim, M

    1992-07-01

    The postoperative rate of reinnervation following corneal surgery is widely considered to be a useful indicator of the healing process. This study reports the corneal sensitivity of 14 patients following epikeratophakia for different indications (myopia, aphakia and keratoconus) after time periods ranging from 7 to 104 weeks. All transplants were clear at the time of measurement. A newly developed aesthesiometer (using a low electric current for stimulation) was employed. Nine positions on the operated eye were chosen for the measurements, five locations of the non-operated fellow eye served as controls. On the operated eye the corneal sensitivity peripheral to the trephination were significantly reduced at the 9 and 12 o'clock positions as compared to the other eye. The 3 and 6 o'clock locations showed no significant difference. On the epikeratophakia lenticule the sensitivity was significantly reduced at all points, the center showing the largest difference (p less than 0.001). No correlation with age, sex or the indication for the procedure was observed. Although there was a trend of a positive correlation between the postoperative time period and the central corneal sensitivity, the follow-up was too short to reach significant levels. The nearly complete lack of corneal sensitivity, particularly in the center of the transplant is therefore well compatible with its long-time survival, even when the lenticule has been prepared with the cryolathe and lyophilized for transportation.

  10. Wide-angle cornea-sclera (OCULAR) topography

    Science.gov (United States)

    Klein, Stanley A.; Corzine, John; Corbin, Jacob A.; Wechsler, Sheldon; Carney, Thom

    2002-06-01

    Most corneal topographers are slope-based instruments, measuring corneal slope based on light reflected by the cornea acting as a mirror. This mirror method limits corneal coverage to about 9 mm diameter. Both refractive surgery and contact lens fitting actually require a larger coverage than is obtainable using slope-based instruments. Height-based instruments should be able to measure a cornea/sclera area that is twice the size (four times the area) of slope-based topographers with an accuracy of a few microns. We have been testing a prototype of a new model height-based topographer manufactured by Euclid Systems. We find that single shots can produce a corneal coverage of up to 16 mm vertical and 20 mm horizontal. The heights and slopes in the corneal region have good replicability. Although the scleral region is noisier, it is the only topographer available able to measure scleral topography that is critically important to contact lens fitting. There are a number of improvements to the Euclid software and hardware that would enable it to fill an important niche in eye care and eye research.

  11. Corneal Biomechanical Properties in Myopic Eyes Measured by a Dynamic Scheimpflug Analyzer

    Directory of Open Access Journals (Sweden)

    Jingyi Wang

    2015-01-01

    Full Text Available Purpose. To evaluate the corneal biomechanical parameters in myopic and emmetropic eyes using Corneal Visualization Scheimpflug Technology (CorVis ST. Methods. 103 myopic and emmetropic eyes of 103 patients were examined. Corneal biomechanical parameters, axial length, and mean keratometry were measured using CorVis ST, IOL Master, and topography, respectively. Corneal biomechanical properties were compared within four groups. Bivariate correlation analysis was used to assess the relationship between corneal biomechanical parameters and ocular characteristics. Results. Four of ten corneal biomechanical parameters, namely, deformation amplitude (DA, first- and second-applanation time (A1-time, A2-time, and radius at highest concavity (HC radius, were significantly different within the four groups (P<0.05. In correlation analysis, DA was positively correlated with axial length (r=0.20, P=0.04; A2-time was positively correlated with spherical equivalent (SE (r=0.24, P=0.02; HC radius was positively correlated with SE (r=0.24, P=0.02 and was negatively correlated with mean keratometry (r=-0.20, P=0.046 and axial length (r=-0.21, P=0.03. Conclusions. The corneal refraction-related biomechanical alterations were associated with ocular characteristics. Highly myopic eyes exhibited longer DA and smaller HC radius than do moderately myopic eyes; the eyes with longer axial length tend to have less corneal stiffness and are easier to deform under stress.

  12. Edge detection and mathematic fitting for corneal surface with Matlab software

    Science.gov (United States)

    Di, Yue; Li, Mei-Yan; Qiao, Tong; Lu, Na

    2017-01-01

    AIM To select the optimal edge detection methods to identify the corneal surface, and compare three fitting curve equations with Matlab software. METHODS Fifteen subjects were recruited. The corneal images from optical coherence tomography (OCT) were imported into Matlab software. Five edge detection methods (Canny, Log, Prewitt, Roberts, Sobel) were used to identify the corneal surface. Then two manual identifying methods (ginput and getpts) were applied to identify the edge coordinates respectively. The differences among these methods were compared. Binomial curve (y=Ax2+Bx+C), Polynomial curve [p(x)=p1xn+p2xn−1 +....+pnx+pn+1] and Conic section (Ax2+Bxy+Cy2+Dx+Ey+F=0) were used for curve fitting the corneal surface respectively. The relative merits among three fitting curves were analyzed. Finally, the eccentricity (e) obtained by corneal topography and conic section were compared with paired t-test. RESULTS Five edge detection algorithms all had continuous coordinates which indicated the edge of the corneal surface. The ordinates of manual identifying were close to the inside of the actual edges. Binomial curve was greatly affected by tilt angle. Polynomial curve was lack of geometrical properties and unstable. Conic section could calculate the tilted symmetry axis, eccentricity, circle center, etc. There were no significant differences between ‘e’ values by corneal topography and conic section (t=0.9143, P=0.3760 >0.05). CONCLUSION It is feasible to simulate the corneal surface with mathematical curve with Matlab software. Edge detection has better repeatability and higher efficiency. The manual identifying approach is an indispensable complement for detection. Polynomial and conic section are both the alternative methods for corneal curve fitting. Conic curve was the optimal choice based on the specific geometrical properties. PMID:28393021

  13. Edge detection and mathematic fitting for corneal surface with Matlab software.

    Science.gov (United States)

    Di, Yue; Li, Mei-Yan; Qiao, Tong; Lu, Na

    2017-01-01

    To select the optimal edge detection methods to identify the corneal surface, and compare three fitting curve equations with Matlab software. Fifteen subjects were recruited. The corneal images from optical coherence tomography (OCT) were imported into Matlab software. Five edge detection methods (Canny, Log, Prewitt, Roberts, Sobel) were used to identify the corneal surface. Then two manual identifying methods (ginput and getpts) were applied to identify the edge coordinates respectively. The differences among these methods were compared. Binomial curve (y=Ax(2)+Bx+C), Polynomial curve [p(x)=p1x(n)+p2x(n-1) +....+pnx+pn+1] and Conic section (Ax(2)+Bxy+Cy(2)+Dx+Ey+F=0) were used for curve fitting the corneal surface respectively. The relative merits among three fitting curves were analyzed. Finally, the eccentricity (e) obtained by corneal topography and conic section were compared with paired t-test. Five edge detection algorithms all had continuous coordinates which indicated the edge of the corneal surface. The ordinates of manual identifying were close to the inside of the actual edges. Binomial curve was greatly affected by tilt angle. Polynomial curve was lack of geometrical properties and unstable. Conic section could calculate the tilted symmetry axis, eccentricity, circle center, etc. There were no significant differences between 'e' values by corneal topography and conic section (t=0.9143, P=0.3760 >0.05). It is feasible to simulate the corneal surface with mathematical curve with Matlab software. Edge detection has better repeatability and higher efficiency. The manual identifying approach is an indispensable complement for detection. Polynomial and conic section are both the alternative methods for corneal curve fitting. Conic curve was the optimal choice based on the specific geometrical properties.

  14. Dynamic Topography Revisited

    Science.gov (United States)

    Moresi, Louis

    2015-04-01

    Dynamic Topography Revisited Dynamic topography is usually considered to be one of the trinity of contributing causes to the Earth's non-hydrostatic topography along with the long-term elastic strength of the lithosphere and isostatic responses to density anomalies within the lithosphere. Dynamic topography, thought of this way, is what is left over when other sources of support have been eliminated. An alternate and explicit definition of dynamic topography is that deflection of the surface which is attributable to creeping viscous flow. The problem with the first definition of dynamic topography is 1) that the lithosphere is almost certainly a visco-elastic / brittle layer with no absolute boundary between flowing and static regions, and 2) the lithosphere is, a thermal / compositional boundary layer in which some buoyancy is attributable to immutable, intrinsic density variations and some is due to thermal anomalies which are coupled to the flow. In each case, it is difficult to draw a sharp line between each contribution to the overall topography. The second definition of dynamic topography does seem cleaner / more precise but it suffers from the problem that it is not measurable in practice. On the other hand, this approach has resulted in a rich literature concerning the analysis of large scale geoid and topography and the relation to buoyancy and mechanical properties of the Earth [e.g. refs 1,2,3] In convection models with viscous, elastic, brittle rheology and compositional buoyancy, however, it is possible to examine how the surface topography (and geoid) are supported and how different ways of interpreting the "observable" fields introduce different biases. This is what we will do. References (a.k.a. homework) [1] Hager, B. H., R. W. Clayton, M. A. Richards, R. P. Comer, and A. M. Dziewonski (1985), Lower mantle heterogeneity, dynamic topography and the geoid, Nature, 313(6003), 541-545, doi:10.1038/313541a0. [2] Parsons, B., and S. Daly (1983), The

  15. Assessment of refractive astigmatism and simulated therapeutic refractive surgery strategies in coma-like-aberrations-dominant corneal optics

    OpenAIRE

    ZHOU Wen; Stojanovic, Aleksandar; Utheim, Tor Paaske

    2016-01-01

    Background The aim of the study is to raise the awareness of the influence of coma-like higher-order aberrations (HOAs) on power and orientation of refractive astigmatism (RA) and to explore how to account for that influence in the planning of topography-guided refractive surgery in eyes with coma-like-aberrations-dominant corneal optics. Methods Eleven eyes with coma-like-aberrations-dominant corneal optics and with low lenticular astigmatism (LA) were selected for astigmatism analysis and f...

  16. Moire topography in odontology

    Science.gov (United States)

    Moreno Yeras, A.

    2001-08-01

    For several decades measurement optical techniques have been used in different branches of Science and Technology and in medicine. One of these techniques is the so-called Moire topography that allows the accurate measurement of different parts of the human body topography. This investigation presents the measurement of topographies of teeth and gums using an automated system of shadow moire, with which precision can be reached up to the order of the microns by the phase shift instrumentation in an original way. Advantages and disadvantages of using the Moire topography and its comparison with other techniques used in the optical metrology are presented. Also, some positive and negative aspects of the implementation of this technique are shown in dentistry.

  17. Morphological and functional correlations in riboflavin UV A corneal collagen cross-linking for keratoconus.

    Science.gov (United States)

    Mazzotta, Cosimo; Caporossi, Tomaso; Denaro, Rosario; Bovone, Cristina; Sparano, Caterina; Paradiso, Anna; Baiocchi, Stefano; Caporossi, Aldo

    2012-05-01

    To investigate the correlations between corneal structural modifications assessed by in vivo corneal confocal microscopy with visual function [uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA)] and morphological data (corneal topography, pachymetry, elevation analysis) after riboflavin UV A corneal collagen cross-linking (CXL) for the stabilization of progressive keratoconus. Forty-four eyes with progressive keratoconus were enrolled in the Siena Eye Cross Study (prospective nonrandomized phase II open trial). All eyes underwent Riboflavin UV A CXL. Preoperative and postoperative evaluation comprised: UCVA, BSCVA, optical pachymetry (Visante OCT, Zeiss, Germany), corneal topography (CSO, Florence, Italy) and tomography (Orbscan IIz; B&L, Rochester, NY, USA) and in vivo confocal microscopy (Heidelberg Retina Tomograph II; Rostock, Heidelberg Gmbh, Germany). Examinations were performed preoperatively 6 months and one day before treatment and at 1, 3, 6 and 12 months of follow-up. In vivo corneal confocal microscopy showed time-dependent postoperative epithelial and stromal modifications after cross-linking. Epithelial thinning associated with stromal oedema and keratocytes apoptosis explained initial tendency towards slightly reduced VA and more glare one month postoperatively in 70% of eyes. Furthermore, a statistically not significant early worsening of topographic mean K values was observed. Orbscan II analysis significantly underestimated pachymetric values after treatment. Pachymetric underestimation was rectified by high-resolution optical pachymetry provided by the Visante OCT system. After the third post-CXL month, epithelial thickening, disappearance of oedema and new collagen compaction recorded by in vivo corneal confocal microscopy explained the improvements in visual performance during the follow-up. Changes in stromal reflectivity and collagen compaction observed by in vivo confocal microscopy were associated with corneal

  18. Consideration of corneal biomechanics in the diagnosis and management of keratoconus: is it important?

    Science.gov (United States)

    Bao, FangJun; Geraghty, Brendan; Wang, QinMei; Elsheikh, Ahmed

    2016-01-01

    Keratoconus is a bilateral, non-inflammatory, degenerative corneal disease. The occurrence and development of keratoconus is associated with corneal thinning and conical protrusion, which causes irregular astigmatism. With the disruption of the collagen organization, the cornea loses its shape and function resulting in progressive visual degradation. Currently, corneal topography is the most important tool for the diagnosis of keratoconus, which may lead to false negatives among the patient population in the subclinical phase. However, it is now hypothesised that biomechanical destabilisation of the cornea may take place ahead of the topographic evidence of keratoconus, hence possibly assisting with disease diagnosis and management. This article provides a review of the definition, diagnosis, and management strategies for keratoconus based on corneal biomechanics.

  19. Bilateral Keratectasia 34 Years after Corneal Transplant

    Directory of Open Access Journals (Sweden)

    Xavier Valldeperas

    2010-07-01

    Full Text Available We report the clinical findings of a patient with severe bilateral keratectasia 34 years after a penetrating keratoplasty (PK in both eyes. An otherwise healthy 67-year-old man complained of deterioration of the eyesight in both eyes over the last 6 months. The patient was diagnosed with bilateral keratoconus at the age of 32 years, and he underwent a bilateral PK. At presentation, visual acuity was 20/200 in the right eye and light perception in the left eye. A Pentacam pachymetric map revealed a central pachymetry of 720 µm in the right eye and of 710 µm in the left eye, as well as an average paracentral pachymetry of 436 and 270 µm in the 9-mm zone in the right and the left eye, respectively. Corneal topography revealed bilateral irregular and asymmetric bowing with generalized steepening and high corneal power. We describe a case of bilateral keratectasia 34 years after PK in a patient who was originally diagnosed with bilateral keratoconus.

  20. Corneal Neurotoxicity Due to Topical Benzalkonium Chloride

    OpenAIRE

    Sarkar, Joy; Chaudhary, Shweta; Namavari, Abed; Ozturk, Okan; Chang, Jin-Hong; Yco, Lisette; Sonawane, Snehal; Khanolkar, Vishakha; Hallak, Joelle; Jain, Sandeep

    2012-01-01

    Topical application of benzalkonium chloride (BAK) to the eye causes dose-related corneal neurotoxicity. Corneal inflammation and reduction in aqueous tear production accompany neurotoxicity. Cessation of BAK treatment leads to recovery of corneal nerve density.

  1. Genetics of corneal endothelial dystrophies

    Indian Academy of Sciences (India)

    Chitra Kannabiran

    2009-12-01

    The corneal endothelium maintains the level of hydration in the cornea. Dysfunction of the endothelium results in excess accumulation of water in the corneal stroma, leading to swelling of the stroma and loss of transparency. There are four different corneal endothelial dystrophies that are hereditary, progressive, non-inflammatory disorders involving dysfunction of the corneal endothelium. Each of the endothelial dystrophies is genetically heterogeneous with different modes of transmission and/or different genes involved in each subtype. Genes responsible for disease have been identified for only a subset of corneal endothelial dystrophies. Knowledge of genes involved and their function in the corneal endothelium can aid understanding the pathogenesis of the disorder as well as reveal pathways that are important for normal functioning of the endothelium.

  2. Bilateral acute corneal calcification.

    Science.gov (United States)

    Freddo, T F; Leibowitz, H M

    1985-04-01

    A 38-year-old man with brittle, juvenile onset diabetes mellitus and bilateral severe dry eyes with recurrent corneal ulcers developed atypical band-shaped calcifications of both corneas during a 24-hour period. Serum calcium, phosphate, and carbon dioxide levels all were within normal limits. The patient was mildly uremic but was not in renal failure. When EDTA chelation failed to clear the deposits, partial keratectomies were performed in both eyes and the specimens were examined by light and electron microscopy, including energy dispersive x-ray analysis. Microscopic studies revealed an atypical calcific keratopathy which involved neither Bowman's layer nor the most superficial stromal lamellae. The deposits were confined to deeper lamellae in the anterior stroma and by electron microscopy were composed of extracellular crystalline aggregates. Energy dispersive x-ray analysis of these aggregates confirmed the presence of calcium and phosphate. Corneal dessication appeared to be a major contributing factor in the rapid formation of these deposits.

  3. Corneal astigmatism change and wavefront aberration evaluation after cataract surgery: "Single" versus "paired opposite" clear corneal incisions

    Directory of Open Access Journals (Sweden)

    Hasan Razmjoo

    2014-01-01

    Full Text Available Background: Correcting the pre-existing astigmatism is an optimal goal in cataract surgery. The aim of this study is to compare the astigmatic correcting effect of a single regular 3.2 mm clear corneal incision (CCI with paired opposite CCI in cataract patients and effect of these incisions on optical aberrations using the wavefront quantitative analysis. Materials and Methods: This was a randomized controlled trial study undertaken in an ophthalmology referral center on 50 patients planned for cataract surgery who were randomized to either single 3.2 mm CCI or paired opposite CCI group. Post-operative evaluation was performed at 12 weeks and included refraction, keratometery, corneal topography and wavefront analysis. Corneal astigmatism and post-operative values were compared in two groups. Results: The mean pre-operative corneal astigmatism was 2.58 ± 1.03 D in the single incision group and 2.70 ± 0.94 D in the paired opposite incisions group. After 12 weeks of surgery, the corneal astigmatism was reached to 2.15 ± 0.82 D in single incision group and 1.63 ± 1.21 in the paired opposite incisions group. There was a statistically significant difference in two arms of treatment regarding to surgically induced astigmatism after 3 months. The mean post-operative total and higher order aberrations and values were not significantly different in two groups. Conclusion: The results of our study showed that paired opposite incisions is an effective procedure for reducing pre-existing corneal astigmatism in cataract surgery. Paired incisions did not show any beneficial effect regarding wavefront aberrations compared with conventional single incision method.

  4. Corneal blindness: prevention, treatment and rehabilitation

    Directory of Open Access Journals (Sweden)

    Matthew J Burton

    2009-12-01

    Full Text Available Blindness from corneal disease is a major ophthalmic public health problem. There are three important elements to addressing corneal blindness: prevention, treatment, and rehabilitation.

  5. Why is topography fractal?

    CERN Document Server

    Pelletier, J D

    1997-01-01

    The power spectrum S of linear transects of the earth's topography is often observed to be a power-law function of wave number k with exponent close to -2: S(k) is proportional to k^-2. In addition, river networks are fractal trees that satisfy many power-law or fractal relationships between their morphologic components. A model equation for the evolution of the earth's topography by erosional processes which produces fractal topography and fractal river networks is presented and its solutions compared in detail to real topography. The model is the diffusion equation for sediment transport on hillslopes and channels with the local diffusivity proportional to the square of the discharge. The dependence of diffusivity on discharge follows from fundamental equations of sediment transport. We study the model in two ways. In the first analysis the diffusivity is parameterized as a function of relief and a Taylor expansion procedure is carried out to obtain a differential equation for the landform elevation which i...

  6. Anatomic Predictive Factors of Acute Corneal Hydrops in Keratoconus: An Optical Coherence Tomography Study.

    Science.gov (United States)

    Fuentes, Esteban; Sandali, Otman; El Sanharawi, Mohamed; Basli, Elena; Hamiche, Taous; Goemaere, Isabelle; Borderie, Vincent; Bouheraoua, Nacim; Laroche, Laurent

    2015-08-01

    To define the optical coherence tomography (OCT) corneal changes predisposing to acute corneal hydrops among patients with advanced keratoconus. Retrospective cohort study. A total of 191 advanced keratoconic eyes from 191 patients with advanced keratoconus cases were studied. Data collected from patients with advanced keratoconus cases were studied during a minimum period of 24 months of follow-up. High-resolution Fourier-domain corneal OCT (5 μm of axial resolution) and corneal topography were performed every 4 months during the follow-up. Several anatomic features at the keratoconus cone were analyzed with OCT, including epithelial and stromal thicknesses, the aspect of Bowman's layer, the presence of Vogt's striae, and stromal opacities. A comparative analysis between anatomic corneal features in eyes that developed corneal hydrops and those that did not develop this complication during the follow-up was performed. Evaluation of anatomic corneal changes at risk of developing a corneal hydrops on the basis of OCT findings. Eleven cases of corneal hydrops (5.8%) occurred in our series during a mean follow-up of 30 months (24-36 months). All of these patients were male and younger (23.7±5.9 years) than patients with no acute keratoconus (32.7±11.3 years). Increased epithelial thickening with stromal thinning at the conus and the presence of anterior hyperreflectives at the Bowman's layer level were significantly associated with corneal hydrops, whereas the presence of corneal scarring was a preventive factor. At the healing stage, a pan-stromal scar occurs, with a significant stromal thickening and cornea flattening. Increased epithelial thickening, stromal thinning at the keratoconus cone, anterior hyperreflectives at the Bowman's layer level, and the absence of stromal scarring are associated with a high risk of developing corneal hydrops. These aspects should be taken into account by the clinician in the evaluation of keratoconus eyes and in the planning of

  7. Corneal Densitometry for Quantification of Corneal Deposits in Monoclonal Gammopathies.

    Science.gov (United States)

    Enders, Philip; Holtick, Udo; Schaub, Friederike; Tuchscherer, Armin; Hermann, Manuel M; Scheid, Christoph; Cursiefen, Claus; Bachmann, Björn O

    2017-04-01

    To assess the capability of Scheimpflug-based densitometry of the cornea to quantify light chain deposits in patients with active monoclonal gammopathies. This is a case-control study in which data from a leading tertiary university center in myeloma care were analyzed. Ten eyes of 5 patients with monoclonal gammopathy and 26 eyes of 13 healthy controls undergoing clinical evaluation and Scheimpflug-based measurements were included in the study. The main outcome measures were densitometry data of the 4 corneal layers-anterior layer (AL), central layer (CL), posterior layer, and total layer (TL)-in 4 different annuli (central annular zone 0-2 mm, intermediate annular zone 2-6 mm, peripheral annular zone 6-10 mm, and total annular zone 0-12 mm). In 8 eyes of 4 patients with IgG-based gammopathy, corneal light backscatter was highest in the AL and decreased with increasing corneal depth. The peripheral annular zone showed a higher densitometry value compared with the corneal center. Compared with healthy controls, the AL (P < 0.001), the CL (P < 0.001), and the TL (P < 0.001) had significantly higher corneal light backscatter in patients with gammopathy in the total and the peripheral annular zones. In one patient with predominantly IgA-based disease, corneal light backscatter was not elevated. Scheimpflug-based densitometry of the cornea is able to quantify opacification by immunoglobulin G light chain deposits in monoclonal gammopathies. This noninvasive technique can complement presently used in vivo confocal microscopy and corneal photography to objectivize corneal changes. Densitometry might allow monitoring of corneal immunoglobulin deposits in follow-up examinations.

  8. Clinical Correlation between Placido, Scheimpflug and LED Color Reflection Topographies in Imaging of a Scarred Cornea

    Directory of Open Access Journals (Sweden)

    Anastasios John Kanellopoulos

    2014-10-01

    Full Text Available This case report aims to evaluate safety, efficacy and feasibility of anterior surface imaging by a novel point-source reflection topographer, in comparison to four other corneal imaging modalities. A 17-year-old female patient, clinically diagnosed with chronic herpetic keratitis in her left eye was imaged by a novel multicolored-spot reflection topography system. We comparatively investigated elevation and curvature maps between the novel topographer and established Placido disk topography and Scheimpflug tomography systems. Pachymetry maps were compared between the Scheimpflug system and anterior-segment optical coherence tomography system. The Placido system failed to properly register the abnormal anterior surface due to incomplete mire registration, while the Scheimpflug topometry device imaged the anterior surface properly, but not the posterior (due to media opacity, and thus pachymetry was highly irregular and erroneous in this case. Imaging of corneas infected with herpes simplex virus keratitis has been rare; we have not identified any such documentation in the peer review literature in the last 10 years. This novel multicolored-spot reflection topography imaging may offer successful corneal imaging in cases where established clinical topography systems may fail to produce accurate reconstruction of the corneal shape. This is an important case demonstrating exceptional clinical feasibility in such rare cases offered by a newly introduced technology in ophthalmic imaging.

  9. Segmentation of 830- and 1310-nm LASIK corneal optical coherence tomography images

    Science.gov (United States)

    Li, Yan; Shekhar, Raj; Huang, David

    2002-05-01

    Optical coherence tomography (OCT) provides a non-contact and non-invasive means to visualize the corneal anatomy at micron scale resolution. We obtained corneal images from an arc-scanning (converging) OCT system operating at a wavelength of 830nm and a fan-shaped-scanning high-speed OCT system with an operating wavelength of 1310nm. Different scan protocols (arc/fan) and data acquisition rates, as well as wavelength dependent bio-tissue backscatter contrast and optical absorption, make the images acquired using the two systems different. We developed image-processing algorithms to automatically detect the air-tear interface, epithelium-Bowman's layer interface, laser in-situ keratomileusis (LASIK) flap interface, and the cornea-aqueous interface in both kinds of images. The overall segmentation scheme for 830nm and 1310nm OCT images was similar, although different strategies were adopted for specific processing approaches. Ultrasound pachymetry measurements of the corneal thickness and Placido-ring based corneal topography measurements of the corneal curvature were made on the same day as the OCT examination. Anterior/posterior corneal surface curvature measurement with OCT was also investigated. Results showed that automated segmentation of OCT images could evaluate anatomic outcome of LASIK surgery.

  10. Central Corneal Thickness in Adult Chinese

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The central corneal thickness (CCT) in age 48 years or less of Chinese was characterized and its relationship with gender, age, refraction and intraocular pressure (IOP) was investigated.Right eyes of 1669 participants were included in this study (880 men, 52.7 % and 789 women,47.3 %). Mean age of the samples was 23.8±5.9 years. After the examination of corneal topography and refraction, Goldman applanation tonometry was carried out by one physician. Tonometric values were the mean of three consecutive readings. Subsequently, another physician carried out ultrasonic pachymetry with the DGH 2000 AP ultrasonic pachymeter. Six measuremen ts were made at the center of the cornea of each eye. The mean value was used for analysis. The results showed that mean CCT of male participants was 551.33± 34. 62 μm, 5.79 μm more than that of female participants. Linear regression analyses revealed that CCT was negatively related with age only in female and no association was found between refractive status and CCT. IOP was positively related to CCT, and there was a difference in IOP of 1.5 mmHg (1 mmHg=0. 133 kPa) per 100 μm difference in CCT. Ocular hypertension group was prone to have thicker cornea than average. The results indicated that in adult Chinese CCT tended to decrease with aging in female only. IOP measured by Goldmann tonometry was positively related with CCT so that CCT should be measured along with IOP.

  11. Study of the tear topography dynamics using a lateral shearing interferometer

    Science.gov (United States)

    Dubra, Alfredo; Paterson, Carl; Dainty, Christopher

    2004-12-01

    The dynamics of the pre-corneal tear film topography are studied on 21 subjects with a purpose-built lateral shearing interferometer. Interesting tear topography features such as post-blink undulation, break-up, eyelid-produced bumps/ridges, bubbles and rough pre-contact lens tear surfaces were recorded. Using the calculated tear topography maps, the effects of the tear dynamics in visual performance, refractive surgery and ophthalmic adaptive optics are discussed in terms of wavefront RMS. The potential of lateral shearing interferometry for clinical applications such as dry eye diagnosis and contact lens performance studies is illustrated by the recorded topography features such as post-blink undulation, break-up, eyelid-produced bumps/ridges, bubbles and rough tear surfaces in front of contact lenses.

  12. Corneal collagen crosslinking: a systematic review.

    Science.gov (United States)

    Sorkin, Nir; Varssano, David

    2014-01-01

    Keratoconus (KCN) is an ectatic disorder with progressive corneal thinning and a clinical picture of corneal protrusion, progressive irregular astigmatism, corneal fibrosis and visual deterioration. Other ectatic corneal disorders include: post-LASIK ectasia (PLE) and pellucid marginal degeneration (PMD). Corneal crosslinking (CXL) is a procedure whereby riboflavin sensitization with ultraviolet A radiation induces stromal crosslinks. This alters corneal biomechanics, causing an increase in corneal stiffness. In recent years, CXL has been an established treatment for the arrest of KCN, PLE and PMD progression. CXL has also been shown to be effective in the treatment of corneal infections, chemical burns, bullous keratopathy and other forms of corneal edema. This is a current review of CXL - its biomechanical principles, the evolution of CXL protocols in the past, present and future, indications for treatment, treatment efficacy and safety.

  13. Patching for corneal abrasion.

    Science.gov (United States)

    Lim, Chris H L; Turner, Angus; Lim, Blanche X

    2016-07-26

    Published audits have demonstrated that corneal abrasions are a common presenting eye complaint. Eye patches are often recommended for treating corneal abrasions despite the lack of evidence for their use. This systematic review was conducted to determine the effects of the eye patch when used to treat corneal abrasions. The objective of this review was to assess the effects of patching for corneal abrasion on healing and pain relief. We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 4), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to May 2016), EMBASE (January 1980 to May 2016), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to May 2016), System for Information on Grey Literature in Europe (OpenGrey) (January 1995 to May 2016), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 9 May 2016. We also searched the reference lists of included studies, unpublished 'grey' literature and conference proceedings and contacted pharmaceutical companies for details of unpublished trials. We included randomised and quasi-randomised controlled trials that compared patching the eye with no patching to treat simple corneal abrasions. Two authors independently assessed the risk of bias and extracted data. Investigators were contacted for further information regarding the quality of trials. The primary outcome was healing at 24, 48 and 72 hours while secondary outcomes included measures of pain, quality of life and adverse effects. We graded the certainty of the evidence using GRADE. We included 12 trials which

  14. Acute Corneal Hydrops Mimicking Infectious Keratitis as Initial Presentation of Keratoconus in a 10-Year-Old Child

    Directory of Open Access Journals (Sweden)

    Elise A. Slim

    2015-01-01

    Full Text Available Purpose. To report a case of acute hydrops in a 10-year-old child with advanced keratoconus. Case Presentation. A ten-year-old boy diagnosed as having right eye (RE infectious keratitis, not responding to antimicrobial therapy, was referred to our hospital. The diagnosis of infectious keratitis was established one month prior to his presentation following an episode of acute corneal whitening, pain, and drop in visual acuity. Topical fortified antibiotics followed by topical antiviral therapy were used with no improvement. Slit lamp examination showed significant corneal protrusion with edema surrounding a rupture in Descemet’s membrane in the RE. The diagnosis of acute corneal hydrops from advanced keratoconus was highly suspected and confirmed with corneal topography. Conclusion. Although a relatively rare disease at the age of 10 years, keratoconus can be rapidly progressive in the pediatric group. Keratoconus should always be considered in the differential diagnosis of progressive vision loss in this age group.

  15. Elimination of Anterior Corneal Steepening With Descemet Membrane Endothelial Keratoplasty in a Patient With Fuchs Dystrophy and Keratoconus: Implications for IOL Calculation.

    Science.gov (United States)

    Gupta, Reena; Kinderyte, Ruta; Jacobs, Deborah S; Jurkunas, Ula V

    2017-10-01

    To report a case of coexistent Fuchs endothelial corneal dystrophy (FECD) and keratoconus (KCN) in which there was normalization of corneal topography after Descemet membrane endothelial keratoplasty (DMEK). Retrospective medical record review. Preoperative findings revealed a best-corrected visual acuity of 20/40 with -1.00 - 2.50 × 147, topographic maximum keratometry of 50.8 D with inferior steeping, and confluent guttae in the left eye. Medical record review revealed myopic shift, but little change in keratometry or corneal thickness over the previous 3 years. The patient developed epithelial edema with contact lens trial, highlighting endothelial dysfunction and eliminating the option of contact lenses for visual rehabilitation. Combined DMEK and cataract extraction with intraocular lens implantation was undertaken. Postoperatively, best-corrected visual acuity was 20/20 with only spherical correction. Elimination of stromal edema led to flattening of maximum anterior keratometry to 46.3 D and reduction of total corneal refractive power (TCRP) by 4.4 D. There was an unanticipated postoperative refractive error of +3.75 D consistent with this normalization of corneal topography. This is the first case report of the role of DMEK in normalizing corneal topography in coexistent FECD and KCN. The potential impact of DMEK on anterior curvature and TCRP must be considered in intraocular lens power calculation for cataract surgery in patients with FECD and KCN.

  16. Videokeratograph (VKS for monitoring corneal curvature during surgery

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    Carvalho Luis Alberto Vieira de

    2002-01-01

    Full Text Available Purpose: We have developed an instrument for computerized surgical videokeratography. A corneal central region of approximately 7.00 mm in diameter may be analyzed, providing the surgeon with information of the power and the astigmatism. Methods: The system is based on a fiber optic Placido disc projecting cone, which is attached to the objective lens of a Zeiss compatible surgical microscope. At the beam splitter we installed a monochromatic high resolution camera. A frame grabber is installed on a PC and images are digitized at a 480x640 resolution. Image processing is used for edge detection of rings. Results: Calibrating curves based on 4 spherical surfaces were generated and approximately 3600 points are calculated for each examination. Preliminary measurements on 10 healthy corneas were compared with those of an EyeSys System 2000 Corneal Topographer. Mean deviation was 0.05 for radius of curvature, 0.24 D for the power and 5.0 degrees for the cylinder. Conclusions: This surgical VKS, with some hardware and software improvements, may be used to reduce residual astigmatisms in conventional cataract and keratoplasty. It could also be used to gather preoperative data in corneal topography assisted LASIK.

  17. Patch graft for corneal perforation following trivial trauma in bilateral terrien′s marginal degeneration

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    Merle Fernandes

    2015-01-01

    Full Text Available A young female presented with blurred vision in the left eye after she rubbed her eye. On examination of both eyes, she had 360° thinning adjacent to the limbus, lipid deposition and superficial vascularization with a perforation in the left eye. The patient was diagnosed with bilateral Terrien′s marginal degeneration (TMD with perforation. Corneal topography of the right eye revealed high oblique astigmatism confirming the diagnosis. A peripheral patch graft was performed for the left eye. At 18 months postoperatively, the best-corrected visual acuity was 20/20 in both eyes. The graft was clear. Topography of right eye was stable, and the left eye had oblique astigmatism. Bilateral advanced TMD in a young patient presenting with corneal perforation following trivial trauma is extremely uncommon. Patch graft may be an option for restoring the globe integrity in such cases. Regular follow-up is necessary as the condition progresses slowly.

  18. 基于精确中心定位的角膜复原算法%An Algorithm of Corneal Reconstruction Based on Precise Location of Corneal Center

    Institute of Scientific and Technical Information of China (English)

    周洪亚; 沈建新; 高绍雷; 唐志豪

    2011-01-01

    Placido盘在角膜地形图系统中应用最为广泛.针对Placido角膜地形图系统中角膜中心定位不准的问题,提出了一种基于Placido盘的角膜复原算法.关键技术是利用图像最内环的数据精确求解角膜中心顶点曲率半径.该方法根据图像分析的结果,利用圆弧连接角膜顶点和第一个反射点,通过迭代精确求解角膜顶点的曲率半径,进而求解角膜各反射点的位置以及屈光度,建立真实人眼的伪彩图.利用标准钢球模拟人眼角膜,结果误差小于0.25 D,表明所采用的算法具有较好的精度和稳定性.%Placido disk is widely used in corneal topography. In order to solve the problem that the convex of the cor-neal can not be precisely located in the Placido corneal topography system, an algorithm of corneal reconstruction based on the Placido disk was introduced. The key of this method is the calculation of radius of corneal convex by u-sing the innermost ring data. Based on image analysis result, we precisely calculated the radius of corneal convex it-eratively by connecting the convex and the first ring using a circle, and then calculated the location of all the reflect point and its power. At last we created the pseudo color map of the human corneal. The corneal was simulated by u-sing standard steel sphere, and the calculating errors of the result were all below 0. 25D. It showed that the algorithm used in this work could get relatively accurate powers and would have fair stability.

  19. Comparison of corneal topographic measurements and high order aberrations in keratoconus and normal eyes.

    Science.gov (United States)

    Colak, Hatice Nur; Kantarci, Feride Aylin; Yildirim, Aydin; Tatar, Mehmet Gurkan; Goker, Hasan; Uslu, Hasim; Gurler, Bulent

    2016-10-01

    The aim of this report was to compare corneal topographic measurements and anterior high order corneal aberrations in eyes with keratoconus and normal eyes by using Scheimpflug-Placido topography. Eighty cases diagnosed with mild (group 1), moderate (group 2), and advanced (group 3) stage keratoconus (KC) according to Amsler-Krumeich Classification and 81 healthy (control group) cases were retrospectively examined. The mean keratometric measurements (as both diopters (Kavg) and mm values (mmavg)), central corneal thickness values (CCT), high order aberration (HOA), total wavefront aberration (TWA), coma, trefoil, and spherical aberration measurements were performed using Sirius topography equipment. The topographic values were compared between the groups. There were 25 cases in group 1 KC (15.5%), 34 cases in group 2 KC (21.1%), 21 cases in group 3 KC (13.1%), and 81 cases (50.3%) in the control group. In terms of mean age and gender distributions, there was no statistically significant difference between the groups (p>0.05). However, there was significant difference between the groups in terms of Kavg, CCT, HOA, TWA, coma, trefoil, and spherical aberration values (pkeratoconus. Anterior high order corneal aberration measurements are a useful tool to guide the physician in diagnosis and classification of keratoconus. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  20. Cultivation of Human Microvascular Endothelial Cells on Topographical Substrates to Mimic the Human Corneal Endothelium

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    Jie Shi Chua

    2013-03-01

    Full Text Available Human corneal endothelial cells have a limited ability to replicate in vivo and in vitro. Allograft transplantation becomes necessary when an accident or trauma results in excessive cell loss. The reconstruction of the cornea endothelium using autologous cell sources is a promising alternative option for therapeutic or in vitro drug testing applications. The native corneal endothelium rests on the Descemet’s membrane, which has nanotopographies of fibers and pores. The use of synthetic topographies mimics the native environment, and it is hypothesized that this can direct the behavior and growth of human microvascular endothelial cells (HMVECs to resemble the corneal endothelium. In this study, HMVECs are cultivated on substrates with micron and nano-scaled pillar and well topographies. Closely packed HMVEC monolayers with polygonal cells and well-developed tight junctions were formed on the topographical substrates. Sodium/potassium (Na+/K+ adenine triphosphatase (ATPase expression was enhanced on the microwells substrate, which also promotes microvilli formation, while more hexagonal-like cells are found on the micropillars samples. The data obtained suggests that the use of optimized surface patterning, in particular, the microtopographies, can induce HMVECs to adopt a more corneal endothelium-like morphology with similar barrier and pump functions. The mechanism involved in cell contact guidance by the specific topographical features will be of interest for future studies.

  1. Factors Influencing Efficacy of Peripheral Corneal Relaxing Incisions during Cataract Surgery

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    Nino Hirnschall

    2015-01-01

    Full Text Available Purpose. To evaluate influencing factors on the residual astigmatism after performing peripheral corneal relaxing incisions (PCRIs during cataract surgery. Methods. This prospective study included patients who were scheduled for cataract surgery with PCRIs. Optical biometry (IOLMaster 500, Carl Zeiss Meditec AG, Germany was taken preoperatively, 1 week, 4 months, and 1 year postoperatively. Additionally, corneal topography (Atlas model 9000, Carl Zeiss Meditec AG, Germany, ORA (Ocular Response Analyzer, Reichert Ophthalmic Instruments, USA, and autorefraction (Autorefractometer RM 8800 Topcon were performed postoperatively. Results. Mean age of the study population n=74 was 73.5 years (±9.3; range: 53 to 90 and mean corneal astigmatism preoperatively was −1.82 D (±0.59; 1.00 to 4.50. Mean corneal astigmatism was reduced to 1.14 D (±0.67; 0.11 to 3.89 4 months postoperatively. A partial least squares regression showed that a high eccentricity of the cornea, a large deviation between keratometry and topography, and a high preoperative astigmatism resulted in a larger postoperative error concerning astigmatism. Conclusions. PCRI causes a reduction of preoperative astigmatism, though the prediction is difficult but several factors were found to be a relevant source of error.

  2. Studies on human corneal shape%人眼角膜形态研究进展

    Institute of Scientific and Technical Information of China (English)

    应靖璐; 施明光

    2015-01-01

    角膜是人眼最重要的屈光介质,其屈光力占眼球总屈光力的2/3.近10年来,随着计算机辅助角膜地形图仪器的发展,对角膜形态的认识越来越具体完善,尤其是角膜前表面.非球面Q值是描述角膜形态的一个重要参数,被广泛运用于各种角膜地形图仪器中.现就角膜非球面Q值计算方法的发展,尤其对用轴向曲率半径和用正切曲率半径计算Q值的差别,作一综述.%The cornea is the major refractive element of the human eye,being responsible for 2/3 of the eye's total refractive power.During the past ten years,the development of computerized corneal topography has provided a complete understanding of corneal shape,especially the anterior surface.Asphericity (Q) is an important parameter describing corneal shape,and is widely described in corneal topography.This overview focuses on the development of the calculation method used for Q,especially the difference in the calculation between the sagittal and tangential radii.

  3. Corneal stromal dystrophies: a clinical pathologic study

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    Elvira Barbosa Abreu

    2012-12-01

    Full Text Available INTRODUCTION: Corneal dystrophy is defined as bilateral and symmetric primary corneal disease, without previous associated ocular inflammation. Corneal dystrophies are classified according to the involved corneal layer in superficial, stromal, and posterior dystrophy. Incidence of each dystrophy varies according to the geographic region studied. PURPOSE: To evaluate the prevalence of stromal corneal dystrophies among corneal buttons specimens obtained by penetrating keratoplasty (PK in an ocular pathology laboratory and to correlate the diagnosis with patient age and gender. METHODS: Corneal button cases of penetrating keratoplasty from January-1996 to May-2009 were retrieved from the archives of The Henry C. Witelson Ophthalmic Pathology Laboratory and Registry, Montreal, Canada. The cases with histopathological diagnosis of stromal corneal dystrophies were stained with special stains (Peroxid acid Schiff, Masson trichrome, Congo red analyzed under polarized light, and alcian blue for classification and correlated with epidemiological information (age at time of PK and gender from patients' file. RESULTS: 1,300 corneal buttons cases with clinical diagnose of corneal dystrophy were retrieved. Stromal corneal dystrophy was found in 40 (3.1% cases. Lattice corneal dystrophy was the most prevalent with 26 cases (65%. Nineteen were female (73.07% and the PK was performed at average age of 59.3 years old. Combined corneal dystrophy was found in 8 (20% cases, 5 (62.5% of them were female and the average age of the penetrating keratoplasty was 54.8 years old. Granular corneal dystrophy was represented by 5 (12.5% cases, and 2 (40% of them were female. Penetrating keratoplasty was performed at average age of 39.5 years old in granular corneal dystrophy cases. Macular corneal dystrophy was present in only 1 (2.5% case, in a 36 years old female. CONCLUSION: Systematic histopathological approach and evaluation, including special stains in all stromal

  4. Evaluation of Factors Limiting Corneal Donation.

    Science.gov (United States)

    Röck, Daniel; Wude, Johanna; Yoeruek, Efdal; Bartz-Schmidt, Karl Ulrich; Röck, Tobias

    2016-11-15

    BACKGROUND This study aimed to investigate factors limiting corneal donation at the University Hospital Tübingen. MATERIAL AND METHODS We retrospectively studied all hospital deaths from January 2012 to December 2015, considering each deceased patient as a potential corneal donor. During this period an ophthalmic resident managed corneal donor procurement on a full-time basis. Various factors limiting corneal donation were examined. RESULTS Among the 3412 deaths, 2937 (86.1%) displayed nonfulfillment of corneal donation. Consent for corneal donation was obtained in 475 cases (13.9%). The mean annual corneal donation rate was 13.9 donors per 100 deaths (range: 11.2-17.8). The leading causes of nonfulfillment of corneal donations were refusal to donate (49.8%, 1698 cases) and medical contraindications (23.6%, 805 cases). After next-of-kin interview of 2173 potential donors (109 potential donors were excluded because of logistical problems), willingness to participate in corneal donation was present in 475 cases (21.9%), whereas in 1698 cases (78.1%) corneal donation was refused. CONCLUSIONS Our study showed refusal to donate is the most important factor limiting corneal donation. It seems that increasing the knowledge of people about corneal donation through public education and media are necessary to address the corneal shortage.

  5. Corneal Biomechanical Findings in Contact Lens Induced Corneal Warpage

    Science.gov (United States)

    Letafatnejad, Mojgan; Beheshtnejad, Amir Hooshang; Ghaffary, Seyed Reza; Hassanpoor, Narges; Yaseri, Mehdi

    2016-01-01

    Purpose. To evaluate the difference in biomechanical properties between contact lens induced corneal warpage and normal and keratoconic eyes. Method. Prospective observational case control study, where 94 eyes of 47 warpage suspicious and 46 eyes of 23 keratoconic patients were included. Warpage suspected cases were followed until a definite diagnosis was made (warpage, normal, or keratoconus). Results. 44 eyes of 22 patients had contact lens related corneal warpage. 46 eyes of 23 people were diagnosed as nonwarpage normal eyes. 46 eyes of 23 known keratoconus patients were included for comparison. The mean age of the participants was 23.8 ± 3.8 years, and 66.2% of the subjects were female. The demographic and refractive data were not different between warpage and normal groups but were different in the keratoconus group. The biomechanical properties (corneal hysteresis or CH and corneal resistance factor or CRF) were different with the highest value in the warpage group followed by normal and keratoconus groups. CRF was 10.08 ± 1.75, 9.23 ± 1.22, and 7.38 ± 2.14 and CH was 10.21 ± 1.57, 9.59 ± 1.21, and 8.69 ± 2.34 in the warpage, normal, and keratoconus groups, respectively. Conclusion. Corneal biomechanics may be different in people who develop contact lens induced warpage. PMID:27688908

  6. Reconstruction of Rabbit Corneal Layer Composed of Corneal Fibroblasts and Corneal Epithelium on the Lyophilized Amniotic Membrane

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Many researchers have employed the cryopreserved amniotic membrane(CAM) and corneal epithelial cells in the treatment of a severely damaged burned cornea, with corneal epithelial cells cultured on an amniotic membrane (AM). The lyophilized amniotic membrane (LAM) has a higher graft take and a longer shelf life; it is easier to store and safer because of gamma irradiation. Two Teflon rings(Ahn's supporter) were made for culturing the cells on the LAM, and were then used to support the LAM. To reconstruct a corneal layer composed of corneal fibroblasts and epithelium, the corneal fibroblasts were first cultivated on the stromal side of LAM for five days, followed by epithelial cells culture on the epithelial side, by using the air-liquid interface culture. The reconstructed corneal layer composed of corneal fibroblasts and corneal epithelial cells has a much healthier basal layer of corneal epithelium than the reconstructed corneal epithelium, which was got by using only corneal epithelial cells, and resembles the epithelium of normal corneas, without the horny layer. Thus, the reconstruction of the corneal layer by using a LAM is considered to be a good in vitro model, not only for its application in toxicological test kits, but also for transplantation in patients with a severely damaged cornea.

  7. Corneal biomechanics: a review.

    Science.gov (United States)

    Piñero, David P; Alcón, Natividad

    2015-03-01

    Biomechanics is often defined as 'mechanics applied to biology'. Due to the variety and complexity of the behaviour of biological structures and materials, biomechanics is better defined as the development, extension and application of mechanics for a better understanding of physiology and physiopathology and consequently for a better diagnosis and treatment of disease and injury. Different methods for the characterisation of corneal biomechanics are reviewed in detail, including those that are currently commercially available (Ocular Response Analyzer and CorVis ST). The clinical applicability of the parameters provided by these devices are discussed, especially in the fields of glaucoma, detection of ectatic disorders and orthokeratology. Likewise, other methods are also reviewed, such as Brillouin microscopy or dynamic optical coherence tomography and others with potential application to clinical practice but not validated for in vivo measurements, such as ultrasonic elastography. Advantages and disadvantages of all these techniques are described. Finally, the concept of biomechanical modelling is revised as well as the requirements for developing biomechanical models, with special emphasis on finite element modelling.

  8. Corneal Decompensation after Selective Laser Trabeculoplasty

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    Ahmet Ozkok

    2014-01-01

    Full Text Available A 64-year-old Caucasian man referred for decreased vision after selective laser trabeculoplasty (SLT. Slit lamp examination revealed diffuse corneal edema. Despite intensive topical treatment including steroids, corneal edema did not resolve; on the contrary, it advanced to bullous keratopathy. Corneal edema after SLT is an exceptionally rare complication and in all of the previous reports edema resolved with medical treatment. To the best of our knowledge, this is the first report presenting persistent corneal edema after SLT.

  9. Progress of research on corneal collagen cross-linking for corneal melting

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    Ke-Ren Xiao

    2016-06-01

    Full Text Available Corneal collagen cross-linking(CXLcould increase the mechanical strength, biological stability and halt ectasia progression due to covalent bond formed by photochemical reaction between ultraviolet-A and emulsion of riboflavin between collagen fibers in corneal stroma. Corneal melting is an autoimmune related noninfectious corneal ulcer. The mechanism of corneal melting, major treatment, the basic fundamental of ultraviolet-A riboflavin induced CXL and the clinical researches status and experiment in CXL were summarized in the study.

  10. Topography of Io (color)

    Science.gov (United States)

    1997-01-01

    The images used to create this color composite of Io were acquired by Galileo during its ninth orbit (C9) of Jupiter and are part of a sequence of images designed to map the topography or relief on Io and to monitor changes in the surface color due to volcanic activity. Obtaining images at low illumination angles is like taking a picture from a high altitude around sunrise or sunset. Such lighting conditions emphasize the topography of the volcanic satellite. Several mountains up to a few miles high can be seen in this view, especially near the upper right. Some of these mountains appear to be tilted crustal blocks. Most of the dark spots correspond to active volcanic centers.North is to the top of the picture which merges images obtained with the clear, red, green, and violet filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. . The resolution is 8.3 kilometers per picture element. The image was taken on June 27, 1997 at a range of 817,000 kilometers by the solid state imaging (CCD) system on NASA's Galileo spacecraft.The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  11. Corneal Cross-Linking in a 4-Year-Old Child With Keratoconus and Down Syndrome.

    Science.gov (United States)

    Sabti, Saad; Tappeiner, Christoph; Frueh, Beatrice E

    2015-09-01

    To describe the clinical outcome of corneal cross-linking (CXL) in a young child with keratoconus. This is a case report of a young girl with keratoconus with ophthalmologic findings and 3-year follow-up. Follow-up visits included visual acuity measurement, retinoscopy, corneal tomography, and topography. A girl with Down syndrome was diagnosed with bilateral keratoconus and relative amblyopia at the age of 4 years. The best-corrected near visual acuity was 20/100 binocularly. Corneal tomography showed the following parameters: OD K(max) 47.2 diopters (D), thinnest location 442 μm; OS K(max) 49.6 D, thinnest location 432 μm. Three months later, the keratoconus in the left eye progressed (K(max) 50.2 D, thinnest location 424 μm), and CXL was performed. One year later, CXL was necessary also in the right eye because of progression. The girl was most recently reexamined at the age of 7 years. The corrected near visual acuity was 20/80 in both eyes. The corneal curvature slightly flattened, and the corneal thickness stabilized (OD K(max) 46.8 D, thinnest location 389 μm; OS K(max) 49.4 D, thinnest location 360 μm). Onset of keratoconus can occur in early childhood, especially in patients with Down syndrome. In this case, CXL was performed at 4 and 5 years of age without complications and stopped further keratoconus progression.

  12. Anterior corneal and internal contributions to peripheral aberrations of human eyes

    Science.gov (United States)

    Atchison, David A.

    2004-03-01

    Anterior corneal and internal component contributions to overall peripheral aberrations of five human eyes were determined, based on corneal topography and overall aberration measurements. Anterior corneal position and orientation (tilt) were referenced to the line of sight. Ray tracing was performed through the anterior cornea for 6-mm-diameter pupils at angles out to 40° in both the temporal and the nasal visual fields. In general, both component and overall Zernike aberrations were greater for the nasal than for the temporal visual field. In general, the anterior corneal aberration components were considerably higher than the overall aberrations across the visual field and were balanced to a considerable degree by the internal ocular aberration components. The component and overall levels of Zernike third-order aberrations showed linear trends away from the fixation axis, and the component levels of Zernike fourth-order aberrations showed quadratic trends away from the fixation axis. The second-order, but not higher-order, aberration components were susceptible to the choice of image radius of curvature, while disregarding corneal position and orientation affected second- and higher-order aberration components.

  13. Evaluation of corneal biomechanical properties following penetrating keratoplasty using ocular response analyzer

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    Vanathi Murugesan

    2014-01-01

    Full Text Available Purpose: To evaluate corneal biomechanical properties in eyes that has undergone penetrating keratoplasty (PK. Materials and Methods: Retrospective observational study in a tertiary care centre. Data recorded included ocular response analyzer (ORA values of normal and post-keratoplasty eyes [corneal hysteresis (CH, corneal resistance factor (CRF, Goldmann-correlated intraocular pressure (IOPg, and cornea-compensated intraocular pressure (IOPcc], corneal topography, and central corneal thickness (CCT. Wilcoxon signed rank test was used to analyze the difference in ORA parameter between post-PK eyes and normal eyes. Correlation between parameters was evaluated with Spearman′s rho correlation. Results: The ORA study of 100 eyes of 50 normal subjects and 54 post-keratoplasty eyes of 51 patients showed CH of 8.340 ± 1.85 and 9.923 ± 1.558, CRF of 8.846 ± 2.39 and 9.577 ± 1.631 in post-PK eyes and normal eyes, respectively. CH and CRF did not correlate with post-keratoplasty astigmatism (P = 0.311 and 0.276, respectively while a significant correlation was observed with IOPg (P = 0.004 and IOPcc (P < 0.001. Conclusion: Biomechanical profiles were significantly decreased in post-keratoplasty eyes with significant correlation with higher IOP as compared with that in normal eyes.

  14. Ocular dimensions, corneal thickness, and corneal curvature in quarter horses with hereditary equine regional dermal asthenia.

    Science.gov (United States)

    Badial, Peres R; Cisneros-Àlvarez, Luis Emiliano; Brandão, Cláudia Valéria S; Ranzani, José Joaquim T; Tomaz, Mayana A R V; Machado, Vania M; Borges, Alexandre S

    2015-09-01

    The aim of this study was to compare ocular dimensions, corneal curvature, and corneal thickness between horses affected with hereditary equine regional dermal asthenia (HERDA) and unaffected horses. Five HERDA-affected quarter horses and five healthy control quarter horses were used. Schirmer's tear test, tonometry, and corneal diameter measurements were performed in both eyes of all horses prior to ophthalmologic examinations. Ultrasonic pachymetry was performed to measure the central, temporal, nasal, dorsal, and ventral corneal thicknesses in all horses. B-mode ultrasound scanning was performed on both eyes of each horse to determine the dimensions of the ocular structures and to calculate the corneal curvature. Each corneal region examined in this study was thinner in the affected group compared with the healthy control group. However, significant differences in corneal thickness were only observed for the central and dorsal regions. HERDA-affected horses exhibited significant increases in corneal curvature and corneal diameter compared with unaffected animals. The ophthalmologic examinations revealed mild corneal opacity in one eye of one affected horse and in both eyes of three affected horses. No significant between-group differences were observed for Schirmer's tear test, intraocular pressure, or ocular dimensions. Hereditary equine regional dermal asthenia-affected horses exhibit decreased corneal thickness in several regions of the cornea, increased corneal curvature, increased corneal diameter, and mild corneal opacity. Additional research is required to determine whether the increased corneal curvature significantly impacts the visual accuracy of horses with HERDA. © 2014 American College of Veterinary Ophthalmologists.

  15. Acute corneal hydrops in keratoconus

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    Prafulla K Maharana

    2013-01-01

    Full Text Available Acute corneal hydrops is a condition characterized by stromal edema due to leakage of aqueous through a tear in descemet membrane. The patient presents with sudden onset decrease in vision, photophobia, and pain. Corneal thinning and ectasias combined with trivial trauma to the eye mostly by eye rubbing is considered as the underlying cause. With conservative approach self-resolution takes around 2 to 3 months. Surgical intervention is required in cases of non-resolution of corneal edema to avoid complications and for early visual rehabilitation. Intracameral injection of air or gas such as perflouropropane is the most common surgical procedure done. Recent investigative modality such as anterior segment optical coherence tomography is an extremely useful tool for diagnosis, surgical planning, and postoperative follow up. Resolution of hydrops may improve the contact lens tolerance and visual acuity but most cases require keratoplasty for visual rehabilitation.

  16. Posterior Corneal Surface Stability after Femtosecond Laser-Assisted Keratomileusis

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    Carlo Cagini

    2015-01-01

    Full Text Available The purpose of this study was to evaluate posterior corneal surface variation after femtosecond laser-assisted keratomileusis in patients with myopia and myopic astigmatism. Patients were evaluated by corneal tomography preoperatively and at 1, 6, and 12 months. We analyzed changes in the posterior corneal curvature, posterior corneal elevation, and anterior chamber depth. Moreover, we explored correlation between corneal ablation depth, residual corneal thickness, percentage of ablated corneal tissue, and preoperative corneal thickness. During follow-up, the posterior corneal surface did not have a significant forward corneal shift: no significant linear relationships emerged between the anterior displacement of the posterior corneal surface and corneal ablation depth, residual corneal thickness, or percentage of ablated corneal tissue.

  17. Comparison of corneal epithelial and stromal thickness distributions between eyes with keratoconus and healthy eyes with corneal astigmatism ≥ 2.0 D.

    Directory of Open Access Journals (Sweden)

    Wen Zhou

    Full Text Available PURPOSE: To identify corneal epithelial- and stromal-thickness distribution patterns in keratoconus using spectral-domain optical coherence tomography (SD-OCT. PATIENTS AND METHODS: We analyzed SD-OCT findings in 20 confirmed cases of keratoconus (group 1 and in 20 healthy subjects with corneal astigmatism ≥ 2 D (group 2. Epithelial and stromal thicknesses were measured at 11 strategic locations along the steepest and flattest meridians, previously located by corneal topography. Vertical mirrored symmetry superimposition was used in the statistical analysis. RESULTS: The mean maximum keratometry measurements in groups 1 and 2 were 47.9 ± 2.9 D (range, 41.8-52.8 and 45.6 ± 1.1 D (range, 42.3-47.5, respectively, with mean corneal cylinders of 3.3 ± 2.2 D (range, 0.5-9.5 and 3.6 ± 1.2 D (range, 2.0-6.4, respectively. The mean epithelial thickness along the steepest meridian in group 1 was the lowest (37.4 ± 4.4 µm at 1.2 mm inferotemporally and the highest (59.3 ± 4.4 µm at 1.4 mm supranasally from the corneal vertex. There was only a small deviation in thickness along the steepest meridian in group 2, as well as along the flattest meridians in both groups. The stromal thickness distribution in the two groups was similar to the epithelial, while the stromal thickness was generally lower in group 1 than in group 2. CONCLUSIONS: SD-OCT provides details about the distribution of corneal epithelial and stromal thicknesses. The epithelium and stroma in keratoconic eyes were thinner inferotemporally and thicker supranasally compared with control eyes. The distribution pattern was more distinct in epithelium than in stroma. This finding may help improve the early diagnosis of keratoconus. TRIAL REGISTRATION: ClinicalTrials.gov NCT02023619.

  18. Progress in corneal wound healing.

    Science.gov (United States)

    Ljubimov, Alexander V; Saghizadeh, Mehrnoosh

    2015-11-01

    Corneal wound healing is a complex process involving cell death, migration, proliferation, differentiation, and extracellular matrix remodeling. Many similarities are observed in the healing processes of corneal epithelial, stromal and endothelial cells, as well as cell-specific differences. Corneal epithelial healing largely depends on limbal stem cells and remodeling of the basement membrane. During stromal healing, keratocytes get transformed to motile and contractile myofibroblasts largely due to activation of transforming growth factor-β (TGF-β) system. Endothelial cells heal mostly by migration and spreading, with cell proliferation playing a secondary role. In the last decade, many aspects of wound healing process in different parts of the cornea have been elucidated, and some new therapeutic approaches have emerged. The concept of limbal stem cells received rigorous experimental corroboration, with new markers uncovered and new treatment options including gene and microRNA therapy tested in experimental systems. Transplantation of limbal stem cell-enriched cultures for efficient re-epithelialization in stem cell deficiency and corneal injuries has become reality in clinical setting. Mediators and course of events during stromal healing have been detailed, and new treatment regimens including gene (decorin) and stem cell therapy for excessive healing have been designed. This is a very important advance given the popularity of various refractive surgeries entailing stromal wound healing. Successful surgical ways of replacing the diseased endothelium have been clinically tested, and new approaches to accelerate endothelial healing and suppress endothelial-mesenchymal transformation have been proposed including Rho kinase (ROCK) inhibitor eye drops and gene therapy to activate TGF-β inhibitor SMAD7. Promising new technologies with potential for corneal wound healing manipulation including microRNA, induced pluripotent stem cells to generate corneal

  19. Progress in corneal wound healing

    Science.gov (United States)

    Ljubimov, Alexander V.; Saghizadeh, Mehrnoosh

    2015-01-01

    Corneal wound healing is a complex process involving cell death, migration, proliferation, differentiation, and extracellular matrix remodeling. Many similarities are observed in the healing processes of corneal epithelial, stromal and endothelial cells, as well as cell-specific differences. Corneal epithelial healing largely depends on limbal stem cells and remodeling of the basement membrane. During stromal healing, keratocytes get transformed to motile and contractile myofibroblasts largely due to activation of transforming growth factor-β system. Endothelial cells heal mostly by migration and spreading, with cell proliferation playing a secondary role. In the last decade, many aspects of wound healing process in different parts of the cornea have been elucidated, and some new therapeutic approaches have emerged. The concept of limbal stem cells received rigorous experimental corroboration, with new markers uncovered and new treatment options including gene and microRNA therapy tested in experimental systems. Transplantation of limbal stem cell-enriched cultures for efficient re-epithelialization in stem cell deficiency and corneal injuries has become reality in clinical setting. Mediators and course of events during stromal healing have been detailed, and new treatment regimens including gene (decorin) and stem cell therapy for excessive healing have been designed. This is a very important advance given the popularity of various refractive surgeries entailing stromal wound healing. Successful surgical ways of replacing the diseased endothelium have been clinically tested, and new approaches to accelerate endothelial healing and suppress endothelial-mesenchymal transformation have been proposed including Rho kinase (ROCK) inhibitor eye drops and gene therapy to activate TGF-β inhibitor SMAD7. Promising new technologies with potential for corneal wound healing manipulation including microRNA, induced pluripotent stem cells to generate corneal epithelium, and

  20. [Corneal manifestations in systemic diseases].

    Science.gov (United States)

    Zarranz Ventura, J; De Nova, E; Moreno-Montañés, J

    2008-01-01

    Systemic diseases affecting the cornea have a wide range of manifestations. The detailed study of all pathologies that cause corneal alteration is unapproachable, so we have centered our interest in the most prevalent or characteristic of them. In this paper we have divided these pathologies in sections to facilitate their study. Pulmonar and conective tissue (like colagen, rheumatologic and idiopathic inflamatory diseases), dermatologic, cardiovascular, hematologic, digestive and hepatopancreatic diseases with corneal alteration are described. Endocrine and metabolic diseases, malnutrition and carential states are also studied, as well as some otorhinolaryngologic and genetic diseases that affect the cornea. Finally, a brief report of ocular toxicity induced by drugs is referred.

  1. Isostasy, flexure, and dynamic topography

    Science.gov (United States)

    Gvirtzman, Zohar; Faccenna, Claudio; Becker, Thorsten W.

    2016-06-01

    A fundamental scientific question is, what controls the Earth's topography? Although the theoretical principles of isostasy, flexure, and dynamic topography are widely discussed, the parameters needed to apply these principles are frequently not available. Isostatic factors controlling lithospheric buoyancy are frequently uncertain and non-isostatic factors, such as lithospheric bending towards subduction zones and dynamic topography, are hard to distinguish. The question discussed here is whether a set of simple rules that relate topography to lithospheric structure in various tectonic environments can be deduced in a way that missing parameters can be approximated; or does each area behave differently, making generalizations problematic. We contribute to this issue analyzing the Asia-Africa-Arabia-Europe domain following a top-down strategy. We compile a new crustal thickness map and remove the contribution of the crust from the observed elevation. Then, the challenge is to interpret the residual topography in terms of mantle lithosphere buoyancy and dynamics. Based on systematic relationships between tectonic environments and factors controlling topography, we argue that crustal buoyancy and mantle lithospheric density can be approximated from available geological data and that regions near mantle upwelling or downwelling are easily identified by their extreme residual topography. Yet, even for other areas, calculating lithospheric thickness from residual topography is problematic, because distinguishing variations in mantle lithosphere thickness from sub-lithospheric dynamics is difficult. Fortunately, the area studied here provides an opportunity to examine this issue. Based on the conjunction between the Afar Plume and the mid-ocean ridge in the nearby Gulf of Aden and southern Red Sea, we constrain the maximal amplitude of dynamic topography to ~ 1 km. This estimate is based on a narrow definition of dynamic topography that only includes sub

  2. Corneal Regeneration After Photorefractive Keratectomy: A Review.

    Science.gov (United States)

    Tomás-Juan, Javier; Murueta-Goyena Larrañaga, Ane; Hanneken, Ludger

    2015-01-01

    Photorefractive keratectomy (PRK) remodels corneal stroma to compensate refractive errors. The removal of epithelium and the ablation of stroma provoke the disruption of corneal nerves and a release of several peptides from tears, epithelium, stroma and nerves. A myriad of cytokines, growth factors, and matrix metalloproteases participate in the process of corneal wound healing. Their balance will determine if reepithelization and stromal remodeling are appropriate. The final aim is to achieve corneal transparency for restoring corneal function, and a proper visual quality. Therefore, wound-healing response is critical for a successful refractive surgery. Our goal is to provide an overview into how corneal wounding develops following PRK. We will also review the influence of intraoperative application of mitomycin C, bandage contact lenses, anti-inflammatory and other drugs in preventing corneal haze and post-PRK pain. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  3. Metabolic topography of Parkinsonism

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Seung [Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of)

    2007-04-15

    Parkinson's disease is one of the most frequent neurodegenerative diseases, which mainly affects the elderly. Parkinson's disease is often difficult to differentiate from atypical parkinson disorder such as progressive supranuclear palsy, multiple system atrophy, dementia with Lewy body, and corticobasal ganglionic degeneration, based on the clinical findings because of the similarity of phenotypes and lack of diagnostic markers. The accurate diagnosis of Parkinson's disease and atypical Parkinson disorders is not only important for deciding on treatment regimens and providing prognosis, but also it is critical for studies designed to investigate etiology and pathogenesis of parkinsonism and to develop new therapeutic strategies. Although degeneration of the nigrostriatal dopamine system results in marked loss of striatal dopamine content in most of the diseases causing parkinsonism, pathologic studies revealed different topographies of the neuronal cell loss in Parkinsonism. Since the regional cerebral glucose metabolism is a marker of integrated local synaptic activity and as such is sensitive to both direct neuronal/synaptic damage and secondary functional disruption at synapses distant from the primary site of pathology, and assessment of the regional cerebral glucose metabolism with F-18 FDG PET is useful in the differential diagnosis of parkinsonism and evaluating the pathophysiology of Parkinsonism.

  4. Corneal stroma microfibrils

    KAUST Repository

    Hanlon, Samuel D.

    2015-03-01

    Elastic tissue was first described well over a hundred years ago and has since been identified in nearly every part of the body. In this review, we examine elastic tissue in the corneal stroma with some mention of other ocular structures which have been more thoroughly described in the past. True elastic fibers consist of an elastin core surrounded by fibrillin microfibrils. However, the presence of elastin fibers is not a requirement and some elastic tissue is comprised of non-elastin-containing bundles of microfibrils. Fibers containing a higher relative amount of elastin are associated with greater elasticity and those without elastin, with structural support. Recently it has been shown that the microfibrils, not only serve mechanical roles, but are also involved in cell signaling through force transduction and the release of TGF-β. A well characterized example of elastin-free microfibril bundles (EFMBs) is found in the ciliary zonules which suspend the crystalline lens in the eye. Through contraction of the ciliary muscle they exert enough force to reshape the lens and thereby change its focal point. It is believed that the molecules comprising these fibers do not turn-over and yet retain their tensile strength for the life of the animal. The mechanical properties of the cornea (strength, elasticity, resiliency) would suggest that EFMBs are present there as well. However, many authors have reported that, although present during embryonic and early postnatal development, EFMBs are generally not present in adults. Serial-block-face imaging with a scanning electron microscope enabled 3D reconstruction of elements in murine corneas. Among these elements were found fibers that formed an extensive network throughout the cornea. In single sections these fibers appeared as electron dense patches. Transmission electron microscopy provided additional detail of these patches and showed them to be composed of fibrils (~10nm diameter). Immunogold evidence clearly

  5. Corneale crosslinking voor progressieve keratoconus

    NARCIS (Netherlands)

    Wisse, Robert P L; Soeters, Nienke; Godefrooij, Daniel A.; De Koning-Tahzib, Nayyirih G.

    2016-01-01

    Keratoconus is a corneal disease with onset typically occurring during puberty or early adulthood. The cornea progressively thins and acquires a cone-like shape which negatively affects visual acuity. In the early stages, visual acuity can be corrected with glasses or contact lenses. In more

  6. Corneale crosslinking voor progressieve keratoconus

    NARCIS (Netherlands)

    Wisse, Robert P L; Soeters, Nienke; Godefrooij, Daniel A.; De Koning-Tahzib, Nayyirih G.

    2016-01-01

    Keratoconus is a corneal disease with onset typically occurring during puberty or early adulthood. The cornea progressively thins and acquires a cone-like shape which negatively affects visual acuity. In the early stages, visual acuity can be corrected with glasses or contact lenses. In more advance

  7. Terahertz sensing of corneal hydration.

    Science.gov (United States)

    Singh, Rahul S; Tewari, Priyamvada; Bourges, Jean Louis; Hubschman, Jean Pierre; Bennett, David B; Taylor, Zachary D; Lee, H; Brown, Elliott R; Grundfest, Warren S; Culjat, Martin O

    2010-01-01

    An indicator of ocular health is the hydrodyanmics of the cornea. Many corneal disorders deteriorate sight as they upset the normal hydrodynamics of the cornea. The mechanisms include the loss of endothelial pump function of corneal dystophies, swelling and immune response of corneal graft rejection, and inflammation and edema, which accompany trauma, burn, and irritation events. Due to high sensitivity to changes of water content in materials, a reflective terahertz (300 GHz and 3 THz) imaging system could be an ideal tool to measure the hydration level of the cornea. This paper presents the application of THz technology to visualize the hydration content across ex vivo porcine corneas. The corneas, with a thickness variation from 470 - 940 µm, were successfully imaged using a reflective pulsed THz imaging system, with a maximum SNR of 50 dB. To our knowledge, no prior studies have reported on the use of THz in measuring hydration in corneal tissues or other ocular tissues. These preliminary findings indicate that THz can be used to accurately sense hydration levels in the cornea using a pulsed, reflective THz imaging system.

  8. Management of corneal bee sting

    Directory of Open Access Journals (Sweden)

    Razmjoo H

    2011-12-01

    Full Text Available Hassan Razmjoo1,2, Mohammad-Ali Abtahi1,2,4, Peyman Roomizadeh1,3, Zahra Mohammadi1,2, Seyed-Hossein Abtahi1,3,41Medical School, Isfahan University of Medical Sciences (IUMS; 2Ophthalmology Ward, Feiz Hospital, IUMS; 3Isfahan Medical Students Research Center (IMSRC, IUMS; 4Isfahan Ophthalmology Research Center (IORC, Feiz Hospital, IUMS, Isfahan, IranAbstract: Corneal bee sting is an uncommon environmental eye injury that can result in various ocular complications with an etiology of penetrating, immunologic, and toxic effects of the stinger and its injected venom. In this study we present our experience in the management of a middle-aged male with a right-sided deep corneal bee sting. On arrival, the patient was complaining of severe pain, blurry vision with acuity of 160/200, and tearing, which he had experienced soon after the injury. Firstly, we administered conventional drugs for eye injuries, including topical antibiotic, corticosteroid, and cycloplegic agents. After 2 days, corneal stromal infiltration and edema developed around the site of the sting, and visual acuity decreased to 100/200. These conditions led us to remove the stinger surgically. Within 25 days of follow-up, the corneal infiltration decreased gradually, and visual acuity improved to 180/200. We suggest a two-stage management approach for cases of corneal sting. For the first stage, if the stinger is readily accessible or primary dramatic reactions, including infiltration, especially on the visual axis, exist, manual or surgical removal would be indicated. Otherwise, we recommend conventional treatments for eye injuries. Given this situation, patients should be closely monitored for detection of any worsening. If the condition does not resolve or even deteriorates, for the second stage, surgical removal of the stinger under local or generalized anesthesia is indicated.Keywords: bee sting, stinger, cornea, removal, management, surgery

  9. Turning the tide of corneal blindness.

    Science.gov (United States)

    Oliva, Matthew S; Schottman, Tim; Gulati, Manoj

    2012-01-01

    Corneal diseases represent the second leading cause of blindness in most developing world countries. Worldwide, major investments in public health infrastructure and primary eye care services have built a strong foundation for preventing future corneal blindness. However, there are an estimated 4.9 million bilaterally corneal blind persons worldwide who could potentially have their sight restored through corneal transplantation. Traditionally, barriers to increased corneal transplantation have been daunting, with limited tissue availability and lack of trained corneal surgeons making widespread keratoplasty services cost prohibitive and logistically unfeasible. The ascendancy of cataract surgical rates and more robust eye care infrastructure of several Asian and African countries now provide a solid base from which to dramatically expand corneal transplantation rates. India emerges as a clear global priority as it has the world's largest corneal blind population and strong infrastructural readiness to rapidly scale its keratoplasty numbers. Technological modernization of the eye bank infrastructure must follow suit. Two key factors are the development of professional eye bank managers and the establishment of Hospital Cornea Recovery Programs. Recent adaptation of these modern eye banking models in India have led to corresponding high growth rates in the procurement of transplantable tissues, improved utilization rates, operating efficiency realization, and increased financial sustainability. The widespread adaptation of lamellar keratoplasty techniques also holds promise to improve corneal transplant success rates. The global ophthalmic community is now poised to scale up widespread access to corneal transplantation to meet the needs of the millions who are currently blind.

  10. Turning the tide of corneal blindness

    Directory of Open Access Journals (Sweden)

    Matthew S Oliva

    2012-01-01

    Full Text Available Corneal diseases represent the second leading cause of blindness in most developing world countries. Worldwide, major investments in public health infrastructure and primary eye care services have built a strong foundation for preventing future corneal blindness. However, there are an estimated 4.9 million bilaterally corneal blind persons worldwide who could potentially have their sight restored through corneal transplantation. Traditionally, barriers to increased corneal transplantation have been daunting, with limited tissue availability and lack of trained corneal surgeons making widespread keratoplasty services cost prohibitive and logistically unfeasible. The ascendancy of cataract surgical rates and more robust eye care infrastructure of several Asian and African countries now provide a solid base from which to dramatically expand corneal transplantation rates. India emerges as a clear global priority as it has the world′s largest corneal blind population and strong infrastructural readiness to rapidly scale its keratoplasty numbers. Technological modernization of the eye bank infrastructure must follow suit. Two key factors are the development of professional eye bank managers and the establishment of Hospital Cornea Recovery Programs. Recent adaptation of these modern eye banking models in India have led to corresponding high growth rates in the procurement of transplantable tissues, improved utilization rates, operating efficiency realization, and increased financial sustainability. The widespread adaptation of lamellar keratoplasty techniques also holds promise to improve corneal transplant success rates. The global ophthalmic community is now poised to scale up widespread access to corneal transplantation to meet the needs of the millions who are currently blind.

  11. Clinical applications of corneal confocal microscopy

    Directory of Open Access Journals (Sweden)

    Mitra Tavakoli

    2008-06-01

    Full Text Available Mitra Tavakoli1, Parwez Hossain2, Rayaz A Malik11Division of Cardiovascular Medicine, University of Manchester and Manchester Royal Infirmary, Manchester, UK; 2University of Southampton, Southampton Eye Unit, Southampton General Hospital, Southampton, UKAbstract: Corneal confocal microscopy is a novel clinical technique for the study of corneal cellular structure. It provides images which are comparable to in-vitro histochemical techniques delineating corneal epithelium, Bowman’s layer, stroma, Descemet’s membrane and the corneal endothelium. Because, corneal confocal microscopy is a non invasive technique for in vivo imaging of the living cornea it has huge clinical potential to investigate numerous corneal diseases. Thus far it has been used in the detection and management of pathologic and infectious conditions, corneal dystrophies and ecstasies, monitoring contact lens induced corneal changes and for pre and post surgical evaluation (PRK, LASIK and LASEK, flap evaluations and Radial Keratotomy, and penetrating keratoplasty. Most recently it has been used as a surrogate for peripheral nerve damage in a variety of peripheral neuropathies and may have potential in acting as a surrogate marker for endothelial abnormalities.Keywords: corneal confocal microscopy, cornea, infective keratitis, corneal dystrophy, neuropathy

  12. Scanning laser system to determine the corneal shape

    Science.gov (United States)

    Ascanio, Gabriel; Caballero-Ruiz, Alberto; Ruiz-Huerta, Leopoldo; Gonzalez-Cardel, Mario; Diaz-Uribe, Rufino

    2005-07-01

    The development and tests of a scanning system to be used to determine the corneal topography with the laser deflectometry method are presented. In this equipment, a He-Ne laser beam scans the cornea by describing a spiral trajectory generated by two components: radial and angular. The first component is produced by the displacement of a plane mirror moved by a linear pneumatic actuator. The second component is produced by passing the beam through a Dove prism which is rotating by means of a belt drive coupled to a high-speed electric motor. Tests were first performed by analyzing both components independently and then they were characterized by combining the two components. Results are discussed and compared to those of an earlier cited work.

  13. Visual outcome after corneal transplantation for corneal perforation and iris prolapse in 37 horses

    DEFF Research Database (Denmark)

    Henriksen, Michala de Linde; Plummer, C. E.; Mangan, B.;

    2012-01-01

    We wanted to investigate the visual outcome of horses presented with iris prolapse and treated with corneal transplantation.......We wanted to investigate the visual outcome of horses presented with iris prolapse and treated with corneal transplantation....

  14. The effect of pterygium surgery on contrast sensitivity and corneal topographic changes

    Directory of Open Access Journals (Sweden)

    Joo Youn Oh

    2010-04-01

    Full Text Available Joo Youn Oh, Won Ryang WeeDepartment of Ophthalmology, Seoul National University Hospital, Seoul, KoreaPurpose: To investigate the effect of pterygium surgery on corneal topography and contrast sensitivity.Patient and methods: The IRB approved this prospective, nonrandomized, self-controlled study. Computerized videokeratography (Orbscan II was performed in 36 patients with primary pterygia, both before and 1 month after pterygium excision with limbal-conjunctival autografting. The topographic parameters were compared. Spatial contrast sensitivity testing was performed using VCTS 6500. Differences between preoperative and postoperative values were evaluated statistically.Results: The mean Sim K astigmatism and irregularity index, significantly decreased after pterygium surgery. The mean refractive power significantly increased after the operation. The “with-the-rule” astigmatism induced by pterygium became “against-the-rule” astigmatism after pterygium removal (P = 0.041. The contrast sensitivity of 6, 12, and 18 cycles per degree, significantly increased from 1.55 ± 0.28, 0.97 ± 0.47, and 0.29 ± 0.16 to 1.72 ± 0.18, 1.21 ± 0.44, and 0.65 ± 0.48, respectively (P = 0.007, <0.001, <0.001, respectively.Conclusions: Pterygium surgery significantly reduces corneal topographic astigmatism and improves contrast sensitivity.Keywords: corneal topography, visual acuity

  15. Toric Intraocular Lens Implantation for Correction of Astigmatism in Cataract Patients with Corneal Ectasia

    Directory of Open Access Journals (Sweden)

    Efstratios A. Parikakis

    2013-11-01

    Full Text Available Our purpose was to examine the long-term efficacy of toric intraocular lens (IOL implantation in cataract patients with high astigmatism due to corneal ectasia, who underwent phacoemulsification cataract surgery. Five eyes of 3 cataract patients with topographically stable keratoconus or pellucid macular degeneration (PMD, in which phacoemulsification with toric IOL implantation was used to correct high astigmatism, are reported. Objective and subjective refraction, visual acuity measurement and corneal topography were performed in all cases before and after cataract surgery. In all cases, there was a significant improvement in visual acuity, as well as refraction, which remained stable over time. Specifically, in subjective refraction, all patients achieved visual acuity from 7/10 to 9/10 with up to -2.50 cyl. Corneal topography also remained stable. Postoperative follow-up was 18-28 months. Cataract surgery with toric IOL implantation seems to be safe and effective in correcting astigmatism and improving visual function in cataract patients with topographically stable keratoconus or PMD.

  16. Outcomes of corneal crosslinking for central and paracentral keratoconus

    Science.gov (United States)

    Tian, Mingxia; Ma, Ping; Zhou, Weiyan; Feng, Jie; Mu, Guoying

    2017-01-01

    Abstract Background: The aim of the study was to compare the therapy of corneal collagen crosslinking (CXL) for central and paracentral keratoconus. Methods: 64 eyes of 43 central keratoconus patients whose highest power of the cornea located in the central 3 mm zone and 24 eyes of 16 paracentral keratoconus patients whose highest power located out of the central 3 mm zone received standard corneal CXL were included. Maximum keratometry (Kmax) and astigmatism according to topography, uncorrected distant visual acuity (UDVA), corrected distant visual acuity (CDVA) were studied preoperatively and 2 years postoperatively. Results: Central group: Preoperative UDVA and CDVA were 0.9 ± 0.4 and 0.5 ± 0.4 logMAR, respectively. At 2 years, UDVA and CDVA significantly improved to 0.8 ± 0.4 and 0.4 ± 0.3 logMAR(P  0.05). Preoperative Kmax and astigmatism were 50.3 ± 5.3 and 2.4 ± 1.7 D, respectively. At 2 years, Kmax significantly decreased to 48.8 ± 4.6 (P  0.05). Conclusion: This study indicated that CXL was more effective for central keratoconus than paracentral keratoconus. PMID:28272223

  17. Genetics Home Reference: lattice corneal dystrophy type I

    Science.gov (United States)

    ... corneal dystrophy type I lattice corneal dystrophy type I Enable Javascript to view the expand/collapse boxes. ... All Close All Description Lattice corneal dystrophy type I is an eye disorder that affects the clear, ...

  18. Immunoglobulins in granular corneal dystrophy Groenouw type I

    DEFF Research Database (Denmark)

    Møller, H U; Bojsen-Møller, M; Schrøder, H D

    1993-01-01

    Three patients with granular corneal dystrophy Groenouw type I underwent corneal grafting, and cryostat sections of the corneal buttons were examined immunohistochemically for immunoglobulins. Positive results were obtained for IgG, Kappa-, and Lambda chains with immunofluorescence technique...

  19. [Regeneration and fibrosis of corneal tissues].

    Science.gov (United States)

    Simirskiĭ, V N

    2014-01-01

    In this review, the features of the regeneration of corneal tissue and its disorders leading to the development of fibrosis are considered. The data on the presence of stem (clonogenic) cell pool in the corneal tissues (epithelium, endothelium, stroma) are given; these cells can serve as a source for regeneration of the tissues at injury or various diseases. The main steps of regeneration of corneal tissues and their disorders that lead to outstripping proliferation of myofibroblasts and secretion of extracellular matrix in the wound area and eventually cause the formation of connective tissue scar and corneal opacity are considered. Particular attention is given to the successes of translational medicine in the treatment of corneal tissue fibrosis. The methods of cell therapy aimed at the restoration of stem cell pool of corneal tissues are the most promising. Gene therapy provides more opportunities; one of its main objectives is the suppression of the myofibroblast proliferation responsible for the development of fibrosis.

  20. Refractive, Topographic, and Aberrometric Results at 2-Year Follow-Up for Accelerated Corneal Cross-Link for Progressive Keratoconus

    Science.gov (United States)

    Bozkurt, Ercüment; Akcay, Betul Ilkay Sezgin; Kurt, Tugba; Yildirim, Yusuf; Günaydin, Zehra Karaagaç; Demirok, Ahmet

    2017-01-01

    Purpose. To report the visual, refractive, and corneal topography and wavefront aberration results of accelerated corneal cross-linking (CXL) during a 24-month follow-up. Methods. Forty-seven eyes underwent riboflavin-ultraviolet A-induced accelerated CXL treatment (30 mW/cm2 with a total dose of 7.2 joules/cm2). Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical and cylindrical values, keratometry (K) measurements (Ksteep, Kflat, Kavg, and Kapex), central corneal thickness, and anterior corneal aberrometric analyses including total wavefront error (WFE), total high order aberration (HOA), astigmatism, trefoil, coma, quadrafoil, secondary astigmatism, and spherical aberration were evaluated. Results. The mean UDVA and CDVA were significantly improved at 1 (p = 0.003 and p = 0.004, resp.) and 2 years after treatment (p = 0.001 and p = 0.001, resp.). The mean Ksteep, Kflat, Kaverage, and Kapex values were significantly lower than baseline at 12 months (p = 0.008, p = 0.024, p = 0.001, and p = 0.014, resp.) and 24 months (p = 0.014, p = 0.017, p = 0.001, and p = 0.012, resp.). Corneal thickness showed a significant decrease at 1 month. Total HOA and coma decreased significantly at the 12-month (p = 0.001 and p = 0.009, resp.) and 24-month visits (p = 0.001 and p = 0.007, resp.). Conclusion. Accelerated CXL (30 mW/cm2) was found to be effective in improving UDVA, CDVA, corneal topography readings, total HOA, and coma aberrations during the 24-month follow-up. PMID:28197339

  1. Obtaining corneal tissue for keratoplasty.

    Science.gov (United States)

    Navarro Martínez-Cantullera, A; Calatayud Pinuaga, M

    2016-10-01

    Cornea transplant is the most common tissue transplant in the world. In Spain, tissue donation activities depend upon transplant coordinator activities and the well-known Spanish model for organ and tissue donation. Tissue donor detection system and tissue donor evaluation is performed mainly by transplant coordinators using the Spanish model on donation. The evaluation of a potential tissue donor from detection until recovery is based on an exhaustive review of the medical and social history, physical examination, family interview to determine will of the deceased, and a laboratory screening test. Corneal acceptance criteria for transplantation have a wider spectrum than other tissues, as donors with active malignancies and infections are accepted for kearatoplasty in most tissue banks. Corneal evaluation during the whole process is performed to ensure the safety of the donor and the recipient, as well as an effective transplant. Last step before processing, corneal recovery, must be performed under standard operating procedures and in a correct environment. Copyright © 2016 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

  2. Combining Placido and Corneal Wavefront Data for the Detection of Forme Fruste Keratoconus.

    Science.gov (United States)

    Saad, Alain; Gatinel, Damien

    2016-08-01

    To evaluate the accuracy of a new objective method based on Placido disk-derived data for the detection of eyes at risk of ectasia. One hundred nineteen eyes of 176 patients were included and separated into two groups, normal and forme fruste keratoconus (FFKC), using automated corneal classification software. Normal eyes (n = 114) were classified as negative for keratoconus and keratoconus suspect and had undergone LASIK with unremarkable follow-up for 4 years. The FFKC group was composed of 62 topographically normal eyes of patients with keratoconus in the fellow eye. Anterior topographic parameters, obtained from specular topography using Placido-based indices and corneal wavefront Zernike coefficients, were compared between groups. Receiver operating characteristic (ROC) curves were used to identify cut-off points in discriminating between keratoconic and normal eyes. Validation was performed on an external group of eyes. A discriminant function was built combining four corneal wavefront variables and four Placido variables. The area under the receiver operating characteristic was 0.970 with this eight-variable model. The validation of this function had 63% sensitivity for detecting FFKC and 100% sensitivity for detecting keratoconus, with a specificity of 82%. Indices generated from corneal wavefront and Placido measurements can assist in identifying early or mild forms of keratoconus undetected by a Placido-based neural network program. [J Refract Surg. 2016;32(8):510-516.]. Copyright 2016, SLACK Incorporated.

  3. Comparison of the Corneal Power Measurements with the TMS4-Topographer, Pentacam HR, IOL Master, and Javal Keratometer

    Science.gov (United States)

    Dehnavi, Zahra; Khabazkhoob, Mehdi; Mirzajani, Ali; Jabbarvand, Mahmood; Yekta, Abbasali; Jafarzadehpur, Ebrahim

    2015-01-01

    Purpose: The aim was to compare the corneal curvature and power measured with a corneal topographer, Scheimpflug camera, optical biometer, and Javal keratometer. Materials and Methods: A total of 76 myopic individuals who were candidates for photorefractive keratectomy were selected in a cross-sectional study. Manual keratometry (Javal Schiotz type; Haag-Streit AG, Koeniz, Switzerland), automated keratometry (IOL Master version 3.02, Carl Zeiss Meditec, Jena, Germany), topography (TMS4, Tomey, Erlangen, Germany), and Pentacam HR (Oculus, Wetzlar, Germany) were performed for all participants. The 95% limits of agreement (LOAs) were reported to evaluate the agreement between devices. Results: The mean corneal power measurements were 44.3 ± 1.59, 44.25 ± 1.59, 43.68 ± 1.44, and 44.31 ± 1.61 D with a Javal keratometer, TMS4-topographer, the Pentacam and IOL Master respectively. Only the IOL Master showed no significant difference with Javal keratometer in measuring the corneal power (P = 0.965). The correlations of the Javal keratometer with TMS4-topography, Pentacam, and IOL Master was 0.991. 0.982, and 0.993 respectively. The 95% LOAs of the Javal keratometer with TMS4-topography, Pentacam, and IOL Master were − 0.361 to 0.49, −0.01 to 1.14, and − 0.36 to 0.36 D, respectively. Conclusion: Although the correlation of Pentacam, TMS4-topography, IOL Master, and Javal keratometer in measuring keratometry was high, only the IOL Master showed no significant difference with the Javal keratometer. The IOL Master had the best agreement with Javal keratometry. PMID:25949084

  4. A native-like corneal construct using donor corneal stroma for tissue engineering.

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    Jing Lin

    Full Text Available Tissue engineering holds great promise for corneal transplantation to treat blinding diseases. This study was to explore the use of natural corneal stroma as an optimal substrate to construct a native like corneal equivalent. Human corneal epithelium was cultivated from donor limbal explants on corneal stromal discs prepared by FDA approved Horizon Epikeratome system. The morphology, phenotype, regenerative capacity and transplantation potential were evaluated by hematoxylin eosin and immunofluorescent staining, a wound healing model, and the xeno-transplantation of the corneal constructs to nude mice. An optically transparent and stratified epithelium was rapidly generated on donor corneal stromal substrate and displayed native-like morphology and structure. The cells were polygonal in the basal layer and became flattened in superficial layers. The epithelium displayed a phenotype similar to human corneal epithelium in vivo. The differentiation markers, keratin 3, involucrin and connexin 43, were expressed in full or superficial layers. Interestingly, certain basal cells were immunopositive to antibodies against limbal stem/progenitor cell markers ABCG2 and p63, which are usually negative in corneal epithelium in vivo. It suggests that this bioengineered corneal epithelium shared some characteristics of human limbal epithelium in vivo. This engineered epithelium was able to regenerate in 4 days following from a 4mm-diameter wound created by a filter paper soaked with 1 N NaOH. This corneal construct survived well after xeno-transplantation to the back of a nude mouse. The transplanted epithelium remained multilayer and became thicker with a phenotype similar to human corneal epithelium. Our findings demonstrate that natural corneal stroma is an optimal substrate for tissue bioengineering, and a native-like corneal construct has been created with epithelium containing limbal stem cells. This construct may have great potential for clinical use in

  5. Late onset post-LASIK keratectasia with reversal and stabilization after use of latanoprost and corneal collagen cross-linking

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    Tor Paaske Utheim

    2012-01-01

    Full Text Available We report a case of late onset keratectasia after laser in situ keratomileusis (LASIK and its quick reversal and stabilization after use of latanoprost and riboflavin/ultraviolet-A corneal collagen cross-linking (CXL. A 39-year-old man with normal intraocular pressure developed a rapid deterioration of vision in his left eye 6 years after LASIK-retreatment for high myopic astigmatism. Keratectasia was diagnosed by corneal topography and ultrasound pachymetry. After two months of treatment with latanoprost and a minor intraocular pressure reduction, uncorrected distance visual acuity improved from 20/100 to 20/20 and corneal topography showed reversal of keratectasia. CXL was performed after the reversal to achieve long-term stabilization. At 1, 3, 6, 13 and 39 months followup exams after the CXL, stable vision, refraction, and topography were registered. This case shows that keratectasia may rapidly occur several years after LASIK and that a quick reversal and stabilization may be achieved by use of latanoprost followed by CXL.

  6. Corneal tomography and biomechanics in primary pterygium.

    Science.gov (United States)

    Vanathi, M; Goel, Sahil; Ganger, Anita; Agarwal, Tushar; Dada, T; Khokhar, Sudarshan

    2017-05-13

    To study the Scheimpflug's imaging and corneal biomechanics in primary pterygium. A prospective observational study of 55 patients with unilateral primary nasal pterygium was done. The normal fellow eyes of patients with pterygium were taken as controls. Clinical parameters noted included visual acuity, values of corneal curvature by doing Scheimpflug imaging, wavefront aberrations in terms of higher and lower-order aberrations and corneal hysteresis (CH) as well as corneal resistance factor (CRF) values by using ocular response analyzer. Of the total 55 patients, mean age was 43.0 + 11.4 years (range: 20-72 years). Mean LogMar uncorrected visual acuity in pterygium eyes and control eyes was 0.21 + 0.20 and 0.12 + 0.15, respectively (p = 0.016). On Scheimpflug imaging the mean anterior corneal curvature values (Ka1/Ka2 D) were 41.09 + 3.38/44.33 + 2.29 in pterygium eyes, 43.13 + 1.79/43.98 + 2.17 in control eyes (p  0.05). Analysis of corneal aberrations showed significantly higher corneal wavefront aberrations in pterygium eyes. Highest correlation of corneal astigmatism was noted with corneal area encroached by pterygium (ρ = 0.540 for LOA and 0.553 for HOA) and distance from pupillary center (ρ = 0.531 for LOA and 0.564 for HOA). Corneal biomechanical parameters including CH and CRF were found to be lower in the pterygium eyes, though not statistically significant (p value 0.60 and 0.59, respectively). Pterygium leads to deterioration of visual performance not only by causing refractive and topographic changes but also by causing a significant increase in corneal wavefront aberrations.

  7. Iontophoresis-Assisted Corneal Collagen Cross-Linking with Epithelial Debridement: Preliminary Results

    Science.gov (United States)

    Legrottaglie, Emanuela F.

    2016-01-01

    Purpose. To report the early outcomes of iontophoresis-assisted corneal collagen cross-linking procedure with epithelial debridement (I-SCXL). Methods. Twenty eyes of twenty patients with progressive keratoconus were included in this prospective clinical study. Best spectacle corrected visual acuity (BSCVA), sphere and cylinder refraction, corneal topography, Scheimpflug tomography, aberrometry, anterior segment optical coherence tomography (AS-OCT), and endothelial cell count were assessed at baseline and at 1, 3, and 6 months of follow-up. The parameters considered to establish keratoconus progression were always proven with differential maps as change in curvature in the cone area of at least 1 diopter obtained with an instantaneous map. Results. Functional parameters showed a significant improvement (p 0.05). Conclusion. The early results indicate that the I-SCXL may be able to reduce the treatment time and improve the riboflavin diffusion. PMID:27547758

  8. Iontophoresis-Assisted Corneal Collagen Cross-Linking with Epithelial Debridement: Preliminary Results

    Directory of Open Access Journals (Sweden)

    Paolo Vinciguerra

    2016-01-01

    Full Text Available Purpose. To report the early outcomes of iontophoresis-assisted corneal collagen cross-linking procedure with epithelial debridement (I-SCXL. Methods. Twenty eyes of twenty patients with progressive keratoconus were included in this prospective clinical study. Best spectacle corrected visual acuity (BSCVA, sphere and cylinder refraction, corneal topography, Scheimpflug tomography, aberrometry, anterior segment optical coherence tomography (AS-OCT, and endothelial cell count were assessed at baseline and at 1, 3, and 6 months of follow-up. The parameters considered to establish keratoconus progression were always proven with differential maps as change in curvature in the cone area of at least 1 diopter obtained with an instantaneous map. Results. Functional parameters showed a significant improvement (p0.05. Conclusion. The early results indicate that the I-SCXL may be able to reduce the treatment time and improve the riboflavin diffusion.

  9. Mathematical analysis of corneal remodelling after intracorneal ring surgery in keratoconus

    Science.gov (United States)

    Jarade, Elias F.; Slim, Elise; Cherfan, Carole; El Rami, Hala; Hassan, Toufic; Chelala, Elias

    2017-01-01

    AIM To represent mathematically the intersection between the ectatic corneal geometry and the plane of intracorneal ring implants (ICRS) in order to determine the corneal response to ICRS surgery in keratoconus (KC). Thereafter, to present the concept and early results of a newly derived topography-guided nomogram for ICRS surgery for the treatment of keratectasia. METHODS The corneal rings plane intersection was modelled to a conic section. Ring effect was the result of: the ring size, position (steep vs flat), location (distance from the geometric centre of the cornea), and the discrepancy between the ring's curvature and the tunnel's curvature. Femtosecond laser was used to create the tunnels and the incision sites were chosen according to the nomogram in order to place the thickest ring in the steepest portion of the cornea regardless of the astigmatism axis of refraction. RESULTS The conic section had a more prolate shape in the steep area of the cornea than in the flat area, depending on the corneal sagittal curvature. Equal ring size had more flattening effect in the steep area than in the flat area. Thick segment should be implanted under the steep portion of the cornea regardless of the cylinder axis of refraction. Single segment in the steep area was sufficient in early and moderate cases of KC. The new nomogram provided more topographic regularity with significant reduction of astigmatism and better improvement in uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) than the conventional nomogram. CONCLUSION The newly derived nomogram can produce better results than the conventional nomogram. Moreover, based on this concept, a new nomogram can be integrated into the femtosecond laser software to create topography-guided, customized, elliptical tunnels with modified focal asphericity that allows for customized focal flattening of the irregularly steepened ectatic cornea. PMID:28393023

  10. The modelling of the influence of a corneal geometry on the pupil image of the human eye

    Science.gov (United States)

    Szczesna, D. H.; Kasprzak, H. T.

    2006-07-01

    In normal conditions, a pupil of the eye is observed through the optical system of the cornea. The cornea is the anterior surface of the eye and is the major refractive element of the human eye. The influence of the corneal shape should not be neglected in measurements of the pupil size. The purpose of this study was to estimate the influence of the corneal geometry, the diameter of the pupil and its position in the anterior chamber on the magnification and position of the image of the pupil. The numerical calculations presented in the paper assume infinitely thin cornea, and the corneal topography was approximated by the elongated ellipsoid. The ray tracing procedure was used in our numerical modelling. The magnification of the pupil image amounted to about 10% and increases with decrease of radius of curvature and eccentricity of the corneal profile and decreases for the largest pupil. The results show also that the pupil image is placed nearer the corneal apex than the real pupil. The image of the pupil is always blurred, which limits the sharp observation of the pupil.

  11. Proposal for a new approach to corneal biomechanics: dynamic corneal opography Proposta de uma nova abordagem da biomecânica corneana: topografia dinâmica de córnea

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    José Américo Bonatti

    2009-04-01

    Full Text Available PURPOSE: To establish the literature basis that could support the idea that it would be possible to analyze changes at the anterior surface of the cornea induced by an air jet applied onto the eye. METHODS: The PUBMED/MEDLINE literature basis regarding the following subjects was searched: videokeratography, high-speed photography, ocular response analyzer (ORA. The information concerning the goal of this paper was selected. RESULTS: The literature showed data that support the idea of gathering 3 nowadays available technologies that could result in a new concept of "dynamic corneal topography": the corneal topography, the air jet applied to histeresis measurement by the Ocular Response Analyzer® and the high-speed photography technique used to study the tear film and the anterior surface of the cornea. CONCLUSION: The literature basis supports the idea of gathering the existent technologies of corneal topography, the air jet of the corneal histeresis device and the high-speed photography to create a new concept in the analysis of the corneal surface: the dynamic corneal topography.OBJETIVO: Estabelecer a base de literatura para apoiar a idéia de que seria possível analisar mudanças da superfície anterior da córnea por um jato de ar aplicado sobre o olho. MÉTODOS: Procurou-se na base de literatura PUBMED/MEDLINE os assuntos videoceratografia, fotografia de alta velocidade, analisador de resposta ocular (ORA, selecionando-se informação concernente ao objetivo deste trabalho. RESULTADOS: A literatura mostrou dados que apoiam a ideia de juntar três tecnologias hoje existentes que poderiam resultar num novo conceito de "topografia dinâmica de córnea": a topografia corneana, o jato de ar aplicado sobre o olho na medida da histerese do aparelho de analisador de resposta ocular (ORA e a técnica de fotografia de alta velocidade usada para estudar o filme lacrimal e a superfície anterior da córnea. CONCLUSÃO: A base de literatura apóia a

  12. Corneal laceration caused by river crab

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    Vinuthinee N

    2015-01-01

    Full Text Available Naidu Vinuthinee,1,2 Anuar Azreen-Redzal,1 Jaafar Juanarita,1 Embong Zunaina2 1Department of Ophthalmology, Hospital Sultanah Bahiyah, Alor Setar, 2Department of Ophthalmology, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Malaysia Abstract: A 5-year-old boy presented with right eye pain associated with tearing and photophobia of 1-day duration. He gave a history of playing with a river crab when suddenly the crab clamped his fingers. He attempted to fling the crab off, but the crab flew and hit his right eye. Ocular examination revealed a right eye corneal ulcer with clumps of fibrin located beneath the corneal ulcer and 1.6 mm level of hypopyon. At presentation, the Seidel test was negative, with a deep anterior chamber. Culture from the corneal scrapping specimen grew Citrobacter diversus and Proteus vulgaris, and the boy was treated with topical gentamicin and ceftazidime eyedrops. Fibrin clumps beneath the corneal ulcer subsequently dislodged, and revealed a full-thickness corneal laceration wound with a positive Seidel test and shallow anterior chamber. The patient underwent emergency corneal toileting and suturing. Postoperatively, he was treated with oral ciprofloxacin 250 mg 12-hourly for 1 week, topical gentamicin, ceftazidime, and dexamethasone eyedrops for 4 weeks. Right eye vision improved to 6/9 and 6/6 with pinhole at the 2-week follow-up following corneal suture removal. Keywords: corneal ulcer, pediatric trauma, ocular injury

  13. Corneal staining after treatment with topical tetracycline

    NARCIS (Netherlands)

    R. Lapid-Gortzak; C.P. Nieuwendaal; A.R. Slomovic; L. Spanjaard

    2006-01-01

    Purpose: The purpose of this paper is to report a case of corneal staining after treatment with topical tetracycline. Methods: A patient with crystalline keratopathy caused by Streptococcus viridans after corneal transplantation was treated topically with tetracycline eye drops, based on results of

  14. Corneal cellular proliferation and wound healing

    OpenAIRE

    Gan, Lisha

    2000-01-01

    Background. Cellular proliferation plays an important role in both physiological and pathological processes. Epithelial hyperplasia in the epithelium, excessive scar formation in retrocorneal membrane formation and neovascularization are examples of excessive proliferation of cornea cells. Lack of proliferative ability causes corneal degeneration. The degree of proliferative and metabolic activity will directly influence corneal transparency and very evidently refractive res...

  15. Corynebacterium macginleyi isolated from a corneal ulcer

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    Kathryn Ruoff

    2010-02-01

    Full Text Available We report the isolation of Corynebacterium macginleyi from the corneal ulcer culture of a patient, later enrolled in the Steroids for Corneal Ulcer Trial (SCUT. To our knowledge this is the first published report from North America of the recovery of C. macginleyi from a serious ocular infection.

  16. Dorsally located corneal dermoid in a cat

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    Alexander J LoPinto

    2016-04-01

    Full Text Available Case summary A 2-month-old, male kitten was presented for evaluation of unilateral blepharospasm and epiphora involving the right eye. Ocular examination revealed conjunctivitis, a superficial corneal ulcer, reflex anterior uveitis and a haired mass within the dorsal cornea of the right eye. The mass was subsequently removed surgically via a lamellar keratectomy. Histologic evaluation of the mass via light microscopy revealed it to be comprised of normal-haired skin with mild inflammation. One week after surgical removal and medical management of the corneal ulcer, all ocular clinical signs had resolved with minimal corneal scarring. On re-examination 6 months following surgical excision of the mass, the kitten was noted to be comfortable with no significant corneal scarring. Relevance and novel information To our knowledge, this is the first case report of a dorsally located corneal dermoid in a cat.

  17. Corneal neovascularization and contemporary antiangiogenic therapeutics.

    Science.gov (United States)

    Hsu, Chih-Chien; Chang, Hua-Ming; Lin, Tai-Chi; Hung, Kuo-Hsuan; Chien, Ke-Hung; Chen, Szu-Yu; Chen, San-Ni; Chen, Yan-Ting

    2015-06-01

    Corneal neovascularization (NV), the excessive ingrowth of blood vessels from conjunctiva into the cornea, is a common sequela of disease insult that can lead to visual impairment. Clinically, topical steroid, argon laser photocoagulation, and subconjunctival injection of bevacizumab have been used to treat corneal NV. Sometimes, the therapies are ineffective, especially when the vessels are large. Large vessels are difficult to occlude and easily recanalized. Scientists and physicians are now dedicated to overcoming this problem. In this article, we briefly introduce the pathogenesis of corneal NV, and then highlight the existing animal models used in corneal NV research-the alkali-induced model and the suture-induced model. Most of all, we review the potential therapeutic targets (i.e., vascular endothelial growth factor and platelet-derived growth factor) and their corresponding inhibitors, as well as the immunosuppressants that have been discovered in recent years by corneal NV studies.

  18. Optics of the average normal cornea from general and canonical representations of its surface topography.

    Science.gov (United States)

    Navarro, Rafael; González, Luis; Hernández, José L

    2006-02-01

    Generally, the analysis of corneal topography involves fitting the raw data to a parametric geometric model that includes a regular basis surface, plus some sort of polynomial expansion to adjust the more irregular residual component. So far, these parametric models have been used in their canonical form, ignoring that the observation (keratometric) coordinate system is different from corneal axes of symmetry. Here we propose, instead, to use the canonical form when the topography is referenced to the intrinsic corneal system of coordinates, defined by its principal axes of symmetry. This idea is implemented using the general expression of an ellipsoid to fit the raw data given by the instrument. Then, the position and orientation of the three orthogonal semiaxes of the ellipsoid, which define the intrinsic Cartesian system of coordinates for normal corneas, can be identified by passing to the canonical form, by standard linear algebra. This model has been first validated experimentally obtaining significantly lower values for rms fitting error as compared with previous standard models: spherical, conical, and biconical. The fitting residual was then adjusted by a Zernike polynomial expansion. The topographies of 123 corneas were analyzed obtaining their radii of curvature, conic constants, Zernike coefficients, and the direction and position of the optical axis of the ellipsoid. The results were compared with those obtained using the standard models. The general ellipsoid model provides more negative values for the conic constants and lower apex radii (more prolate shapes) than the standard models applied to the same data. If the data are analyzed using standard models, the resulting mean shape of the cornea is consistent with previous studies, but when using the ellipsoid model we find new interesting features: The mean cornea is a more prolate ellipsoid (apical power 50 D), the direction of the optical axis is about 2.3 degrees nasal, and the residual term shows

  19. Optics of the average normal cornea from general and canonical representations of its surface topography

    Science.gov (United States)

    Navarro, Rafael; González, Luis; Hernández, José L.

    2006-02-01

    Generally, the analysis of corneal topography involves fitting the raw data to a parametric geometric model that includes a regular basis surface, plus some sort of polynomial expansion to adjust the more irregular residual component. So far, these parametric models have been used in their canonical form, ignoring that the observation (keratometric) coordinate system is different from corneal axes of symmetry. Here we propose, instead, to use the canonical form when the topography is referenced to the intrinsic corneal system of coordinates, defined by its principal axes of symmetry. This idea is implemented using the general expression of an ellipsoid to fit the raw data given by the instrument. Then, the position and orientation of the three orthogonal semiaxes of the ellipsoid, which define the intrinsic Cartesian system of coordinates for normal corneas, can be identified by passing to the canonical form, by standard linear algebra. This model has been first validated experimentally obtaining significantly lower values for rms fitting error as compared with previous standard models: spherical, conical, and biconical. The fitting residual was then adjusted by a Zernike polynomial expansion. The topographies of 123 corneas were analyzed obtaining their radii of curvature, conic constants, Zernike coefficients, and the direction and position of the optical axis of the ellipsoid. The results were compared with those obtained using the standard models. The general ellipsoid model provides more negative values for the conic constants and lower apex radii (more prolate shapes) than the standard models applied to the same data. If the data are analyzed using standard models, the resulting mean shape of the cornea is consistent with previous studies, but when using the ellipsoid model we find new interesting features: The mean cornea is a more prolate ellipsoid (apical power 50 D), the direction of the optical axis is about 2.3° nasal, and the residual term shows three

  20. Parameterizing turbulence over abrupt topography

    Science.gov (United States)

    Klymak, Jody

    2016-11-01

    Stratified flow over abrupt topography generates a spectrum of propagating internal waves at large scales, and non-linear overturning breaking waves at small scales. For oscillating flows, the large scale waves propagate away as internal tides, for steady flows the large-scale waves propagate away as standing "columnar modes". At small-scales, the breaking waves appear to be similar for either oscillating or steady flows, so long as in the oscillating case the topography is significantly steeper than the internal tide angle of propagation. The size and energy lost to the breaking waves can be predicted relatively well from assuming that internal modes that propagate horizontally more slowly than the barotropic internal tide speed are arrested and their energy goes to turbulence. This leads to a recipe for dissipation of internal tides at abrupt topography that is quite robust for both the local internal tide generation problem (barotropic forcing) and for the scattering problem (internal tides incident on abrupt topography). Limitations arise when linear generation models break down, an example of which is interference between two ridges. A single "super-critical" ridge is well-modeled by a single knife-edge topography, regardless of its actual shape, but two supercritical ridges in close proximity demonstrate interference of the high modes that makes knife-edfe approximations invalid. Future direction of this research will be to use more complicated linear models to estimate the local dissipation. Of course, despite the large local dissipation, many ridges radiate most of their energy into the deep ocean, so tracking this low-mode radiated energy is very important, particularly as it means dissipation parameterizations in the open ocean due to these sinks from the surface tide cannot be parameterized locally to where they are lost from the surface tide, but instead lead to non-local parameterizations. US Office of Naval Research; Canadian National Science and

  1. Corneal Regeneration by Deep Anterior Lamellar Keratoplasty (DALK Using Decellularized Corneal Matrix.

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    Yoshihide Hashimoto

    Full Text Available The purpose of this study is to demonstrate the feasibility of DALK using a decellularized corneal matrix obtained by HHP methodology. Porcine corneas were hydrostatically pressurized at 980 MPa at 10°C for 10 minutes to destroy the cells, followed by washing with EGM-2 medium to remove the cell debris. The HHP-treated corneas were stained with H-E to assess the efficacy of decellularization. The decellularized corneal matrix of 300 μm thickness and 6.0 mm diameter was transplanted onto a 6.0 mm diameter keratectomy wound. The time course of regeneration on the decellularized corneal matrix was evaluated by haze grading score, fluorescein staining, and immunohistochemistry. H-E staining revealed that no cell nuclei were observed in the decellularized corneal matrix. The decellularized corneal matrices were opaque immediately after transplantation, but became completely transparent after 4 months. Fluorescein staining revealed that initial migration of epithelial cells over the grafts was slow, taking 3 months to completely cover the implant. Histological sections revealed that the implanted decellularized corneal matrix was completely integrated with the receptive rabbit cornea, and keratocytes infiltrated into the decellularized corneal matrix 6 months after transplantation. No inflammatory cells such as macrophages, or neovascularization, were observed during the implantation period. The decellularized corneal matrix improved corneal transparency, and remodelled the graft after being transplanted, demonstrating that the matrix obtained by HHP was a useful graft for corneal tissue regeneration.

  2. United States Multicenter Clinical Trial of Corneal Collagen Crosslinking for Keratoconus Treatment.

    Science.gov (United States)

    Hersh, Peter S; Stulting, R Doyle; Muller, David; Durrie, Daniel S; Rajpal, Rajesh K

    2017-09-01

    To evaluate the safety and efficacy of corneal collagen crosslinking (CXL) for the treatment of progressive keratoconus. Prospective, randomized, multicenter, controlled clinical trial. Patients with progressive keratoconus (n = 205). The treatment group underwent standard CXL and the sham control group received riboflavin alone without removal of the epithelium. The primary efficacy criterion was the change over 1 year of topography-derived maximum keratometry value, comparing treatment with control group. Secondary outcomes evaluated were corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), manifest refraction spherical equivalent, endothelial cell count, and adverse events. In the CXL treatment group, the maximum keratometry value decreased by 1.6 diopters (D) from baseline to 1 year, whereas keratoconus continued to progress in the control group. In the treatment group, the maximum keratometry value decreased by 2.0 D or more in 28 eyes (31.4%) and increased by 2.0 D or more in 5 eyes (5.6%). The CDVA improved by an average of 5.7 logarithm of the minimum angle of resolution (logMAR) units. Twenty-three eyes (27.7%) gained and 5 eyes lost (6.0%) 10 logMAR or more. The UDVA improved 4.4 logMAR. Corneal haze was the most frequently reported CXL-related adverse finding. There were no significant changes in endothelial cell count 1 year after treatment. Corneal collagen crosslinking was effective in improving the maximum keratometry value, CDVA, and UCVA in eyes with progressive keratoconus 1 year after treatment, with an excellent safety profile. Corneal collagen crosslinking affords the keratoconic patient an important new option to decrease progression of this ectatic corneal process. Copyright © 2017 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  3. Corneal Asphericity and IOL Power Calculation in Eyes With Aspherical IOLs.

    Science.gov (United States)

    Savini, Giacomo; Hoffer, Kenneth J; Barboni, Piero; Schiano Lomoriello, Domenico; Ducoli, Pietro

    2017-07-01

    Given that a previous study found that corneal asphericity influences the refractive outcome of intraocular lens (IOL) power calculation by means of thin-lens formulas in eyes with spherical IOLs, the authors aimed to verify whether such influence can also be observed in eyes with aspherical IOLs. In this retrospective comparative case series, IOL power was calculated with the Haigis, Hoffer Q, Holladay 1, and SRK/T formulas in two groups of eyes undergoing phacoemulsification and implantation of an aspherical IOL (Acrysof SN60WF; Alcon Laboratories, Inc., Fort Worth, TX). For each formula, the refractive prediction error was calculated once the constants had been optimized. Biometric data were obtained by partial coherence interferometry in one group and immersion ultrasound biometry and corneal topography in the other. Corneal asphericity was assessed by two different corneal topographers in the optical biometry group (Magellan; Nidek, Gamagori, Japan) and ultrasound biometry group (Keratron, Optikon 2000 Spa, Rome, Italy). The mean Q-value was -0.12 ± 0.08 in the optical biometry group (n = 51) and -0.22 ± 0.14 in the ultrasound biometry group (n = 79). In both groups, linear regression disclosed a statistically significant correlation between the Q-value and the prediction error (the only exception being the SRK/T formula). More negative Q-values were correlated to a positive prediction error, indicating a myopic outcome for prolate corneas. However, the correlation coefficients were lower than those previously reported for spherical IOLs. Corneal asphericity also influences the refractive outcomes of IOL power calculation by thinlens formulas when aspherical IOLs are implanted, although this influence is exerted to a lesser degree compared to spherical IOLs. [J Refract Surg. 2017;33(7):476-481.]. Copyright 2017, SLACK Incorporated.

  4. Biomechanical corneal changes induced by different flap thickness created by femtosecond laser

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    Fabricio W. Medeiros

    2011-01-01

    Full Text Available OBJECTIVE: To evaluate the impact of the creation of corneal flaps at different thicknesses on the biomechanical properties of swine corneas. METHOD: Twelve swine eyes were obtained to form two groups: 100 μm flap thickness and 300 μm flap thickness. Each eye was submitted to the following examinations: raster topography to investigate corneal curvature alterations, ocular response analyzer to investigate corneal hysteresis change, optical coherence tomography to measure central corneal and flap thickness and sonic wave propagation velocity as a measure of stiffness, before and immediately after flap creation. After flap amputation, surface wave velocity measurements were repeated. RESULTS: Measured flap thicknesses were statistically different for thin and thick flap groups, with an average of 108.5 + 6.9 and 307.8 + 11.5 μm respectively. Hysteresis and corneal resistance factor did not change significantly after flap creation in the thin flap group. With thicker flaps, both parameters decreased significantly from 8.0 +1.0 to 5.1 +1.5 mmHg and from 8.2 + 1.6 to 4.1 +2.5 mmHg respectively. Simulated keratometry values increased in the thick flap group (from 39.5 + 1 D to 45.9+1.2 D after flap creation but not in the thin flap group (from 40.6 + 0.6 D to 41.4+ 1.0 D. Regarding surface wave velocity analysis, the surgical procedures induced statistically lower results in some positions. CONCLUSION: In the experimental conditions established by this model, thicker flaps presented a greater biomechanical impact on the cornea.

  5. First Identification of a Triple Corneal Dystrophy Association: Keratoconus, Epithelial Basement Membrane Corneal Dystrophy and Fuchs' Endothelial Corneal Dystrophy

    Directory of Open Access Journals (Sweden)

    Cosimo Mazzotta

    2014-09-01

    Full Text Available Purpose: To report the observation of a triple corneal dystrophy association consisting of keratoconus (KC, epithelial basement membrane corneal dystrophy (EBMCD and Fuchs' endothelial corneal dystrophy (FECD. Methods: A 55-year-old male patient was referred to our cornea service for blurred vision and recurrent foreign body sensation. He reported bilateral recurrent corneal erosions with diurnal visual fluctuations. He underwent corneal biomicroscopy, Scheimpflug tomography, in vivo HRT confocal laser scanning microscopy and genetic testing for TGFBI and ZEB1 mutations using direct DNA sequencing. Results: Biomicroscopic examination revealed the presence of subepithelial central and paracentral corneal opacities. The endothelium showed a bilateral flecked appearance, and the posterior corneal curvature suggested a possible concomitant ectatic disorder. Corneal tomography confirmed the presence of a stage II KC in both eyes. In vivo confocal laser scanning microscopy revealed a concomitant bilateral EBMCD with hyperreflective deposits in basal epithelial cells, subbasal Bowman's layer microfolds and ridges with truncated subbasal nerves as pseudodendritic elements. Stromal analysis revealed honeycomb edematous areas, and the endothelium showed a strawberry surface configuration typical of FECD. The genetic analysis resulted negative for TGFBI mutations and positive for a heterozygous mutation in exon 7 of the gene ZEB1. Conclusion: This is the first case reported in the literature in which KC, EBMCD and FECD are present in the same patient and associated with ZEB1 gene mutation. The triple association was previously established by means of morphological analysis of the cornea using corneal Scheimpflug tomography and in vivo HRT II confocal laser scanning microscopy.

  6. Mapping Bedrock Topography using Electromagnetic Profiling ...

    African Journals Online (AJOL)

    Mapping Bedrock Topography using Electromagnetic Profiling. ... Journal of Applied Sciences and Environmental Management ... within the Abakaliki Urban, to map the bedrock topography which also aids us to determine the position of the ...

  7. Surface Micro Topography Replication in Injection Moulding

    DEFF Research Database (Denmark)

    Arlø, Uffe Rolf; Hansen, Hans Nørgaard; Kjær, Erik Michael

    2005-01-01

    carried out with rough EDM (electrical discharge machining) mould surfaces, a PS grade, and by applying established three-dimensional topography parameters. Significant quantitative relationships between process parameters and topography parameters were established. It further appeared that replication...

  8. Factors Affecting Corneal Hysteresis in Taiwanese Adults

    Institute of Scientific and Technical Information of China (English)

    Jia-Kang Wang; Tzu-Lun Huang; Pei-Yuan Su; Pei-Yao Chang

    2015-01-01

    Purpose: To investigate the correlation of various corneal hysteresis (CH) factors in Chinese adults. Methods: From January 2009 to November 2011, the healthy right eyes of a total of 292 adults were recruited into the study. Goldmann-correlated intraocular pressure (IOPG) and CH were measured using an ocular response analyzer (ORA). Central corneal thickness was measured using the ORA’s in-tegrated handheld ultrasonic pachymeter. The IOLMaster was used to obtain the ocular biometric measurements including axial length, anterior chamber depth, and keratometric values. The Pearson correlation coefficient was used to test correla-tions between CH and quantitative factors. The chi-square test was used to detect differences in categorical values. Results: Longer axial length (P=0.0001), lower IOPG (P=0.03), older age(P=0.003),and thinner central corneal thick-ness (P=0.0001) were significantly associated with lower CH. The anterior chamber depth (P=0.34), gender (P=0.23), and corneal curvature (P=0.18) had no relationship to CH. Conclusion:Various factors including axial length, intraocular pressure, age, and central corneal thickness can affect measure-ment of corneal biomechanical properties in Chinese adults. But the anterior chamber depth, gender, and corneal curvature were irrelevant to CH.

  9. Corneal sensitivity in five horse breeds

    Directory of Open Access Journals (Sweden)

    Eunice Santos de Andrade

    Full Text Available ABSTRACT: This study aimed to determine and compare corneal sensitivity values in different regions of the cornea in five horse breeds. One hundred and forty five healthy horses, adults of both sexes, of the following breeds - Arabian horse (AH; n=20, Mangalarga Marchador (MM; n=50, Pure Blood Lusitano (PBL; n=35, Quarter Horse (QH; n=20, Brazilian Sport Horse (BSH; n=20-were investigated. Corneal touch threshold (CTT was measured with a Cochet-Bonnet esthesiometer in five different corneal regions. Measurements of the median central CTT were: 4.50±0.50cm (AH, 3.50±0.56cm (MM, 3.00±0.25cm (PBL, 2.50±0.44cm (QH and 2.50±0.00cm (BSH. The central region was the most sensitive and the dorsal region the least sensitive corneal region for all breeds. CTT values differed for corneal regions and horse breeds. The CTT values were different among the corneal regions and the horse breeds. Arabian horses presented higher sensitivity values being the most sensitive in all of the corneal regions.

  10. Surface micro topography replication in injection moulding

    DEFF Research Database (Denmark)

    Arlø, Uffe Rolf

    of the mechanisms controlling topography replication. Surface micro topography replication in injection moulding depends on the main elements of  Process conditions  Plastic material  Mould topography In this work, the process conditions is the main factor considered, but the impact of plastic material...

  11. Morphological evaluation of normal human corneal epithelium

    DEFF Research Database (Denmark)

    Ehlers, Niels; Heegaard, Steffen; Hjortdal, Jesper

    2010-01-01

    PURPOSE: The human corneal epithelium is usually described as a 50-µm-thick layer of regular stratified squamous non-keratinized cells with a thickness of 5-7 cells. The purpose of this study is systemically to revisit the histopathological appearance of 100 corneas. METHODS: 5-µm-thick sections...... in Bowman's membrane. No intraepithelial microcysts, as found in Meesmann corneal dystrophy, were observed. CONCLUSION: The total corneal thickness was higher than reported in in vivo studies and with a wider variation. This may be an effect of uncontrolled swelling and dehydration during preparation...

  12. Mapping of sea bottom topography

    Science.gov (United States)

    Calkoen, C. J.; Wensink, G. J.; Hesselmans, G. H. F. M.

    1992-01-01

    Under suitable conditions the bottom topography of shallow seas is visible in remote sensing radar imagery. Two experiments were performed to establish which remote sensing technique or combination yields optimal imaging of bottom topography and which hydro-meteorological conditions are favorable. A further goal is to gain experience with these techniques. Two experiments were performed over an area in the North Sea near the measuring platform Meetpost Noordwijk (MPN). The bottom topography in the test area is dominated by sand waves. The crests of the sand waves are perpendicular to the coast line and the dominating (tidal-)current direction. A 4x4 sq km wide section of the test area was studied in more detail. The first experiment was undertaken on 16 Aug. 1989. During the experiment the following remote sensing instruments were used: Landsat-Thematic Mapper, and NASA/JPL Airborne Imaging Radar (AIR). The hydro-meteorological conditions; current, wind, wave, and air and water temperature were monitored by MPN, a ship of Rijkswaterstaat (the OCTANS), and a pitch-and-roll WAVEC-buoy. The second experiment took place on 12 July 1992. During this experiment data were collected with the NASA/JPL polarimetric synthetic aperture radar (SAR), and a five-band helicopter-borne scatterometer. Again the hydro-meteorological conditions were monitored at MPN and the OCTANS. Furthermore, interferometric radar data were collected.

  13. Earth rotation and core topography

    Science.gov (United States)

    Hager, Bradford H.; Clayton, Robert W.; Spieth, Mary Ann

    1988-01-01

    The NASA Geodynamics program has as one of its missions highly accurate monitoring of polar motion, including changes in length of day (LOD). These observations place fundamental constraints on processes occurring in the atmosphere, in the mantle, and in the core of the planet. Short-timescale (t less than or approx 1 yr) variations in LOD are mainly the result of interaction between the atmosphere and the solid earth, while variations in LOD on decade timescales result from the exchange of angular momentum between the mantle and the fluid core. One mechanism for this exchange of angular momentum is through topographic coupling between pressure variations associated with flow in the core interacting with topography at the core-mantel boundary (CMB). Work done under another NASA grant addressing the origin of long-wavelength geoid anomalies as well as evidence from seismology, resulted in several models of CMB topography. The purpose of work supported by NAG5-819 was to study further the problem of CMB topography, using geodesy, fluid mechanics, geomagnetics, and seismology. This is a final report.

  14. The accuracy of corneal curvature measured by different types of keratometry%不同仪器测量角膜曲率的准确性研究

    Institute of Scientific and Technical Information of China (English)

    柏全豪; 苗雨晴; 扈月平; 张戈非

    2015-01-01

    Objective We compared and evaluated the accuracy of the four types of keratometry: manual keratometer, auto-refractometer, corneal topography and IOL-Master for measurement the corneal curvature. Methods Preoperative measurement of corneal curvature was prospectively obtained in 124 eyes of 86 subjects that underwent phacoemusification with intraocular lens implantation with four types of keratometry. Corneal refractive powers in mean values, corneal refractive powers in maximum axis, corneal refractive powers in minimum axis and the degree of axis were analysized by using SPSS 15.0 in one way ANOVA for statistics. Results There was no significant difference in measuring of the mean corneal refractive powers by using four different types of keratometry (P>0.05). There were also no significant differences in measuring degrees of the corneal refractive powers in maximum axis, corneal refractive powers in minimum axis and corneal astigmatism degree(P > 0.05). But there was significant difference in measuring of the axis values of corneal astigmatism (P < 0.01). Conclusion The accuracy of corneal curvature measured by different types of keratometry is perfect.%目的:研究比较手动角膜曲率计、电脑自动验光仪、角膜地形图和光学相干生物测量仪(IOL-Master)四种仪器测量角膜曲率的测量结果准确性。方法应用四种仪器分别测量拟施行白内障超声乳化摘除及人工晶体植入术的患者86例(124眼)的平均、最大及最小角膜屈光力、角膜散光度数及散光轴位,用SPSS15.0软件对测量参数进行统计学分析。结果这四种仪器测得的平均、最大及最小角膜屈光力、角膜散光度数无显著差异(P>0.05),角膜散光轴位测量结果有显著差异(P<0.01)。结论四种仪器测量角膜曲率的准确性较好。

  15. Corneal topography measurement by means of radial shearing interference: Part III - measurement errors

    Science.gov (United States)

    Kowalik, Waldemar W.; Garncarz, Beata E.; Kasprzak, Henryk T.

    This work contains results of computer simulation researches, which define requirements for measurement conditions, which should be fulfilled so that measurement results ensure allowable errors. They define: allowable measurement errors (interferogram's scanning) and conditions, which should fulfill computer programs, so that errors introduced by mathematical operations and computer are the smallest.

  16. Tangential and sagittal curvature from the normals computed by the null screen method in corneal topography

    Science.gov (United States)

    Estrada-Molina, Amilcar; Díaz-Uribe, Rufino

    2011-08-01

    A new method for computing the tangential and sagittal curvatures from the normals to a cornea is proposed. The normals are obtained through a Null Screen method from the coordinates of the drops shaped spots at the null screen, the coordinates on a reference approximating surface and the centroids on the image plane. This method assumes that the cornea has rotational symmetry and our derivations will be carried out in the meridional plane that contains the symmetry axis. Experimental results are shown for a calibration spherical surface, using cylindrical null screens with radial point arrays.

  17. Evaluation of the effective corneal ablation in refractive surgery by two 3D topographic surface matching methods

    Science.gov (United States)

    Bueeler, M.; Donitzky, Ch.; Mrochen, M.

    2006-02-01

    The effectiveness of the corneal ablation process in refractive surgery is mostly evaluated by indirect measures of vision or optical quality such as post-operative refraction or wavefront aberrometry. Yet, the effective amount of corneal tissue removed in the treatment can only be determined by correctly overlapping a pre- and a post-operative topography measurement. However such an overlap is not trivial due to the discrepancy in the centration axes used in the measurement and the treatment, as well as due to the shift of ocular axes through the treatment or tilt between the two surfaces. We therefore present two methods for overlapping pre- and post-operative topographies for the purpose of extracting an effective corneal ablation profile. Method one uses a 3-dimensional profile matching algorithm and cross-correlation analysis on surface rings outside the optical zone of the topographies. Method two employs a surface normal matching routine to align the two surfaces along their common ablation axis. The profile matching method implies the problem that it requires measurement data outside of the optical zone which was found to be uncertain with placido-disk-based topographers. Method number two is more simple and implies the advantage of using measurement data within the optical zone. For regular profiles the extracted ablation profiles showed a very good match with the planned ones. Surprisingly, even for highly irregular profiles of topography-guided laser treatments the method delivered reasonable overlaps when being compared to the planned profiles. Analysis of the effective tissue removal yields valuable information on the quality of the ablation process.

  18. Surgical compensation of presbyopia with corneal inlays.

    Science.gov (United States)

    Konstantopoulos, Aris; Mehta, Jodhbir S

    2015-05-01

    Presbyopia, the physiological change in near vision that develops with ageing, gradually affects individuals older than 40 years and is a growing cause of visual disability due to ageing demographics of the global population. The routine use of computers and 'smartphones', combined with the affluence of the 'baby boomers' generation has set high standards for near vision correction. Corneal inlays are a relatively new treatment modality that is effective at compensating for presbyopia. The dimensions of these devices vary from 2 to 3.8 mm in diameter and 5 to 32 μm in thickness. They are implanted in the anterior corneal stroma of the non-dominant eye, most commonly, in a femtosecond laser created corneal pocket. They improve near vision by increasing the depth of focus, creating a hyper-prolate region of increased central cornea power or providing a refractive add power. This article reviews the literature on the efficacy and safety of corneal inlays.

  19. Conjunctival intraepithelial neoplasia with corneal furrow degeneration

    Directory of Open Access Journals (Sweden)

    Pukhraj Rishi

    2014-01-01

    Full Text Available A 68-year-old man presented with redness of left eye since six months. Examination revealed bilateral corneal furrow degeneration. Left eye lesion was suggestive of conjunctival squamous cell carcinoma, encroaching on to cornea. Anterior segment optical coherence tomography (AS-OCT confirmed peripheral corneal thinning. Fluorescein angiography confirmed intrinsic vascularity of lesion. Patient was managed with "no touch" surgical excision, dry keratectomy without alcohol, cryotherapy, and primary closure. Pathologic examination of removed tissue confirmed clinical diagnosis. Management of this particular case required modification of standard treatment protocol. Unlike the alcohol-assisted technique of tumor dissection described, ethyl alcohol was not used for risk of corneal perforation due to underlying peripheral corneal thinning. Likewise, topical steroids were withheld in the post-operative period. Three weeks post-operatively, left eye was healing well. Hence, per-operative usage of absolute alcohol and post-operative use of topical steroids may be best avoided in such eyes.

  20. Serological profile of candidates for corneal donation

    OpenAIRE

    Adroaldo Lunardelli; Richard Beraldini Alvarenga; Maria Luiza Assmann; Dário Eduardo de Lima Brum; Mirna Adolfina Barison

    2014-01-01

    Objetive: The purpose of this study is to map the serological profile of candidates to corneal donation at Irmandade Santa Casa de Misericórdia de Porto Alegre, identifying the percentage of disposal by serology and the marker involved. Methods: There have been analised – retrospectively – the results of serology of all corneal donors, made between the period of 1st january 2006 and 31st december 2012. Data analised were related to age, gender and the results of serology pert...

  1. In vivo corneal confocal microscopic analysis in patients with keratoconus

    Institute of Scientific and Technical Information of China (English)

    Gulfidan; Bitirgen; Ahmet; Ozkagnici; Banu; Bozkurt; Rayaz; A; Malik

    2015-01-01

    AIM: To quantify corneal ultrastructure using laser scanning in vivo confocal microscopy(IVCM) in patients with keratoconus and control subjects. METHODS: Unscarred corneas of 78 keratoconic subjects without a history of contact lens use and 36age-matched control subjects were evaluated with slit-lamp examination(SLE), corneal topography and laser scanning IVCM. One eye was randomly chosen for analysis. Anterior and posterior stromal keratocyte,endothelial cell and basal epithelial cell densities and sub-basal nerve structure were evaluated.RESULTS: IVCM qualitatively demonstrated enlarged basal epithelial cells, structural changes in sub-basal and stromal nerve fibers, abnormal stromal keratocytes and keratocyte nuclei, and pleomorphism and enlargement of endothelial cells. Compared with control subjects, significant reductions in basal epithelial cell density( 5817 ± 306 cells / mm2 vs 4802 ±508 cells/mm2,P < 0. 001), anterior stromal keratocyte density(800 ±111 cells/mm2 vs 555 ±115 cells/mm2, P <0.001),posterior stromal keratocyte density(333±34 cells/mm2vs270 ±47 cells/mm2, P <0.001), endothelial cell density(2875 ±223 cells/mm2 vs 2686 ±265 cells/mm2, P <0.001),sub-basal nerve fiber density(31.2 ±8.4 nerves/mm2vs18.1 ±9.2 nerves/mm2, P <0.001), sub-basal nerve fiber length(21.4±3.4 mm/mm2 vs 16.1±5.1 mm/mm2, P <0.001),and sub-basal nerve branch density(median 50.0(first quartile 31.2- third quartile 68.7) nerve branches/mm2 vs median 25.0(first quartile 6.2- third quartile 45.3) nerve branches/mm2, P <0.001) were observed in patients with keratoconus.CONCLUSION: Significant microstructural abnormalities were identified in all corneal layers in the eyes of subjects with keratoconus using IVCM. This non-invasive in vivo technique provides an important means to define and follow progress of microstructural changes in patients with keratoconus.

  2. Corneal Collagen Cross-Linking in Pellucid Marginal Degeneration: 2 Patients, 4 Eyes

    Directory of Open Access Journals (Sweden)

    Serife Bayraktar

    2015-01-01

    Full Text Available Purpose. To report the long-term results of corneal collagen cross-linking (CXL with riboflavin and ultraviolet-A irradiation in 4 eyes of 2 patients affected by pellucid marginal degeneration (PMD. Methods. This study involved the retrospective analysis of 4 eyes of 2 patients with PMD that underwent CXL treatment. Of the eyes, three had only CXL treatment and one had CXL treatment after an intrastromal corneal ring segment implantation. We have pre- and postoperatively evaluated uncorrected distance visual acuity (UDVA, best corrected distance visual acuity (BCDVA, corneal topography (Pentacam, specular microscopy, and pachymetry. Results. Patient 1 was a woman, aged 35, and Patient 2 was a man, aged 33. The right eye of Patient 1 showed an improvement in her BCDVA, from 16/40 to 18/20 in 15 months, and her left eye improved from 12/20 to 18/20 in 20 months. Patient 2’s right eye showed an improvement in his BCDVA, from 18/20 to 20/20 in 43 months, and his left eye improved from 16/20 to 18/20 in 22 months. No complications were recorded during or after the treatment. Conclusion. CXL is a safe tool for the management of PMD, and it can help to stop the progression of this disease.

  3. Transverse depth-dependent changes in corneal collagen lamellar orientation and distribution.

    Science.gov (United States)

    Abass, Ahmed; Hayes, Sally; White, Nick; Sorensen, Thomas; Meek, Keith M

    2015-03-06

    It is thought that corneal surface topography may be stabilized by the angular orientation of out-of plane lamellae that insert into the anterior limiting membrane. In this study, micro-focus X-ray scattering data were used to obtain quantitative information about lamellar inclination (with respect to the corneal surface) and the X-ray scatter intensity throughout the depth of the cornea from the centre to the temporal limbus. The average collagen inclination remained predominantly parallel to the tissue surface at all depths. However, in the central cornea, the spread of inclination angles was greatest in the anterior-most stroma (reflecting the increased lamellar interweaving in this region), and decreased with tissue depth; in the peripheral cornea inclination angles showed less variation throughout the tissue thickness. Inclination angles in the deeper stroma were generally higher in the peripheral cornea, suggesting the presence of more interweaving in the posterior stroma away from the central cornea. An increase in collagen X-ray scatter was identified in a region extending from the sclera anteriorly until about 2 mm from the corneal centre. This could arise from the presence of larger diameter fibrils, probably of scleral origin, which are known to exist in this region. Incorporation of this quantitative information into finite-element models will further improve the accuracy with which they can predict the biomechanical response of the cornea to pathology and refractive procedures.

  4. Corneal collagen cross-linking in keratoconus: A systematic review and meta-analysis

    Science.gov (United States)

    Chunyu, Tian; Xiujun, Peng; Zhengjun, Fan; Xia, Zhang; Feihu, Zhou

    2014-01-01

    The aim of this study was to determine the effectiveness of corneal collagen cross-linking (CXL) for the treatment of progressive keratoconus (KC). Some of the published literature, including a few small, randomized controlled trials (RCTs), demonstrated good results after CXL, but large RCTs with long-term follow-up to establish a cause-effect relationship are lacking. Using PubMed, EMBASE, and the Cochrane Library database, we searched for relevant studies published between October 2007 and March 2014. A comprehensive literature search was performed using the Cochrane Collaboration methodology to identify the effectiveness of CXL for treating KC. The primary outcome parameters included uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), refraction, corneal topography, and corneal thickness at baseline and at 1, 3, 6, 12, and 18 months after CXL. A total of 1171 participants (1557 eyes) were enrolled in this meta-analysis. CXL may be effective in halting the progress of KC for at least 12 months under certain conditions. However, further research from randomized trials is needed to confirm our findings. PMID:25007895

  5. Update on pathologic diagnosis of corneal infections and inflammations

    Directory of Open Access Journals (Sweden)

    Geeta K Vemuganti

    2011-01-01

    Full Text Available One of the most frequent types of corneal specimen that we received in our pathology laboratory is an excised corneal tissue following keratoplasty. Several of these cases are due to corneal infections or the sequelae, like corneal scar. Advances in the histological and molecular diagnosis of corneal infections and inflammations have resulted in rapid and accurate diagnosis of the infectious agent and in the overall understanding of the mechanisms in inflammatory diseases of the cornea. This review provides an update of histopathological findings in various corneal infections and inflammations.

  6. Survival and integration of tissue-engineered corneal stroma in a model of corneal ulcer.

    Science.gov (United States)

    Zhang, Chao; Nie, Xin; Hu, Dan; Liu, Yuan; Deng, Zhihong; Dong, Rui; Zhang, Yongjie; Jin, Yan

    2007-08-01

    Tissue-engineered replacement of diseased or damaged tissue has become a reality for some types of tissue, such as skin and cartilage. Tissue-engineered corneal stroma represents a promising concept to overcome the limitations of cornea replacement with allograft. In this study, porcine cornea was decellularized by a series of extraction methods, and the in vivo biocompatibility of the scaffold was measured subcutaneously in rabbits (n = 8). These were not acutely rejected and no abscesses were observed by hematoxylin and eosin staining at the 8th week, indicating that the scaffolds had good biocompatibility. To investigate the potential value of clinical applications, rabbit stromal keratocytes were implanted onto decellularized scaffolds to fabricate tissue-engineered corneal stroma. Allograft, tissue-engineered corneal stroma, or scaffolds were implanted into a model of corneal ulcer. The survival and reconstruction of corneal transplantation were morphologically evaluated by light and electron microscopy until the 32nd week after implantation. Experiments involving transplantation indicated that the epithelial and stromal defect healed quickly, with improvement in corneal clarity. The integration of the graft was accompanied by neurite ingrowth from the host tissue. By 16 weeks after transplantation, the cornea had gradually regained an intact state similar to that of normal cornea. Our results demonstrate that the tissue-engineered corneal stroma with allogenetic cells is a promising therapeutic method for corneal injury.

  7. Extrusão do anel intra-estromal corneano e vascularização do túnel Extrusion and vascularization of the intrastromal corneal ring tunnel

    Directory of Open Access Journals (Sweden)

    Larissa Casteluber

    2007-12-01

    Full Text Available O objetivo deste trabalho é relatar e discutir os aspectos de um caso clínico em que foi observada a formação de neovascularização no túnel do anel intra-estromal corneano. Trata-se de paciente com ectasia corneana 4 anos após LASIK, comprovada pela paquimetria e topografia, e submetido ao implante de anel intra-estromal corneano. No terceiro ano de acompanhamento após implante do anel intraestromal, com o paciente em uso de lente de contato gelatinosa, verificou-se extrusão de um segmento e neovascularização no túnel. Removeu-se o segmento afetado, realizou-se fotocoagulação vascular, observando-se regressão completa do quadro neovascular.The purpose of this paper is to describe the clinical aspects of one case with deep corneal vascularization after corneal ring implantation to treat corneal ectasia due to LASIK 4 years before. The corneal ectasia diagnostic was performed by corneal pachimetry and topography. Intrastromal corneal ring segment was implanted. On the third year of follow-up, extrusion of one segment was noted and deep corneal neovascularization was found. The segment was removed, laser photocoagulation was applied and complete vascular regression was observed.

  8. Analysis of pseudoprogression after corneal cross-linking in children with progressive keratoconus.

    Science.gov (United States)

    Schuerch, Kaspar; Tappeiner, Christoph; Frueh, Beatrice E

    2016-11-01

    To analyse the long-term efficacy of corneal cross-linking (CXL) in children with keratoconus and to describe criteria for the detection of pseudoprogression. Evaluation of retrospectively collected corneal topography (Placido system) and tomography (Scheimpflug system) results after CXL in children (age 18 or younger). Twenty-five patients (33 eyes) were included. Follow-up was assessed after 1, 2, 3 and 4 years. Progression was defined as an increase in maximal keratometry (Kmax) of at least one dioptre (D) in 1 year. For the entire group, mean Kmax prior to CXL was 55.3 ± 7.3D and decreased significantly (p = 0.00001) after 1 year to 53.4 ± 7.4D. In 23 patients, the progression could be halted. Five cases of presumed progression were identified. One case showed marked steepening in Kmax 4 years after CXL, but the topographic parameters were unchanged. The tomography was repeated and showed that Kmax was stable. Two cases with limbal vernal keratoconjunctivitis (VKC) worsened both in corneal tomography and topography. After resolution of the limbal inflammation, the Kmax values returned to the values before the inflammation. We found two cases of true progression both of which had advanced keratoconus prior to CXL with a preoperative Kmax of 64.4, respectively, 75.1D. Our results confirm that CXL is effective in stabilizing keratoconus in children. True progression after CXL could only be verified in two of 33 eyes in a follow-up period of 37.5 months (SD ± 10 months). Two different measuring methods can help to detect diagnostic discrepancies and prevent false conclusions. Moreover, limbal vernal changes can cause transient pseudoprogression, reversible upon sufficient treatment. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  9. 角膜屈光手术后继发性圆锥角膜的RGP矫正疗效观察%RGP Correct Corneal Ectasia after Corneal Refractive Surgery

    Institute of Scientific and Technical Information of China (English)

    赵江浩; 吴年浪; 张惠成

    2012-01-01

    目的 评价硬性透气性角膜接触镜(rigid permeability contact lenses,RGP)矫正角膜屈光手术后圆锥角膜的疗效.方法 选择笔者医院收治的11例(21眼)角膜屈光手术后圆锥角膜患者配戴RGP,观察1年后角膜前后表明曲率,RGP和普通软性角膜接触镜的角膜地形图改变.结果 配戴RGP1年后角膜前表面最平平均曲率值和后表面曲率值没有明显变化.RGP矫正1年后角膜前表面的最陡平均曲率明显下降,角膜地形图SRI,SAI,散光减少,PVA提高.对照组佩戴普通软性角膜接触镜1年后角膜地形图无明显改善.结论 经1年的随访观察,RGP对角膜屈光手术后的圆锥角膜能明显改善患者的角膜前表面最陡平均曲率,角膜后表面和角膜前表面最平平均曲率保持稳定.是目前矫正角膜屈光手术后圆锥角膜的有效方法.%Objective To evaluate the effect of rigid permeability contact lenses (RGP) for correcting corneal ectasia after comeal refractive surgery. Methods 21 eyes from 11 patients identified as developing corneal ectasia after comeal refractive surgery were used in this study. The change of corneal curvature front surface and after the surface was observed. Also the change of corneal topography of after wearing RCP and soft contact lens after 1 year was observed. Results Front surface MIX corneal curvature value and after surface corneal curvature value did not change significantly. Front surface MAX cornea] curvature was decreased significantly after wearing RGP 1 year. SRI, SAI and stigmatism were obviously decreased, and PVA was improved after wearing RGP 1 year. At the same time corneal topography did not change significantly after wearing soft contact lens 1 year. Conclusion By 1 years of follow -up, front surface MAX corneal curvature ,stigmatism are obviously decreased after comeal refractive surgery. The patient's vision is obviously improved. Front surface MIX corneal curvature value and after surface comeal

  10. Ultrasound biomicroscopy confirmation of corneal overriding due to improper suturing of full-thickness corneal laceration

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    Murat Kucukevcilioglu

    2014-12-01

    Full Text Available We herein present a case with corneal overriding due to improper suturing of a full-thickness corneal laceration. There was a 2.5-mm difference between horizontal and vertical white-to-white measurements in the cornea. However, slit lamp examination failed to demonstrate the exact architecture of the laceration. Ultrasound biomicroscopy defined the wound edges thoroughly and confirmed the presence of corneal overriding. Six weeks after suture enhancement, the abnormal oval appearance of the cornea was absent and correct apposition of the corneal edges was seen on ultrasound biomicroscopy. Ultrasound biomicroscopy can be used in preoperative surgical planning of cases with complicated corneal lacerations. It can be used to adjust and enhance wound architecture in eyes with penetrating injury.

  11. A role for topographic cues in the organization of collagenous matrix by corneal fibroblasts and stem cells.

    Science.gov (United States)

    Karamichos, Dimitrios; Funderburgh, Martha L; Hutcheon, Audrey E K; Zieske, James D; Du, Yiqin; Wu, Jian; Funderburgh, James L

    2014-01-01

    Human corneal fibroblasts (HCF) and corneal stromal stem cells (CSSC) each secrete and organize a thick stroma-like extracellular matrix in response to different substrata, but neither cell type organizes matrix on tissue-culture polystyrene. This study compared cell differentiation and extracellular matrix secreted by these two cell types when they were cultured on identical substrata, polycarbonate Transwell filters. After 4 weeks in culture, both cell types upregulated expression of genes marking differentiated keratocytes (KERA, CHST6, AQP1, B3GNT7). Absolute expression levels of these genes and secretion of keratan sulfate proteoglycans were significantly greater in CSSC than HCF. Both cultures produced extensive extracellular matrix of aligned collagen fibrils types I and V, exhibiting cornea-like lamellar structure. Unlike HCF, CSSC produced little matrix in the presence of serum. Construct thickness and collagen organization was enhanced by TGF-ß3. Scanning electron microscopic examination of the polycarbonate membrane revealed shallow parallel grooves with spacing of 200-300 nm, similar to the topography of aligned nanofiber substratum which we previously showed to induce matrix organization by CSSC. These results demonstrate that both corneal fibroblasts and stromal stem cells respond to a specific pattern of topographical cues by secreting highly organized extracellular matrix typical of corneal stroma. The data also suggest that the potential for matrix secretion and organization may not be directly related to the expression of molecular markers used to identify differentiated keratocytes.

  12. A role for topographic cues in the organization of collagenous matrix by corneal fibroblasts and stem cells.

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    Dimitrios Karamichos

    Full Text Available Human corneal fibroblasts (HCF and corneal stromal stem cells (CSSC each secrete and organize a thick stroma-like extracellular matrix in response to different substrata, but neither cell type organizes matrix on tissue-culture polystyrene. This study compared cell differentiation and extracellular matrix secreted by these two cell types when they were cultured on identical substrata, polycarbonate Transwell filters. After 4 weeks in culture, both cell types upregulated expression of genes marking differentiated keratocytes (KERA, CHST6, AQP1, B3GNT7. Absolute expression levels of these genes and secretion of keratan sulfate proteoglycans were significantly greater in CSSC than HCF. Both cultures produced extensive extracellular matrix of aligned collagen fibrils types I and V, exhibiting cornea-like lamellar structure. Unlike HCF, CSSC produced little matrix in the presence of serum. Construct thickness and collagen organization was enhanced by TGF-ß3. Scanning electron microscopic examination of the polycarbonate membrane revealed shallow parallel grooves with spacing of 200-300 nm, similar to the topography of aligned nanofiber substratum which we previously showed to induce matrix organization by CSSC. These results demonstrate that both corneal fibroblasts and stromal stem cells respond to a specific pattern of topographical cues by secreting highly organized extracellular matrix typical of corneal stroma. The data also suggest that the potential for matrix secretion and organization may not be directly related to the expression of molecular markers used to identify differentiated keratocytes.

  13. Validation of a combined corneal topographer and aberrometer based on Shack-Hartmann wave-front sensing

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    Zhou, Fan; Hong, Xin; Miller, Donald T.; Thibos, Larry N.; Bradley, Arthur

    2004-05-01

    A corneal aberrometer based on Shack-Hartmann wave-front sensing was developed and validated by using calibrated aspheric surfaces. The aberrometer was found to accurately measure corneal reflective aberrations, from which corneal topography and corneal refractive aberrations were derived. Measurements of reflective aberrations correlated well with theory (R^2=0.964 to 0.994). The sag error root mean square (RMS) was small, ranging from 0.1 to 0.17 µm for four of the five calibrated surfaces with the fifth at 0.36 µm as a result of residual defocus. Measured refractive aberrations matched with theory and whole-eye aberrometry to within a small fraction of a wavelength. Measurements on three human corneas revealed very large refractive astigmatism (0.65-1.2 µm) and appreciable levels of trefoil (0.08-0.47 µm), coma (0.14-0.19 µm), and spherical aberration (0.18-0.25 µm). The mean values of these aberrations were significantly larger than the RMS in repeated measurements.

  14. Thinner Corneas Appear to Have More Striking Effects of Corneal Collagen Crosslinking in Patients with Progressive Keratoconus

    Science.gov (United States)

    Han, Yunfei; Xu, Yanyun; Zhu, Wei; Liu, Yuling; Liu, Zhen; Dou, Xiaoxiao

    2017-01-01

    Purpose. To analyze the outcomes and difference after UVA/riboflavin corneal collagen crosslinking (CXL) in four different corneal thickness groups of patients with progressive keratoconus. Methods. Retrospective study. Eyes with progressive keratoconus after CXL were divided into 4 subgroups as follows: group 1, thinnest corneal thickness (TCT) ≤ 400 µm; group 2, 400 µm corneal topography, TCT, and endothelial cell density were evaluated. Results. The analysis included 123 eyes of 101 patients. At 6 and 12 months after CXL, there was a mean improvement about visual acuity and keratometry values in all patients. There was a reduction in the change of maximum keratometry (Kmax) with the increase of TCT. After 1 year of treatment, it was 3.04 ± 0.75 D in group 1, 2.38 ± 0.51 D in group 2, 1.57 ± 0.35 D in group 3, and 0.31 ± 0.20 D in group 4. Conclusion. CXL is successful in halting the progression of keratoconus and there was a negative linear correlation between TCT and Kmax. Advanced cases of progressive keratoconus seemed to obtain more benefits from the flatting effects of CXL. PMID:28392939

  15. Clinical and Topographical Corneal Changes after Keraring Implantation in Keratoconus Patients

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    Mirzaei Mohamad

    2015-01-01

    Full Text Available Introduction: Keratoconus is a progressive, non-inflammatory, bilateral, ecstatic disease of the cornea that is characterized by corneal steepening which progresses to irregular conical shape, with subsequent irregular astigmatism and decreased visual acuity. In early stages of disease, spectacles or RGP lenses are the main treatment. At advanced stages, when these treatment options fail to correct visual acuity, surgical procedures such as penetrating keratoplasty or lamellar keratoplasty are required. METHODS: Keraring segments were placed in 30 eyes of 21 keratoconus patients. The mean follow-up time was 6.2 months. All patients underwent a complete ocular examination and corneal topography which was obtained by Pentacam (Oculus Pentacam®, USA. Improvement in uncorrected visual acuity (UCVA, best spectacle corrected visual acuity, refraction and topographic changes including keratometry, maximum anterior and posterior elevation, central corneal thickness and thinnest point thickness and location were evaluated. RESULTS: No intraoperative or postoperative complications occurred in any of the patients. ICRS implantation significantly improved UCVA (P=0.005 and BSCVA (P=0.000. Mean Spherical equivalent significantly reduced from -6.66±3.52 to -4.42±3.20 (p=0.000. A clinically significant reduction in mean keratometry (p=0.000, Max Ant Elevation (P=0.024 and Max Post Elevation (P=0.002 were recorded. No clinically significant changes in central corneal thickness, thinnest point thickness and thinnest point location were observed. Conclusion: With mean follow-up of 6.2 months, Keraring segments implantation caused significant clinical improvement in UCVA, BCVA Refractive Error and Keratometric findings of the most keratoconic patients.   Keywords: keratoconus; ICRS; Keraring

  16. Carbon Dioxide Exchange in Complex Topography

    Science.gov (United States)

    Reif, Matthias; Rotach, Mathias; Wohlfahrt, Georg; Gohm, Alexander

    2015-04-01

    On a global scale the budget of carbon dioxide (CO_2) bears a quite substantial uncertainty, which is commonly understood to be mainly due to land-surface exchange processes. In this project we investigate to what extent complex topography can amplify these land-surface exchange processes. The hypothesis is that, on the meso-scale, topography adds additional atmospheric mechanisms that drive the exchange of CO2 at the surface. This sensitivity model study investigates an idealized sine shaped valley with the atmospheric numerical model Weather Research and Forecasting (WRF) coupled to the community land model (CLM) to study the effect of complex topography on the CO2 budget compared to flat terrain. The experiment is designed to estimate the effect of the topography during maximum ecosystem exchange in summer using meteorological and ecosystem conditions at solstice, the 21. of June. Systematic variation of meteorological initial conditions, plant functional types and the topography creates an ensemble that unveils the fundamental factors that dominate the differences of CO2 between simulations with topography compared to plain surfaces in the model. The sign and magnitude of the difference between the CO2 exchange over topography and over a plain simulation are strongly dependent on the CLM plant functional type, the initial temperature, the initial relative humidity, the latitude and the area height distribution of the topography. However, in this model experiment the topography is, in the mean, a sink to the CO2 budget in the order of 5% per day.

  17. Morphology, topography, and optics of the orthokeratology cornea

    Science.gov (United States)

    Faria-Ribeiro, Miguel; Belsue, Rafael Navarro; López-Gil, Norberto; González-Méijome, José Manuel

    2016-07-01

    The goal of this work was to objectively characterize the external morphology, topography, and optics of the cornea after orthokeratology (ortho-k). A number of 24 patients between the ages of 17 and 30 years (median=24 years) were fitted with Corneal Refractive Therapy® contact lenses to correct myopia between -2.00 and -5.00 diopters (D) (median=-3.41 D). A classification algorithm was applied to conduct an automatic segmentation based on the mean local curvature. As a result, three zones (optical zone, transition zone, and peripheral zone) were delimited. Topographical analysis was provided through global and zonal fit to a general ellipsoid. Ray trace on partially customized eye models provided wave aberrations and retinal image quality. Monozone topographic description of the ortho-k cornea loses accuracy when compared with zonal description. Primary (C40) and secondary (C60) spherical aberration (SA) coefficients for a 5-mm pupil increased 3.68 and 19 times, respectively, after the treatments. The OZ area showed a strong correlation with C40 (r=-0.49, p<0.05) and a very strong correlation with C60 (r=0.78, p<0.01). The OZ, as well as the TZ, areas did not correlate with baseline refraction. The increase in the eye's positive SA after ortho-k is the major factor responsible for the decreased retinal optical quality of the unaccommodated eye.

  18. Adjuvant corneal crosslinking to prevent hyperopic LASIK regression

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    Aslanides IM

    2013-03-01

    Full Text Available Ioannis M Aslanides, Achyut N MukherjeeEmmetropia Mediterranean Eye Clinic, Heraklion, Crete, GreecePurpose: To report the long term outcomes, safety, stability, and efficacy in a pilot series of simultaneous hyperopic laser assisted in situ keratomileusis (LASIK and corneal crosslinking (CXL.Method: A small cohort series of five eyes, with clinically suboptimal topography and/or thickness, underwent LASIK surgery with immediate riboflavin application under the flap, followed by UV light irradiation. Postoperative assessment was performed at 1, 3, 6, and 12 months, with late follow up at 4 years, and results were compared with a matched cohort that received LASIK only.Results: The average age of the LASIK-CXL group was 39 years (26–46, and the average spherical equivalent hyperopic refractive error was +3.45 diopters (standard deviation 0.76; range 2.5 to 4.5. All eyes maintained refractive stability over the 4 years. There were no complications related to CXL, and topographic and clinical outcomes were as expected for standard LASIK.Conclusion: This limited series suggests that simultaneous LASIK and CXL for hyperopia is safe. Outcomes of the small cohort suggest that this technique may be promising for ameliorating hyperopic regression, presumed to be biomechanical in origin, and may also address ectasia risk.Keyword: CXL

  19. [Representation and mathematical analysis of human corneal surface].

    Science.gov (United States)

    Tălu, Stefan; Tălu, Mihai; Giovanzana, Stefano

    2011-01-01

    In the description and analysis of human corneal surface are used various mathematical models based on parametric representations, used in biomechanical studies and 3D solid modeling of the cornea. Mathematical models are important into the biomechanics of the cornea to model the corneal behavior. Corneal biomechanics also has the potential to improve outcomes in refractive surgery. The objective of this paper is to present the most representative mathematical models currently used for modeling of human corneal in optics and biomechanics fields.

  20. The molecular genetics of the corneal dystrophies--current status.

    Science.gov (United States)

    Klintworth, Gordon K

    2003-05-01

    The pertinent literature on inherited corneal diseases is reviewed in terms of the chromosomal localization and identification of the responsible genes. Disorders affecting the cornea have been mapped to human chromosome 1 (central crystalline corneal dystrophy, familial subepithelial corneal amyloidosis, early onset Fuchs dystrophy, posterior polymorphous corneal dystrophy), chromosome 4 (Bietti marginal crystalline dystrophy), chromosome 5 (lattice dystrophy types 1 and IIIA, granular corneal dystrophy types 1, 2 and 3, Thiel-Behnke corneal dystrophy), chromosome 9 (lattice dystrophy type II), chromosome 10 (Thiel-Behnke corneal dystrophy), chromosome 12 (Meesmann dystrophy), chromosome 16 (macular corneal dystrophy, fish eye disease, LCAT disease, tyrosinemia type II), chromosome 17 (Meesmann dystrophy, Stocker-Holt dystrophy), chromosome 20 (congenital hereditary endothelial corneal dystrophy types I and II, posterior polymorphous corneal dystrophy), chromosome 21 (autosomal dominant keratoconus) and the X chromosome (cornea verticillata, cornea farinata, deep filiform corneal dystrophy, keratosis follicularis spinulosa decalvans, Lisch corneal dystrophy). Mutations in nine genes (ARSC1, CHST6, COL8A2, GLA, GSN, KRT3, KRT12, M1S1and TGFBI [BIGH3]) account for some of the corneal diseases and three of them are associated with amyloid deposition in the cornea (GSN, M1S1, TGFBI) including most of the lattice corneal dystrophies (LCDs) [LCD types I, IA, II, IIIA, IIIB, IV, V, VI and VII] recognized by their lattice pattern of linear opacities. Genetic studies on inherited diseases affecting the cornea have provided insight into some of these disorders at a basic molecular level and it has become recognized that distinct clinicopathologic phenotypes can result from specific mutations in a particular gene, as well as some different mutations in the same gene. A molecular genetic understanding of inherited corneal diseases is leading to a better appreciation of the

  1. Contact lens rehabilitation following repaired corneal perforations

    Directory of Open Access Journals (Sweden)

    Sreenivas V

    2006-03-01

    Full Text Available Abstract Background Visual outcome following repair of post-traumatic corneal perforation may not be optimal due to presence of irregular keratometric astigmatism. We performed a study to evaluate and compare rigid gas permeable contact lens and spectacles in visual rehabilitation following perforating corneal injuries. Method Eyes that had undergone repair for corneal perforating injuries with or without lens aspiration were fitted rigid gas permeable contact lenses. The fitting pattern and the improvement in visual acuity by contact lens over spectacle correction were noted. Results Forty eyes of 40 patients that had undergone surgical repair of posttraumatic corneal perforations were fitted rigid gas permeable contact lenses for visual rehabilitation. Twenty-four eyes (60% required aphakic contact lenses. The best corrected visual acuity (BCVA of ≥ 6/18 in the snellen's acuity chart was seen in 10 (25% eyes with spectacle correction and 37 (92.5% eyes with the use of contact lens (p Conclusion Rigid gas permeable contact lenses are better means of rehabilitation in eyes that have an irregular cornea due to scars caused by perforating corneal injuries.

  2. Corneal Phaeohyphomycosis Caused by Bipolaris hawaiiensis

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    Winai Chaidaroon

    2016-07-01

    Full Text Available Purpose: To report a rare case of keratitis infected by Bipolaris hawaiiensis. Methods: A patient who was diagnosed as fungal keratitis caused by B. hawaiiensis was retrospectively reviewed for history, clinical characteristics, risk factors, laboratory findings, treatments, and outcomes. Results: A 63-year-old man with a history of trauma and saw dust in the left eye presented with a corneal ulcer. Eye examination revealed whitish infiltration with a feathery edge and small brownish deposits in the anterior stroma of the left cornea. Numerous septate hyphal fragments were detected in a corneal specimen, and nucleotide sequence analysis identified B. hawaiiensis. Treatment was started with 5% natamycin eyedrops and oral itraconazole. Subsequently, a corneal plaque developed which did not respond to medication and debridement. The patient underwent therapeutic penetrating keratoplasty. Conclusions: B. hawaiiensis is a rare cause of corneal phaeohyphomycosis. A brownish pigmented infiltration is an important diagnostic clue, however microbiologic studies are required to obtain a definite diagnosis. Although antifungal medication and debridement are the mainstay of most corneal fungal infection, therapeutic penetrating keratoplasty can prevent morbidity related to this fungal infection.

  3. Corneal Phaeohyphomycosis Caused by Bipolaris hawaiiensis

    Science.gov (United States)

    Chaidaroon, Winai; Supalaset, Sumet; Tananuvat, Napaporn; Vanittanakom, Nongnuch

    2016-01-01

    Purpose To report a rare case of keratitis infected by Bipolaris hawaiiensis. Methods A patient who was diagnosed as fungal keratitis caused by B. hawaiiensis was retrospectively reviewed for history, clinical characteristics, risk factors, laboratory findings, treatments, and outcomes. Results A 63-year-old man with a history of trauma and saw dust in the left eye presented with a corneal ulcer. Eye examination revealed whitish infiltration with a feathery edge and small brownish deposits in the anterior stroma of the left cornea. Numerous septate hyphal fragments were detected in a corneal specimen, and nucleotide sequence analysis identified B. hawaiiensis. Treatment was started with 5% natamycin eyedrops and oral itraconazole. Subsequently, a corneal plaque developed which did not respond to medication and debridement. The patient underwent therapeutic penetrating keratoplasty. Conclusions B. hawaiiensis is a rare cause of corneal phaeohyphomycosis. A brownish pigmented infiltration is an important diagnostic clue, however microbiologic studies are required to obtain a definite diagnosis. Although antifungal medication and debridement are the mainstay of most corneal fungal infection, therapeutic penetrating keratoplasty can prevent morbidity related to this fungal infection. PMID:27721785

  4. Corneal trephination with the femtosecond laser.

    Science.gov (United States)

    Meltendorf, Christian; Schroeter, Jan; Bug, Reinhold; Kohnen, Thomas; Deller, Thomas

    2006-10-01

    To evaluate the feasibility and cut quality of corneal trephination in human donor corneal tissue with the femtosecond laser. Twelve human corneoscleral discs were inserted in an artificial anterior chamber. After corneal thickness measurement and tonometry, the cornea was mounted on a femtosecond laser (FEMTEC; 20/10 Perfect Vision, Heidelberg, Germany) through a contact lens (patient interface). Trephination was performed with diameters of 7.0, 7.5, 8.0, and 8.5 mm in 3 corneas each. The corneal button was removed from the corneoscleral disc in 2 of the 3 corneas in each case. The cut was not manipulated in the remaining corneas to enable histologic detection of possible tissue bridges. The cut edges were macroscopically and light-microscopically examined for quality. Corneal buttons and corneoscleral discs could be separated by blunt dissection in all cases. Tissue bridges were more common in thicker edematous corneas than in thinner ones. Both the macro- and microscopic examination disclosed smooth rectilinear cut margins with a perpendicular cut edge. This feasibility study shows that the femtosecond laser enables sufficient trephination of human donor corneas.

  5. Corneal reconstruction by stem cells and bioengineering

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    Arjamaa O

    2012-09-01

    Full Text Available Olli ArjamaaDepartment of Biology, University of Turku, Turku, FinlandAbstract: Almost 300 million people are visually impaired worldwide due to various eye diseases such as cataracts, glaucoma, age-related macular degeneration, diabetic retinopathy, and corneal diseases. Notably, ten million people are blind because of severe ocular surface diseases and the majority of cases occur in developing countries. Blinding ocular surface diseases have, however, become treatable by grafting of surface layers, or by full-thickness transplantation of the cornea. As the demand for human corneal tissue for surface reconstruction and transplantation far exceeds the supply, methods are being developed to supplement tissue donation. Xenotransplantation of the cornea or cells from genetically modified pigs may become one of the solutions. Transplantation of limbal stem cells within tissue biopsies, to restore the transparency of the cornea is another remarkable method, which has shown its potential in several clinical studies. The combination of stem cell technology and engineering of biocompatible tissue equivalent, still at preclinical stage, has shown us how synthetic corneal tissue is able to guide cultured corneal stromal stem cells of human origin, to become native-like stroma, the most important layer of the cornea. These findings give hope for a large-quantity production of biomaterial for corneal reconstruction. As such, clinical ophthalmologists should become more familiar with the methods of laboratory science.Keywords: eye, grafting, keratoplasty, xenotransplantation, cell reservoir, biocompatible tissue equivalent

  6. Analysis of the horizontal corneal diameter, central corneal thickness, and axial length in premature infants

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    Ozdemir Ozdemir

    2014-08-01

    Full Text Available Purpose: To determine the horizontal corneal diameter, central corneal thickness, and axial length in premature infants. Methods: Infants with a birth weight of less than 2,500 g or with a gestation period of less than 36 weeks were included in the study. Infants with retinopathy of prematurity (ROP were allocated to Group 1 (n=138, while those without ROP were allocated to Group 2 (n=236. All infants underwent a complete ophthalmologic examination, including corneal diameter measurements, pachymetry, biometry, and fundoscopy. Between-group comparisons of horizontal corneal diameter, central corneal thickness, and axial lengths were performed. Independent sample t-tests were used for statistical analysis. Results: Data was obtained from 374 eyes of 187 infants (102 female, 85 male. The mean gestational age at birth was 30.7 ± 2.7 weeks (range 25-36 weeks, the mean birth weight was 1,514 ± 533.3 g (range 750-1,970 g, and the mean postmenstrual age at examination was 40.0 ± 4.8 weeks. The mean gestational age and the mean birth weight of Group 1 were statistically lower than Group 2 (p0.05. Conclusions: The presence of ROP in premature infants does not alter the horizontal corneal diameter, central corneal thickness, or axial length.

  7. High-resolution land topography

    Science.gov (United States)

    Massonnet, Didier; Elachi, Charles

    2006-11-01

    After a description of the background, methods of production and some scientific uses of high-resolution land topography, we present the current status and the prospect of radar interferometry, regarded as one of the best techniques for obtaining the most global and the most accurate topographic maps. After introducing briefly the theoretical aspects of radar interferometry - principles, limits of operation and various capabilities -, we will focus on the topographic applications that resulted in an almost global topographic map of the earth: the SRTM map. After introducing the Interferometric Cartwheel system, we will build on its expected performances to discuss the scientific prospects of refining a global topographic map to sub-metric accuracy. We also show how other fields of sciences such as hydrology may benefit from the products generated by interferometric radar systems. To cite this article: D. Massonnet, C. Elachi, C. R. Geoscience 338 (2006).

  8. 21 CFR 886.1450 - Corneal radius measuring device.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Corneal radius measuring device. 886.1450 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1450 Corneal radius measuring device. (a) Identification. A corneal radius measuring device is an AC-powered device intended to...

  9. Epithelium-off photochemical corneal collagen cross-linkage using riboflavin and ultraviolet a for keratoconus and keratectasia: a systematic review and meta-analysis.

    Science.gov (United States)

    Craig, Joyce A; Mahon, James; Yellowlees, Ann; Barata, Teresa; Glanville, Julie; Arber, Mick; Mandava, Lakshmi; Powell, John; Figueiredo, Francisco

    2014-07-01

    This report presents the results of a systematic review and meta-analyses of studies on epithelium-off photochemical corneal collagen cross-linkage for the management of keratoconus and secondary ectasia. The literature search identified 3,400 records of which 49 were considered for inclusion in the meta-analyses. Eight papers reported 4 unique randomized controlled trials, 29 studies were prospective, and 12 were retrospective studies. The majority of the studies (39/49) were graded as very low quality evidence. Twenty-six studies described adverse events and were included in the safety analysis. Meta-analyses are presented for changes in four outcomes: visual acuity, topography, refraction and astigmatism, and central corneal thickness. Statistically significant improvements were found in all efficacy outcomes at 12 months after the operation. Common side effects were pain, corneal edema, and corneal haze, which resolved usually within a few days after the procedure. The remaining uncertainty is duration of benefit to establish the procedure's potential benefit in avoiding or delaying disease progression and possibly reducing the need for corneal transplantation.

  10. Corneal nerve microstructure in Parkinson's disease.

    Science.gov (United States)

    Misra, Stuti L; Kersten, Hannah M; Roxburgh, Richard H; Danesh-Meyer, Helen V; McGhee, Charles N J

    2017-03-03

    Ocular surface changes and blink abnormalities are well-established in Parkinson's disease. Blink rate may be influenced by corneal sub-basal nerve density, however, this relationship has not yet been investigated in Parkinson's disease. This case-control study examined the ocular surface in patients with moderately severe Parkinson's disease, including confocal microscopy of the cornea. Fifteen patients with moderately severe Parkinson's disease (modified Hoehn and Yahr grade 3 or 4) and fifteen control participants were recruited. Ophthalmic assessment included slit-lamp examination, blink rate assessment, central corneal aesthesiometry and in vivo corneal confocal microscopy. The effect of disease laterality was also investigated. Of the 15 patients with Parkinson's disease, ten were male and the mean age was 65.5±8.6years. The corneal sub-basal nerve plexus density was markedly reduced in patients with Parkinson's disease (7.56±2.4mm/mm(2)) compared with controls (15.91±2.6mm/mm(2)) (pParkinson's disease (0.79±1.2mBAR) and the control group (0.26±0.35mBAR), p=0.12. Sub-basal nerve density was not significantly different between the eye ipsilateral to the side of the body with most-severe motor symptoms, and the contralateral eye. There was a significant positive correlation between ACE-R scores and sub-basal corneal nerve density (R(2)=0.66, p=0.02). This is the first study to report a significant reduction in corneal sub-basal nerve density in Parkinson's disease and demonstrate an association with cognitive dysfunction. These results provide further evidence to support the involvement of the peripheral nervous system in Parkinson's disease, previously thought to be a central nervous system disorder.

  11. Normal corneal endothelial cell density in Nigerians

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    Ewete T

    2016-03-01

    Full Text Available Temitope Ewete,1 Efeoghene Uchenna Ani,2 Adegboyega Sunday Alabi1 1MeCure Eye Center, Lagos, 2Department of Ophthalmology, University of Port Harcourt, Port Harcourt, Nigeria Aim: The aim of the study was to describe the corneal endothelial cell density of adults at the MeCure Eye Center and to determine the relationship between age, sex, and corneal endothelial cell density. Methods: This study was a retrospective study looking at those records of individuals who had undergone specular microscopy or corneal endothelial cell count measurement at the MeCure Eye Center. Results: The endothelial cell characteristics of 359 healthy eyes of 201 volunteers were studied. The mean corneal endothelial cell density (MCD was 2,610.26±371.87 cells/mm2 (range, 1,484–3,571 cells/mm2. The MCD decreased from 2,860.70 cells/mm2 in the 20–30-year age group to 2,493.06 cells/mm2 in the >70-year age group, and there was a statistically significant relationship between age and MCD with a P-value of <0.001. There was no statistically significant correlation between sex and corneal endothelial cell density (P=0.45. Conclusion: This study shows that endothelial cell density in Nigerian eyes is less than that reported in the Japanese, American, and Chinese eyes, and is comparable to that seen in Indian and Malaysian eyes. Keywords: corneal, endothelial cell density, Nigerian

  12. Surface Micro Topography Replication in Injection Moulding

    DEFF Research Database (Denmark)

    Arlø, Uffe Rolf; Hansen, Hans Nørgaard; Kjær, Erik Michael

    2005-01-01

    The surface micro topography of injection moulded plastic parts can be important for aesthetical and technical reasons. The quality of replication of mould surface topography onto the plastic surface depends among other factors on the process conditions. A study of this relationship has been...

  13. SECTION 6.2 SURFACE TOPOGRAPHY ANALYSIS

    DEFF Research Database (Denmark)

    Seah, M. P.; De Chiffre, Leonardo

    2005-01-01

    Surface physical analysis, i.e. topography characterisation, encompasses measurement, visualisation, and quantification. This is critical for both component form and for surface finish at macro-, micro- and nano-scales. The principal methods of surface topography measurement are stylus profilomet...

  14. Corneal collagen crosslinking for keratoconus. A review

    Directory of Open Access Journals (Sweden)

    M. M. Bikbov

    2014-10-01

    Full Text Available Photochemical crosslinking is widely applied in ophthalmology. Its biochemical effect is due to the release of singlet oxygen that promotes anaerobic photochemical reaction. Keratoconus is one of the most common corneal ectasia affecting 1 in 250 to 250 000 persons. Currently, the rate of iatrogenic ectasia following eximer laser refractive surgery increases due to biomechanical weakening of the cornea. Morphologically and biochemically, ectasia is characterized by corneal layers thinning, contact between the stroma and epithelium resulting from Bowman’s membrane rupture, chromatin fragmentation in keratocyte nuclei, phagocytosis, abnormal staining and arrangement of collagen fibers, enzyme system disorders, and keratocyte apoptosis. In corneal ectasia, altered enzymatic processes result in the synthesis of abnormal collagen. Collagen packing is determined by the activity of various extracellular matrix enzymes which bind amines and aldehydes of collagen fiber amino acids. In the late stage, morphological changes of Descemet’s membrane (i.e., rupture and detachment develop. Abnormal hexagonal-shaped keratocytes and their apoptosis are the signs of endothelial dystrophy. The lack of analogs in domestic ophthalmology encouraged the scientists of Ufa Eye Research Institute to develop a device for corneal collagen crosslinking. The parameters of ultraviolet (i.e., wavelength, exposure time, power to achieve the desired effect were identified. The specifics of some photosensitizers in the course of the procedure were studied. UFalink, a device for UV irradiation of cornea, and photosensitizer Dextralink were developed and adopted. Due to the high risk of endothelial damage, this treatment is contraindicated in severe keratoconus (CCT less than 400 microns. Major effects of corneal collagen crosslinking are the following: Young’s modulus (modulus of elasticity increase by 328.9 % (on average, temperature tolerance increase by 5

  15. Corneal collagen crosslinking for keratoconus. A review

    Directory of Open Access Journals (Sweden)

    M. M. Bikbov

    2014-01-01

    Full Text Available Photochemical crosslinking is widely applied in ophthalmology. Its biochemical effect is due to the release of singlet oxygen that promotes anaerobic photochemical reaction. Keratoconus is one of the most common corneal ectasia affecting 1 in 250 to 250 000 persons. Currently, the rate of iatrogenic ectasia following eximer laser refractive surgery increases due to biomechanical weakening of the cornea. Morphologically and biochemically, ectasia is characterized by corneal layers thinning, contact between the stroma and epithelium resulting from Bowman’s membrane rupture, chromatin fragmentation in keratocyte nuclei, phagocytosis, abnormal staining and arrangement of collagen fibers, enzyme system disorders, and keratocyte apoptosis. In corneal ectasia, altered enzymatic processes result in the synthesis of abnormal collagen. Collagen packing is determined by the activity of various extracellular matrix enzymes which bind amines and aldehydes of collagen fiber amino acids. In the late stage, morphological changes of Descemet’s membrane (i.e., rupture and detachment develop. Abnormal hexagonal-shaped keratocytes and their apoptosis are the signs of endothelial dystrophy. The lack of analogs in domestic ophthalmology encouraged the scientists of Ufa Eye Research Institute to develop a device for corneal collagen crosslinking. The parameters of ultraviolet (i.e., wavelength, exposure time, power to achieve the desired effect were identified. The specifics of some photosensitizers in the course of the procedure were studied. UFalink, a device for UV irradiation of cornea, and photosensitizer Dextralink were developed and adopted. Due to the high risk of endothelial damage, this treatment is contraindicated in severe keratoconus (CCT less than 400 microns. Major effects of corneal collagen crosslinking are the following: Young’s modulus (modulus of elasticity increase by 328.9 % (on average, temperature tolerance increase by 5

  16. Colletotrichum graminicola: a new corneal pathogen.

    Science.gov (United States)

    Ritterband, D C; Shah, M; Seedor, J A

    1997-05-01

    We report the first case of an ocular infection with the fungus Colletotrichum graminicola causing keratitis in a 27-year-old man. Twenty-four months after a postoperative course complicated by recurrent fungal keratitis requiring two penetrating keratoplasties, two anterior chamber washouts, a conjunctival flap, and medical treatment with topical natamycin, intracameral amphotericin B, and oral fluconazole. The patient has shown no signs of fungal recurrence despite a failed corneal graft. C. graminicola is a new corneal pathogen and should be included in the differential diagnosis of mycotic keratitis.

  17. Research on inhibition of corneal neovascularization

    Directory of Open Access Journals (Sweden)

    Zhang-Hui Yang

    2015-12-01

    Full Text Available Corneal transparency is the basis of the normal physiological functions.However, corneal neovascularization(CNVmay occur in the infection, mechanical and chemical injury or under other pathological conditions,which make the cornea lose original transparency and severe visual impairment. In recent years, along with the development of immunology, molecular biology, biochemistry and other disciplines, there is more in-depth understanding on the CNV, and clinical treatment of CNV has made new breakthroughs. This article provides an overview of the inhibition of CNV.

  18. 兔角膜上皮细胞广泛丧失对角膜形态的影响%Effect of Epithelial Injury on Corneal Morphology

    Institute of Scientific and Technical Information of China (English)

    张阳; 聂庆珠; 盖春柳; 徐旭; 尹树国

    2001-01-01

    目的:观察兔角膜上皮广泛丧失对角膜形态的影响。方法:用大耳白兔20只,随机分为两组,左眼为实验眼,右眼作对照眼。将一组兔左眼角膜中央8 mm上皮刮除,另一组兔左眼角膜上皮广泛刮除,仅保留角膜缘部0.2 mm上皮。术后每日观察角膜上皮愈合情况,4周后测量角膜厚度、前房深度、角膜中央曲率。结果:广泛刮除角膜上皮眼上皮愈合时间明显延长,角膜厚度明显变薄,前房深度明显变深,角膜中央曲率明显变大。结论:兔角膜上皮广泛丧失可使角膜变薄,引起角膜曲率变大。%Objective: Our purpose was to observe the effect of epithelial scrape injury on corneal morphology. Methods: Twenty 4-week-old white rabbits were used. We scraped the corneal epithelia of the left eye of each rabbit (0.2 mm near the limbus of corneal were left in 10 eyes, in the remaining rabbits within 8 mm in the center). The right eyes were control group. We observed the healing of corneal protrusion with slit-lamp microscope, examined the corneal form with corneal topography, and measured the depth of anterior chamber and the corneal thickness with A-ultrasound. Results: The extensive epithelial scrape significantly increased the healing time. The corneal protrusion of experimental group and the depth of anterior chamber increased. The corneal thickness became thinner. Conclusion: The extensive epithelial injury can make cornea thinner, which results in the changes of corneal protrusion.

  19. Reversible corneal toxicity of retained intracameral Perfluoro-n-octane

    Directory of Open Access Journals (Sweden)

    Saad S Alharbi

    2016-01-01

    Full Text Available A 58-year-old female presented with intracameral retained perfluoro-n-octane (PFO following previous retinal reattachment surgery. After 4 years of follow-up without related sequelae, the patient complained of a gradual decrease in vision secondary to corneal edema with whitish corneal precipitate inferiorly corresponding to the area of retained PFO. Three weeks after anterior chamber washout, corneal edema resolved and the patient obtained 20/40 visual acuity. Even though PFO considered to have a relatively good safety profile, early anterior chamber washout may prevent corneal toxicity and avoid later persistent corneal decompensation.

  20. Current status of accelerated corneal cross-linking

    Directory of Open Access Journals (Sweden)

    Michael Mrochen

    2013-01-01

    Full Text Available Corneal cross-linking with riboflavin is a technique to stabilize or reduce corneal ectasia, in diseases such as keratoconus and post-laser-assisted in situ keratomileusis (LASIK ectasia. There is an interest by patient as well as clinicians to reduce the overall treatment time. Especially, the introduction of corneal cross-linking in combination with corneal laser surgery demands a shorter treatment time to assure a sufficient patient flow. The principles and techniques of accelerated corneal cross-linking is discussed.

  1. Topography and Landforms of Ecuador

    Science.gov (United States)

    Chirico, Peter G.; Warner, Michael B.

    2005-01-01

    EXPLANATION The digital elevation model of Ecuador represented in this data set was produced from over 40 individual tiles of elevation data from the Shuttle Radar Topography Mission (SRTM). Each tile was downloaded, converted from its native Height file format (.hgt), and imported into a geographic information system (GIS) for additional processing. Processing of the data included data gap filling, mosaicking, and re-projection of the tiles to form one single seamless digital elevation model. For 11 days in February of 2000, NASA, the National Geospatial-Intelligence Agency (NGA), the German Aerospace Center (DLR), and the Italian Space Agency (ASI) flew X-band and C-band radar interferometry onboard the Space Shuttle Endeavor. The mission covered the Earth between 60?N and 57?S and will provide interferometric digital elevation models (DEMs) of approximately 80% of the Earth's land mass when processing is complete. The radar-pointing angle was approximately 55? at scene center. Ascending and descending orbital passes generated multiple interferometric data scenes for nearly all areas. Up to eight passes of data were merged to form the final processed SRTM DEMs. The effect of merging scenes averages elevation values recorded in coincident scenes and reduces, but does not completely eliminate, the amount of area with layover and terrain shadow effects. The most significant form of data processing for the Ecuador DEM was gap-filling areas where the SRTM data contained a data void. These void areas are a result of radar shadow, layover, standing water, and other effects of terrain, as well as technical radar interferometry phase unwrapping issues. To fill these gaps, topographic contours were digitized from 1:50,000 - scale topographic maps which date from the mid-late 1980's (Souris, 2001). Digital contours were gridded to form elevation models for void areas and subsequently were merged with the SRTM data through GIS and remote sensing image-processing techniques

  2. Corneal invasion of ocular surface squamous neoplasia after clear corneal phacoemulsification: in vivo confocal microscopy analysis.

    Science.gov (United States)

    Balestrazzi, Angelo; Martone, Gianluca; Pichierri, Patrizia; Tosi, Gian Marco; Caporossi, Aldo

    2008-06-01

    We describe an unusual case of ocular surface squamous neoplasia (OSSN) that occurred in a male patient after superonasal clear corneal phacoemulsification with extensive papillomatous corneal invasion near a side port. The features of the macroscopic invasion of the corneal superficial layers were analyzed by in vivo confocal analysis using the Heidelberg Retina Tomograph II. After OSSN was diagnosed, topical mitomycin-C 0.02% eyedrops were prescribed 4 times a day in a cyclic manner (3 cycles of 1 week on drops followed by 1 week off). After 1 month (second cycle), the natural visual acuity was 20/20, the corneal epithelium had healed completely, and the limbal lesion had regressed markedly. The patient remained asymptomatic without recurrence during a 6-month follow-up.

  3. Sub-micron and nanoscale feature depth modulates alignment of stromal fibroblasts and corneal epithelial cells in serum-rich and serum-free media.

    Science.gov (United States)

    Fraser, Sarah A; Ting, Yuk-Hong; Mallon, Kelly S; Wendt, Amy E; Murphy, Christopher J; Nealey, Paul F

    2008-09-01

    Topographic features are generally accepted as being capable of modulating cell alignment. Of particular interest is the potential that topographic feature geometry induces cell alignment indirectly through impacting adsorbed proteins from the cell culture medium on the surface of the substrate. However, it has also been reported that micron-scale feature depth significantly impacts the level of alignment of cellular populations on topography, despite being orders of magnitude larger than the average adsorbed protein layer (nm). In order to better determine the impact of biomimetic length scale topography and adsorbed protein interaction on cellular morphology we have systematically investigated the effect of combinations of sub-micron to nanoscale feature depth and lateral pitch on corneal epithelial cell alignment. In addition we have used the unique properties of a serum-free media alternative in direct comparison to serum-rich medium to investigate the role of culture medium protein composition on cellular alignment to topographically patterned surfaces. Our observation that increasing groove depth elicited larger populations of corneal epithelial cells to align regardless of culture medium composition and of cell orientation with respect to the topography, suggests that these cells can sense changes in topographic feature depths independent of adsorbed proteins localized along ridge edges and tops. However, our data also suggests a strong combinatory effect of topography with culture medium composition, and also a cell type dependency in determining the level of cell elongation and alignment to nanoscale topographic features.

  4. The Effect of Corneal Epithelium on Corneal Curvature in Patients with Keratoconus.

    Science.gov (United States)

    Akcay, Emine Kalkan; Uysal, Betul Seher; Sarac, Ozge; Ugurlu, Nagehan; Yulek, Fatma; Cagil, Nurullah; Aslan, Nabi

    2015-01-01

    To investigate the effects of corneal epithelium on corneal curvature in patients with keratoconus. This is a prospective, nonrandomized study. Fifty-nine eyes of 47 patients diagnosed as keratoconus and for whom corneal collagen crosslinking (CXL) was recruited in this study. This study is a single-center clinical trial. Pregnancy, lactation, connective tissue disease, corneal thickness below 350 μm, severe dry eyes, or scar of corneal surgery were exclusion criteria. Before and during CXL procedure after removing the corneal epithelium, maximum values of corneal apical curvature, simulated keratometry 1 (Sim-K1), simulated keratometry 2 (Sim-K2), temporal and inferior curvature values, all of which are 1.5 mm from the corneal center, were calculated. These values before and after removal of epithelium were compared statistically. Mean age of patients was 23.30 ± 5.5 (12-38) years. Twenty-eight (59%) were male while 19 (41%) were female. Mean values measured before and after removing the corneal epithelium were: apical curvature; 59.19 ± 7.2 (47.06-82.40) diopter (D) and 61.70 ± 8.8 (49.19-92.66) D (p = 0.001), SimK1; 47.57 ± 4.3 (39.14-64.57) D and 48.23 ± 4.3 (41.89-66.70) D (p = 0.001), SimK2; 52.04 ± 5.3 (43.56-69.34) D and 53.34 ± 5.6 (43.73-70.89) D (p = 0.001), inferior curvature; 53,85 ± 5.2 (43.47-76.56) D and 55.05 ± 5.8 (44.56-81.93) D (p = 0.002), temporal curvature 49.49 ± 5.1 (41.50-71.03) D and 51.53 ± 5.4 (41.58-73.34) D (p = 0.001), respectively. In keratoconus patients during CXL treatment, after removing the corneal epithelium, more steepness is detected in the curvature of the steeper area of the cornea. When evaluating patients with keratoconus, the masking effect of corneal epithelium on values of curvature should be taken into consideration.

  5. Congenital Unilateral Corneal Anaesthesia with Microphthalmos: A Case Report

    Directory of Open Access Journals (Sweden)

    George Voyatzis

    2012-01-01

    Full Text Available Congenital corneal anaesthesia (CCA is an uncommon condition difficult to diagnose. We report the case of a 20-month-old boy who presented with unilateral congenital corneal anaesthesia. The child was referred with a persistent corneal epithelial defect, unresponsive to symptomatic local treatment for over 10 months. Intensive topical treatment and strict corneal protection led to quick corneal healing. Congenital corneal anaesthesia occurs either alone or in association with neurological diseases or systemic congenital abnormalities. It is important to search for corneal anaesthesia in children with chronic ulcerations of the cornea and self-inflicted injuries. Early diagnosis and treatment are important due to the risk of poor visual prognosis. Management of CCA should aim for the prevention of epithelial defects and is a life-long process.

  6. Corneal Higher Order Aberrations in Granular, Lattice and Macular Corneal Dystrophies

    Science.gov (United States)

    Yagi-Yaguchi, Yukari; Yamaguchi, Takefumi; Okuyama, Yumi; Satake, Yoshiyuki; Tsubota, Kazuo; Shimazaki, Jun

    2016-01-01

    Purpose To evaluate the corneal higher-order aberrations (HOAs) in granular, lattice and macular corneal dystrophies. Methods This retrospective study includes consecutive patients who were diagnosed as granular corneal dystrophy type2 (GCD2; 121 eyes), lattice corneal dystrophies type 1, type 3A (LCDI; 20 eyes, LCDIIIA; 32 eyes) and macular corneal dystrophies (MCD; 13 eyes), and 18 healthy control eyes. Corneal HOAs were calculated using anterior segment optical coherence tomography, and the correlations between HOAs and visual acuity were analyzed. Results HOAs of the total cornea within 4 mm diameter were significantly larger in GCD2 (0.17 ± 0.35 μm), in LCDI (0.33 ± 0.27), LCDIIIA (0.61 ± 1.56) and in MCD (0.23 ± 0.18), compared with healthy controls (0.09 ± 0.02μm, all P GCD2 (0.32 ± 0.48), in LCDI (0.60 ± 0.46), LCDIIIA (0.83 ± 2.29) and in MCD (0.44 ± 0.24), compared with healthy controls (0.19 ± 0.06, all P GCD2, there was no significant correlation between logMAR and HOAs (r = 0.113, P = 0.227). In MCD, LCDI and LCDIIIA, logMAR was positively significantly correlated with HOAs (r = 0.620 and P = 0.028, r = 0.587 and P = 0.007, r = 0.614 and P < 0.001, respectively). Conclusions Increased HOAs occur in eyes with corneal dystrophies, especially in eye with LCD and MCD. Larger amount corneal HOAs are associated with poorer visual acuity in patients with LCD and MCD. PMID:27536778

  7. The relationship between central corneal thickness and corneal curvature in adult Nigerians

    Directory of Open Access Journals (Sweden)

    E. Iyamu

    2011-12-01

    Full Text Available Purpose: The aim of this study was to provide average values for central corneal thickness (CCT and corneal curvature (CC and also to determine a regression model for the relationship between CCT and CC in adult Nigerians without glaucoma.Methods: A total of 95 subjects consisting of 56 males and 39 females aged between 20 and 69 years with mean age of 47.1 ± 14.1 years were recruited for the study. Central corneal thickness was measured by ultrasound pachymetry (SW-1000P ultrasound pachymeter, Tianjin Suowei Electronic Technology, China and corneal curvature was measured by keratometry (Bausch & Lomb keratometer H-135A, USA.Results: The average values of 550.1 ± 33.1µm and 43.0 ± 1.1 D were obtained for CCT and CC respectively. CCT significantly correlated with age (p=0.01, and the regression model predicts a decrease of 6.0 µm in CCT per decade. No significant association was found between CC and age (p=0.56. Also, no significant association was found between CCT and CC (p=0.07. Female subjects had significantly steeper corneas than their male counterparts.Conclusion: Central corneal thickness decreases with increasing age. Neither CCT nor age appear to be significantly correlated with corneal curvature. (S Afr Optom 2011 70(1 44-50

  8. CORNEAL STROMAL THINNING: A RARE CORNEAL COMPLICATION AFTER BARE SCL ERA PTERYG I UM EXCISION TECHNIQUE

    Directory of Open Access Journals (Sweden)

    Sulaiman Abdul

    2015-06-01

    Full Text Available INTRODUCTION : Bare sclera technique without using any anti - mitotic drugs are commonly employed in rural population. Corneal dellen formation and recurrence of pterygium are more common in these cases. But the corneal complication like stromal thinning, necrosis of corne a and sclera are not common. The corneal epithelium is a highly differentiated cell type that is self - renewing. Also corneal epithelium is important for the stromal replacement in the situations like chemical, thermal burns, ocular surgery like pterygium s urgery. Interference with status of stem cell replacement and as a consequent to it, stromal thinning is occurring in the pterygium surgery. P atient 1: A 68 yr s. old male patient underwent pterygium surgery ( B aresclera excision technique. After 30 days he developed corneal thinning with the punched out partial stromal loss without perforation or descmetocele or scleral thinning. Patient 2: A 60yr s. old male patient underwent pterygium surgery 2months back, he developed same type of corneal thinning. Both P atients were treated with tear drops and improved. CONCLUSION : The stromal thinning in these two cases is may be due to chemical factors like collagenase which might have been released from the traumatised conjunctival epithelial cells causing thinning wit hout replacement of stroma by limbal stem cells.

  9. Quantitative proteomic analysis of mice corneal tissues reveals angiogenesis-related proteins involved in corneal neovascularization.

    Science.gov (United States)

    Shen, Minqian; Tao, Yimin; Feng, Yifan; Liu, Xing; Yuan, Fei; Zhou, Hu

    2016-07-01

    Corneal neovascularization (CNV) was induced in Balb/c mice by alkali burns in the central area of the cornea with a diameter of 2.5mm. After fourteen days, the cornea from one eye was collected for histological staining for CNV examination, while the cornea from the other eye of the same mouse was harvested for proteomic analysis. The label-free quantitative proteomic approach was applied to analyze five normal corneal tissues (normal group mice n=5) and five corresponding neovascularized corneal tissues (model group mice n=5). A total of 2124 proteins were identified, and 1682 proteins were quantified from these corneal tissues. Among these quantified proteins, 290 proteins were significantly changed between normal and alkali burned corneal tissues. Of these significantly changed proteins, 35 were reported or predicted as angiogenesis-related proteins. Then, these 35 proteins were analyzed using Ingenuity Pathway Analysis Software, resulting in 26 proteins enriched and connected to each other in the protein-protein interaction network, such as Lcn-2, αB-crystallin and Serpinf1 (PEDF). These three significantly changed proteins were selected for further Western blotting validation. Consistent with the quantitative proteomic results, Western blotting showed that Lcn-2 and αB-crystallin were significantly up-regulated in CNV model, while PEDF was down-regulated. This study provided increased understanding of angiogenesis-related proteins involved in corneal vascular development, which will be useful in the ophthalmic clinic of specifically target angiogenesis.

  10. A brief history of corneal transplantation: From ancient to modern

    Directory of Open Access Journals (Sweden)

    Alexandra X Crawford

    2013-01-01

    Full Text Available This review highlights many of the fundamental concepts and events in the development of corneal transplantation - from ancient times to modern. Tales of eye, limb, and even heart transplantation appear in ancient and medieval texts; however, in the scientific sense, the original concepts of corneal surgery date back to the Greek physician Galen (130-200 AD. Although proposals to provide improved corneal clarity by surgical interventions, including keratoprostheses, were better developed by the 17 th and 18 th centuries, true scientific and surgical experimentation in this field did not begin until the 19 th century. Indeed, the success of contemporary corneal transplantation is largely the result of a culmination of pivotal ideas, experimentation, and perseverance by inspired individuals over the last 200 years. Franz Reisinger initiated experimental animal corneal transplantation in 1818, coining the term "keratoplasty". Subsequently, Wilhelmus Thorne created the term corneal transplant and 3 years later Samuel Bigger, 1837, reported successful corneal transplantation in a gazelle. The first recorded therapeutic corneal xenograft on a human was reported shortly thereafter in 1838-unsurprisingly this was unsuccessful. Further progress in corneal transplantation was significantly hindered by limited understanding of antiseptic principles, anesthesiology, surgical technique, and immunology. There ensued an extremely prolonged period of debate and experimentation upon the utility of animal compared to human tissue, and lamellar versus penetrating keratoplasty. Indeed, the first successful human corneal transplant was not performed by Eduard Zirm until 1905. Since that first successful corneal transplant, innumerable ophthalmologists have contributed to the development and refinement of corneal transplantation aided by the development of surgical microscopes, refined suture materials, the development of eye banks, and the introduction of

  11. A brief history of corneal transplantation: From ancient to modern.

    Science.gov (United States)

    Crawford, Alexandra Z; Patel, Dipika V; McGhee, Charles Nj

    2013-09-01

    This review highlights many of the fundamental concepts and events in the development of corneal transplantation - from ancient times to modern. Tales of eye, limb, and even heart transplantation appear in ancient and medieval texts; however, in the scientific sense, the original concepts of corneal surgery date back to the Greek physician Galen (130-200 AD). Although proposals to provide improved corneal clarity by surgical interventions, including keratoprostheses, were better developed by the 17(th) and 18(th) centuries, true scientific and surgical experimentation in this field did not begin until the 19(th) century. Indeed, the success of contemporary corneal transplantation is largely the result of a culmination of pivotal ideas, experimentation, and perseverance by inspired individuals over the last 200 years. Franz Reisinger initiated experimental animal corneal transplantation in 1818, coining the term "keratoplasty". Subsequently, Wilhelmus Thorne created the term corneal transplant and 3 years later Samuel Bigger, 1837, reported successful corneal transplantation in a gazelle. The first recorded therapeutic corneal xenograft on a human was reported shortly thereafter in 1838-unsurprisingly this was unsuccessful. Further progress in corneal transplantation was significantly hindered by limited understanding of antiseptic principles, anesthesiology, surgical technique, and immunology. There ensued an extremely prolonged period of debate and experimentation upon the utility of animal compared to human tissue, and lamellar versus penetrating keratoplasty. Indeed, the first successful human corneal transplant was not performed by Eduard Zirm until 1905. Since that first successful corneal transplant, innumerable ophthalmologists have contributed to the development and refinement of corneal transplantation aided by the development of surgical microscopes, refined suture materials, the development of eye banks, and the introduction of corticosteroids. Recent

  12. Corneal injuries from liquid detergent pods.

    Science.gov (United States)

    Gray, Michael E; West, Constance E

    2014-10-01

    Laundry and dishwasher detergent "pods" were introduced to the United States market in 2010 and are sold by several manufacturers. They represent a high percentage of household cleaning product exposure in the United Kingdom. We present a consecutive case series of 10 children seen in a 9-month period with corneal injuries from exposure to liquid detergent pods.

  13. Evaluation and Treatment of Perioperative Corneal Abrasions

    Directory of Open Access Journals (Sweden)

    Kira L. Segal

    2014-01-01

    Full Text Available Purpose. To evaluate perioperative risk factors for corneal abrasion (CA and to determine current care for perioperative CA in a tertiary care setting. Methods. Hospital-based, cross-sectional study. In Operating Room and Post-Anesthesia Care Units patients, a comparison of cases and controls was evaluated to elucidate risk factors, time to treatment, and most common treatments prescribed for corneal abrasions. Results. 86 cases of corneal abrasion and 89 controls were identified from the 78,542 surgical procedures performed over 2 years. Statistically significant risk factors were age (P=0.0037, general anesthesia (P<0.001, greater average estimated blood loss (P<0.001, eyes taped during surgery (P<0.001, prone position (P<0.001, trendelenburg position (P<0.001, and supplemental oxygen en route to and in the Post-Anesthesia Care Units (P<0.001. Average time to complaint was 129 minutes. 94% of cases had an inpatient ophthalmology consult, with an average time to consult of 164 minutes. The most common treatment was artificial tears alone (40%, followed by combination treatment of antibiotic ointment and artificial tears (35.3%. Conclusions. Trendelenburg positioning is a novel risk factor for CA. Diagnosis and treatment of perioperative corneal abrasions by an ophthalmologist typically require three hours in the tertiary care setting.

  14. Serological profile of candidates for corneal donation

    Directory of Open Access Journals (Sweden)

    Adroaldo Lunardelli

    2014-10-01

    Full Text Available Objetive: The purpose of this study is to map the serological profile of candidates to corneal donation at Irmandade Santa Casa de Misericórdia de Porto Alegre, identifying the percentage of disposal by serology and the marker involved. Methods: There have been analised – retrospectively – the results of serology of all corneal donors, made between the period of 1st january 2006 and 31st december 2012. Data analised were related to age, gender and the results of serology pertinent to viral markers (HBsAg, anti-HBc, anti-HCV and anti-HIV, these, determined by immunosorbent tests (ELISA. Results: In the period of the study, there were 2476 corneal donors at the institution, with a major incidence on the male gender, on an average of 58.7 years old. 23% of retention because of serological unfitness was also identified, that is, 570 samples were non-negative to any of the used tests. The marker anti- HBc was the most prevalent on the studied population, followed by the Hepatitis C virus (HCV and by the Human Immunodeficiency Virus (HIV. Conclusion: From the data found through this study, it is essential to have the participation of an efficient service on the serological evaluation of the candidates to corneal donation, once the security of the receptor must be taken into consideration in a population of donors with 23% of unfitness prevalence, in which the most prevalent marker is the one of Hepatits B.

  15. Peptide Amphiphiles in Corneal Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Martina Miotto

    2015-08-01

    Full Text Available The increasing interest in effort towards creating alternative therapies have led to exciting breakthroughs in the attempt to bio-fabricate and engineer live tissues. This has been particularly evident in the development of new approaches applied to reconstruct corneal tissue. The need for tissue-engineered corneas is largely a response to the shortage of donor tissue and the lack of suitable alternative biological scaffolds preventing the treatment of millions of blind people worldwide. This review is focused on recent developments in corneal tissue engineering, specifically on the use of self-assembling peptide amphiphiles for this purpose. Recently, peptide amphiphiles have generated great interest as therapeutic molecules, both in vitro and in vivo. Here we introduce this rapidly developing field, and examine innovative applications of peptide amphiphiles to create natural bio-prosthetic corneal tissue in vitro. The advantages of peptide amphiphiles over other biomaterials, namely their wide range of functions and applications, versatility, and transferability are also discussed to better understand how these fascinating molecules can help solve current challenges in corneal regeneration.

  16. Aspergillus terreus recovered from a corneal scraping.

    Science.gov (United States)

    Campbell, Suzanne

    2014-01-01

    A 52 year old, healthy male presented to his optometrist complaining of redness and irritation in the right eye. A foreign body was removed from the eye. The patient was started on ophthalmic solutions of vigamox and systane. At 48 hours, the patient reported increased redness, limited vision, and yellow discharge from the eye. The patient was referred to an ophthalmologist for further evaluation. Physical assessment revealed a superlative central infiltrate (extreme, centrally located injury that had permeated the cornea), diffuse corneal haze, and edema with a 3- to 4+ conjunctival injection and a 1 millimeter hypopyon (an effusion of pus into the anterior chamber of the eye). Corneal scrapings were collected for aerobic and anaerobic bacterial and fungal cultures. The patient was then prescribed. vancomycin, tobramycin, and natamycin ophthalmic eyedrops. On day three, fungal culture results indicated possible fungal forms seen. On day 12, results from the fungal culture of the corneal scraping revealed the causative agent to be Aspergillus terreus. Voriconazole eyedrops were added to the treatment regimen and continued for 10 weeks. The physician order for a fungal culture as well as laboratory data providing the final identification of Aspergillus terreus and laboratory comments indicating an elevated minimum inhibitory concentration (MIC) (> 2 microg/mL) to amphotericin B is associated with treatment failure positively impacted the patient outcome. After completion of the treatment regimen, a photo-therapeutic keratectomy (PTK) was performed in an attempt to remove the dense corneal scarring caused by the fungal infection.

  17. [Purulent corneal ulcers: etiology, pathogenesis, classification].

    Science.gov (United States)

    Kasparova, Evg A

    2015-01-01

    Advanced purulent corneal ulcer, as well as abscess, is a serious vision-threatening condition notable for its fulminant course and possible loss of the eye due to endophthalmitis. Its leading causes, pathogenesis, and classifications are described and analyzed in this paper.

  18. Change in corneal curvature induced by surgery

    NARCIS (Netherlands)

    G. van Rij (Gabriel)

    1987-01-01

    textabstractThe first section deals with the mechanisms by which sutures, incisions and intracorneal contact lenses produce a change in corneal curvature. To clarify the mechanisms by which incisions and sutures produce astigmatism, we made incisions and placed sutures in the corneoscleral limbus of

  19. Autophagy in granular corneal dystrophy type 2.

    Science.gov (United States)

    Choi, Seung-Il; Kim, Eung Kweon

    2016-03-01

    Autophagy is a lysosomal degradative process that is essential for cellular homeostasis and metabolic stress adaptation. Defective autophagy is involved in the pathogenesis of many diseases including granular corneal dystrophy type 2 (GCD2). GCD2 is an autosomal dominant disorder caused by substitution of histidine for arginine at codon 124 (R124H) in the transforming growth factor β-induced gene (TGFBI) on chromosome 5q31. Transforming growth factor β-induced protein (TGFBIp) is degraded by autophagy, but mutant-TGFBIp accumulates in autophagosomes and/or lysosomes, despite significant activation of basal autophagy, in GCD2 corneal fibroblasts. Furthermore, inhibition of autophagy induces cell death of GCD2 corneal fibroblasts through active caspase-3. As there is currently no pharmacological treatment for GCD2, development of novel therapies is required. A potential strategy for preventing cytoplasmic accumulation of mutant-TGFBIp in GCD2 corneal fibroblasts is to enhance mutant-TGFBIp degradation. This could be achieved by activation of the autophagic pathway. Here, we will consider the role and the potential therapeutic benefits of autophagy in GCD2, with focus on TGFBIp degradation, in light of the recently established role of autophagy in protein degradation.

  20. Polysaccharide coating of human corneal endothelium

    DEFF Research Database (Denmark)

    Schroder, H D; Sperling, S

    1977-01-01

    Electron microscopy revealed the presence of a 600-1500 A thick layer of polysaccharide on the surface of human corneal endothelial cells. The surface layer was visualized by combined fixation and staining in a mixture of ruthenium red and osmium tetroxide. The coating material was stable...

  1. Traumatic wound dehiscence after corneal keratoplasty

    Directory of Open Access Journals (Sweden)

    Patrick Frensel Tzelikis

    2015-10-01

    Full Text Available ABSTRACTPurpose:To assess patient characteristics, risk factors, outcomes, and the treatment of wound dehiscence (WD in patients after corneal keratoplasty.Methods:Retrospective chart review of 11 eyes of 11 patients with corneal grafts who underwent repair of WD from January 1, 2004 to December 31, 2012 at Hospital Oftalmologico de Brasilia.Results:Eight (72.7% patients were men and three were women. Six (54.5% patients had deep anterior lamellar keratoplasty (DALK and 5 had penetrating keratoplasty. The mean age at trauma was 31.1 years. The mean time from corneal keratoplasty to WD was 12.82 months (range, 3-33 months. The mean best-corrected visual acuity of patients before trauma was 20/60 (0.48 logMAR and after final treatment was 20/160 (0.90 logMAR (P=0.15. In one case, visual acuity decreased to no light perception because of retinal detachment and phthisis bulbi. Accidental blunt trauma and fall were the most common causes of WD.Conclusion:Patients who undergo corneal keratoplasty have a life-long risk of WD. The full-thickness rupture at the graft-host junction in our study suggests that the junction remains vulnerable, even following DALK, and can rupture with trauma. In our series, depending upon the severity of the trauma, postkeratoplastic WD can be associated with a good visual prognosis.

  2. Past and present of corneal refractive surgery

    DEFF Research Database (Denmark)

    Vestergaard, Anders Højslet

    Surgical correction of refractive errors is becoming increasingly popular. In the 1990s, the excimer laser revolutionized the field of corneal refractive surgery with PRK and LASIK, and lately refractive lenticule extraction (ReLEx) of intracorneal tissue, using only a femtosecond laser, has become...

  3. Keratoconus and Normal-Tension Glaucoma: A Study of the Possible Association with Abnormal Biomechanical Properties as Measured by Corneal Hysteresis (An AOS Thesis)

    Science.gov (United States)

    Cohen, Elisabeth J.

    2009-01-01

    Purpose: To test the hypothesis that keratoconus and pellucid patients who have glaucoma or are suspected of having glaucoma have lower corneal hysteresis (CH) and/or corneal resistance factor (CRF) measurements compared to controls. Methods: A prospective study at a tertiary eye center of keratoconus and pellucid patients with glaucoma or suspected of having glaucoma, and age-matched keratoconus and pellucid controls, was performed. After informed consent was obtained, corneal topography, ocular response analyzer measurements, pachymetry, intraocular pressure, A-scan measurements, Humphrey visual fields (VFs), and disc photos were done. Analyses compared cases to controls on primary (CH and CRF) and secondary variables. Disc photos and VFs were rated in a masked fashion. Results: The mean CH (8.2, SD=1.6, vs 8.3, SD=1.5) and CRF (7.3, SD=2.0, vs 6.9, SD=2.1) were low and did not differ significantly between 20 study patients (29 eyes) and 40 control patients (61 eyes), respectively. CH had a negative, significant correlation with maximum corneal curvature by topography (P < .002) and positive, significant correlation with central corneal thickness (P < .003). The mean cup-disc ratio was larger among cases than controls (0.54, SD=0.20, vs 0.38, SD=0.20; P = .003). VFs were suggestive of glaucoma more often among the study eyes than controls (11 of 29, 37.9%, vs 8 of 60, 13.3%; P =.019). Conclusions: CH was low in study and control patients and was correlated with severity of keratoconus/pellucid, but not with glaucoma/suspected glaucoma or control status. Evidence of glaucoma was more common in study eyes than controls, but was present in both. PMID:20126503

  4. Oxygen-deficient metabolism and corneal edema.

    Science.gov (United States)

    Leung, B K; Bonanno, J A; Radke, C J

    2011-11-01

    Wear of low-oxygen-transmissible soft contact lenses swells the cornea significantly, even during open eye. Although oxygen-deficient corneal edema is well-documented, a self-consistent quantitative prediction based on the underlying metabolic reactions is not available. We present a biochemical description of the human cornea that quantifies hypoxic swelling through the coupled transport of water, salt, and respiratory metabolites. Aerobic and anaerobic consumption of glucose, as well as acidosis and pH buffering, are incorporated in a seven-layer corneal model (anterior chamber, endothelium, stroma, epithelium, postlens tear film, contact lens, and prelens tear film). Corneal swelling is predicted from coupled transport of water, dissolved salts, and especially metabolites, along with membrane-transport resistances at the endothelium and epithelium. At the endothelium, the Na+/K+ - ATPase electrogenic channel actively transports bicarbonate ion from the stroma into the anterior chamber. As captured by the Kedem-Katchalsky membrane-transport formalism, the active bicarbonate-ion flux provides the driving force for corneal fluid pump-out needed to match the leak-in tendency of the stroma. Increased lactate-ion production during hypoxia osmotically lowers the pump-out rate requiring the stroma to swell to higher water content. Concentration profiles are predicted for glucose, water, oxygen, carbon dioxide, and hydronium, lactate, bicarbonate, sodium, and chloride ions, along with electrostatic potential and pressure profiles. Although the active bicarbonate-ion pump at the endothelium drives bicarbonate into the aqueous humor, we find a net flux of bicarbonate ion into the cornea that safeguards against acidosis. For the first time, we predict corneal swelling upon soft-contact-lens wear from fundamental biophysico-chemical principles. We also successfully predict that hypertonic tear alleviates contact-lens-induced edema.

  5. Partial-thickness corneal tissue restoration after a chemical burn

    Directory of Open Access Journals (Sweden)

    Galan A

    2016-04-01

    Full Text Available Alessandro Galan, Anton Giulio Catania, Giuseppe Lo Giudice San Paolo Ophthalmic Center, San Antonio Hospital, Padova, Italy Purpose: We describe a case of full-thickness corneal restoration after an acute corneal burn with an acid agent. Methods: A 32-year-old male reported painful discomfort, redness, photophobia, and a decrease in visual acuity in the left eye after a unilateral burn with an acid agent. Slit-lamp examination revealed massive corneal melting involving necrotic sequestrum of the entire corneal surface. Surgical approach was carried out in order to preserve residual ocular tissues. Results: Extensive corneal–conjunctival layer curettage of the necrotic tissue was performed showing perfectly clear undamaged deep lamellar corneal layers. The patient underwent multilayered amniotic membrane transplantation and total capsular–conjunctival flap in order to preserve ocular tissue from further melting or corneal perforation. A complete and spontaneous “restitutio ad integrum” of the corneal layers was shown during the follow-up. The cornea was perfectly clear with restored normal anatomical architecture. Conclusion: In this case, a spontaneous full-thickness corneal tissue restoration occurred after an acute chemical burn. Studies about the mechanisms whereby different cells interact and replicate within the stroma may unveil the biology behind corneal regeneration and transparency. Keywords: amniotic membrane, chemical burn, corneal healing

  6. Emodin ameliorates lipopolysaccharides-induced corneal inflammation in rats

    Institute of Scientific and Technical Information of China (English)

    Guo-Ling; Chen; Jing-Jing; Zhang; Xin; Kao; Lu-Wan; Wei; Zhi-Yu; Liu

    2015-01-01

    · AIM: To investigate the effect of emodin on pseudomonas aeruginosa lipopolysaccharides(LPS)-induced corneal inflammation in rats.· METHODS: Corneal infection was induced by pseudomonas aeruginosa LPS in Wistar rats. The inflammation induced by LPS were examined by slit lamp microscope and cytological checkup of aqueous humor.Corneal tissue structure was observed by hematoxylin and eosin(HE) staining. The activation of nuclear factor kappa B(NF-κB) was determined by Western blot.Messenger ribonucleic acid(m RNA) of tumor necrosis factor-α(TNF-α) and intercellular adhesion molecule-1(ICAM-1) in LPS-challenged rat corneas were measured with reverse transcription-polymerase chain reaction(RT-PCR).· RESULTS: Typical manifestations of acute corneal inflammation were observed in LPS-induce rat model,and the corneal inflammatory response and structure were improved in rats pretreated with emodin. Treatment with emodin could improve corneal structure, reduce corneal injure by reducing corneal inflammatory response. Emodin could inhibit the decreasing lever of inhibitor of kappa B alpha(IкBα) express, and the m RNA expression of TNF-α and ICAM-1 in corneal tissues was also inhibited by emodin. The differences were statistically significant between groups treated with emodin and those without treatment(P <0.01).·CONCLUSION: Emodin could ameliorate LPS-induced corneal inflammation, which might via inhibiting the activation of NF-κB.

  7. Ocular histopathological changes after eyeball enucleation induced by corneal trauma

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective: To observe the ocular histopathological changes aftereyeball enucleation induced by corneal trauma.Methods: Light microscopic examination was done on 117 eyeball specimens enucleated after corneal trauma (18 with corneal fissure and 99 with corneal perforating trauma).Results: Acute, subacute or chronic inflammatory changes, and fibrous membrane formation were observed in well-closed corneal wounds, whereas inflammation, atrophy and scar were observed in the focal tissues. But at the late period, secondary glaucoma, retinal detachment, endophthalmitis and eyeball atrophy resulted in blindness. Corneal fistula was observed in those with inadequate cure of wounds caused by ingrowth of corneal epithelium, embedment of iris and vitreous body, and large area of centrally located tissue deficiency of the corneal. A high incidence of endophthalmitis was noted due to the presence of corneal fistula. Severe inflammation was observed in the anterior segmental tissues with fibrous infiltration in the anterior chamber, which might result in rapid destruction of the eyeballs.Conclusions: Ocular pathology varies with the difference of the position, form, size and closing conditions of the corneal laceration after trauma.

  8. Anatomical characterization of central, apical and minimal corneal thickness

    Institute of Scientific and Technical Information of China (English)

    Federico; Saenz-Frances; Martha; Cecilia; Bermúdez-Vallecilla; Lara; Borrego-Sanz; Luis; Jaez; J; osé; Marìa; Martinez-de-la-Casa; Laura; Morales-Fernandez; Enrique; Santos-Bueso; Julián; Garcia-Sanchez; Julián; Garcia-Feijoo

    2014-01-01

    ·AIM: To anatomically locate the points of minimum corneal thickness and central corneal thickness(pupil center) in relation to the corneal apex.·METHODS: Observational, cross-sectional study, 299 healthy volunteers. Thickness at the corneal apex(AT),minimum corneal thickness(MT) and corneal thickness at the pupil center(PT) were determined using the pentacam. Distances from the corneal apex to MT(MD)and PT(PD) were calculated and their quadrant position(taking the corneal apex as the reference) determined:point of minimum thickness(MC) and point of central thickness(PC) depending on the quadrant position. Two multivariate linear regression models were constructed to examine the influence of age, gender, power of the flattest and steepest corneal axes, position of the flattest axis, corneal volume(determined using the Pentacam)and PT on MD and PD. The effects of these variables on MC and PC were also determined in two multinomial regression models.·RESULTS: MT was located at a mean distance of 0.909 mm from the apex(79.4% in the inferior-temporal quadrant). PT was located at a mean distance of 0.156 mm from the apex. The linear regression model for MD indicated it was significantly influenced by corneal volume(B =-0.024; 95% CI:-0.043 to-0.004). No significant relations were identified in the linear regression model for PD or the multinomial logisticregressions for MC and PC.·CONCLUSION: MT was typically located at the inferiortemporal quadrant of the cornea and its distance to the corneal apex tended to decrease with the increment of corneal volume.

  9. Anatomical characterization of central, apical and minimal corneal thickness

    Directory of Open Access Journals (Sweden)

    Federico Saenz-Frances

    2014-08-01

    Full Text Available AIM: To anatomically locate the points of minimum corneal thickness and central corneal thickness (pupil center in relation to the corneal apex.METHODS: Observational, cross-sectional study, 299 healthy volunteers. Thickness at the corneal apex (AT, minimum corneal thickness (MT and corneal thickness at the pupil center (PT were determined using the pentacam. Distances from the corneal apex to MT (MD and PT (PD were calculated and their quadrant position (taking the corneal apex as the reference determined:point of minimum thickness (MC and point of central thickness (PC depending on the quadrant position. Two multivariate linear regression models were constructed to examine the influence of age, gender, power of the flattest and steepest corneal axes, position of the flattest axis, corneal volume (determined using the Pentacam and PT on MD and PD. The effects of these variables on MC and PC were also determined in two multinomial regression models.RESULTS: MT was located at a mean distance of 0.909 mm from the apex (79.4% in the inferior-temporal quadrant. PT was located at a mean distance of 0.156 mm from the apex. The linear regression model for MD indicated it was significantly influenced by corneal volume (B=-0.024; 95%CI:-0.043 to -0.004. No significant relations were identified in the linear regression model for PD or the multinomial logistic regressions for MC and PC.CONCLUSION: MT was typically located at the inferior-temporal quadrant of the cornea and its distance to the corneal apex tended to decrease with the increment of corneal volume.

  10. Sensory properties of menthol and smoking topography

    Directory of Open Access Journals (Sweden)

    Hoffman Allison C

    2011-05-01

    Full Text Available Abstract Although there is a great deal known about menthol as a flavoring agent in foods and confections, less is known about the particular sensory properties of menthol cigarette smoke. Similarly, although smoking topography (the unique way an individual smokes a cigarette has been well studied using non-menthol cigarettes, there is relatively less known about how menthol affects smoking behavior. The objective of this review is to assess the sensory properties of menthol tobacco smoke, and smoking topography associated with menthol cigarettes. The cooling, analgesic, taste, and respiratory effects of menthol are well established, and studies have indicated that menthol’s sensory attributes can have an influence on the positive, or rewarding, properties associated smoking, including ratings of satisfaction, taste, perceived smoothness, and perceived irritation. Despite these sensory properties, the data regarding menthol’s effect on smoking topography are inconsistent. Many of the topography studies have limitations due to various methodological issues.

  11. Enhanced Characterization of Niobium Surface Topography

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xu, Hui Tian, Charles Reece, Michael Kelley

    2011-12-01

    Surface topography characterization is a continuing issue for the Superconducting Radio Frequency (SRF) particle accelerator community. Efforts are underway to both to improve surface topography, and its characterization and analysis using various techniques. In measurement of topography, Power Spectral Density (PSD) is a promising method to quantify typical surface parameters and develop scale-specific interpretations. PSD can also be used to indicate how chemical processes modifiesy the roughnesstopography at different scales. However, generating an accurate and meaningful topographic PSD of an SRF surface requires careful analysis and optimization. In this report, polycrystalline surfaces with different process histories are sampled with AFM and stylus/white light interferometer profilometryers and analyzed to indicate trace topography evolution at different scales. evolving during etching or polishing. Moreover, Aan optimized PSD analysis protocol will be offered to serve the SRF surface characterization needs is presented.

  12. 三种仪器测量角膜曲率的准确性比较%Compare the accuracy of corneal curvature measured by three instruments

    Institute of Scientific and Technical Information of China (English)

    陈文静; 张瑞智; 袁晓成

    2016-01-01

    目的 比较手动角膜曲率计、电脑自动验光仪、角膜地形图仪三种仪器测量角膜曲率结果的准确性,指导白内障术前测量应用.方法 仪器应用对照研究.对2014年12月至2015年4月在武清区人民医院眼科应用三种仪器分别测量拟实施白内障超声乳化及人工晶状体植入术的患者140例(140只眼)的最大、最小及平均角膜屈光力,应用电脑自动验光仪和角膜地形图仪测量角膜散光值及散光轴位,使用SPSS 20.0软件对所测参数进行统计学分析比较.结果 三种仪器测得的最大、最小及平均角膜屈光力对比差异无统计学意义(P>0.05),电脑自动验光仪和角膜地形图仪测得的角膜散光值对比差异无统计学意义(P>0.05),散光轴位对比差异有统计学意义(P<0.05).结论 三种仪器测量角膜曲率的准确性较好,均适用于白内障术前测量.%Objective To compare the accuracy of three types of keratometry:manual keratometer,auto-refractometer and corneal topography for measurement the corneal curvature.Methods Totally 140 eyes of maximum corneal refractive power,the minimum comeal refractive power and the mean corneal refractive power were measured by three different types of keratometry before cataract surgery.Corneal astigmatism degree and the axis value of corneal astigmatism by auto-refractometer and corneal topography were measured.All values were analyzed by SPSS 20.0.Results There was no significant difference in the maximum corneal refractive power,the minimum corneal refractive power and the mean corneal refractive power by three different types of keratometry (P >0.05).There was no significant difference in measuring comeal astigmatism degree (P >0.05).However,there was significant difference in measuring of the axis values of corneal astigmatism (P <0.05).Conclusions The accuracy of corneal curvature measured by different types of keratometry is good,all can be used before cataract

  13. Corneal collagen cross-linking to stop corneal ectasia exacerbated by radial keratotomy.

    Science.gov (United States)

    Mazzotta, Cosimo; Baiocchi, Stefano; Denaro, Rosario; Tosi, Gian Marco; Caporossi, Tomaso

    2011-02-01

    To assess the efficacy of riboflavin ultraviolet A (UV-A) corneal collagen cross-linking in the management of keratoconic corneal ectasia exacerbated by radial keratotomy (RK). A patient with progressive corneal ectasia and hyperopic shift, occurring 10 years after RK performed in the left eye, was treated with riboflavin UV-A corneal collagen cross-linking according to the Siena protocol: Pilocarpin 0.1% drop (1 hour before), lidocaine 4% drops 15 minutes before, mechanical scraping of epithelium (9-mm-diameter area), preirradiation stromal soaking for 10 minutes in riboflavin 0.1%-dextrane 20% (Ricrolin; Sooft Italy) applied every 2 minutes, and 30 minutes of total exposure (6 steps of 5 minutes) to solid-state UV-A illuminator (Caporossi, Baiocchi, Mazzotta Vega X linker; CSO Opthalmics, Florence, Italy), energy delivered 3 mW/cm, and irradiated area 9 mm in diameter. After the operation, uncorrected visual acuity and best spectacle-corrected visual acuity improved from 0.2 to 0.6 and from 0.3 to 0.8 Snellen lines, respectively, in a 12-month follow-up. Improved topographical K readings and corneal symmetry index were also recorded starting from the first postoperative month and continuing thereafter. No adverse effects were recorded after treatment. Riboflavin UV-A-induced corneal cross-linking seems to be a promising surgical option in the management of unstable corneal ectasia exacerbated by RK, particularly in eyes with preexisting keratoconus. A large cohort and longer follow-up are needed to determine its long-term efficacy in this clinical setting.

  14. Manifestaciones corneales en las enfermedades sistémicas Corneal manifestations in systemic diseases

    Directory of Open Access Journals (Sweden)

    J. Zarranz-Ventura

    2008-01-01

    Full Text Available Un gran número de enfermedades sistémicas presentan manifestaciones corneales dentro de su espectro de enfermedad. El estudio detallado de todos los cuadros que asocian patología corneal resulta inabarcable, por ello se presentan las enfermedades más prevalentes o características. Este estudio contempla las enfermedades pulmonares y conectivopatías (colagenosis, enfermedades reumatológicas y enfermedades inflamatorias idiopáticas, las enfermedades dermatológicas, cardiovasculares, hematológicas y la patología digestiva y hepatopancreática. Se contemplan también, por ocasionar alteraciones corneales, las enfermedades endocrinas y metabólicas con algunas situaciones de malnutrición y estados carenciales, las infecciones sistémicas y las enfermedades renales. Otro área que produce afectación corneal es la patología otorrinolaringológica y las enfermedades genéticas. Se repasa brevemente la toxicidad y las alteraciones corneales provocadas por fármacos.Systemic diseases affecting the cornea have a wide range of manifestations. The detailed study of all pathologies that cause corneal alteration is unapproachable, so we have centered our interest in the most prevalent or characteristic of them. In this paper we have divided these pathologies in sections to facilitate their study. Pulmonar and conective tissue (like colagen, rheumatologic and idiopathic inflamatory diseases, dermatologic, cardiovascular, hematologic, digestive and hepatopancreatic diseases with corneal alteration are described. Endocrine and metabolic diseases, malnutrition and carential states are also studied, as well as some otorhinolaryngologic and genetic diseases that affect the cornea. Finally, a brief report of ocular toxicity induced by drugs is referred.

  15. SECTION 6.2 SURFACE TOPOGRAPHY ANALYSIS

    DEFF Research Database (Denmark)

    Seah, M. P.; De Chiffre, Leonardo

    2005-01-01

    Surface physical analysis, i.e. topography characterisation, encompasses measurement, visualisation, and quantification. This is critical for both component form and for surface finish at macro-, micro- and nano-scales. The principal methods of surface topography measurement are stylus profilometry...... representing some average property of the surface under examination. Measurement methods, as well as their application and limitations, are briefly reviewed, including standardisation and traceability issues....

  16. Dynamic Topography of the Bering Sea

    Science.gov (United States)

    2011-01-01

    Bering Sea. Comparisons also indicate that MDT estimates derived from the latest Gravity Recovery and Climate Experiment geoid model have more in common...with the presented sea surface topography than with the MDTs based on earlier versions of the geoid . The presented MDT will increase the accuracy of...estimating the geoid in the Bering Sea. 15. SUBJECT TERMS dynamic topography, sea surface height, Bering Sea, 4DVar 16. SECURITY CLASSIFICATION OF: a

  17. ROLE OF CORNEAL COLLAGEN CROSS LINKING IN KERATOCONUS

    Directory of Open Access Journals (Sweden)

    Atul

    2015-09-01

    Full Text Available To evaluate the outcome of collagen cross linkage using riboflavin 0.1% and ultraviolet A radiation of a wavelength 370nm . PURPOSE : To determine the effect of collagen cross linking for keratoconus on pachymetry , corneal topography, uncorrected visual acuity, specular count, IOP at 1, 3, 6 months . METHODS : The current study was designed as a prospective interventional trial of corneal collagen cross - linking in subjects with progressive keratoconus between a period of J anuary 2013 to J uly 2014 including 50 eyes of 30 patients. This study rece ived approval from Ethics committee. Informed written consent was obtained from all patients prior to treatment. RESULTS: Mean follow up period of 6 months. There was statistically significant decline in effective k readings from mean pre op (51.7D to pos t op value (49.65D . Pachymetry showed initial increase post operatively followed by reduction in corneal thickness in 3 month s follow up , followed by gradual increase in thickness over a period of 6 months though it was not equivalent to pre - operative values. paired t test p value was 0.00 1 in 1 n 3 month and 0. 043 in 6 month, concluding significant reduction in early post op period with im provement over time . Specular count reduced from pre - op (2673.80 levels to post - op (2654.60 levels ,the reduction in specular count was not statistically significant P value (0.014 The uncorrected visual acuity showed decrease in refractive error with in crease in visual acuity gradually over 6 months, log MAR scale visual acuity was used for statistical analysis with P value (0.001 which was statistically significant .visual acuity improved by 1.5 lines in snellens equivalence or from 0.5 to 0.4 in log MA R char y ± 20cells/mm 3 , P value(0. 001 . IOP statically show ed no significant change in pre - operative and post operatively , paired t test p value was 0. 44 showing it was not significant . CONCLUSIONS : 1. Visual acuity improved in

  18. Corneal Collagen Cross-Linking for Keratoconus in Pediatric Patients-Long-Term Results.

    Science.gov (United States)

    Padmanabhan, Prema; Rachapalle Reddi, Sudhir; Rajagopal, Rama; Natarajan, Radhika; Iyer, Geetha; Srinivasan, Bhaskar; Narayanan, Niveditha; Lakshmipathy, Meena; Agarwal, Shweta

    2017-02-01

    To report the long-term outcome of corneal collagen cross-linking (CXL) for progressive keratoconus in pediatric patients. "Epithelium-off" CXL was performed in pediatric eyes with progressive keratoconus. Spectacle-corrected distance visual acuity (CDVA), retinoscopy, topography, and tomography were documented preoperatively and postoperatively at 3 months, 6 months, 1 year, and annually thereafter. A total of 377 eyes of 336 pediatric patients aged 8 to 18 years with progressive keratoconus underwent CXL. Of these, 194 eyes had a follow-up beyond 2 years and up to 6.7 years. At last follow-up, there was significant improvement in mean CDVA from 0.33 ± 0.22 to 0.27 ± 0.19 logMAR (P ≤ 0.0001), reduction in mean topographic astigmatism from 7.22 ± 3.55 to 6.13 ± 3.28 D (P = 0.0001), mean flattening of 1.20 ± 3.55 diopters in maximum keratometry (Kmax) (P = 0.0002), and mean corneal thinning of 31.1 ± 36.0 μm (P keratoconus (average keratometry 48-53 diopters). Central cones showed more corneal flattening than peripheral cones. Stabilization or flattening of Kmax was seen in 85% of eyes at 2 years and in 76% after 4 years. Stabilization or improvement of CDVA was seen in 80.1% of eyes at 2 years and in 69.1% after 4 years. CXL remains effective in stabilizing keratoconus for longer than 2 years in a majority of pediatric eyes. Flattening of Kmax was greater in moderately advanced keratoconus and central cones. Long-term follow-up beyond 4 years, however, revealed that a few eyes showed features suggestive of reversal of the effect of CXL.

  19. Intra-individual variability of penetrating keratoplasty outcome after excimer laser versus motorized corneal trephination.

    Science.gov (United States)

    Szentmáry, Nóra; Langenbucher, Achim; Naumann, Gottfried O H; Seitz, Berthold

    2006-10-01

    To assess the intra-individual variability of outcomes after penetrating keratoplasty by comparing mechanical and nonmechanical corneal trephination. Fifteen patients (30 eyes, 16 with keratoconus and 14 with Fuchs' dystrophy; median age at penetrating keratoplasty 56.3/53.5 years) were assessed whose trephination was performed using a motor trephine in one eye and the 193-nm excimer laser (MEL 60, Carl Zeiss-Meditec) in the other eye by one experienced surgeon. Subjective refractometry, standard keratometry, and corneal topography were used to assess best spectacle-corrected visual acuity (BSCVA); spherical equivalent refraction; keratometric and topographic central corneal power; refractive, keratometric, and topographic astigmatism; surface regularity index; surface asymmetry index; and potential visual acuity preoperatively, before first suture removal (at 1 year), and at last available follow-up after final suture removal but before additional surgery (1.3 and 1.9 years, respectively). Before first suture removal BSCVA was significantly higher (0.7 vs 0.5; P=.008) after excimer laser trephination. At the end of follow-up, refractive/ keratometric/topographic astigmatism (2.20/2.10/2.40 diopters [D] vs 5.00/6.00/7.10 D) and surface regularity index (0.8 vs 1.1) were significantly lower (P=.02, P=.005, P=.01, and P=.03, respectively) and potential visual acuity was significantly higher (0.9/0.6; P=.02) after excimer laser trephination. During long-term follow-up, all-sutures-out postkeratoplasty astigmatism and surface regularity are superior in the eye where nonmechanical excimer laser was applied in contrast to the fellow eye with motor trephination in the same individual.

  20. Ocular manifestations of Noonan syndrome in twin siblings: A case report of keratoconus with acute corneal hydrops

    Directory of Open Access Journals (Sweden)

    Anna Lee

    2014-01-01

    Full Text Available Ocular manifestations of Noonan syndrome (NS in a set of healthy 20-year-old African-American fraternal twins are reported with emphasis on a rare finding of keratoconus with acute corneal hydrops in one twin. Both the twins had learning disabilities and attended a special needs school. Evaluation included visual acuity assessment, tonometry and external eye, slit lamp and dilated fundus examinations, topography with Pentacam and external photographs. The first case was more remarkable as keratoconus with acute corneal hydrops was observed. The patient presented with severe cloudy vision that had worsened over a span of 1 month. It improved significantly on follow-up. The second case included a unique constellation of ocular pathology that highlights the diversity of NS manifestations even amongst twins. Conservative treatment of keratoconus with acute corneal hydrops in a NS patient helped largely resolve the patient′s condition. We report the diverse spectrum of ocular manifestations associated with this rare congenital disorder.

  1. Late Stage of Corneal Decompensation Caused by Progressive Keratoconus: Can We Treat It and Save the Cornea?

    Directory of Open Access Journals (Sweden)

    Igor Knezović

    2015-01-01

    Full Text Available Aim. To report a case of 40-year-old male with progressive bilateral keratoconus who had undergone transepithelial phototherapeutic keratectomy (TE-PTK and corneal collagen cross-linking (CXL using hypoosmolar riboflavin solution in a same day procedure. Methods. Eye examination showed that UCDVA on both eyes was 0,01 according to Snellen charts, and slit lamp biomicroscopy showed paracentral diffuse intrastromal corneal haze. Anterior OCT marked stromal hyperreflective zones and localized paracentral thinning of the cornea. Scheimpflug tomography noted keratoconus stages III-IV on both eyes. After 40/35 microns TE-PTK, a CXL was performed for 30 minutes using hypoosmolar riboflavin solution. The left eye was treated first and the right eye 1 month after. Follow-up period was 10 months. Results. One month after the treatment both eyes showed improvement in corneal topography and the UCDVA was better. Eight months after the treatment BSCVA improved to 0,6 in both eyes using Rose K2 contact lenses and remained stable. Conclusion. TE-PTK and CXL using hypotonic riboflavin solution as a same day procedure have been shown to be a safe and promising method in this case of progressive keratoconus. It was necessary to consider certain parameters that could influence the safety and the final outcome of this combined protocol.

  2. Eye Morphology and Retinal Topography in Hummingbirds (Trochilidae: Aves).

    Science.gov (United States)

    Lisney, Thomas J; Wylie, Douglas R; Kolominsky, Jeffrey; Iwaniuk, Andrew N

    2015-01-01

    Hummingbirds are a group of small, highly specialized birds that display a range of adaptations to their nectarivorous lifestyle. Vision plays a key role in hummingbird feeding and hovering behaviours, yet very little is known about the visual systems of these birds. In this study, we measured eye morphology in 5 hummingbird species. For 2 of these species, we used stereology and retinal whole mounts to study the topographic distribution of neurons in the ganglion cell layer. Eye morphology (expressed as the ratio of corneal diameter to eye transverse diameter) was similar among all 5 species and was within the range previously documented for diurnal birds. Retinal topography was similar in Amazilia tzacatl and Calypte anna. Both species had 2 specialized retinal regions of high neuron density: a central region located slightly dorso-nasal to the superior pole of the pecten, where densities reached ∼ 45,000 cells · mm(-2), and a temporal area with lower densities (38,000-39,000 cells · mm(-2)). A weak visual streak bridged the two high-density areas. A retina from Phaethornis superciliosus also had a central high-density area with a similar peak neuron density. Estimates of spatial resolving power for all 3 species were similar, at approximately 5-6 cycles · degree(-1). Retinal cross sections confirmed that the central high-density region in C. anna contains a fovea, but not the temporal area. We found no evidence of a second, less well-developed fovea located close to the temporal retina margin. The central and temporal areas of high neuron density allow for increased spatial resolution in the lateral and frontal visual fields, respectively. Increased resolution in the frontal field in particular may be important for mediating feeding behaviors such as aerial docking with flowers and catching small insects.

  3. Effects of biophysical and biochemical cues on human corneal epithelial cell behavior

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    Tocce, Elizabeth J.

    2011-12-01

    Recent advances in the design of biomaterials aim at mimicking the natural biophysical and biochemical components found in a tissue's extracellular environment (ECM). Of particular interest in this work is mimicking the specialized ECM of the human corneal epithelium called the basement membrane (BM) and understanding how corneal epithelial cells (HCECs) respond to biophysical and biochemical cues. To this end, well defined topographic features with dimension of the BM (20 to 200 nm) were fabricated to support controlled cell interactions with biochemical motifs (e.g., adhesive peptide ligands) found in the BM. Here, features of 30 to 70 nm that represent the smallest features found in the BM were used to demonstrate that the smallest features that HCECs can recognize are 30 and 45 nm, depending on the soluble environment. In addition, HCECs demonstrate contact guidance on the smallest BM features (30 to 70 nm) and on the largest BM features (200 nm), but differs from contact guidance on micron-scale features, suggesting that BM scale topography scale is an influential factor in regulating HCEC behavior. To study the simultaneous presentation of biophysical and biochemical cues, topographic features are coated with thin films using a layer-by-layer deposition of covalently reacting polymers, poly(ethylene imine) and poly(2-vinyl-4,4-dimethylazlactone (PEI/PVDMA). The films are functionalized with the bioactive peptide argenine-glycine-aspartic acid (RGD) to control cell-substrate interactions. We demonstrate that PEI/PVDMA films can be functionalized with monotonically increasing densities of ROD to control HCEC attachment and proliferation. In addition PEI/PVDMA films functionalized with RGD were used to demonstrate that HCEC response to topographic cues is dependent on the scale of the topography, the surface chemical composition and the soluble environment. Results from these studies will advance the understanding of how BM-relevant biophysical and biochemical

  4. In-vivo high resolution corneal imaging and analysis on animal models for clinical applications

    Science.gov (United States)

    Hong, Jesmond; Shinoj, V. K.; Murukeshan, V. M.; Baskaran, M.; Aung, Tin

    2015-07-01

    A simple and low cost optical probe system for the high resolution imaging of the cornea is proposed, based on a Gaussian beam epi-illumination configuration. Corneal topography is obtained by moving the scanning spot across the eye in a raster fashion whereas pachymetry data is achieved by reconstructing the images obtained at different depths. The proposed prototype has been successfully tested on porcine eye samples ex vivo and subsequently on laboratory animals, such as the New Zealand White Rabbit, in vivo. This proposed system and methodology pave the way for realizing a simple and inexpensive optical configuration for pachymetry and keratometry readings, with achievable resolution up to the cellular level. This novel and non-contact high resolution imaging modality demonstrates high intraobserver reproducibility and repeatability. Together with its sophisticated data analysis strategies and safety profile, it is believed to complement existing imaging modalities in the assessment and evaluation of corneal diseases, which enable a decrease in morbidity and improvement in the effectiveness of subsequent treatment.

  5. Induction of corneal collagen cross-linking in experimental corneal alkali burns in rabbits

    Directory of Open Access Journals (Sweden)

    Marcello Colombo-Barboza

    2014-10-01

    Full Text Available Objective: To evaluate the effect of riboflavin-ultraviolet-A-induced cross-linking (CXL following corneal alkali burns in rabbits. Methods: The right corneas and limbi of ten rabbits were burned using a 1N solution of NaOH and the animals were then divided into two groups: a control group submitted to clinical treatment alone and an experimental group that was treated 1 h after injury with CXL, followed by the same clinical treatment as administered to the controls. Clinical parameters were evaluated post-injury at 1, 7, 15, and 30 days by two independent observers. Following this evaluation, the corneas were excised and examined histologically. Results: There were no statistically significant differences in clinical parameters, such as hyperemia, corneal edema, ciliary injection, limbal ischemia, secretion, corneal neovascularization, symblepharon, or blepharospasm, at any of the time-points evaluated. However, the size of the epithelial defect was significantly smaller in the CXL group (p<0.05 (day 15: p=0.008 and day 30: p=0.008 and the extent of the corneal injury (opacity lesion was also smaller (day 30: p=0.021. Histopathology showed the presence of collagen bridges linking the collagen fibers in only the CXL group. Conclusions: These results suggest that the use of CXL may improve the prognosis of acute corneal alkali burns.

  6. Spontaneous corneal melting in pregnancy: a case report

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    Arya Sudesh K

    2007-11-01

    Full Text Available Abstract Background To report a case of spontaneous corneal melting in pregnancy. We reviewed the literature on corneal melting and the effect of pregnancy on cornea and collagen containing tissues. Case presentation A 29-year-old woman who underwent radial keratotomy in both eyes followed by trabeculectomy in her left eye developed corneal melting in the same eye, in her seventh month of pregnancy. Despite screening, no infectious or immune mediated condition could be identified. She was managed conservatively with cyanoacrylate glue, bandage contact lens, lubricants and antibiotics. Conclusion It may not always be possible to find the underlying cause of corneal melting but the more common underlying causes should be ruled out by proper investigations. Pregnancy with its host of hormonal changes could potentially have some effect on corneal collagen leading to corneal melting in compromised corneas.

  7. Systemic Immunomodulatory Strategies in High-risk Corneal Transplantation

    Science.gov (United States)

    Abud, Tulio B.; Di Zazzo, Antonio; Kheirkhah, Ahmad; Dana, Reza

    2017-01-01

    The cornea is the most commonly transplanted tissue in the body. Although corneal grafts generally have high success rates, transplantation onto inflamed and vascularized host beds, or so-called high-risk corneal transplantation, has a high rate of graft rejection. The management of this high-risk corneal transplantation is challenging and involves numerous measures. One of the key measures to prevent graft rejection in these cases is the use of systemic immunosuppressive agents. In this article, we will review the systemic immunosuppressive agents most commonly used for high-risk corneal transplantation, which include corticosteroids, cysclosporine A, tacrolimus, mycophenolate mofetil, and rapamycin. Benefits, risks, and published data on the use of these medications for high-risk corneal transplantation will be detailed. We will also summarize novel immunoregulatory approaches that may be used to prevent graft rejection in high-risk corneal transplantation.

  8. Indocyanine green staining for the triple corneal procedure.

    Science.gov (United States)

    Kobayashi, Akira; Segawa, Yoji; Nishimura, Akira; Shirao, Yutaka; Sugiyama, Kazuhisa

    2004-01-01

    In the triple corneal procedure, successful completion of capsulorhexis is of the utmost importance. Another use of indocyanine green dye for better visualization of the anterior lens capsule of mature cataract during the triple corneal procedure is described. Four consecutive patients (mean age, 69.5 years) with both mature cataracts and corneal opacity underwent the triple corneal procedure. After trephination of the recipient cornea, the anterior capsule of the lens was stained with indocyanine green. A continuous curvilinear capsulorhexis (CCC) was performed, after which conventional triple corneal procedures were followed. In all four cases, this technique markedly improved visualization of the lens capsule and resulted in successful and easy manipulation of the CCC and subsequent removal of residual lens cortex. Staining of the anterior capsule of mature cataract in the triple corneal procedure clearly defines the border of the capsule, thus allowing easy and complete execution of CCC.

  9. Modificaciones de la curvatura posterior corneal después de la cirugía refractiva láser Modifications in the corneal posterior curve after laser refractive surgery

    Directory of Open Access Journals (Sweden)

    Lorelei Ortega Díaz

    2011-06-01

    in an universe of 257 patients (504 eyes underwent to laser refractive surgery. Sample included 31 patients (59 eyes. Variables analyzed were: age, sex, spherical equivalent, preoperative pachymetry, ablation amount, residual stroma and difference of corneal posterior elevation, this latter achieved from the difference map of Galilei topography, with preoperative measurement at month and at three months after surgery. By multiple regression analysis the changes of pachymetry, the ablation amount and the residual stroma were assessed. RESULTS: The spherical equivalent, the pachymetry, the ablation amount and the residual stroma were within the established safety parameters. The mean difference of posterior corneal elevation was of 15,62 ?m at three months, with a significant decrease in time (p= 0,000. There was association with preoperative pachymetry and the residual stroma and also an inverse correlation between this latter and the posterior corneal elevation at three months. CONCLUSIONS: The laser refractive surgery produces an early increase in the posterior corneal elevation with a progressive decrease at third month. The factors that more influenced in such changes were the residual stroma and the preoperative pachymetry.

  10. EXPERIMENTAL STUDY ON THE CORNEAL ENDOTHELIUM OF TRAUMATIC CATARACT

    Institute of Scientific and Technical Information of China (English)

    1991-01-01

    The cell morphology of corneal endothelium in 84 mice with experimental traumatic cataract was investigated with stained corneal buttons. In the experimental group, the boundaries between adjacent corneal endothelial cells were significantly distorted, some cell boundaries manifested degenerative changes that led to coalescence of the cells. The mean density and mean area of endothelial cells of the controls showed significant difference from those of the experimental group during the 12 weeks of observ...

  11. A brief history of corneal transplantation: From ancient to modern

    OpenAIRE

    Alexandra X Crawford; Patel, Dipika V.; Charles NJ McGhee

    2013-01-01

    This review highlights many of the fundamental concepts and events in the development of corneal transplantation - from ancient times to modern. Tales of eye, limb, and even heart transplantation appear in ancient and medieval texts; however, in the scientific sense, the original concepts of corneal surgery date back to the Greek physician Galen (130-200 AD). Although proposals to provide improved corneal clarity by surgical interventions, including keratoprostheses, were better developed by ...

  12. Retinal evaluation and treatment after refractive corneal surgery.

    Science.gov (United States)

    Swinger, C A; Kraushar, M F

    1985-08-01

    Refractive corneal surgery (a collective term used to describe a variety of surgical procedures that alter the refractive status of the eye through the surgical modification of corneal curvature) shows promise for use in situations where current methods of optical correction do not meet the patient's needs. This article reviews our experiences with the retinal evaluation of patients who have undergone corneal refractive surgery and offers recommendations for the treatment of retinal pathology after such surgery.

  13. Organism Isolation in Corneal Ulcer- Utility of Different Techniques

    OpenAIRE

    M Thapa; A.K. Sharma; D.N. Shah; S KC; Shrestha, S.

    2012-01-01

    Introduction: Various techniques are available for isolation of microorganism in cases of microbial keratitis including conventional methods of scraping, re-scraping inoculation in different media and corneal biopsy. Methods: This was a cross sectional descriptive study conducted from February 2002 to July 2003. A total of 161 eyes of corneal ulcers were evaluated with scraping inoculation. Re-scraping and corneal biopsy were performed in those cases which did not grow any organism in t...

  14. Corneal Chromoblastomycosis Caused by Fonsecaea pedrosoi

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    Winai Chaidaroon

    2015-02-01

    Full Text Available Purpose: To report 2 unusual cases of fungal keratitis due to Fonsecaea pedrosoi. Methods: Two patients were diagnosed with Fonsecaea pedrosoi keratitis. Their files were reviewed for predisposing factors, clinical characteristics, microbiological study, treatment, and outcome. Results: Two consecutive patients presented with brownish pigmented corneal ulcers in their eyes after sustaining eye trauma from vegetative matter. In both cases, corneal scrapings were collected for microscopic examination and culture. Dematiaceous hyphae were seen on the smears, and dark pigmented colonies grew on the culture media, identified as F. pedrosoi. Both patients were treated and cured with combined topical antifungal agents and oral itraconazole. The first patient required an amniotic membrane patch, while the second received an intracameral amphotericin B injection. Conclusions: Pigmented infiltrates can be an important diagnostic clue, but a microscopic evaluation and culture are required to obtain an accurate diagnosis of Fonsecaea keratitis. The prompt diagnosis and combined antifungal treatment can prevent morbidity associated with this fungal infection.

  15. Prevalence of corneal astigmatism before cataract surgery.

    Science.gov (United States)

    Mohammadi, Mehran; Naderan, Mohammad; Pahlevani, Rozhin; Jahanrad, Ali

    2016-12-01

    The purpose of this study was to describe and analyze the prevalence and pattern of corneal astigmatism in cataract surgery candidates. In a prospective cross-sectional study, preoperative demographics, and keratometric and refractive values of cataract surgery candidates were collected from January 2013 to December 2014. Axial length (AL) and flat and steep keratometry measurements were optically measured by a partial coherence interferometry device (IOLMaster). This study consisted of 2156 eyes of 1317 patients with a mean age of 64.92 ± 11.48 (SD) (30-88 years). The mean of AL was 23.33 ± 1.37 mm, and the mean of corneal astigmatism was 1.12 ± 1.10 diopter (D) (range 0.0-7.00), in all patients. Furthermore, the mean of flat and steep keratometry were 43.70 ± 1.70 and 44.83 ± 1.79 D, respectively. Corneal astigmatism was 1.50 D or less in 1590 eyes (73.7 %), more than 1.50 D in 566 eyes (26.2 %), 3.00 D or more in 161 eyes (7.4 %), WTR in 796 eyes (36.9 %), ATR in 1010 eyes (46.8 %), and oblique in 350 eyes (16.2 %). ATR astigmatism axis significantly increased with the increase in age. Corneal astigmatism of most cataract surgery candidates fell between 0.50 and 1.50 D. The results of our study however is confined to our demographics might provide useful data for cataract patients, surgeons, and intraocular lens manufacturers for different purposes.

  16. Corneal Neurotoxicity Due to Topical Benzalkonium Chloride

    Science.gov (United States)

    Sarkar, Joy; Chaudhary, Shweta; Namavari, Abed; Ozturk, Okan; Chang, Jin-Hong; Yco, Lisette; Sonawane, Snehal; Khanolkar, Vishakha; Hallak, Joelle; Jain, Sandeep

    2012-01-01

    Purpose. The aim of this study was to determine and characterize the effect of topical application of benzalkonium chloride (BAK) on corneal nerves in vivo and in vitro. Methods. Thy1-YFP+ neurofluorescent mouse eyes were treated topically with vehicle or BAK (0.01% or 0.1%). Wide-field stereofluorescence microscopy was performed to sequentially image the treated corneas in vivo every week for 4 weeks, and changes in stromal nerve fiber density (NFD) and aqueous tear production were determined. Whole-mount immunofluorescence staining of corneas was performed with antibodies to axonopathy marker SMI-32. Western immunoblot analyses were performed on trigeminal ganglion and corneal lysates to determine abundance of proteins associated with neurotoxicity and regeneration. Compartmental culture of trigeminal ganglion neurons was performed in Campenot devices to determine whether BAK affects neurite outgrowth. Results. BAK-treated corneas exhibited significantly reduced NFD and aqueous tear production, and increased inflammatory cell infiltration and fluorescein staining at 1 week (P < 0.05). These changes were most significant after 0.1% BAK treatment. The extent of inflammatory cell infiltration in the cornea showed a significant negative correlation with NFD. Sequential in vivo imaging of corneas showed two forms of BAK-induced neurotoxicity: reversible neurotoxicity characterized by axonopathy and recovery, and irreversible neurotoxicity characterized by nerve degeneration and regeneration. Increased abundance of beta III tubulin in corneal lysates confirmed regeneration. A dose-related significant reduction in neurites occurred after BAK addition to compartmental cultures of dissociated trigeminal ganglion cells. Although both BAK doses (0.0001% and 0.001%) reduced nerve fiber length, the reduction was significantly more with the higher dose (P < 0.001). Conclusion. Topical application of BAK to the eye causes corneal neurotoxicity, inflammation, and reduced aqueous

  17. RECURRENT CORNEAL EROSION SYNDROME (a review

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    S. V. Trufanov

    2015-01-01

    Full Text Available Recurrent corneal erosion (RCE syndrome is characterized by episodes of recurrent spontaneous epithelial defects. Main clinical symptoms (pain, redness, photophobia, lacrimation occurred at night. Corneal lesions revealed by slit lamp exam vary depending on the presence of corneal epithelium raise, epithelial microcysts or epithelial erosions, stromal infiltrates and opacities. Microtraumas, anterior corneal dystrophies, and herpesvirus give rise to RCE. Other causes or factors which increase the risk of RCE syndrome include meibomian gland dysfunction, keratoconjunctivitis sicca, diabetes, and post-LASIK conditions. Basal membrane abnormalities and instability of epithelial adhesion to stroma play a key role in RCE pathogenesis. Ultrastructural changes in RCE include abnormalities of basal epithelial cells and epithelial basal membrane, absence or deficiency of semi-desmosomes, loss of anchor fibrils. Increase in matrix metalloproteinases and collagenases which contribute to basal membrane destruction results in recurrent erosions and further development of abnormal basal membrane. The goals of RCE therapy are to reduce pain (in acute stage, to stimulate re-epithelization, and to restore «adhesion complex» of basal membrane. In most cases, RCE responds to simple conservative treatment that includes lubricants, healing agents, and eye patches. RCEs that are resistant to simple treatment, require complex approach. Non-invasive methods include long-term contact lens use, instillations of autologous serum (eye drops, injections of botulinum toxin (induces ptosis, antiviral agent use or oral intake of metalloproteinase inhibitors. Cell membrane stabilizers, i.e., antioxidants, should be included into treatment approaches as well. Antioxidant effect of Emoxipine promotes tissue reparation due to the prevention of cell membrane lipid peroxidation as well as due to its anti-hypoxic, angioprotective, and antiplatelet effects. If conservative therapy

  18. 个性超声乳化切口并不同类型人工晶状体植入术后角膜散光和视觉质量的比较%The clinical investigation of dynamic changes of corneal astigmatism and visual quality for patients after phacoemulsification surgery through different incision and implantation of different designed intraocular lens

    Institute of Scientific and Technical Information of China (English)

    王佃科; 张杰; 王杰; 李艳; 梁山; 刘育霞

    2009-01-01

    Objective To compare the corneal astigmatism and wavefront aberration differences of patients with cataract coexisting corneal astigmatism after phacoemulsification surgery through traditional superior clear corneal incision or phacoemulsification surgery through clear corneal incision guided by corneal topography and implantation of different spherical aberration intraocular lenses (IOL). Methods In a prospective randomized sample controlled clinical trial, 90 patients (90 eyes) with age-related cataract and corneal astigmatism were randomly divided into 3 groups: (Group A) traditional superior corneal incision phacoemulsification surgery and AcrySof SN60AT IOL implantation, (Group B) corneal topography guiding incision phacoemulsification surgery and AcrySof SN60AT IOL implantation and (Group C ) corneal topography guiding incision phacoemulsification surgery and AcrySof SN60WF IOL implantation. Corneal topography tests were performed at 1 week, 1 month, 3 months and 6 months postoperatively. The Wavefront aberration was measured using a custom built Tschcming wavefront sensor--ALLEGRETTO WAVE Analyze at 90 days postoperatively. Third-, 4th-, 5th-, total and higher-order aberration (HOA) root-mean-square (RMS), spherical aberration and coma aberration were compared at virtual pupil diameters of 6 mm postoperatively. Statistical analyses were performed using the analysis of chi square test, repeated measurement data analysis of variance, one-way analysis of variance (ANOVA), and multiple comparisons Studcnts-Newman-Keuls test. Results Corneal topography tests indicated that no significant difference for corneal astigmatism was found between these three groups preoperatively( F =0. 08 ,P >0. 05). The corneal astigmatism was decomposed into J0, J45 and P with a Vector-based method, and statistically analyzed . When compared with Group B and GroupC, Group A had higher values of corneal J0 ( F = 9.54, P 0. 05 ). However groups and times had interactions ( F = 13

  19. Clinical correlates of common corneal neovascular diseases: a literature review

    Institute of Scientific and Technical Information of China (English)

    Nizar; Saleh; Abdelfattah; Mohamed; Amgad; Amira; A; Zayed; Hamdy; Salem; Ahmed; E; Elkhanany; Heba; Hussein; Nawal; Abd; El-Baky

    2015-01-01

    A large subset of corneal pathologies involves the formation of new vessels(neovascularization), leading to compromised visual acuity. This article aims to review the clinical causes and presentations of corneal neovascularization(CNV) by examining the mechanisms behind common CNV-related corneal pathologies, with a particular focus on herpes simplex stromal keratitis,contact lenses-induced keratitis and CNV secondary to keratoplasty. Moreover, we reviewed CNV in the context of different types of corneal transplantation and keratoprosthesis, and summarized the most relevant treatment available so far.

  20. Decreased central corneal thickness in ankylosing spondylitis.

    Science.gov (United States)

    Ortak, Huseyin; Inanır, Ahmet; Demir, Selim; Uysal, Alper; Şahin, Şafak; Sağcan, Mustafa; Önder, Yalçın; Alim, Sait; Demir, Ayşe Kevser

    2014-04-01

    Central corneal thickness and dry eye tests were evaluated in a study population consisting of 68 ankylosing spondylitis patients diagnosed according to the modified New York criteria, and 61 age-matched controls without ankylosing spondylitis. A full ophthalmological evaluation was performed on each subject. All subjects were screened for age, gender, HLA-B27, tear break-up time test, Schirmer test, and duration of disease. Central corneal thickness was measured under topical anesthesia with an ultrasonic pachymeter. The mean central corneal thickness was 537.3 ± 30.6 μm, range 462-600 μm, in ankylosing spondylitis patients, whereas it was 551.7 ± 25.2 μm, range 510-620 μm, in controls (p = 0.005). The Schirmer test result was 7.3 ± 5.9 mm for the ankylosing spondylitis patients and 11.7 ± 5.8 mm for the control group (p = 0.002). Tear break-up time was 7.3 ± 3.2 s for the ankylosing spondylitis patients and 14.0 ± 4.5 s for the control group (p ankylosing spondylitis. In addition, attention must be given to lower dry eye tests in surgical interventions such as photorefractive keratectomy and laser in situ keratomileusis in ankylosing spondylitis patients.

  1. Meretoja's Syndrome: Lattice Corneal Dystrophy, Gelsolin Type

    Science.gov (United States)

    Abreu, C.; Neves, M.; Oliveira, L.; Beirão, M.

    2017-01-01

    Lattice corneal dystrophy gelsolin type was first described in 1969 by Jouko Meretoja, a Finnish ophthalmologist. It is caused by an autosomal dominant mutation in gelsolin gene resulting in unstable protein fragments and amyloid deposition in various organs. The age of onset is usually after the third decade of life and typical diagnostic triad includes progressive bilateral facial paralysis, loose skin, and lattice corneal dystrophy. We report a case of a 53-year-old female patient referred to our Department of Ophthalmology by severe dry eye and incomplete eyelid closure. She had severe bilateral facial paresis, significant orbicularis, and perioral sagging as well as hypoesthesia of extremities and was diagnosed with Meretoja's syndrome at the age of 50, confirmed by the presence of gelsolin mutation. At our observation she had bilateral diminished tear film break-up time and Schirmer test, diffuse keratitis, corneal opacification, and neovascularization in the left eye. She was treated with preservative-free lubricants and topical cyclosporine, associated with nocturnal complete occlusion of both eyes, and underwent placement of lacrimal punctal plugs. Ocular symptoms are the first to appear and our role as ophthalmologists is essential for the diagnosis, treatment, and monitoring of ocular alterations in these patients. PMID:28250773

  2. Putative epidermal stem cell convert into corneal epithelium-like cell under corneal tissue in vitro

    Institute of Scientific and Technical Information of China (English)

    GAO Nan; CUI GuangHui; WANG ZhiChong; HUANG Bing; GE Jian; LU Rong; ZHANG KeFei; FAN ZhiGang; LU Li; PENG Zhan

    2007-01-01

    Rhesus putative epidermal stem cells are being investigated for their potential use in regenerative corneal epithelium-like cells, which may provide a practical source of autologous seed cells for the construction of bioengineered corneas. The goal of this study was to investigate the potential of epidermal stem cells for trans-differentiation into corneal epithelium-like cells. Rhesus putative epidermal stem cells were isolated by type IV collagen attachment method. Flow cytometry analysis, immunohistology and RT-PCR were conducted to identify the expression of specific markers (β1, α6 integrin, K15, K1/K10, K3/K12 and CD71) on the isolated rapid attaching cells. The isolated cells were cocultured with human corneal limbal stroma and corneal epithelial cells. After coculture, the expression of the same specific markers was evaluated in order to identify expression difference caused by the coculture conditions. K3/K12 expression was analyzed in coculture cells on day 2, 4, 6, 8 and 10. Putative epidermal stem cells in conditioned culture media were used as control. Putative epidermal stem cells were predominant in rapid attaching cells by type IV collagen attachment isolation. Before being cocultured, the rhesus putative epidermal stem cells expressed K15, α6 and β1 integrin, but no CD71, K1/K10 and K3/K12. After coculture, these cells expressed K3/K12 (a marker of corneal epithelial cells), K15 and β 1 integrin, but no K1/K10. Cells being not coculture converted into terminally differentiated cells expressing K1/K10. These results indicate that rhesus putative epidermal stem cells can trans-differentiate into corneal epithelium-like cells and, therefore, may have potential therapeutic application as autologous seed cells for the construction of bioengineered corneas.

  3. Putative epidermal stem cell convert into corneal epithelium-like cell under corneal tissue in vitro

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Rhesus putative epidermal stem cells are being investigated for their potential use in regenerative corneal epithelium-like cells, which may provide a practical source of autologous seed cells for the construction of bioengineered corneas. The goal of this study was to investigate the potential of epi-dermal stem cells for trans-differentiation into corneal epithelium-like cells. Rhesus putative epidermal stem cells were isolated by type IV collagen attachment method. Flow cytometry analysis, immuno-histology and RT-PCR were conducted to identify the expression of specific markers (β1, α6 integrin, K15, K1/K10, K3/K12 and CD71) on the isolated rapid attaching cells. The isolated cells were cocultured with human corneal limbal stroma and corneal epithelial cells. After coculture, the expression of the same specific markers was evaluated in order to identify expression difference caused by the coculture conditions. K3/K12 expression was analyzed in coculture cells on day 2, 4, 6, 8 and 10. Putative epi-dermal stem cells in conditioned culture media were used as control. Putative epidermal stem cells were predominant in rapid attaching cells by type IV collagen attachment isolation. Before being co-cultured, the rhesus putative epidermal stem cells expressed K15, α6 and β1 integrin, but no CD71, K1/K10 and K3/K12. After coculture, these cells expressed K3/K12 (a marker of corneal epithelial cells), K15 and β 1 integrin, but no K1/K10. Cells being not coculture converted into terminally differentiated cells expressing K1/K10. These results indicate that rhesus putative epidermal stem cells can trans-differentiate into corneal epithelium-like cells and, therefore, may have potential therapeutic application as autologous seed cells for the construction of bioengineered corneas.

  4. Development of new therapeutic modalities for corneal endothelial disease focused on the proliferation of corneal endothelial cells using animal models.

    Science.gov (United States)

    Koizumi, Noriko; Okumura, Naoki; Kinoshita, Shigeru

    2012-02-01

    This review describes our recent attempts to develop new therapeutic modalities for corneal endothelial disease using animal models including non-human primate model in which the proliferative ability of corneal endothelial cells is severely limited, as is the case in humans. First, we describe our attempt to develop new surgical treatments using cultivated corneal endothelial cells for advanced corneal endothelial dysfunction. It includes two different approaches; a "corneal endothelial cell sheet transplantation" with cells grown on a type-I collagen carrier, and a "cell-injection therapy" combined with the application of Rho-kinase (ROCK) inhibitor. Recently, it was reported that the selective ROCK inhibitor, Y-27632, promotes cell adhesion and proliferation and inhibits the apoptosis of primate corneal endothelial cells in culture. When cultivated corneal endothelial cells were injected into the anterior chamber of animal eyes in the presence of ROCK inhibitor, endothelial cell adhesion was promoted and the cells achieved a high cell density and a morphology similar to corneal endothelial cells in vivo. We are also trying to develop a novel medical treatment for the early phase of corneal endothelial disease by the use of ROCK inhibitor eye drops. In rabbit and monkey experiments using partial endothelial dysfunction models, corneal endothelial wound healing was accelerated by the topical application of ROCK inhibitor to the ocular surface, and resulted in the regeneration of a corneal endothelial monolayer with a high endothelial cell density. We are now trying to advance the clinical application of these new therapies for patients with corneal endothelial dysfunction.

  5. Electronic Cigarette Topography in the Natural Environment.

    Directory of Open Access Journals (Sweden)

    R J Robinson

    Full Text Available This paper presents the results of a clinical, observational, descriptive study to quantify the use patterns of electronic cigarette users in their natural environment. Previously published work regarding puff topography has been widely indirect in nature, and qualitative rather than quantitative, with the exception of three studies conducted in a laboratory environment for limited amounts of time. The current study quantifies the variation in puffing behaviors among users as well as the variation for a given user throughout the course of a day. Puff topography characteristics computed for each puffing session by each subject include the number of subject puffs per puffing session, the mean puff duration per session, the mean puff flow rate per session, the mean puff volume per session, and the cumulative puff volume per session. The same puff topography characteristics are computed across all puffing sessions by each single subject and across all subjects in the study cohort. Results indicate significant inter-subject variability with regard to puffing topography, suggesting that a range of representative puffing topography patterns should be used to drive machine-puffed electronic cigarette aerosol evaluation systems.

  6. Manifestaciones corneales en las enfermedades sistémicas Corneal manifestations in systemic diseases

    OpenAIRE

    J. Zarranz-Ventura; E. De Nova; Moreno-Montañés, J

    2008-01-01

    Un gran número de enfermedades sistémicas presentan manifestaciones corneales dentro de su espectro de enfermedad. El estudio detallado de todos los cuadros que asocian patología corneal resulta inabarcable, por ello se presentan las enfermedades más prevalentes o características. Este estudio contempla las enfermedades pulmonares y conectivopatías (colagenosis, enfermedades reumatológicas y enfermedades inflamatorias idiopáticas), las enfermedades dermatológicas, cardiovasculares, hematológi...

  7. Corneal tissue welding with infrared laser irradiation after clear corneal incision.

    Science.gov (United States)

    Rasier, Rfat; Ozeren, Mediha; Artunay, Ozgür; Bahçecioğlu, Halil; Seçkin, Ismail; Kalaycoğlu, Hamit; Kurt, Adnan; Sennaroğlu, Alphan; Gülsoy, Murat

    2010-09-01

    The aim of this study was to investigate the potential of infrared lasers for corneal welding to seal corneal cuts done in an experimental animal model. Full-thickness corneal cuts on freshly enucleated bovine eyes were irradiated with infrared (809-nm diode, 980-nm diode, 1070-nm YLF, and 1980-nm Tm:YAP) lasers to get immediate laser welding. An 809-nm laser was used with the topical application of indocyanine green to enhance the photothermal interaction at the weld site. In total, 60 bovine eyes were used in this study; 40 eyes were used in the first part of the study for the determination of optimal welding parameters (15 eyes were excluded because of macroscopic carbonization, opacification, or corneal shrinkage; 2 eyes were used for control), and 20 eyes were used for further investigation of more promising lasers (YLF and Tm:YAP). Laser wavelength, irradiating power, exposure time, and spot size were the dose parameters, and optimal dose for immediate closure with minimal thermal damage was estimated through histological examination of welded samples. In the first part of the study, results showed that none of the applications was satisfactory. Full-thickness success rates were 28% (2 of 7) for 809-nm and for 980-nm diode lasers and 67% (2 of 3) for 1070-nm YLF and (4 of 6) for 1980-nm Tm:YAP lasers. In the second part of the study, YLF and Tm:YAP lasers were investigated with bigger sample size. Results were not conclusive but promising again. Five corneal incisions were full-thickness welded out of 10 corneas with 1070-nm laser, and 4 corneal incisions were partially welded out of 10 corneas with 1980-nm laser in the second part of the study. Results showed that noteworthy corneal welding could be obtained with 1070-nm YLF laser and 1980-nm Tm:YAP laser wavelengths. Furthermore, in vitro and in vivo studies will shed light on the potential usage of corneal laser welding technique.

  8. Corneal layer plate removal with Fluconazole injected corneal stroma and autologous conjunctival transplantation for keratomycosis

    Directory of Open Access Journals (Sweden)

    Li-Dong Yang

    2013-08-01

    Full Text Available AIM: To investigate the clinical effect of corneal layer plate removal with Fluconazole injected corneal stroma and autologous conjunctival transplantation for keratomycosis.METHODS: There were 168 cases suffered keratomycosis that the focus located shallow of the cornea and was not obvious to drug, who registered in our hospital from March 2005 to June 2010. In surgery we removed plate layer to cormea clear, the region was greater than focus for 0.5mm,then we injected fluconazole which is 2g/L density in corneal stroma to make the edema area greater than Removal of area for 0.5mm. At last we took pedicle conjunctival flap to cover the plant bed by continuous suture. Postoperative day use drug to drop eye and to observe that whether recurrent of the keratomycosis and how was the edema degrade, the blood supply of conjunctival graft pieces, how about the stimulating signs of the surgery eye, the vision.RESULTS: The improvement rate was 96.2% after surgery for seven days and the cure rate was 95.5% after surgery for one months. We found in 157 eyes accepted trigeminy surgery there were 6 eyes recurrence and the recurrence rate was 3.8%. The mean time of corneal stromal edema faded away was 13.4 hours. After surgery for one month there were 39 eyes(24.8%whose vision removed than preoperative, there were 91 eyes(58.0%whose vision were same as preoperative and there were 27 eyes(17.2%whose vision lower than preoperative. In these operations the loss ratio of corneal endothelium was from 0%-8%, the mean was 2.9%. The irritative symptoms postoperative were mild for 87%, moderate for 10% and severe for 3%. By this surgery the mean length of stay was 7.3 days so the mean hospitalization expenses only were 2160 RMB. Three months after surgery, 4 cases were slight corneal ectasia.CONCLUSION: This operation combined corneal layer plate removal, Fluconazole injected corneal stroma and autologous conjunctival transplantation for keratomycosis which was in

  9. Corneal donations in South Africa: A 15-year review.

    Science.gov (United States)

    York, Nicholas J; Tinley, Christopher

    2017-07-28

    Corneal pathology is one of the leading causes of preventable blindness in South Africa (SA). A corneal transplant can restore or significantly improve vision in most cases. However, in SA there is a gross shortage of corneal tissue available to ophthalmologists. Little has been published describing the magnitude of the problem. To describe trends in the number of corneal donors per year in SA, the number of corneal transplants performed each year, the origin of donors, the allocation of corneas to the public or private sector, and the demographics of donors. This was a retrospective review of all corneal donations to SA eye banks over the 15-year period 1 January 2002 - 31 December 2016. There was a progressive year-on-year decline in corneal donors over the study period, from 565 per year in 2002 to 89 in 2016. As a direct result, there has been an 85.5% decrease in the number of corneal transplants performed per year using locally donated corneas, from 1 049 in 2002 to 152 in 2016. Of the donors, 48.8% originated from mortuaries, 39.0% from private hospitals and 12.2% from government hospitals; donors from mortuaries showed the most significant decline over the 15-year period, decreasing by 94.8%. Of donated corneas, 79.3% were allocated to the private sector and 21.7% to the public sector. Males comprised 69.1% of donors, while 77.2% were white, 14.0% coloured, 6.3% black and 2.5% Indian/Asian. Donor age demonstrated a bimodal peak at 25 and 55 years. The number of corneal donations in SA has declined markedly, causing the burden of corneal disease requiring transplantation to rise steadily. Population groups with a low donor rate may have cultural and other objections to corneal donation, which should be a major focus of future research and initiatives aimed at reversing the current trends.

  10. Moiré topography in odontology

    Science.gov (United States)

    Moreno Yeras, A.

    2003-07-01

    For several decades, measurement of optical techniques has been used in different branches of science and technology. One of these techniques is the so-called moiré topography (MT) that enables the accurate measurement of different parts of the human body topography. This investigation presents the measurement of topographies of teeth and gums using an automated system of shadow moiré and the phase shift method in an original way. The fringe patterns used to compute the shape and the shape matrix itself are presented in the article. The phase shift method ensures precisions up to the order of microns. Advantages and disadvantages of using the MT are included. Besides, some positive and negative aspects concerned with the implementation of this technique in odontology are shown in the article.

  11. Interferometer for measuring the dynamic surface topography of a human tear film

    Science.gov (United States)

    Primeau, Brian C.; Greivenkamp, John E.

    2012-03-01

    The anterior refracting surface of the eye is the thin tear film that forms on the surface of the cornea. Following a blink, the tear film quickly smoothes and starts to become irregular after 10 seconds. This irregularity can affect comfort and vision quality. An in vivo method of characterizing dynamic tear films has been designed based upon a near-infrared phase-shifting interferometer. This interferometer continuously measures light reflected from the tear film, allowing sub-micron analysis of the dynamic surface topography. Movies showing the tear film behavior can be generated along with quantitative metrics describing changes in the tear film surface. This tear film measurement allows analysis beyond capabilities of typical fluorescein visual inspection or corneal topography and provides better sensitivity and resolution than shearing interferometry methods. The interferometer design is capable of identifying features in the tear film much less than a micron in height with a spatial resolution of about ten microns over a 6 mm diameter. This paper presents the design of the tear film interferometer along with the considerations that must be taken when designing an interferometer for on-eye diagnostics. Discussions include eye movement, design of null optics for a range of ocular geometries, and laser emission limits for on-eye interferometry.

  12. Effects of patterned topography on biofilm formation

    Science.gov (United States)

    Vasudevan, Ravikumar

    2011-12-01

    Bacterial biofilms are a population of bacteria attached to each other and irreversibly to a surface, enclosed in a matrix of self-secreted polymers, among others polysaccharides, proteins, DNA. Biofilms cause persisting infections associated with implanted medical devices and hospital acquired (nosocomial) infections. Catheter-associated urinary tract infections (CAUTIs) are the most common type of nosocomial infections accounting for up to 40% of all hospital acquired infections. Several different strategies, including use of antibacterial agents and genetic cues, quorum sensing, have been adopted for inhibiting biofilm formation relevant to CAUTI surfaces. Each of these methods pertains to certain types of bacteria, processes and has shortcomings. Based on eukaryotic cell topography interaction studies and Ulva linza spore studies, topographical surfaces were suggested as a benign control method for biofilm formation. However, topographies tested so far have not included a systematic variation of size across basic topography shapes. In this study patterned topography was systematically varied in size and shape according to two approaches 1) confinement and 2) wetting. For the confinement approach, using scanning electron microscopy and confocal microscopy, orienting effects of tested topography based on staphylococcus aureus (s. aureus) (SH1000) and enterobacter cloacae (e. cloacae) (ATCC 700258) bacterial models were identified on features of up to 10 times the size of the bacterium. Psuedomonas aeruginosa (p. aeruginosa) (PAO1) did not show any orientational effects, under the test conditions. Another important factor in medical biofilms is the identification and quantification of phenotypic state which has not been discussed in the literature concerning bacteria topography characterizations. This was done based on antibiotic susceptibility evaluation and also based on gene expression analysis. Although orientational effects occur, phenotypically no difference

  13. Deformidade corneana em usuário de lente de contato portador de ceratocone: relato de caso Corneal warpage in contact lens wearer with keratoconus: a case report

    Directory of Open Access Journals (Sweden)

    César Lipener

    1999-12-01

    wearer with keratoconus who developed corneal warpage symptoms that were diag-nosed and studied by topographies and a series of clinical examinations. Case report: A forty-year-old patient with diagnosis of bilateral keratoconus for 12 years was wearing rigid gas permeable contact lenses since the initial diagnosis. On the first exa-mination in 05/95, it was impossible to determine the RE refraction and keratometry was more than 60.00 D. Topogra-phy was carried out being compatible with keratoconus and a Soper RGP lens was fitted with a 20/70 vision. One year later a control topography showed an increase in the central curve and a flattening of the inferior periphery. The use of contact lenses was interrupted and after further six months there was a reversal of the changes, and a new Soper lens was fitted with a better pattern and a 20/40 vision. Discussion: This case shows the occurrence of corneal de-formity in a keratoconus patient using RGP lenses. The au-thor discusses the pathophysiology and clinical and topographical diagnosis of corneal warpage, emphasizing the fact that patients with keratoconus as well as normal patients, can have these alterations which should be differentiated from the keratoconus evolution itself.

  14. Analysis of corneal refractive changes in pterygium%翼状胬肉角膜表面屈光状态分析

    Institute of Scientific and Technical Information of China (English)

    张春燕; 吴卫华; 黄慧玲; 郭妮娜

    2012-01-01

    目的 了解不同大小的翼状胬肉的角膜表面屈光状况方法 对我科80只眼大小不同的翼状胬肉进行裂隙灯显微镜记录翼状胬肉横径(胬肉角膜缘与其顶端距离)、竖径(跨过角巩膜缘时的弧长)及面积(横径X竖径/2),同时应用角膜地形图分析,记录simK(最徒径与最平径,散光值及轴向)、角膜中心屈光度、平均屈光度、以胬肉尖部为中心的扁平区内的最小屈光波(P-屈光波)、角膜散光并将上述数据进行统计分析.结果 70只眼单侧翼状胬肉长度和面积与散光呈正相关.10只眼双侧(鼻侧及颞侧长度<4 mm)均生长胬肉的患者胬肉长度和面积与散光无相关性.但总屈光力较正常屈光力下降.结论 翼状胬肉对角膜屈光有明显的影响,角膜地形图对此有很好的评估作用.%Objective To study the corneal refractive changes in pterygium . Methods Pterygia length, width and area was measured by slit-lamp microscope in 80 eyes with primary pterygium. Central corneal power, mean corneal power, the flattest meridional power , the astigmatism of the pterygium, and SIK including (the biggest meridional power , the flattest meridional power and the refractive location ) were recorded. Pterygium-associated flattening was also recorded as the refractive power and its location. Results The length and size of those had a positive correlation with corneal refrac -tion in 70 eyes with one side pterygium. There was no relation between the length and size of corneal refraction in 10 eyes with two sides pterygium (length <4 mm) , while the corneal refraction decreased. Conclusion Pterygium can change the corneal refraction and corneal topography is an satisfactory method to evaluate these changes .

  15. Comparison of corneal sensitivity, tear function and corneal staining following laser in situ keratomileusis with two femtosecond laser platforms

    Directory of Open Access Journals (Sweden)

    Petznick A

    2013-03-01

    Full Text Available Andrea Petznick,1 Annabel Chew,2 Reece C Hall,2 Cordelia ML Chan,2 Mohamad Rosman,1,2 Donald Tan,1–3 Louis Tong,1–4 Jodhbir S Mehta1–31Singapore Eye Research Institute, Singapore; 2Singapore National Eye Centre, Singapore; 3Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; 4Duke-NUS Graduate Medical School, SingaporePurpose: To evaluate longitudinal changes in corneal sensitivity, tear function, and corneal staining in patients who underwent laser in situ keratomileusis (LASIK using two different femtosecond lasers.Methods: In a prospective, randomized clinical trial, contralateral eyes of 45 patients underwent flap creation by either VisuMax or IntraLase™ femtosecond laser. Corneal sensitivity, tear break up time (TBUT, Schirmer’s test, and corneal fluorescein staining were assessed preoperatively and at 1 week, 1 month, and 3 months postoperatively.Results: There were no statistical differences in any clinical outcome measure between the two femtosecond lasers (P > 0.05, although there was a trend towards slightly lower reductions for corneal sensitivity and TBUT in VisuMax-operated eyes. Overall, corneal sensitivity was significantly reduced at 1 week (P 0.05.Conclusion: This study showed that changes in corneal sensitivity, tear function, and corneal staining were statistically similar in LASIK using VisuMax and IntraLase femtosecond lasers for flap creation. However, the trend towards faster recovery of corneal sensitivity and TBUT observed in VisuMax-operated eyes may be attributable to improved technical specifications.Keywords: femtosecond laser, corneal sensitivity, tear film break-up time, Schirmer’s, corneal staining

  16. Gelatinous drop-like corneal dystrophy: a review.

    Science.gov (United States)

    Kaza, Hrishikesh; Barik, Manas R; Reddy, Mamatha M; Mittal, Ruchi; Das, Sujata

    2017-01-01

    Gelatinous drop-like corneal dystrophy (GDLD) is a rare autosomal recessive form of corneal dystrophy characterised by subepithelial and stromal amyloid deposits. It is relatively common in Japan. It usually presents in the first two decades of life with subepithelial nodular lesions that later coalesce to form mulberry-like opacities. Although various surgical modalities have been attempted, recurrence remains a major challenge.

  17. Outcome of corneal transplantation: can a prioritisation system predict outcome?

    OpenAIRE

    Saunders, Patrick P R; Sibley, Lyn M; Richards, John S F; Simon P. Holland; Chow, Debbie L; Courtright, Paul

    2002-01-01

    Background: In 1995 a prioritisation system for patients waiting for corneal transplantation surgery was adopted in British Columbia. In 1997 a routine outcome assessment programme was adopted. The authors sought to determine the outcomes of corneal transplant surgery in the province of British Columbia and to evaluate if they were associated with waiting list prioritisation.

  18. Genomics of corneal wound healing: a review of the literature.

    Science.gov (United States)

    Maycock, Nick J R; Marshall, John

    2014-05-01

    Corneal wound healing is a complex process: its mechanisms and the underlying genetic control are not fully understood. It involves the integrated actions of multiple growth factors, cytokines and proteases produced by epithelial cells, stromal keratocytes, inflammatory cells and lacrimal gland cells. Following an epithelial insult, multiple cytokines are released triggering a cascade of events that leads to repair the epithelial defect and remodelling of the stroma to minimize the loss of transparency and function. In this review, we examine the literature surrounding the genomics of corneal wound healing with respect to the following topics: epithelial and stromal wound healing (including inhibition); corneal neovascularisation; the role of corneal nerves in wound healing; the endothelium; the role of aquaporins and aptamers. We also examine the effect of ectasia on corneal wound healing with regard to keratoconus and following corneal surgery. A better understanding of the cellular and molecular changes that occur during repair of corneal wounds will provide the opportunity to design treatments that selectively modulate key phases of the healing process resulting in scars that more closely resemble normal corneal architecture.

  19. Applications and advantages of corneal crosslinking for treatment of keratoconus

    NARCIS (Netherlands)

    Soeters, N.

    2015-01-01

    Keratoconus is a corneal disorder in which the cornea becomes cone-shaped due to stromal thinning and corneal weakening. It mainly affects young individuals and although the prevalence is low (1:2000), the impact on quality of life is high. Despite much effort, still no cure has been found for

  20. Applications and advantages of corneal crosslinking for treatment of keratoconus

    NARCIS (Netherlands)

    Soeters, N.

    2015-01-01

    Keratoconus is a corneal disorder in which the cornea becomes cone-shaped due to stromal thinning and corneal weakening. It mainly affects young individuals and although the prevalence is low (1:2000), the impact on quality of life is high. Despite much effort, still no cure has been found for kerat

  1. Effects of genipin corneal crosslinking in rabbit corneas.

    Science.gov (United States)

    Avila, Marcel Y; Narvaez, Mauricio; Castañeda, Juan P

    2016-07-01

    To evaluate the effect of genipin, a natural crosslinking agent, in rabbit eyes. Department of Ophthalmology, Universidad Nacional de Colombia Centro de Tecnologia Oftalmica, Bogotá, Colombia. Experimental study. Ex vivo rabbit eyes (16; 8 rabbits) were treated with genipin 1.00%, 0.50%, and 0.25% for 5 minutes with a vacuum device to increase corneal permeability. Penetration was evaluated using Scheimpflug pachymetry (Pentacam). In the in vivo model (20 rabbits; 1 eye treated, 1 eye with vehicle), corneas were crosslinked with genipin as described. Corneal curvature, corneal pachymetry, and intraocular pressure (IOP) assessments as well as slitlamp examinations were performed 0, 7, 30, and 60 days after treatment. In the ex vivo model, Scheimpflug pachymetry showed deep penetration in the rabbit corneas with an increase in corneal density and a dose-dependent relationship. Corneal flattening was observed in treated eyes (mean 4.4 diopters ± 0.5 [SD]) compared with the control eyes. Pachymetry and IOP were stable in all evaluations. No eye showed toxicity in the anterior chamber or in the lens. Corneal crosslinking induced by genipin produced significant flattening of the cornea with no toxicity in rabbit eyes. This crosslinking could be useful in the treatment of corneal ectasia and in the modification of corneal curvature. None of the authors has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  2. Less Invasive Corneal Transepithelial Electrical Resistance Measurement Method.

    Science.gov (United States)

    Uematsu, Masafumi; Mohamed, Yasser Helmy; Onizuka, Naoko; Ueki, Ryotaro; Inoue, Daisuke; Fujikawa, Azusa; Sasaki, Hitoshi; Kitaoka, Takashi

    2016-01-01

    To evaluate acute corneal permeability changes after instillation of benzalkonium chloride (BAC) using a newly developed in vivo less invasive corneal transepithelial electrical resistance (TER) measurement method in animals and humans. We previously developed an in vivo method for measuring corneal TER using intraocular electrodes in animals. This method can be used to precisely measure the decline of the corneal barrier function after instillation of BAC. To lessen the invasiveness of that procedure, we further refined the method for measuring the corneal TER by developing electrodes that could be placed on the surface of the cornea and in the conjunctival sac instead of inserting them into the anterior chamber. Corneal TER changes before and after exposure to 0.02% BAC were determined in this study using the new device in both rabbits and humans. There was a significant decrease in the corneal TER after exposure of the cornea to 0.02% BAC solution in both rabbits and humans (Pmeasurement method enables us for the first time to measure TER of the human cornea, allowing safe and reliable investigation of the direct effect of different eye drop treatments on the corneal epithelium. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Corneal stem cells and tissue engineering: Current advancesand future perspectives

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    Major advances are currently being made in regenerativemedicine for cornea. Stem cell-based therapiesrepresent a novel strategy that may substituteconventional corneal transplantation, albeit there aremany challenges ahead given the singularities of eachcellular layer of the cornea. This review recapitulatesthe current data on corneal epithelial stem cells,corneal stromal stem cells and corneal endothelialcell progenitors. Corneal limbal autografts containingepithelial stem cells have been transplanted in humansfor more than 20 years with great successful rates,and researchers now focus on ex vivo cultures andother cell lineages to transplant to the ocular surface.A small population of cells in the corneal endotheliumwas recently reported to have self-renewal capacity,although they do not proliferate in vivo . Two mainobstacles have hindered endothelial cell transplantationto date culture protocols and cell delivery methods tothe posterior cornea in vivo . Human corneal stromalstem cells have been identified shortly after therecognition of precursors of endothelial cells. Stromalstem cells may have the potential to provide a directcell-based therapeutic approach when injected tocorneal scars. Furthermore, they exhibit the ability todeposit organized connective tissue in vitro and maybe useful in corneal stroma engineering in the future.Recent advances and future perspectives in the field arediscussed.

  4. In Vivo Corneal Biomechanical Properties with Corneal Visualization Scheimpflug Technology in Chinese Population

    Directory of Open Access Journals (Sweden)

    Ying Wu

    2016-01-01

    Full Text Available Purpose. To determine the repeatability of recalculated corneal visualization Scheimpflug technology (CorVis ST parameters and to study the variation of biomechanical properties and their association with demographic and ocular characteristics. Methods. A total of 783 healthy subjects were included in this study. Comprehensive ophthalmological examinations were conducted. The repeatability of the recalculated biomechanical parameters with 90 subjects was assessed by the coefficient of variation (CV and intraclass correlation coefficient (ICC. Univariate and multivariate linear regression models were used to identify demographic and ocular factors. Results. The repeatability of the central corneal thickness (CCT, deformation amplitude (DA, and first/second applanation time (A1/A2-time exhibited excellent repeatability (CV% ≤ 3.312% and ICC ≥ 0.929 for all measurements. The velocity in/out (Vin/out, highest concavity- (HC- radius, peak distance (PD, and DA showed a normal distribution. Univariate linear regression showed a statistically significant correlation between Vin, Vout, DA, PD, and HC-radius and IOP, CCT, and corneal volume, respectively. Multivariate analysis showed that IOP and CCT were negatively correlated with Vin, DA, and PD, while there was a positive correlation between Vout and HC-radius. Conclusion. The ICCs of the recalculated parameters, CCT, DA, A1-time, and A2-time, exhibited excellent repeatability. IOP, CCT, and corneal volume significantly influenced the biomechanical properties of the eye.

  5. Customized toric intraocular lens implantation for correction of extreme corneal astigmatism due to corneal scarring

    Directory of Open Access Journals (Sweden)

    R Bassily

    2010-03-01

    Full Text Available R Bassily, J LuckOphthalmology Department, Royal United Hospital, Combe Park, Bath, UKAbstract: A 76-year-old woman presented with decreased visual function due to cataract formation. Twenty-five years prior she developed right sided corneal ulceration that left her with 10.8 diopters (D of irregular astigmatism at 71.8° (steep axis. Her uncorrected visual acuity was 6/24 and could only ever wear a balanced lens due to the high cylindrical error. Cataract surgery was planned with a custom designed toric intraocular lens (IOL with +16.0 D sphere inserted via a wound at the steep axis of corneal astigmatism. Postoperative refraction was -0.75/+1.50 × 177° with a visual acuity of 6/9 that has remained unchanged at six-week follow-up with no IOL rotation. This case demonstrates the value of high power toric IOLs for the correction of pathological corneal astigmatism.Keywords: intraocular lens, corneal ulceration, visual acuity, scarring

  6. Evidence-based Homoeopathy: A case of corneal abscess

    Directory of Open Access Journals (Sweden)

    Sandeep Sudhakar Sathye

    2016-01-01

    Full Text Available Corneal abscess is a circumscribed collection of pus within the layers of cornea. It is usually endogenous in origin and commonly found near the limbal blood vessels close to corneal margin. Treatment in modern medicine is use of local and systemic antibiotics. Homoeopathy has mentioned medicines for corneal abscess. A case reported was a female of 68 years of age suffering from symptoms of redness, dull pain, and foreign body sensation in the right eye and was diagnosed as corneal abscess. The homoeopathic medicine Hepar sulphuris 200C was prescribed on the basis of pathology. Abscess was reduced considerably within 5 days and it was absorbed completely in 21 days. No recurrence of abscess was observed thereafter. Ocular photographs during follow-up visits have provided documentary evidence about the effectiveness of homoeopathic Hepar sulphuris 200C in corneal abscess.

  7. Paracentral Corneal Dellen:A Rare Sign of Graves Ophthalmopathy

    Institute of Scientific and Technical Information of China (English)

    Jianhua Yan; Zhongyao Wu

    2003-01-01

    Purpose: To report a rare sign, paracentral corneal dellen that developed in a middleaged female patient with Graves ophthalmopathy.Methods:A paracentral corneal dellen developed in the left eye in a 42-year-old woman who was diagnosed as Graves ophthalmopathy. The patient had remarkable upper eyelid retraction, upper eyelid lag and upward motility restriction. The Graves ophthalmopathy was classified as Grade V according to NOSPECS classification.Results:Local artificial tear film and 0.3% Tobramycin eye drops were administered to both eyes.Twenty-four hours later, the left corneal dellen disappeared.Conclusions:Graves ophthalmopathy can lead to paracentral corneal dellen because of severe upper eyelid retraction and upward motility restriction of the eye in spite of the lack of lagophthalmos. Artificial tear drop and antibiotic eye drop therapy helped even though the patient did not have corneal exposure.

  8. Mechanism of Corneal Endothelial Cells Lesion during Phacoemulsification and Aspiration

    Institute of Scientific and Technical Information of China (English)

    Songtao Yuan; Lina Xie; Qinghuai Liu; Nanrong Yuan

    2003-01-01

    Purpose: To evaluate the proportions of corneal endothelial lesion caused by differentfactors during phacoemulsification and aspiration.Methods: Fourteen cats (twenty eight eyes) were divided into four groups. The processedfactors were ultrasonic power, lens extraction by phacoemulsification or not, and lensextraction using different levels of ultrasonic power. The density of central cornealendothelial cells was measured before and after operation.Results: There is no statistic difference between pre-operation density and post-operationdensity for releasing ultrasonic power only without lens extraction group. But for the lensextraction group, there is difference in density of central corneal endothelial cells andthe higher level of ultrasonic power, the more the central corneal endothelial cells densitydecreased through operation.Conclusion: The primary factor that causes corneal endothelial lesion duringphacoemulsification and aspiration procedure is debris of lens nucleus, and the otherfactors cause the lesion of corneal endothelium in normal operations just in very smalldegree.

  9. Corneal refractive change after microincision vitrectomy%微创玻璃体手术后角膜屈光状态的观察

    Institute of Scientific and Technical Information of China (English)

    屠颖; 魏文斌

    2012-01-01

    Objective To observe corneal refractive change after 20-G and 23-G incision vitreoretinal surgery.Methods It was a prospective case-control study.Forty-four patients (44 eyes) who underwent 23-G vitreoretinal surgery were selected for a 23-G group and 48 patients (48 eyes)who underwent 20-G vitreoretinal surgery during the same period were selected tor the 20-G group.Corneal topography was performed before surgery and 3 days,2 weeks,1 month and 3 months postoperatively.The corneal topography parameters were recorded and the data were analyzed by ANOVA,independent samples t test and x2 test.Results ①Corneal topography showed no significant differences in shape preoperatively compared to 3 months postoperatively (x2=5.26,P>0.05).②In the 20-G group: corneal curvature was reduced at 1 and 3 months postoperatively compared to preoperative parameters (t=1.08,-3.67,P<0.05).Corneal astigmatisn 3 days,2 weeks and 1 month postoperatively was higher than preoperative parameters (t=0.53,0.9,0.56,P<0.05).The regular parameters of the corneal surface were higher 3 days postoperatively compared to preoperative parameters (t=0.74,0.63,1.08,P<0.05).In the 23-G group:corneal curvature was higher 3 days and 2 weeks postoperatively compared to preoperative parameters (t=0.37,0.46,P<0.05).Corneal astigmatism and the regular parameters of the corneal surface were higher 3 days postoperatively compared to preoperative parameters (P<0.01).③The 20-G group had lower corneal curvature parameters (P<0.05),higher astigmatism parameters (t=0.81,1.08,P<0.05),and higher corneal surface regularity (P<0.05) compared to the 23-G group.Conclusion Astigmatism recovered to preoperative levels in 1-3 months postoperatively,and corneal curvature was lower 3 months postoperatively compared to preoperative curvature.In the 23-G group,the corneal refractive status recovered to preoperative levels in from 2 weeks to 3 months postoperatively.Postoperative corneal curvature was lower

  10. Biomechanical and morphological corneal response to placement of intrastromal corneal ring segments for keratoconus.

    Science.gov (United States)

    Dauwe, Caroline; Touboul, David; Roberts, Cynthia J; Mahmoud, Ashraf M; Kérautret, Julien; Fournier, Pierre; Malecaze, François; Colin, Joseph

    2009-10-01

    To evaluate the biomechanical and morphological changes in keratoconic corneas after Intacs intrastromal corneal ring segment (ICRS) implantation. Department of Ophthalmology, National Reference Center for Keratoconus, Bordeaux University, Bordeaux, France. Keratoconic eyes were retrospectively analyzed after ICRS implantation; preoperative and 6-month postoperative evaluation were done using the Ocular Response Analyzer (ORA) and the Orbscan II topographer. Biomechanical parameters included corneal hysteresis (CH), the corneal resistance factor (CRF), and other parameters extracted from the signal curves. Morphological parameters included simulated keratometry and the cone location magnitude index from the axial map (aCLMI) and tangential map (tCLMI). Parameters were extracted using software designed to read and process topographic maps. There were no significant differences between preoperatively and postoperatively in mean CH (7.7 mm Hg +/- 1.4 [SD] versus 7.4 +/- 1.4 mm Hg) or mean CRF (6.6 +/- 1.8 mm Hg versus 6.1 +/- 1.4 mm Hg). Only 2 ORA signal parameters were significantly different. Topographic parameters with significant decreases were minimum central keratometry (K) (mean change -5.8 +/- 2.9 diopters [D]) (P<.001), minimum central K (mean change -5.8 +/- 2.3 D) (P<.001), mean aCLMI (9.6 +/- 2.7 preoperatively versus 7.7 +/- 2.5 postoperatively) (P<.009), and mean tCLMI (18.9 +/- 2.8 versus 12.9 +/- 4.4) (P<.002). The only significant correlation between biomechanical and topographic parameters was postoperative ORA infrared signal peak 1 and postoperative aCLMI. Intrastromal corneal ring implantation significantly decreased corneal curvature, with preoperative values predicting magnitude of change. However, it did not alter the viscoelastic biomechanical parameters of CH and CRF.

  11. Corneal confocal microscopy is a rapid reproducible ophthalmic technique for quantifying corneal nerve abnormalities.

    Science.gov (United States)

    Kalteniece, Alise; Ferdousi, Maryam; Adam, Safwaan; Schofield, Jonathan; Azmi, Shazli; Petropoulos, Ioannis; Soran, Handrean; Malik, Rayaz A

    2017-01-01

    To assess the effect of applying a protocol for image selection and the number of images required for adequate quantification of corneal nerve pathology using in vivo corneal confocal microscopy (IVCCM). IVCCM was performed in 35 participants by a single examiner. For each participant, 4 observers used a standardized protocol to select 6 central corneal nerve images to assess the inter-observer variability. Furthermore, images were selected by a single observer on two occasions to assess intra-observer variability and the effect of sample size was assessed by comparing 6 with 12 images. Corneal nerve fiber density (CNFD), branch density (CNBD) and length (CNFL) were quantified using fully automated software. The data were compared using the intra class correlation coefficient (ICC) and Bland-Altman agreement plots for all experiments. The ICC values for CNFD, CNBD and CNFL were 0.93 (P<0.0001), 0.96 (P<0.0001) and 0.95 (P<0.0001) for inter-observer variability and 0.95 (P<0.0001), 0.97 (P<0.001) and 0.97 (P<0.0001) for intra-observer variability. For sample size variability, ICC values were 0.94 (P<0.0001), 0.95 (P<0.0001), and 0.96 (P<0.0001) for CNFD, CNBD and CNFL. Bland-Altman plots showed excellent agreement for all parameters. This study shows that implementing a standardized protocol to select IVCCM images results in high intra and inter-observer reproducibility for all corneal nerve parameters and 6 images are adequate for analysis. IVCCM could therefore be deployed in large multicenter clinical trials with confidence.

  12. Mountains: Geology, Topography and Environmental Concerns

    OpenAIRE

    Martin F. Price

    2016-01-01

    Reviewed: Mountains: Geology, Topography and Environmental Concerns. Edited by António José, Bento Gonçalves, and António Avelino Batista Vieria. New York, NY: Nova Science Publishers, 2014. ix + 371 pp. US$ 175.00. ISBN 978-1-63117-288-5.

  13. Mountains: Geology, Topography and Environmental Concerns

    OpenAIRE

    Price, Martin F.

    2016-01-01

    Reviewed: Mountains: Geology, Topography and Environmental Concerns. Edited by António José, Bento Gonçalves, and António Avelino Batista Vieria. New York, NY: Nova Science Publishers, 2014. ix + 371 pp. US$ 175.00. ISBN 978-1-63117-288-5.

  14. Mountains: Geology, Topography and Environmental Concerns

    Directory of Open Access Journals (Sweden)

    Martin F. Price

    2016-05-01

    Full Text Available Reviewed: Mountains: Geology, Topography and Environmental Concerns. Edited by António José, Bento Gonçalves, and António Avelino Batista Vieria. New York, NY: Nova Science Publishers, 2014. ix + 371 pp. US$ 175.00. ISBN 978-1-63117-288-5.

  15. Geostatistical modeling of topography using auxiliary maps

    NARCIS (Netherlands)

    Hengl, T.; Bajat, B.; Blagojević, D.; Reuter, H.I.

    2008-01-01

    This paper recommends computational procedures for employing auxiliary maps, such as maps of drainage patterns, land cover and remote-sensing-based indices, directly in the geostatistical modeling of topography. The methodology is based on the regression-kriging technique, as implemented in the R pa

  16. Influence of mesoscale topography on vortex intensity

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effect of mesoscale topography on multi-vortex self-organization is investigated numerically in this paper using a barotropic primitive equation model with topographic term. In the initial field there are one DeMaria major vortex with the maximum wind radius rm of 80 km at the center of the computational domain, and four meso-β vortices in the vicinity of rm to the east of the major vortex center.When there is no topography present, the initial vortices self-organize into a quasi-final state flow pattern, I.e. A quasi-axisymmetric vortex whose intensity is close to that of the initial major vortex. However, when a mesoscale topography is incorporated, the spatial scale of the quasi-final state vortex reduces, and the relative vorticity at the center of the vortex and the local maximum wind speed remarkably increase. The possible mechanism for the enhancement of the quasi-final state vortex might be that the negative relative vorticity lump,generated above the mesoscale topography because of the constraint of absolute vorticity conservation, squeezes the center of positive vorticity towards the mountain slope area, and thus reduces the spatial range of the major vortex. Meanwhile, because the total kinetic energy is basically conservative, the squeezing directly leads to the concentration of the energy in a smaller area, I.e. The strengthening of the vortex.

  17. [Corneal permeability of topically applied pirenzepine solution].

    Science.gov (United States)

    Wang, Kai-di; Zhang, Jin-song; Yan, Pan-shi

    2006-06-01

    To study the corneal permeability of three different pirenzepine eye-drop solutions and provide reference for further clinical use. Sixty-three New Zealand white rabbits were divided into three groups. Each group of rabbits received 2% pirenzepine (pirenzepine group), 2% pirenzepine with 0.1% hyaluronic acid (hyaluronic acid group), or 2% pirenzepine with 0.1% azone (azone group). One drop eye-drops was applied to conjunctive sac every 5 min for six times. Aqueous samples were obtained from each group at 0.5, 1.0, 2.0, 4.0, 8.0, 12.0, 24.0 h after the last drop, respectively. Concentration of pirenzepine in these samples was determined by the HPLC (high pressure liquid chromatography). Stimulation symptom of rabbit eyes was also observed. The concentrations of pirenzepine in aqueous humor were (0.40 +/- 0.06) microg/ml at 0.5 h, (0.53 +/- 0.03) microg/ml at 1.0 h, (1.52 +/- 0.33) microg/ml at 2.0 h and (0.15 +/- 0.02) microg/ml at 4.0 h in pirenzepine group. Aqueous humor concentration of pirenzepine in both 2% pirenzepine with 0.1% azone and 2% pirenzepine with 0.1% hyaluronic acid were significantly higher than that of single pirenzepine application, and their bioavailability in the groups with combinations of pirenzepine with 0.1% azone or 0.1% hyaluronic acid were 23.0 times and 3.4 times higher than that of single pirenzepine usage. No obvious irritate symptom was found in rabbit of all three groups after eye-drop applying. The combination application of pirenzepine with azone or hyaluronic acid has higher corneal permeability compared with pirenzepine alone. This result indicates that azone and hyaluronic acid could be used in pirenzepine eye-drop solution to increase corneal permeability.

  18. Automated Decision Tree Classification of Corneal Shape

    Science.gov (United States)

    Twa, Michael D.; Parthasarathy, Srinivasan; Roberts, Cynthia; Mahmoud, Ashraf M.; Raasch, Thomas W.; Bullimore, Mark A.

    2011-01-01

    Purpose The volume and complexity of data produced during videokeratography examinations present a challenge of interpretation. As a consequence, results are often analyzed qualitatively by subjective pattern recognition or reduced to comparisons of summary indices. We describe the application of decision tree induction, an automated machine learning classification method, to discriminate between normal and keratoconic corneal shapes in an objective and quantitative way. We then compared this method with other known classification methods. Methods The corneal surface was modeled with a seventh-order Zernike polynomial for 132 normal eyes of 92 subjects and 112 eyes of 71 subjects diagnosed with keratoconus. A decision tree classifier was induced using the C4.5 algorithm, and its classification performance was compared with the modified Rabinowitz–McDonnell index, Schwiegerling’s Z3 index (Z3), Keratoconus Prediction Index (KPI), KISA%, and Cone Location and Magnitude Index using recommended classification thresholds for each method. We also evaluated the area under the receiver operator characteristic (ROC) curve for each classification method. Results Our decision tree classifier performed equal to or better than the other classifiers tested: accuracy was 92% and the area under the ROC curve was 0.97. Our decision tree classifier reduced the information needed to distinguish between normal and keratoconus eyes using four of 36 Zernike polynomial coefficients. The four surface features selected as classification attributes by the decision tree method were inferior elevation, greater sagittal depth, oblique toricity, and trefoil. Conclusions Automated decision tree classification of corneal shape through Zernike polynomials is an accurate quantitative method of classification that is interpretable and can be generated from any instrument platform capable of raw elevation data output. This method of pattern classification is extendable to other classification

  19. Mycotic corneal ulcers in upper Assam

    Directory of Open Access Journals (Sweden)

    Reema Nath

    2011-01-01

    Full Text Available Purpose : To study the association of various risk factors and epidemiological variables of mycotic keratitis treated at a tertiary referral hospital of upper Assam. Materials and Methods: In this hospital-based prospective study a total of 310 consecutive corneal ulcer cases attending the ophthalmology outpatient department of Assam Medical College were enrolled between April 2007 and March 2009. After clinical and slit-lamp biomicroscopic examination in all suspected cases, smears and culture examination for fungus was done to establish the etiology. Demographic information and associated probable risk factors of individual cases were noted in a predesigned questionnaire. Results: In 188 (60.6% cases fungal etiology could be established. Out of them 67.6% were males. The most commonly affected age group was 41-50 years (25.5%. The maximum (23.4% cases were reported during the paddy harvesting season in Assam (January and February. Fungal element could be demonstrated in 65.2% cases in direct potassium hydroxide (KOH mount. The commonest predisposing factor was corneal injury (74.5%. While diabetes was a significant systemic predisposing factor in mixed bacterial and fungal infections in 11.1% cases, blocked naso-lacrimal duct was the local predisposing factor in 11.1% of cases. Fusarium solani (25% was the commonest isolate followed by Aspergillus species (19%, Curvularia species (18.5% and Penicillium species (15.2%. Yeasts were isolated in 2.7% (n=5 cases. Conclusions : Ocular trauma was the commonest cause of fungal corneal ulcer in Assam and Fusarium solani was the commonest species responsible for it. Most of the mycotic ulcer cases come from rural areas including the tea gardens.

  20. Fractal dimension based corneal fungal infection diagnosis

    Science.gov (United States)

    Balasubramanian, Madhusudhanan; Perkins, A. Louise; Beuerman, Roger W.; Iyengar, S. Sitharama

    2006-08-01

    We present a fractal measure based pattern classification algorithm for automatic feature extraction and identification of fungus associated with an infection of the cornea of the eye. A white-light confocal microscope image of suspected fungus exhibited locally linear and branching structures. The pixel intensity variation across the width of a fungal element was gaussian. Linear features were extracted using a set of 2D directional matched gaussian-filters. Portions of fungus profiles that were not in the same focal plane appeared relatively blurred. We use gaussian filters of standard deviation slightly larger than the width of a fungus to reduce discontinuities. Cell nuclei of cornea and nerves also exhibited locally linear structure. Cell nuclei were excluded by their relatively shorter lengths. Nerves in the cornea exhibited less branching compared with the fungus. Fractal dimensions of the locally linear features were computed using a box-counting method. A set of corneal images with fungal infection was used to generate class-conditional fractal measure distributions of fungus and nerves. The a priori class-conditional densities were built using an adaptive-mixtures method to reflect the true nature of the feature distributions and improve the classification accuracy. A maximum-likelihood classifier was used to classify the linear features extracted from test corneal images as 'normal' or 'with fungal infiltrates', using the a priori fractal measure distributions. We demonstrate the algorithm on the corneal images with culture-positive fungal infiltrates. The algorithm is fully automatic and will help diagnose fungal keratitis by generating a diagnostic mask of locations of the fungal infiltrates.

  1. Production of Hypoxia-induced Corneal Edema in Aged Eyes

    Institute of Scientific and Technical Information of China (English)

    Alan K. Cheung; Andrew W. Siu; Digby W. Cheung; Edwin C. Mo

    2004-01-01

    Purpose:Corneal thickness assessment is a common clinical procedure applied in corneal and contact lens care. This study aims to investigate the effect of age on hypoxiainduced corneal swelling.Methods:Eighteen male subjects were equally divided into the younger [(23.7±0.8) and older [(74.4±2.5) years old]groups.Each subject wore a thick soft contact lens (uniform thickness of 0.3 mm) on the left cornea. With the contact lens in place, the baseline central corneal thickness was measured using a specially designed photo-pachometer. The lens was then patched behind the closed eyelids, producing an extremely hypoxic stress to the cornea. The change in central corneal thickness was monitored every 20 minutes with momentary disruptions to the hypoxic stress over the next 2 hours. The increase in thickness was taken as an index of corneal edema. The rate of change in corneal thickness, as derived from a non-linear mathematical model, was compared between groups. Results:The corneal thickness of both age groups increased significantly with time (P<0.000 1 ). The mean corneal swelling constant for the older subjects was 16.5 × 10-3 (S.E.M. = 2.65 × 10-3) and the value for the younger subjects was 46.5 × 10-3 (S.E.M. = 3.25× 10-3). The difference was statistically significant (P < 0.000 1 ).Conclusion:Aging cornea has a slower hypoxia-induced edema response compared with the younger group. Whether it is caused by a decreased corneal lactate production or an increased resistance to physical expansion deserves further investigation. Eye Science2004;20:1-5.

  2. Riboflavin concentration in corneal stroma after intracameral injection

    Institute of Scientific and Technical Information of China (English)

    Na; Li; Xiu-Jun; Peng; Zheng-Jun; Fan; Xu; Pang; Yu; Xia; Teng-Fei; Wu

    2015-01-01

    AIM: To evaluate the enrichment of riboflavin in the corneal stroma after intracameral injection to research the barrier ability of the corneal endothelium to riboflavin in vivo.METHODS: The right eyes of 30 New Zealand white rabbits were divided into three groups. Different concentrations riboflavin-balanced salt solutions(BSS)were injected into the anterior chamber(10 with 0.5%, 10 with 1%, and 10 with 2%). Eight corneal buttons of 8.5mm in diameter from each group were dissected at 30 min after injection and the riboflavin concentrations in the corneal stroma were determined using high-performance liquid chromatography(HPLC) after removing the epithelium and endothelium. The other two rabbits in every group were observed for 24 h and sacrificed. As a comparison, the riboflavin concentrations from 16 corneal stromal samples were determined using HPLC after instillation of 0.1% riboflavin-BSS solution for30 min on the corneal surface(8 without epithelium and 8with intact epithelium).RESULTS: The mean riboflavin concentrations were11.19, 18.97, 25.08, 20.18, and 1.13 μg/g for 0.5%, 1%, 2%,de-epithelialzed samples, and the transepithelial groups,respectively. The color change of the corneal stroma and the HPLC results showed that enrichment with riboflavin similar to classical de-epithelialized corneal collagen crosslinking(CXL) could be achieved by intracameral 1%riboflavin-BSS solution after 30min; the effect appeared to be continuous for at least 30 min.CONCLUSION: Riboflavin can effectively penetrate the corneal stroma through the endothelium after an intracameral injection in vivo, so it could be an enhancing method that could improve the corneal riboflavin concentration in transepithelial CXL.

  3. Corneal surface reconstruction - a short review

    Directory of Open Access Journals (Sweden)

    Madhavan H N

    2009-01-01

    Full Text Available Cornea is the clear, dome-shaped surface that covers the front of the eye and when damage due to burns or injury and several other diseases, stem cells residing in its rim called "limbus" are stimulated to multiply to support growth of new epithelial cells over its surface. If this ready source of stem cells is damaged or destroyed the natural repair is not possible and such a condition is known as corneal limbal stem cell deficiency (CLSCD disease. Stem cell transplant helps such persons to regenerate the corneal surface. Human corneal limbal stem cell transplantation is at present an established procedure with reasonable good clinical outcome particularly when autologous limbal epithelial tissue from a fellow unaffected eye is used. 1, 2 A major concern related to the autograft is the possibility of CLSCD at the donor site, 3 techniques that allowed the expansion of a small limbal biopsy in the laboratory using cell cultures that could be then transplanted to the affected eye have been developed ,4, 5 Human amniotic membrane (HAM is used as a scaffold for both culturing the human limbal epithelial cells and for ocular surface reconstruction with the cultured limbal epithelial cells. 4-7 However, researchers have used alternative scaffolds like collagen 8, fibrin gel 9 and cross-linked gel of fibronectin and fibrin. 10 All these are biological materials and also need for animal 3T3 feeder layer for stem cell cultures. The properties of HAM are unique including antiadhesive effects, bacteriostatic effects, wound protection, pain reduction, and improvement of epithelialization and characteristically lacking imunogenicity. The use of amniotic membrane transplantation (AMT to treat ocular surface abnormalities was first reported by Graziella Pellegrini, chief of stem cell laboratory at Giovanni Paolo Hospital in Venice, Italy, who was the first to demonstrate the limbal stem cell transplant in 1997. Amniotic membrane has been successfully used in

  4. Graft Biomechanics Following Three Corneal Transplantation Techniques

    Science.gov (United States)

    Feizi, Sepehr; Montahai, Talieh; Moein, Hamidreza

    2015-01-01

    Purpose: To compare corneal biomechanical properties following three different transplantation techniques, including Descemet stripping automated endothelial keratoplasty (DSAEK), deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in comparison to normal eyes. Methods: This cross-sectional comparative study included 118 eyes: 17 eyes of 17 patients received DSAEK, 23 eyes of 21 patients underwent DALK using Anwar's big bubble technique, and 45 eyes of 36 patients had PK; 33 right eyes of 33 normal subjects served as the control group. Using the ocular response analyzer (ORA, Reichert Ophthalmic Instruments, Buffalo, New York, USA), corneal hysteresis (CH) and corneal resistance factor (CRF) were measured and compared among the study groups at least 3 months after all sutures were removed. Results: Mean patient age was 26.9 ± 5.0 years in the control group, 28.8 ± 4.2 in the PK group, 27.2 ± 6.5 in the DALK group, and 62.5 ± 16.8 in the DSAEK group (P < 0.001). Central corneal thickness (CCT) was 539.0 ± 24.8, 567.5 ± 38.8, 547.0 ± 42.6 and 631.1 ± 84.8 μm, respectively (P < 0.001). CH and CRF were significantly lower in the DSAEK group (7.79 ± 2.0 and 7.88 ± 1.74 mmHg, respectively) as compared to the PK (10.23 ± 2.07 and 10.13 ± 2.22 mmHg, respectively) and DALK (9.64 ± 2.07 and 9.36 ± 2.09 mmHg, respectively) groups. The two latter groups demonstrated biomechanical parameters comparable to normal subjects (9.84 ± 1.59 and 9.89 ± 1.73 mmHg, respectively). Conclusion: Graft biomechanical parameters after DSAEK are lower than those following PK and DALK. After PK and DALK in keratoconic eyes, these metrics are increased to normal values. These differences may have implications for interpreting intraocular pressure or planning graft refractive surgery after keratoplasty. PMID:26730307

  5. Exploring scaling laws in surface topography

    Energy Technology Data Exchange (ETDEWEB)

    Abedini, M.J. [Dept. of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON, N2L 3G1 (Canada)], E-mail: abedini@shirazu.ac.ir; Shaghaghian, M.R. [Dept. of Civil and Environmental Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of)

    2009-11-30

    Surface topography affects many soil properties and processes, particularly surface water storage and runoff. Application of fractal analysis helps understand the scaling laws inherent in surface topography at a wide range of spatial scales and climatic regimes. In this research, a high resolution digital elevation model with a 3 mm resolution on one side of the spectrum and large scale DEMs, with a 500 m spatial resolution on the other side were used to explore scaling laws in surface topography. With appropriate exploratory spatial data analysis of both types of data sets, two conventional computational procedures - variogram and Box Counting Methods (BCM) - address scaling laws in surface topography. The results respect scaling laws in surface topography to some extent as neither the plot treatment nor the direction treatment has a significant impact on fractal dimension variability. While in the variogram method, the change in slope in Richardson's plots appears to be the norm rather than the exception; Richardson's plots resulting from box counting implementation lack such mathematical behavior. These breaks in slope might have useful implications for delineating homogeneous hydrologic units and detecting change in trend in hydrologic time series. Furthermore, it is shown that fractal dimension cannot be used to capture anisotropic variabilities both within and among micro-plots. In addition, its numerical value remains insignificant at the 5% level in moving from one direction to another and also from one spatial scale to another while the ordinate intercept could discriminate the surface roughness variability from one spatial scale to another.

  6. Tendency of excimer laser corneal refractive surgeries%准分子激光角膜屈光手术的发展趋势

    Institute of Scientific and Technical Information of China (English)

    陈跃国

    2011-01-01

    In next decade, the excimer laser corneal refractive surgeries will keep the role of main stream with the continuing development and employment of femto-second laser thin flap,advanced surface ablation, wavefront and topography guided ablation, eyeball online tracking,modified monovision for compensating presbyopia. Pre-operational screening and ruling out sub-clinical keratoconus is crucial for preventing corneal ectasia and secondary keratocouns after corneal ablations.In the correction of extreme high myopia, phakic IOL implantation seems to be superior in visual quality to excimer laser corneal refractive surgeries and can keep the intact corneal biomechanical structure, suggesting that it may be a better surgical option for the treatnent of such eyes.%随着飞秒激光定制薄角膜瓣技术、改良表层切削技术、波阵面像差与角膜地形图引导技术、眼球定位及联机跟踪技术,以及老视补偿技术的不断改进和广泛应用,未来5~10年,准分子激光角膜屈光手术仍将是屈光手术的主流.术前筛选出亚临床圆锥角膜,是预防屈光手术后角膜扩张及继发性圆锥角膜的关键.为保持角膜生物力学的完整性和更好的视觉质量,可选择有晶状体眼人工晶状体植入术矫治超高度近视.

  7. The heritability of glaucoma-related traits corneal hysteresis, central corneal thickness, intraocular pressure, and choroidal blood flow pulsatility.

    Directory of Open Access Journals (Sweden)

    Ellen E Freeman

    Full Text Available PURPOSE: The purpose of this work was to investigate the heritability of potential glaucoma endophenotypes. We estimated for the first time the heritability of the pulsatility of choroidal blood flow. We also sought to confirm the heritability of corneal hysteresis, central corneal thickness, and 3 ways of measuring intraocular pressure. METHODS: Measurements were performed on 96 first-degree relatives recruited from Maisonneuve-Rosemont Hospital in Montreal. Corneal hysteresis was determined using the Reichert Ocular Response Analyser. Central corneal thickness was measured with an ultrasound pachymeter. Three measures of intraocular pressure were obtained: Goldmann-correlated and corneal compensated intraocular pressure using the Ocular Response Analyser, and Pascal intraocular pressure using the Pascal Dynamic Contour Tonometer. The pulsatility of choroidal blood velocity and flow were measured in the sub-foveolar choroid using single-point laser Doppler flowmetry (Oculix. We estimated heritability using maximum-likelihood variance components methods implemented in the SOLAR software. RESULTS: No significant heritability was detected for the pulsatility of choroidal blood flow or velocity. The Goldman-correlated, corneal compensated, and Pascal measures of intraocular pressure measures were all significantly heritable at 0.94, 0.79, and 0.53 after age and sex adjustment (p = 0.0003, p = 0.0023, p = 0.0239. Central corneal thickness was significantly heritable at 0.68 (p = 0.0078. Corneal hysteresis was highly heritable but the estimate was at the upper boundary of 1.00 preventing us from giving a precise estimate. CONCLUSION: Corneal hysteresis, central corneal thickness, and intraocular pressure are all heritable and may be suitable as glaucoma endophenotypes. The pulsatility of choroidal blood flow and blood velocity were not significantly heritable in this sample.

  8. [New stimulants of corneal reparative regeneration].

    Science.gov (United States)

    Egorov, E A; Kalinin, N I; Kiiasov, A P

    1999-01-01

    The efficacy of corneregel, a drug containing pantothenic acid, a component of coenzyme A, in healing of corneal wounds has been evaluated. The study was carried out on 19 rabbits (38 eyes) with standard corneal defect made with a 5-mm trephine for lamellar transplantation of the cornea, divided into 2 groups: 1) instillations of corneregel (10 eyes) and 0.25% levomycetin solution (10 eyes) and 2) 20% solcoseryl gel (9 eyes) and 0.25% levomycetin (9 eyes). Time course of changes were evaluated by biomicroscopy (fluorescent test), histologically (hematoxylin-eosin staining), and immunohistochemically after 1, 2, 4, 7, 30, and 90 days. Proliferative activity was studied by expression of the proliferating cell nuclear antigen and the migration capacity of cells by expression of alpha-smooth muscle actin. The terms of epithelialization were as follows: corneregel 10 +/- 7 h, 20% solcoseryl gel 108 +/- 10 h, levomycetin 124 +/- 6.93 h. Earlier epithelialization in the corneregel group was apparently due to increased expression of alpha-smooth muscle actin and increase in the cell migration capacity. Hence, corneregel is recommended for practical use as a stimulant of reparative regeneration of the cornea.

  9. Femtosecond laser's application in the corneal surgery

    Directory of Open Access Journals (Sweden)

    Shu-Liang Wang

    2015-10-01

    Full Text Available With the rapid development over the past two decades,femtosecond(10-15slasers(FShas become a new application in ophthalmic surgery. As laser power is defined as energy delivered per unit time, decreasing the pulse duration to femtosecond level(100fsnot only increases the power delivered but also decreases the fluence threshold for laser induced optical breakdown. In ablating tissue, FS has an edge over nanosecond lasers as there is minimal collateral damage from shock waves and heat conduction during surgical ablation. Thus, application of FS has been widely spread, from flap creation for laser-assisted in situ keratomileusis(LASIKsurgery, cutting of donor and recipient corneas in keratoplasty, creation of pockets for intracorneal ring implantation. FS applied in keratoplasty is mainly used in making graft and recipient bed, and can exactly cut different tissue of keratopathy. FS can also cut partial tissue of cornea, even if it is under the moderate corneal macula and corneal edema condition.

  10. IOL Power Calculation after Corneal Refractive Surgery

    Directory of Open Access Journals (Sweden)

    Maddalena De Bernardo

    2014-01-01

    Full Text Available Purpose. To describe the different formulas that try to overcome the problem of calculating the intraocular lens (IOL power in patients that underwent corneal refractive surgery (CRS. Methods. A Pubmed literature search review of all published articles, on keyword associated with IOL power calculation and corneal refractive surgery, as well as the reference lists of retrieved articles, was performed. Results. A total of 33 peer reviewed articles dealing with methods that try to overcome the problem of calculating the IOL power in patients that underwent CRS were found. According to the information needed to try to overcome this problem, the methods were divided in two main categories: 18 methods were based on the knowledge of the patient clinical history and 15 methods that do not require such knowledge. The first group was further divided into five subgroups based on the parameters needed to make such calculation. Conclusion. In the light of our findings, to avoid postoperative nasty surprises, we suggest using only those methods that have shown good results in a large number of patients, possibly by averaging the results obtained with these methods.

  11. Clinical utility of the KAMRA corneal inlay.

    Science.gov (United States)

    Naroo, Shehzad Anjam; Bilkhu, Paramdeep Singh

    2016-01-01

    The treatment of presbyopia has been the focus of much scientific and clinical research over recent years, not least due to an increasingly aging population but also the desire for spectacle independence. Many lens and nonlens-based approaches have been investigated, and with advances in biomaterials and improved surgical methods, removable corneal inlays have been developed. One such development is the KAMRA™ inlay where a small entrance pupil is exploited to create a pinhole-type effect that increases the depth of focus and enables improvement in near visual acuity. Short- and long-term clinical studies have all reported significant improvement in near and intermediate vision compared to preoperative measures following monocular implantation (nondominant eye), with a large proportion of patients achieving Jaeger (J) 2 to J1 (~0.00 logMAR to ~0.10 logMAR) at the final follow-up. Although distance acuity is reduced slightly in the treated eye, binocular visual acuity and function remain very good (mean 0.10 logMAR or better). The safety of the inlay is well established and easily removable, and although some patients have developed corneal changes, these are clinically insignificant and the incidence appears to reduce markedly with advancements in KAMRA design, implantation technique, and femtosecond laser technology. This review aims to summarize the currently published peer-reviewed studies on the safety and efficacy of the KAMRA inlay and discusses the surgical and clinical outcomes with respect to the patient's visual function.

  12. Topography data from the Elwha River delta, Washington, September 2014

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of the data release presents topography data from the Elwha River delta collected in September 2014. Topography data were collected on foot with global...

  13. Corneal power evaluation after myopic corneal refractive surgery using artificial neural networks.

    Science.gov (United States)

    Koprowski, Robert; Lanza, Michele; Irregolare, Carlo

    2016-11-15

    Efficacy and high availability of surgery techniques for refractive defect correction increase the number of patients who undergo to this type of surgery. Regardless of that, with increasing age, more and more patients must undergo cataract surgery. Accurate evaluation of corneal power is an extremely important element affecting the precision of intraocular lens (IOL) power calculation and errors in this procedure could affect quality of life of patients and satisfaction with the service provided. The available device able to measure corneal power have been tested to be not reliable after myopic refractive surgery. Artificial neural networks with error backpropagation and one hidden layer were proposed for corneal power prediction. The article analysed the features acquired from the Pentacam HR tomograph, which was necessary to measure the corneal power. Additionally, several billion iterations of artificial neural networks were conducted for several hundred simulations of different network configurations and different features derived from the Pentacam HR. The analysis was performed on a PC with Intel(®) Xeon(®) X5680 3.33 GHz CPU in Matlab(®) Version 7.11.0.584 (R2010b) with Signal Processing Toolbox Version 7.1 (R2010b), Neural Network Toolbox 7.0 (R2010b) and Statistics Toolbox (R2010b). A total corneal power prediction error was obtained for 172 patients (113 patients forming the training set and 59 patients in the test set) with an average age of 32 ± 9.4 years, including 67% of men. The error was at an average level of 0.16 ± 0.14 diopters and its maximum value did not exceed 0.75 dioptres. The Pentacam parameters (measurement results) providing the above result are tangential anterial/posterior. The corneal net power and equivalent k-reading power. The analysis time for a single patient (a single eye) did not exceed 0.1 s, whereas the time of network training was about 3 s for 1000 iterations (the number of neurons in the hidden layer was 400).

  14. Hypercalcemia Leads to Delayed Corneal Wound Healing in Ovariectomized Rats.

    Science.gov (United States)

    Nagai, Noriaki; Ogata, Fumihiko; Kawasaki, Naohito; Ito, Yoshimasa; Funakami, Yoshinori; Okamoto, Norio; Shimomura, Yoshikazu

    2015-01-01

    Hypercalcemia is often observed in postmenopausal women as well as in patients with primary hyperparathyroidism or malignant tumors. In this study, we investigated the relationship between calcium ion (Ca(2+)) levels in lacrimal fluid and the rate of corneal wound healing in hypercalcemia using ovariectomized (OVX) rat debrided corneal epithelium. We also determined the effects of Ca(2+) levels on cell adhesion, proliferation and viability in a human cornea epithelial cell line (HCE-T). The calcium content in bones of OVX rats decreased after ovariectomy. Moreover, the Ca(2+) content in the blood of OVX rats was increased 1 month after ovariectomy, and decreased. The Ca(2+) content in the lacrimal fluid of OVX rats was also increased after ovariectomy, and then decreased similarly as in blood. Corneal wound healing in OVX rats was delayed in comparison with Sham rats (control rats), and a close relationship was observed between the Ca(2+) levels in lacrimal fluid and the rate of corneal wound healing in Sham and OVX rats (y=-0.7863x+8.785, R=0.78, n=25). In addition, an enhancement in Ca(2+) levels caused a decrease in the viability in HCE-T cells. It is possible that enhanced Ca(2+) levels in lacrimal fluid may cause a decrease in the viability of corneal epithelial cells, resulting in a delay in corneal wound healing. These findings provide significant information that can be used to design further studies aimed at reducing corneal damage of patients with hypercalcemia.

  15. Characteristics of corneal lens chitin in dragonfly compound eyes.

    Science.gov (United States)

    Kaya, Murat; Sargin, Idris; Al-Jaf, Ivan; Erdogan, Sevil; Arslan, Gulsin

    2016-08-01

    Chitin in the compound eyes of arthropods serves as a part of the visual system. The quality of chitin in such highly specialised body parts deserves more detailed examination. Chitin in the corneal (ommatidial) lenses of dragonfly (Sympetrum fonscolombii) compound eyes was isolated by using the classical chemical method. The chitin content of the corneal lenses was determined to be quite high (20.3±0.85%). The FT-IR analysis showed that corneal lens chitin was in the α-form as found in all arthropod species where mechanical strength is required. The surface morphology analysis by scanning electron microscopy revealed that the outer part of corneal lenses consisted of long chitin fibrils with regular arrays of papillary structures while the smoother inner part had concentric lamellated chitin formation with shorter chitin nanofibrils. Chitinase enzymatic digestion studies, elemental analysis results and the degree of acetylation value showed the purity of chitin samples from corneal lens. The maximum degradation temperature value of the corneal lens chitin was observed at 369.2°C. X-ray analysis revealed that corneal lens chitin has high crystallinity index; 96.4%. Identification of chitin found in ommaditia of insect compound eyes can provide insights into insect vision and chitin-based optical material design studies.

  16. Cytocompatibility of Three Corneal Cell Types with Amniotic Membrane

    Institute of Scientific and Technical Information of China (English)

    CHENJian-su; CHENRui; XUJin-tang; DINGYong; ZHAOSong-bin; LISui-lian

    2004-01-01

    Rabbit limbal corneal epithelial cells, corneal endothelial cells and keratocytes were cultured on amniotic membrane. Phase contrast microscope examination was performed daily. Histological and scan electron microscopic examinations were carried out to observe the growth, arrangement and adhesion of cultivated cells. Results showed that three corneal cell types seeded on amniotic membrane grew well and had normal cell morphology. Cultured cells attached firmly on the surface of amniotic membrane. Corneal epithelial cells showed singular layer or stratification. Cell boundaries were formed and tightly opposed. Corneal endothelial cells showed cobblestone or polygonal morphologic characteristics that appeared uniform in size. The cellular arrangement was compact. Keratocytes elongated and showed triangle or dendritic morphology with many intercellular joints which could form networks. In conclusion, amniotic membrane has good scaffold property, diffusion effect and compatibility with corneal cells. The basement membrane side of amniotic membrane facilitated the growth of corneal epithelial cells and endothelial cells and cell junctions were tightly developed. The spongy layer of amniotic membrane facilitated the growth of keratocytes and intercellular joints were rich. Amniotic membrane is an ideal biomaterial for layering tissue engineered cornea.

  17. Impact of facial conformation on canine health: corneal ulceration.

    Directory of Open Access Journals (Sweden)

    Rowena M A Packer

    Full Text Available Concern has arisen in recent years that selection for extreme facial morphology in the domestic dog may be leading to an increased frequency of eye disorders. Corneal ulcers are a common and painful eye problem in domestic dogs that can lead to scarring and/or perforation of the cornea, potentially causing blindness. Exaggerated juvenile-like craniofacial conformations and wide eyes have been suspected as risk factors for corneal ulceration. This study aimed to quantify the relationship between corneal ulceration risk and conformational factors including relative eyelid aperture width, brachycephalic (short-muzzled skull shape, the presence of a nasal fold (wrinkle, and exposed eye-white. A 14 month cross-sectional study of dogs entering a large UK based small animal referral hospital for both corneal ulcers and unrelated disorders was carried out. Dogs were classed as affected if they were diagnosed with a corneal ulcer using fluorescein dye while at the hospital (whether referred for this disorder or not, or if a previous diagnosis of corneal ulcer(s was documented in the dogs' histories. Of 700 dogs recruited, measured and clinically examined, 31 were affected by corneal ulcers. Most cases were male (71%, small breed dogs (mean± SE weight: 11.4±1.1 kg, with the most commonly diagnosed breed being the Pug. Dogs with nasal folds were nearly five times more likely to be affected by corneal ulcers than those without, and brachycephalic dogs (craniofacial ratio <0.5 were twenty times more likely to be affected than non-brachycephalic dogs. A 10% increase in relative eyelid aperture width more than tripled the ulcer risk. Exposed eye-white was associated with a nearly three times increased risk. The results demonstrate that artificially selecting for these facial characteristics greatly heightens the risk of corneal ulcers, and such selection should thus be discouraged to improve canine welfare.

  18. Impact of facial conformation on canine health: corneal ulceration.

    Science.gov (United States)

    Packer, Rowena M A; Hendricks, Anke; Burn, Charlotte C

    2015-01-01

    Concern has arisen in recent years that selection for extreme facial morphology in the domestic dog may be leading to an increased frequency of eye disorders. Corneal ulcers are a common and painful eye problem in domestic dogs that can lead to scarring and/or perforation of the cornea, potentially causing blindness. Exaggerated juvenile-like craniofacial conformations and wide eyes have been suspected as risk factors for corneal ulceration. This study aimed to quantify the relationship between corneal ulceration risk and conformational factors including relative eyelid aperture width, brachycephalic (short-muzzled) skull shape, the presence of a nasal fold (wrinkle), and exposed eye-white. A 14 month cross-sectional study of dogs entering a large UK based small animal referral hospital for both corneal ulcers and unrelated disorders was carried out. Dogs were classed as affected if they were diagnosed with a corneal ulcer using fluorescein dye while at the hospital (whether referred for this disorder or not), or if a previous diagnosis of corneal ulcer(s) was documented in the dogs' histories. Of 700 dogs recruited, measured and clinically examined, 31 were affected by corneal ulcers. Most cases were male (71%), small breed dogs (mean± SE weight: 11.4±1.1 kg), with the most commonly diagnosed breed being the Pug. Dogs with nasal folds were nearly five times more likely to be affected by corneal ulcers than those without, and brachycephalic dogs (craniofacial ratio ulcer risk. Exposed eye-white was associated with a nearly three times increased risk. The results demonstrate that artificially selecting for these facial characteristics greatly heightens the risk of corneal ulcers, and such selection should thus be discouraged to improve canine welfare.

  19. Surface micro topography replication in injection moulding

    DEFF Research Database (Denmark)

    Arlø, Uffe Rolf

    , the topography itself, and other factors were also investigated. The experimental work is based on a multi-purpose experimental injection mould with a collection of test surface inserts manufactured by EDM (electrical discharge machining). Experimental production took place with an injection moulding machine......Thermoplastic injection moulding is a widely used industrial process that involves surface generation by replication. The surface topography of injection moulded plastic parts can be important for aesthetical or technical reasons. With the emergence of microengineering and nanotechnology additional...... in a clean room environment. The mould and the injection moulding machine were fitted with transducers for subsequent process analysis. A total of 13 different plastic material grades were applied. Topographical characterisation was performed with an optical laser focus detection instrument. Replication...

  20. Impact of watershed topography on hyporheic exchange

    Science.gov (United States)

    Caruso, Alice; Ridolfi, Luca; Boano, Fulvio

    2016-08-01

    Among the interactions between surface water bodies and aquifers, hyporheic exchange has been recognized as a key process for nutrient cycling and contaminant transport. Even though hyporheic exchange is strongly controlled by groundwater discharge, our understanding of the impact of the regional groundwater flow on hyporheic fluxes is still limited because of the complexity arising from the multi-scale nature of these interactions. In this work, we investigate the role of watershed topography on river-aquifer interactions by way of a semi-analytical model, in which the landscape topography is used to approximate the groundwater head distribution. The analysis of a case study shows how the complex topographic structure is the direct cause of a substantial spatial variability of the aquifer-river exchange. Groundwater upwelling along the river corridor is estimated and its influence on the hyporheic zone is discussed. In particular, the fragmentation of the hyporeic corridor induced by groundwater discharge at the basin scale is highlighted.

  1. Scholte waves generated by seafloor topography

    CERN Document Server

    Zheng, Yingcai; Liu, Jing; Fehler, Michael C

    2013-01-01

    Seafloor topography can excite strong interface waves called Scholte waves that are often dispersive and characterized by slow propagation but large amplitude. This type of wave can be used to invert for near seafloor shear wave velocity structure that is important information for multi-component P-S seismic imaging. Three different approaches are taken to understand excitation of Scholte waves and numerical aspects of modeling Scholte waves, including analytical Cagniard-de Hoop analysis, the boundary integral method and a staggered grid finite difference method. For simple media for which the Green's function can be easily computed, the boundary element method produces accurate results. The finite difference method shows strong numerical artifacts and stagnant artificial waves can be seen in the vicinity of topography at the fluid-solid interface even when using fine computational grids. However, the amplitude of these artificial waves decays away from the seafloor. It is sensible to place receivers away fr...

  2. Methylene blue-related corneal edema and iris discoloration.

    Science.gov (United States)

    Timucin, Ozgur Bulent; Karadag, Mehmet Fatih; Aslanci, Mehmet Emin; Baykara, Mehmet

    2016-04-01

    We report the case of a 70-year-old female patient who developed corneal edema and iris discoloration following the inadvertent use of 1% methylene blue instead of 0.025% trypan blue to stain the anterior capsule during cataract phacoemulsification surgery. Copious irrigation was performed upon realization of incorrect dye use. Corneal edema and iris discoloration developed during the early postoperative period and persisted at 24-months follow-up. However, keratoplasty was not required. The intracameral use of 1% methylene blue has a cytotoxic effect on the corneal endothelium and iris epithelium. Copious irrigation for at least 30 min using an anterior chamber maintainer may improve outcomes.

  3. Repositioning of pedicle conjunctival flap performed for refractory corneal ulcer

    Directory of Open Access Journals (Sweden)

    Ashok Sharma

    2014-01-01

    Full Text Available A 50-year-old male was referred with a previous history of conjunctival flap (CF for a nonhealing fungal corneal ulcer with extreme corneal thinning in the right eye. The peritomy for the CF extended from 6:30 to 9:30 clock h on the cornea. The CF was disengaged, peritomy area deepithelialized, and CF was repositioned. He later underwent penetrating keratoplasty and achieved 20/40 best corrected visual acuity. The authors present a new concept for surgically repositioning CF s to the original site immediately after healing of the corneal ulcer.

  4. Repositioning of pedicle conjunctival flap performed for refractory corneal ulcer.

    Science.gov (United States)

    Sharma, Ashok; Mohan, Kanwar; Sharma, Rajan; Nirankari, Verinder S

    2014-01-01

    A 50-year-old male was referred with a previous history of conjunctival flap (CF) for a nonhealing fungal corneal ulcer with extreme corneal thinning in the right eye. The peritomy for the CF extended from 6:30 to 9:30 clock h on the cornea. The CF was disengaged, peritomy area deepithelialized, and CF was repositioned. He later underwent penetrating keratoplasty and achieved 20/40 best corrected visual acuity. The authors present a new concept for surgically repositioning CF s to the original site immediately after healing of the corneal ulcer.

  5. Septo-optic dysplasia with bilateral congenital corneal anesthesia.

    Science.gov (United States)

    Chow, Clement C; Kapur, Rashmi; Wood, Michael G; Setabutr, Pete; Tu, Elmer Y

    2009-10-01

    Septo-optic dysplasia, or de Morsier syndrome, is characterized by optic nerve hypoplasia with an absent septum pellucidum and/or pituitary abnormalities. Congenital corneal anesthesia is a rare disorder that has been associated with many neurological disorders. Here we present a patient with both conditions who was successfully treated with permanent lateral tarsorrhaphy and aggressive lubrication. To our knowledge, congenital corneal anesthesia has not been reported in association with septo-optic dysplasia. The purpose of this report is to make pediatric ophthalmologists aware of a potential association since the diagnosis of congenital corneal anesthesia is often difficult and delayed.

  6. UUnilateral corneal edema caused by a hidden foreign body.

    Science.gov (United States)

    Galvis, V; Tello, A; Frederick, G A; Laiton, A N

    2017-09-01

    A middle-aged adult male was referred to our institution due to unilateral corneal edema for a possible corneal transplant. At first, the patient denied a history of trauma. A small foreign body, which had been overlooked by the primary ophthalmologist, was detected by gonioscopy, embedded in the anterior chamber angle. It was successfully surgically removed and visual results were good. In any patient with unilateral unexplained corneal edema, it is necessary to rule out the presence of a foreign body in the anterior chamber. Copyright © 2016 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

  7. Randomized Controlled Trial Comparing Transepithelial Corneal Cross-linking Using Iontophoresis with the Dresden Protocol in Progressive Keratoconus.

    Science.gov (United States)

    Lombardo, Marco; Giannini, Daniela; Lombardo, Giuseppe; Serrao, Sebastiano

    2017-06-01

    improvements were found 12 months after T-ionto CL, though the average improvement in corneal topography readings was slightly lower than the Dresden protocol in the same period. Copyright © 2017 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  8. Topography over South America from ERS altimetry

    Science.gov (United States)

    Brenner, Anita; Frey, Herb; DiMarzio, John; Tsaoussi, Lucia

    1997-01-01

    The results of the surface topography mapping of South America during the ERS-1 geodetic mission are presented. The altimeter waveforms, the range measurement, and the internal and Doppler range corrections were obtained. The atmospheric corrections and solid tides were calculated. Comparisons between Shuttle laser altimetry and ERS-1 altimetry grid showed good agreement. Satellite radar altimetry data can be used to improve the topographic knowledge of regions for which only poor elevation data currently exist.

  9. ATM Coastal Topography-Alabama 2001

    Science.gov (United States)

    Nayegandhi, Amar; Yates, Xan; Brock, John C.; Sallenger, A.H.; Bonisteel, Jamie M.; Klipp, Emily S.; Wright, C. Wayne

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the Alabama coastline, acquired October 3-4, 2001. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative scanning Lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning Lidar system that measures high-resolution topography of the land surface, and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for pre-survey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is routinely used to create maps that

  10. ATM Coastal Topography-Mississippi, 2001

    Science.gov (United States)

    Nayegandhi, Amar; Yates, Xan; Brock, John C.; Sallenger, A.H.; Klipp, Emily S.; Wright, C. Wayne

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of lidar-derived first-surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the Mississippi coastline, from Lakeshore to Petit Bois Island, acquired September 9-10, 2001. The datasets are made available for use as a management tool to research scientists and natural-resource managers. An innovative scanning lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning lidar system that measures high-resolution topography of the land surface and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser-ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of lidar data in an interactive or batch mode. Modules for presurvey flight-line definition, flight-path plotting, lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS

  11. Corneal melanosis successfully treated using topical mitomycin-C and alcohol corneal epitheliectomy: a 3-year follow-up case report

    Directory of Open Access Journals (Sweden)

    Mehmet Balcı

    2015-08-01

    Full Text Available ABSTRACTWe report a case of primary acquired corneal melanosis without atypia associated with corneal haze in a patient with a history of limbal malignant melanoma and the effect of mitomycin-C. A 75-year-old woman with a history of limbal malignant melanoma presented with loss of vision in right eye. Corneal examination showed a patchy melanotic pigmentation with a central haze. Topical mitomycin-C improved visual acuity and corneal haze. However, the pigmented lesions persisted, and they were removed with alcohol corneal epitheliectomy. Histopathological examination demonstrated primary acquired melanosis without atypia. The lesions were successfully removed, and there were no recurrences during the follow-up period of 36 months. The association of conjunctival and corneal melanosis without atypia is a rare condition. In addition, co-existence of central corneal haze and melanosis may decrease visual acuity. Topical mitomycin-C and alcohol corneal epitheliectomy can be useful treatments in this condition.

  12. Corneal melanosis successfully treated using topical mitomycin-C and alcohol corneal epitheliectomy: a 3-year follow-up case report.

    Science.gov (United States)

    Balcı, Mehmet; Yağcı, Ramazan; Güler, Emre; Haltaş, Hacer; Duman, Rahmi; Hepşen, İbrahim F

    2015-01-01

    We report a case of primary acquired corneal melanosis without atypia associated with corneal haze in a patient with a history of limbal malignant melanoma and the effect of mitomycin-C. A 75-year-old woman with a history of limbal malignant melanoma presented with loss of vision in right eye. Corneal examination showed a patchy melanotic pigmentation with a central haze. Topical mitomycin-C improved visual acuity and corneal haze. However, the pigmented lesions persisted, and they were removed with alcohol corneal epitheliectomy. Histopathological examination demonstrated primary acquired melanosis without atypia. The lesions were successfully removed, and there were no recurrences during the follow-up period of 36 months. The association of conjunctival and corneal melanosis without atypia is a rare condition. In addition, co-existence of central corneal haze and melanosis may decrease visual acuity. Topical mitomycin-C and alcohol corneal epitheliectomy can be useful treatments in this condition.

  13. Intraoperative Corneal Thickness Changes during Pulsed Accelerated Corneal Cross-Linking Using Isotonic Riboflavin with HPMC

    Directory of Open Access Journals (Sweden)

    Ahmed M. Sherif

    2016-01-01

    Full Text Available Purpose. To evaluate corneal thickness changes during pulsed accelerated corneal cross-linking (CXL for keratoconus using a new isotonic riboflavin formula. Methods. In this prospective, interventional, clinical study patients with grades 1-2 keratoconus (Amsler-Krumeich classification underwent pulsed accelerated (30 mW/cm2 CXL after application of an isotonic riboflavin solution (0.1% with HPMC for 10 minutes. Central corneal thickness (CCT measurements were taken using ultrasound pachymetry before and after epithelial removal, after riboflavin soaking, and immediately after completion of UVA treatment. Results. Twenty eyes of 11 patients (4 males, 7 females were enrolled. Mean patient age was 26±3 (range from 18 to 30 years. No intraoperative or postoperative complications were observed in any of the patients. Mean CCT was 507±35 μm (range: 559–459 μm before and 475±40 μm (range: 535–420 μm after epithelial removal (P<0.001. After 10 minutes of riboflavin instillation, there was a statistically significant decrease of CCT by 6.2% from 475±40 μm (range: 535–420 μm to 446±31 μm (range: 508–400 (P<0.005. There was no other statistically significant change of CCT during UVA irradiation. Conclusions. A significant decrease of corneal thickness was demonstrated during the isotonic riboflavin with HPMC application while there was no significant change during the pulsed accelerated UVA irradiation.

  14. Generation of corneal epithelial cells from induced pluripotent stem cells derived from human dermal fibroblast and corneal limbal epithelium.

    Directory of Open Access Journals (Sweden)

    Ryuhei Hayashi

    Full Text Available Induced pluripotent stem (iPS cells can be established from somatic cells. However, there is currently no established strategy to generate corneal epithelial cells from iPS cells. In this study, we investigated whether corneal epithelial cells could be differentiated from iPS cells. We tested 2 distinct sources: human adult dermal fibroblast (HDF-derived iPS cells (253G1 and human adult corneal limbal epithelial cells (HLEC-derived iPS cells (L1B41. We first established iPS cells from HLEC by introducing the Yamanaka 4 factors. Corneal epithelial cells were successfully induced from the iPS cells by the stromal cell-derived inducing activity (SDIA differentiation method, as Pax6(+/K12(+ corneal epithelial colonies were observed after prolonged differentiation culture (12 weeks or later in both the L1B41 and 253G1 iPS cells following retinal pigment epithelial and lens cell induction. Interestingly, the corneal epithelial differentiation efficiency was higher in L1B41 than in 253G1. DNA methylation analysis revealed that a small proportion of differentially methylated regions still existed between L1B41 and 253G1 iPS cells even though no significant difference in methylation status was detected in the specific corneal epithelium-related genes such as K12, K3, and Pax6. The present study is the first to demonstrate a strategy for corneal epithelial cell differentiation from human iPS cells, and further suggests that the epigenomic status is associated with the propensity of iPS cells to differentiate into corneal epithelial cells.

  15. OpenTopography: Enabling Online Access to High-Resolution Lidar Topography Data and Processing Tools

    Science.gov (United States)

    Crosby, Christopher; Nandigam, Viswanath; Baru, Chaitan; Arrowsmith, J. Ramon

    2013-04-01

    High-resolution topography data acquired with lidar (light detection and ranging) technology are revolutionizing the way we study the Earth's surface and overlying vegetation. These data, collected from airborne, tripod, or mobile-mounted scanners have emerged as a fundamental tool for research on topics ranging from earthquake hazards to hillslope processes. Lidar data provide a digital representation of the earth's surface at a resolution sufficient to appropriately capture the processes that contribute to landscape evolution. The U.S. National Science Foundation-funded OpenTopography Facility (http://www.opentopography.org) is a web-based system designed to democratize access to earth science-oriented lidar topography data. OpenTopography provides free, online access to lidar data in a number of forms, including the raw point cloud and associated geospatial-processing tools for customized analysis. The point cloud data are co-located with on-demand processing tools to generate digital elevation models, and derived products and visualizations which allow users to quickly access data in a format appropriate for their scientific application. The OpenTopography system is built using a service-oriented architecture (SOA) that leverages cyberinfrastructure resources at the San Diego Supercomputer Center at the University of California San Diego to allow users, regardless of expertise level, to access these massive lidar datasets and derived products for use in research and teaching. OpenTopography hosts over 500 billion lidar returns covering 85,000 km2. These data are all in the public domain and are provided by a variety of partners under joint agreements and memoranda of understanding with OpenTopography. Partners include national facilities such as the NSF-funded National Center for Airborne Lidar Mapping (NCALM), as well as non-governmental organizations and local, state, and federal agencies. OpenTopography has become a hub for high-resolution topography

  16. Generation of Solitary Rossby Waves by Unstable Topography

    Institute of Scientific and Technical Information of China (English)

    YANG Hong-Wei; YIN Bao-Shu; DONG Huan-He

    2012-01-01

    The effect of topography on generation of the solitary Rossby waves is researched. Here, the topography, as a forcing for waves generation, is taken as a function of longitude variable x and time variable t, which is called unstable topography. With the help of a perturbation expansion method, a forced mKdv equation governing the evolution of amplitude of the solitary Rossby waves is derived from quasi-geostrophic vortieity equation and is solved by the pseudo-spectral method. Basing on the waterfall plots, the generational features of the solitary Rossby waves under the influence of unstable topography and stable topography are compared and some conclusions are obtained.

  17. Age-Related Long-Term Functional Results after Riboflavin UV A Corneal Cross-Linking.

    Science.gov (United States)

    Caporossi, Aldo; Mazzotta, Cosimo; Baiocchi, Stefano; Caporossi, Tomaso; Denaro, Rosario

    2011-01-01

    Purpose. To report a comparative prospective long-term functional analysis after Riboflavin UV A corneal cross-linking (CXL) in three different age groups of patients affected by progressive keratoconus (KC). Methods. Functional analysis comprised paediatric patients (≤18 years) included 152 eyes (29.5%); intermediate group (19-26 years) 286 eyes (55.4%), and adults (≥27 years) 78 eyes (15.1%). CXL was performed according to the Siena protocol by using the Vega CBM (Caporossi-Baiocchi-Mazzotta) X linker (CSO, Florence, Italy) at Siena University by the same authors. Pre- and post-op examinations included UCVA, BSCVA, corneal topography, and surface aberrometry (CSO Eye Top, Florence, Italy), at 48 months followup. Results. At 48 months followup paediatrics, intermediate, and adult patients showed a mean gain in UCVA of +0.2, +0.14 and +0.12 Snellen lines. BSCVA gained by a mean of +0.21, +0.2, and +0.1 Snellen lines. K(max) was reduced by a mean value of -0.9 D, -0.6 D, and -0.5 D, respectively. Coma values improved by a mean of -0.45 μm, -0.91 μm, and -0.19 μm, respectively. Treatment ensured a long-term keratoconus stabilization in over 90% of treated patients. Conclusion. According to our long-term comparative results, epithelium-off Riboflavin UV A cross-linking should be the first choice therapy of progressive KC, particularly in paediatric age and patients under 26 years.

  18. Age-Related Long-Term Functional Results after Riboflavin UV A Corneal Cross-Linking

    Directory of Open Access Journals (Sweden)

    Aldo Caporossi

    2011-01-01

    Full Text Available Purpose. To report a comparative prospective long-term functional analysis after Riboflavin UV A corneal cross-linking (CXL in three different age groups of patients affected by progressive keratoconus (KC. Methods. Functional analysis comprised paediatric patients (≤18 years included 152 eyes (29.5%; intermediate group (19–26 years 286 eyes (55.4%, and adults (≥27 years 78 eyes (15.1%. CXL was performed according to the Siena protocol by using the Vega CBM (Caporossi-Baiocchi-Mazzotta X linker (CSO, Florence, Italy at Siena University by the same authors. Pre- and post-op examinations included UCVA, BSCVA, corneal topography, and surface aberrometry (CSO Eye Top, Florence, Italy, at 48 months followup. Results. At 48 months followup paediatrics, intermediate, and adult patients showed a mean gain in UCVA of +0.2, +0.14 and +0.12 Snellen lines. BSCVA gained by a mean of +0.21, +0.2, and +0.1 Snellen lines. Kmax was reduced by a mean value of −0.9 D, −0.6 D, and −0.5 D, respectively. Coma values improved by a mean of −0.45 μm, −0.91 μm, and −0.19 μm, respectively. Treatment ensured a long-term keratoconus stabilization in over 90% of treated patients. Conclusion. According to our long-term comparative results, epithelium-off Riboflavin UV A cross-linking should be the first choice therapy of progressive KC, particularly in paediatric age and patients under 26 years.

  19. A novel color-LED corneal topographer to assess astigmatism in pseudophakic eyes

    Directory of Open Access Journals (Sweden)

    Ferreira TB

    2016-08-01

    Full Text Available Tiago B Ferreira, Filomena J Ribeiro Department of Ophthalmology, Hospital da Luz, Lisbon, Portugal Purpose: To assess the accuracy of corneal astigmatism evaluation measured by four techniques, Orbscan IIz®, Lenstar LS900®, Cassini®, and Total Cassini (anterior + posterior surface, in pseudophakic eyes. Patients and methods: A total of 30 patients (46 eyes who had undergone cataract surgery with the implantation of a monofocal intraocular lens (AcrySof IQ were assessed after surgery. For each eye, subjective assessment of astigmatism and its axis was performed. Minimum, maximum, and mean keratometry and astigmatism and its axis were evaluated using the four measurement techniques. All measurements were compared with the subjective measurements. Agreement between each measurement technique and subjective assessment was evaluated using Bland–Altman plots. Linear regressions were performed and compared. Results: Linear regression analysis of astigmatism axis showed very high R2 for all models, with Total Cassini showing the least difference to the unit slope (0.052 and the least difference to a null constant (3.790, although not statistically different from the other models. Regarding astigmatism value, the Cassini and Total Cassini models were similar and statistically better than the Lenstar model. Cassini and Total Cassini showed better J0 compared with Orbscan. Conclusion: On linear regression models, Cassini and Total Cassini showed the best performance regarding astigmatism value. Cassini and Total Cassini also showed the least J0 deviation from the Cartesian origin compared with Orbscan, which had the lowest performance. Total corneal measurement with the color LED topographer seems to be a better technique for astigmatism assessment. Keywords: astigmatism, keratometry, topography

  20. Pediatric Corneal Crosslinking: Comparison of Visual and Topographic Outcomes between Conventional and Accelerated Treatment.

    Science.gov (United States)

    Baenninger, Philipp B; Bachmann, Lucas M; Wienecke, Ludmilla; Thiel, Michael A; Kaufmann, Claude

    2017-08-29

    To compare visual and topographic outcomes 1 year after conventional (C-CXL) versus accelerated corneal crosslinking (A-CXL) in pediatric keratoconus DESIGN: Comparative, retrospective, consecutive case-series METHODS: Patients with topography confirmed, progressive KC and a corneal thickness of ≥400 micrometers at the time of surgery were enrolled. Uncorrected (UCVA) and best phoropter-corrected visual acuity (BCVA) and Kmax were measured at study entry and the 12-months follow-up. Treatment failure rate was defined as the percentage of eyes with an increase in Kmax of more than 1.0 diopter during follow-up. The adverse event rate was the percentage of eyes with a loss of ≥2 Snellen lines of BCVA from baseline. Single center analysis of 78 eyes of 58 patients that underwent in 39 eyes C-CXL and in 39 eyes A-CXL. No eyes were lost to follow-up after 12 months. No significant difference between changes in 12 months after as compared to the time before CXL for UCVA (0.01 log MAR; 95%CI (-0.14-0.15), p=0.944), BCVA (0.05 log MAR; 95%CI (-0.05-0.15), p=0.310) and Kmax (-0.77 Diopters; 95%CI (-2.20-0.65), p=0.282) between the C-CXL and A-CXL group were observed. Treatment failure rate was observed in 9/39 eyes (23.1%) in C-CXL and in 6/39 eyes (15.4%) in A-CXL (p=0.389). Adverse events were seen only in 1 eye in the C-CXL group. In this retrospective comparison, the accelerated approach was equally effective than the conventional protocol to treat pediatric keratoconus. Copyright © 2017 Elsevier Inc. All rights reserved.