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Tetsuro Oshika - One of the best experts on this subject based on the ideXlab platform.
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longitudinal analysis of Corneal Topography in suspected keratoconus
British Journal of Ophthalmology, 2009Co-Authors: Mariko Shirayamasuzuki, Shiro Amano, Norihiko Honda, Satoru Yamagami, Tomohiko Usui, Tetsuro OshikaAbstract:Aims: To examine the incidence of progression of suspected keratoconus to true keratoconus and compare quantitative descriptors of Corneal Topography between eyes with and without progression. Methods: 34 eyes with suspected keratoconus were retrospectively reviewed in 34 patients. Their age at the initial examination was 13 to 40 years (24.1 (7.5), mean (SD)), and the follow-up periods ranged from 3 to 10 years (6.0 (2.2) years). Suspected keratoconus was defined as the fellow eye of a clinically apparent keratoconus but that had no slit-lamp signs of keratoconus (Fleischer ring, Vogt striae and Munson sign) with a best spectacle-corrected visual acuity of 20/20 or better. Eyes were monitored for the progression of apparent slit-lamp findings of keratoconus during the follow-up period. Using a Fourier analysis of the Corneal Topography data, regular astigmatism, asymmetry component and higher-order irregularity component were calculated in the central 3 mm zone. Quantitative descriptors of Corneal Topography were compared between eyes which progressed to true keratoconus and those which did not. Results: Five eyes (14.7%) progressed to apparent keratoconus from suspected keratoconus (progression group), and 29 eyes did not (non-progression group). On average, it took 5.2 years for the eyes to develop apparent slit-lamp findings of keratoconus. The cumulative incidence of progression by Kaplan–Meier analysis was 21.5% in 6 years. The asymmetry component and regular astigmatism by Fourier analysis at the initial examination were significantly larger in the progression group than in the non-progression group. Conclusion: In our retrospective study, approximately 20% of eyes with suspected keratoconus progressed to true keratoconus in 6 years, and these eyes had presented greater asymmetry and regular astigmatism at the initial examination.
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changes in Corneal Topography after 25 gauge transconjunctival sutureless vitrectomy versus after 20 gauge standard vitrectomy
Ophthalmology, 2007Co-Authors: Fumiki Okamoto, C Okamoto, N Sakata, K Hiratsuka, N Yamane, Takahiro Hiraoka, Yuichi Kaji, Tetsuro OshikaAbstract:Purpose To evaluate the changes in regular and irregular Corneal astigmatism after 25-gauge transconjunctival sutureless vitrectomy and 20-gauge standard vitrectomy. Design Prospective observational comparative case series. Participants Thirty-two eyes of 32 patients undergoing 25-gauge transconjunctival sutureless vitrectomy and 25 eyes of 24 patients undergoing 20-gauge standard vitrectomy. Methods Corneal Topography was obtained preoperatively and at 2 weeks and 1 month postoperatively. Main Outcome Measures The dioptric data of the central 3-mm zone of the cornea were decomposed using Fourier harmonic analysis into spherical power, regular astigmatism, asymmetry, and higher-order irregularity. Results None of the 4 Fourier indices changed throughout the observation period in the 25-gauge group. In the 20-gauge group, regular astigmatism, asymmetry, and higher-order irregularity were increased significantly at 2 weeks after vitrectomy ( P P U test). Conclusions Twenty-five–gauge transconjunctival sutureless vitrectomy does not induce significant changes in Corneal Topography and exerts little influence on the optical quality of the cornea.
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structural analysis of the cornea using scanning slit Corneal Topography in eyes undergoing excimer laser refractive surgery
Cornea, 2004Co-Authors: Kazutaka Kamiya, Kazunori Miyata, Takahiro Hiraoka, Tadatoshi Tokunaga, Takahiro Kiuchi, Tetsuro OshikaAbstract:PURPOSE To review the time course of Corneal anteroposterior shift and refractive stability after myopic excimer laser keratorefractive surgery. METHODS We examined 65 eyes undergoing photorefractive keratectomy (PRK) and 45 eyes undergoing laser in situ keratomileusis (LASIK). Corneal elevation maps and pachymetry were obtained by scanning-slit Corneal Topography before; 1 week; and 1, 3, 6, and 12 months after surgery. RESULTS Both PRK and LASIK induced significant forward shifts of the cornea. Corneal forward shift was progressive up to 6 months after PRK, but no progression was seen after LASIK. Progressive thinning and expansion of the cornea were not observed after either procedure. The amount of Corneal forward shift showed a significant negative correlation with preoperative Corneal thickness (r = -0.586; P < 0.01) and a significant positive correlation with the amount of myopic correction (r = 0.504; P < 0.01). A significant correlation was found between the amount of forward shift and the degree of myopic regression after surgery (r = -0.347; P < 0.05). CONCLUSION Myopic PRK and LASIK induce significant forward shifts of the cornea, which are not true Corneal ectasia. Eyes with thinner corneas and higher myopia requiring greater ablation are more predisposed to anterior protrusion of the cornea. Corneal forward shift was progressive up to 6 months after PRK but not progressive after LASIK. Forward shift of the cornea can be one of the factors responsible for myopic regression after surgery.
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Corneal thickness measurements scanning slit Corneal Topography and noncontact specular microscopy versus ultrasonic pachymetry
Journal of Cataract and Refractive Surgery, 2003Co-Authors: Shigenobu Suzuki, Isao Sakabe, Shiro Amano, Aiko Iwase, Tetsuro Oshika, Makoto AraieAbstract:Abstract Purpose To compare central Corneal thickness measurements taken with 3 pachymetry systems: Orbscan scanning-slit Corneal Topography/pachymetry, Topcon SP2000P noncontact specular microscopy, and Tomey ultrasonic pachymetry. Setting Multicenter study, Tokyo, Japan. Methods In 216 healthy eyes of 114 subjects, scanning-slit Topography, noncontact specular microscopy, and ultrasonic pachymetry were used in that sequence to record central Corneal thickness. In another 20 healthy eyes of 13 subjects, 2 sets of measurements were repeated for each pachymetry to assess repeatability. Results The mean central Corneal thickness was compatible between scanning-slit Topography (546.9 μm ± 35.4 [SD] ) and ultrasonic pachymetry (548.1 ± 33.0 μm); however, noncontact specular microscopy gave a significantly smaller mean (525.3 ± 31.4 μm) than the other 2 tests (P Conclusions Corneal thickness readings were comparable between scanning-slit Topography and pachymetry; noncontact specular microscopy gave significantly smaller values. The measurements of the 3 methods showed significant linear correlations with one another. All methods provided acceptable repeatability of measurements.
Peter S Hersh - One of the best experts on this subject based on the ideXlab platform.
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removal and repositioning of intraCorneal ring segments improving Corneal Topography and clinical outcomes in keratoconus and ectasia
Cornea, 2017Co-Authors: Kahei Chan, Peter S HershAbstract:Purpose To evaluate the efficacy of removal and relocation of intraCorneal ring segments for improving outcomes in treatment of keratoconus and Corneal ectasia. Methods This is a retrospective case series conducted at a cornea and refractive surgery subspecialty practice setting. Patients with previous insertion of 2 intraCorneal ring segments underwent surgical removal and repositioning of segments because of unsatisfactory visual and topographic outcomes. The principal outcomes included uncorrected and corrected visual acuities, manifest refraction, Topography-derived maximum keratometry (Kmax), inferior-superior Topography power difference (I - S), and higher-order aberration profile derived from wavefront analysis. Results Three patients are presented in this case series. Uncorrected visual acuity improved in all eyes by an average of 2.75 lines. Corrected visual acuity improved in 2 eyes and remained unchanged in 1 eye. Refractive astigmatism decreased in all patients by an average of 2.50 D. Kmax decreased by an average of 1.43 D. All patients had improvement in the I - S value with a mean decrease of 5.13 D. Conclusions Topography-guided repositioning and/or replacement of Corneal ring segments can result in improved topographic, optical, and visual outcomes in patients in whom the initial result is suboptimal. In these cases, a single segment repositioned beneath the cone resulted in an improved outcome. Analysis of Corneal Topography can guide the surgeon in treatment planning and can suggest patients in whom such an effort will be rewarded with better results.
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Corneal Topography indices after Corneal collagen crosslinking for keratoconus and Corneal ectasia one year results
Journal of Cataract and Refractive Surgery, 2011Co-Authors: Steven A Greenstein, Kristen Fry, Peter S HershAbstract:PURPOSE: To evaluate changes in Corneal Topography indices after Corneal collagen crosslinking (CXL) in patients with keratoconus and Corneal ectasia and analyze associations of these changes with visual acuity. SETTING: Cornea and refractive surgery subspecialty practice. DESIGN: Prospective randomized controlled clinical trial. METHODS:Cornealcollagencrosslinkingwasperformed ineyes withkeratoconusorectasia.Quantitative descriptors of Corneal Topography were measured with the Pentacam topographer and included 7 indices: index of surface variance, index of vertical asymmetry, keratoconus index, central keratoconus index, minimum radius of curvature, index of height asymmetry, and index of height decentration. Follow-up was 1 year. RESULTS: The study comprised 71 eyes, 49 with keratoconus and 22 with post-LASIK ectasia. In theentire patient cohort,there were significant improvements inthe index ofsurfacevariance, index of vertical asymmetry, keratoconus index, and minimum radius of curvature at 1 year compared with baseline (all P<.001). There were no significant differences between the keratoconus and ectasia subgroups. Improvements in postoperative indices were not correlated with changes in corrected or uncorrected distance visual acuity. CONCLUSIONS:Therewereimprovementsin4of7Topographyindices 1yearafter CXL,suggesting an overall improvement in Corneal shape. However, no significant correlation was found between the changes in individual Topography indices and changes in visual acuity after CXL.
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Corneal Topography of photorefractive keratectomy versus laser in situ keratomileusis
Ophthalmology, 1998Co-Authors: Peter S Hersh, Kevin S Scher, Rashna IraniAbstract:Abstract Objective This study aimed to compare qualitative patterns of Corneal Topography early in the postoperative course after excimer laser photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) when used for the treatment of myopia of 6.0 to 15.0 diopters. Design The study design was a prospective, multicenter, randomized clinical trial. Participants A total of 64 eyes were treated with PRK and 54 eyes were treated with LASIK. Intervention Using the Summit Apex excimer laser, patients received either PRK or LASIK using a single pass, multizone excimer laser ablation. Computer-assisted videokeratography was performed at designated postoperative examinations. Main outcome measures Videokeratography maps at 1 and 3 months after surgery were classified using a standard classification scheme. The association of Topography patterns to loss of spectacle-corrected visual acuity was tested. Results At 1 month, for the PRK (n = 60) and LASIK (n = 51) groups, respectively, 63.3% and 19.6% of eyes fell into one of the four optically irregular groups (central island, keyhole, semicircular, or irregularly irregular; P P = 0.004). Comparing the 1- and 3-month examination results in the PRK and LASIK groups, respectively, 19 (42%) of 45 eyes and 11 (31%) of 36 eyes had a change in Topography, generally to an optically smoother pattern. The irregular groups, taken together, were associated with a greater tendency toward loss of spectacle-corrected visual acuity of two or more Snellen lines ( P = 0.01). There also was greater tendency toward loss of spectacle-corrected visual acuity in the PRK group that diminished with time ( P P = 0.05 at 3 months). Conclusions After treatment for moderate-to-high myopia, LASIK Topography patterns generally are more regular than are PRK patterns. This may be a result either of masking of underlying Topography perturbations by the lamellar Corneal flap, thus mitigating induced Topography changes, or differences in surface wound healing. This study suggests that more rapid return of spectacle-corrected visual acuity found in patients treated with LASIK may be a result of more regular Topography patterns early in the postoperative course.
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Corneal Topography of phase iii excimer laser photorefractive keratectomy characterization and clinical effects
Ophthalmology, 1995Co-Authors: Peter S Hersh, Barbara H Schwartzgoldstein, Daniel S Durrie, Timothy B Cavanaugh, John D Hunkeler, Marc Michelson, John Owen, Michael Gordon, Roger F Steinert, Carmen A PuliafitoAbstract:Purpose: To define qualitative patterns of Corneal Topography after excimer laser photorefractive keratectomy (PRK), assess changes in patterns, associations with clinical outcomes, and the accuracy of videokeratography in predicting results, and define quantitatively the optical zone contour. Methods: Computer-assisted videokeratography data obtained from 181 patients after PRK was analyzed. Topography patterns at two time points were characterized, and associations with clinical outcomes were tested. Power change predicted by Topography was compared with refractive change, and cross-sectional power contours were analyzed. Results: Seven Topography patterns were defined. At 1 year, 58.6% of corneas showed a homogeneous Topography, 17.7% showed a toric-with-axis configuration, 2.8% showed a toric-against-axis configuration, 13.8% showed an irregularly irregular Topography, 2.8% showed a keyhole/semicircular pattern, and 4.4% showed focal topographic variants. No central island patterns were found. Of the maps, 41 % changed over time. Uncorrected vision, predictability, and patient satisfaction were best in the homogeneous group. Astigmatism increased in the irregular and toric-against-axis groups and decreased in the toric-with-axis group. There was no relation of Topography pattern to best-corrected vision or subjective glare/halo. Cross-sectional power profiles showed a homogeneous power change for the central 3 mm with a diminution in correction toward the periphery. The Topography unit tended to overestimate refractive change for corrections of 5 diopters or less and underestimate the change for corrections greater than 5 diopters. Conclusions: Topography patterns after PRK are identifiable, time dependent, and may affect clinical outcomes. Understanding the actual Corneal optical contour resulting from PRK may aid in improving both laser techniques and optical results in the future.
Steven E Wilson - One of the best experts on this subject based on the ideXlab platform.
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changes in Corneal Topography after excimer laser photorefractive keratectomy for myopia
Ophthalmology, 1991Co-Authors: Stephen D Klyce, Steven E Wilson, Marguerite B Mcdonald, James C Liu, Herbert E KaufmanAbstract:Abstract Computer-assisted analysis of Corneal Topography was performed in 17 normally sighted human eyes during the first year after excimer laser photorefractive keratectomy (PRK) for myopia. Laser ablation of the central cornea produced an optical zone with a smooth power transition to the peripheral cornea. Decentration of the ablation was noted in some eyes (
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quantitative descriptors of Corneal Topography a clinical study
Archives of Ophthalmology, 1991Co-Authors: Steven E Wilson, Stephen D KlyceAbstract:• Quantitative descriptors of Corneal Topography determined by computerized algorithm and designed to augment the information derived from topographic maps were evaluated in a clinical study. The surface regularity index, a measure of central Corneal optical quality, was highly correlated with best spectacle-corrected visual acuity ( p = 0.80, P p = 0.62, P
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advances in the analysis of Corneal Topography
Survey of Ophthalmology, 1991Co-Authors: Steven E Wilson, Stephen D KlyceAbstract:Recent advances in topographic analysis have provided powerful tools for detecting subtle, but clinically significant, alterations of Corneal contour. This article compares keratometry, keratoscopy, and computer-assisted topographic analysis and provides specific examples of the sensitivity of computer-assisted systems in revealing topographic alterations that were not previously discernable. Quantitative descriptors of Corneal Topography such as the surface asymmetry index, the surface regularity index, and simulated keratometry value augment the information provided by color-coded topographic maps.
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Corneal Topography of keratoconus
Cornea, 1991Co-Authors: Steven E Wilson, David T C Lin, Stephen D KlyceAbstract:Sixty-three eyes of 49 patients with keratoconus were studied by means of computer-assisted Corneal topographic analysis. Two patients with keratoconus in one eye had no topographic evidence of keratoconus in the opposite eye. Keratoconic topographic alterations were classified into two groups. The majority of the patients (72%) had peripheral cones, with steepening extending to the limbus. In this group, the steepening was commonly restricted to one or two quadrants. In some cases, however, the changes involved nearly the entire Corneal surface. The remaining group (about one quarter of the keratoconus patients) had steepening that was restricted to the central cornea. In either group, the topographic alterations in the two eyes of any single patient were characterized by a high degree of nonsuperimposable mirror-image symmetry (enantiomorphism). In the majority of patients, however, there was a large and statistically significant disparity between the two eyes in the power at the apex of the cone and the total cylinder [mean differences 8.2 +/- 6.0 D (p less than 0.0001) and 4.3 +/- 2.7 D (p less than 0.0001), respectively].
Shiro Amano - One of the best experts on this subject based on the ideXlab platform.
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longitudinal analysis of Corneal Topography in suspected keratoconus
British Journal of Ophthalmology, 2009Co-Authors: Mariko Shirayamasuzuki, Shiro Amano, Norihiko Honda, Satoru Yamagami, Tomohiko Usui, Tetsuro OshikaAbstract:Aims: To examine the incidence of progression of suspected keratoconus to true keratoconus and compare quantitative descriptors of Corneal Topography between eyes with and without progression. Methods: 34 eyes with suspected keratoconus were retrospectively reviewed in 34 patients. Their age at the initial examination was 13 to 40 years (24.1 (7.5), mean (SD)), and the follow-up periods ranged from 3 to 10 years (6.0 (2.2) years). Suspected keratoconus was defined as the fellow eye of a clinically apparent keratoconus but that had no slit-lamp signs of keratoconus (Fleischer ring, Vogt striae and Munson sign) with a best spectacle-corrected visual acuity of 20/20 or better. Eyes were monitored for the progression of apparent slit-lamp findings of keratoconus during the follow-up period. Using a Fourier analysis of the Corneal Topography data, regular astigmatism, asymmetry component and higher-order irregularity component were calculated in the central 3 mm zone. Quantitative descriptors of Corneal Topography were compared between eyes which progressed to true keratoconus and those which did not. Results: Five eyes (14.7%) progressed to apparent keratoconus from suspected keratoconus (progression group), and 29 eyes did not (non-progression group). On average, it took 5.2 years for the eyes to develop apparent slit-lamp findings of keratoconus. The cumulative incidence of progression by Kaplan–Meier analysis was 21.5% in 6 years. The asymmetry component and regular astigmatism by Fourier analysis at the initial examination were significantly larger in the progression group than in the non-progression group. Conclusion: In our retrospective study, approximately 20% of eyes with suspected keratoconus progressed to true keratoconus in 6 years, and these eyes had presented greater asymmetry and regular astigmatism at the initial examination.
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comparison of central Corneal thickness measurements by rotating scheimpflug camera ultrasonic pachymetry and scanning slit Corneal Topography
Ophthalmology, 2006Co-Authors: Shiro Amano, Norihiko Honda, Yuki Amano, Satoru Yamagami, Takashi Miyai, Tomokazu Samejima, Miyuki Ogata, Kazunori MiyataAbstract:Purpose To compare central Corneal thickness measurements and their reproducibility when taken by a rotating Scheimpflug camera, ultrasonic pachymetry, and scanning-slit Corneal Topography/pachymetry. Design Experimental study. Participants Seventy-four eyes of 64 subjects without ocular abnormalities other than cataract. Methods Corneal thickness measurements were compared among the 3 methods in 54 eyes of 54 subjects. Two sets of measurements were repeated by a single examiner for each pachymetry in another 10 eyes of 5 subjects, and the intraexaminer repeatability was assessed as the absolute difference of the first and second measurements. Two experienced examiners took one measurement for each pachymetry in another 10 eyes of 5 subjects, and the interexaminer reproducibility was assessed as the absolute difference of the 2 measurements of the first and second examiners. Main Outcome Measures Central Corneal thickness measurements by the 3 methods, absolute difference of the first and second measurements by a single examiner, absolute difference of the 2 measurements by 2 examiners, and relative amount of variation. Results The average measurements of central Corneal thickness by a rotating Scheimpflug camera, scanning-slit Topography, and ultrasonic pachymetry were 538±31.3 μm, 541±40.7 μm, and 545±31.3 μm, respectively. There were no statistically significant differences in the measurement results among the 3 methods ( P = 0.569, repeated-measures analysis of variance). There was a significant linear correlation between the rotating Scheimpflug camera and ultrasonic pachymetry ( r = 0.908, P r = 0.930, P r = 0.887, P Conclusions Mean Corneal thicknesses were comparable among rotating Scheimpflug camera, ultrasonic pachymetry, and scanning-slit Topography with the acoustic equivalent correction factor. The measurements of the 3 instruments had significant linear correlations with one another, and all methods had highly satisfactory measurement repeatability.
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Corneal thickness measurements scanning slit Corneal Topography and noncontact specular microscopy versus ultrasonic pachymetry
Journal of Cataract and Refractive Surgery, 2003Co-Authors: Shigenobu Suzuki, Isao Sakabe, Shiro Amano, Aiko Iwase, Tetsuro Oshika, Makoto AraieAbstract:Abstract Purpose To compare central Corneal thickness measurements taken with 3 pachymetry systems: Orbscan scanning-slit Corneal Topography/pachymetry, Topcon SP2000P noncontact specular microscopy, and Tomey ultrasonic pachymetry. Setting Multicenter study, Tokyo, Japan. Methods In 216 healthy eyes of 114 subjects, scanning-slit Topography, noncontact specular microscopy, and ultrasonic pachymetry were used in that sequence to record central Corneal thickness. In another 20 healthy eyes of 13 subjects, 2 sets of measurements were repeated for each pachymetry to assess repeatability. Results The mean central Corneal thickness was compatible between scanning-slit Topography (546.9 μm ± 35.4 [SD] ) and ultrasonic pachymetry (548.1 ± 33.0 μm); however, noncontact specular microscopy gave a significantly smaller mean (525.3 ± 31.4 μm) than the other 2 tests (P Conclusions Corneal thickness readings were comparable between scanning-slit Topography and pachymetry; noncontact specular microscopy gave significantly smaller values. The measurements of the 3 methods showed significant linear correlations with one another. All methods provided acceptable repeatability of measurements.
Makoto Araie - One of the best experts on this subject based on the ideXlab platform.
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Corneal thickness measurements scanning slit Corneal Topography and noncontact specular microscopy versus ultrasonic pachymetry
Journal of Cataract and Refractive Surgery, 2003Co-Authors: Shigenobu Suzuki, Isao Sakabe, Shiro Amano, Aiko Iwase, Tetsuro Oshika, Makoto AraieAbstract:Abstract Purpose To compare central Corneal thickness measurements taken with 3 pachymetry systems: Orbscan scanning-slit Corneal Topography/pachymetry, Topcon SP2000P noncontact specular microscopy, and Tomey ultrasonic pachymetry. Setting Multicenter study, Tokyo, Japan. Methods In 216 healthy eyes of 114 subjects, scanning-slit Topography, noncontact specular microscopy, and ultrasonic pachymetry were used in that sequence to record central Corneal thickness. In another 20 healthy eyes of 13 subjects, 2 sets of measurements were repeated for each pachymetry to assess repeatability. Results The mean central Corneal thickness was compatible between scanning-slit Topography (546.9 μm ± 35.4 [SD] ) and ultrasonic pachymetry (548.1 ± 33.0 μm); however, noncontact specular microscopy gave a significantly smaller mean (525.3 ± 31.4 μm) than the other 2 tests (P Conclusions Corneal thickness readings were comparable between scanning-slit Topography and pachymetry; noncontact specular microscopy gave significantly smaller values. The measurements of the 3 methods showed significant linear correlations with one another. All methods provided acceptable repeatability of measurements.