The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Berthold Seitz - One of the best experts on this subject based on the ideXlab platform.
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Changes in corneal power and refraction due to sequential suture removal following nonmechanical penetrating keratoplasty in eyes with keratoconus.
American journal of ophthalmology, 2006Co-Authors: Achim Langenbucher, Berthold SeitzAbstract:Purpose: To assess the changes in corneal power and refraction due to sequential suture removal after penetrating keratoplasty (PK). Design Retrospective consecutive case series. Methods setting: Clinical practice. study population: We studied 67 phakic keratoconus eyes (central excimer laser trephination, primary keratoplasty, graft/recipient diameter 8.1/8.0 mm; double running suture) in this longitudinal study. main outcome measures: Zeiss keratometry (equivalent power (KEQ), astigmatism (KAST)), corneal topography (equivalent power (TEQ), astigmatism (TAST)) and subjective refractometry (spherical equivalent (SEQ), refractive cylinder (RAST)) were assessed with sutures in place (interval 1), with one suture out (interval 2), and with all sutures out (interval 3). Observation Procedure: Corneal power and refraction was decomposed into vector components and the changes were derived between time stages. Results The mean follow-up period was 3.9 ± 1.7 years. At interval 1, the axes of KAST/TAST/RAST were almost randomly distributed. At interval 2, the with/against the rule component of KAST/TAST/RAST decreased slightly and the oblique component increased significantly, so that the axes tended to have a preferred oblique direction. At interval 3, the with/against the rule component of KAST/TAST/RAST increased slightly and the oblique component decreased significantly, so that the with/against the rule component exceeded the oblique component by approximately 23%/28%/25%. Median KEQ/TEQ/SEQ changed by 0.64/0.62/−1.11 diopters (interval 1 to interval 2) and by −0.85/−0.90/1.56 diopters (interval 2 to interval 3). Conclusions As a result of removal of the first running suture, corneal astigmatism as well as the refractive cylinder tend to oblique axes. As a result of removal of the second running suture, the final corneal astigmatism and refractive cylinder tend to orientation axes with/against the rule.
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Spontaneous long-term changes of corneal power and astigmatism after suture removal after penetrating keratoplasty using a regression model.
American journal of ophthalmology, 2005Co-Authors: Achim Langenbucher, Gottfried O. H. Naumann, Berthold SeitzAbstract:Purpose To assess the diagnosis-based spontaneous long-term changes in corneal power and refraction with a regression model in the all-sutures-out time period following non-mechanical penetrating keratoplasty (PK). Design Retrospective non-randomized clinical trial. Methods setting: Clinical practice. study population: 147 eyes [47 Fuchs dystrophy (FD); 100 keratoconus (KC)] were studied after suture removal in this retrospective longitudinal study. main outcome measures: Zeiss keratometry [equivalent power (KEQ) and astigmatism (KAST)], corneal topography analysis [equivalent power (TEQ) and astigmatism (TAST)], and subjective refractometry [spherical equivalent (SEQ) and refractive cylinder (RAST)] were assessed in at least three up to 16 ophthalmologic examinations in the all-sutures-out time period. Observation Procedure: The time course of each target variable was analyzed in a longitudinal manner (time interval ≥ 12 months) separately for each patient with a linear regression model. Results Post-keratoplasty follow-up ranged from 31 months to 10.3 years. In the linear regression model, the annual change in FD/KC showed an increase/a decrease in KEQ (0.29 ± 0.50/−0.63 ± 0.46 diopters, P = .02) and an increase/a decrease in TEQ (0.37 ± 0.54/−0.69 ± 0.49 diopters, P = .04) corresponding to a decrease/an increase in SEQ (−0.31 ± 0.47/0.63 ± 0.43 diopters, P = .02). KAST/TAST/RAST showed a minimal annual decrease (−0.06 ± 0.41/−0.05 ± 0.45/−0.06 ± 0.41 diopters) in FD but an increase in KC (0.46 ± 0.41/0.51 ± 0.43/0.46 ± 0.38 diopters) ( P = .05/0.06/0.12). Conclusions In the follow-up after post-keratoplasty suture removal, patients with FD/KC tend to develop a spontaneous myopic shift (steepening of the cornea)/hyperopic shift (flattening of the cornea). In contrast with those with FD, patients with KC should be counseled on the fact that astigmatism may increase again over time after suture removal.
Felipe A Medeiros - One of the best experts on this subject based on the ideXlab platform.
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glaucomatous retinal nerve fiber layer thickness loss is associated with slower reaction times under a divided attention task
American Journal of Ophthalmology, 2014Co-Authors: Andrew J Tatham, Pete Rose, Mauro Della Penna, Daniel Meirafreitas, Robert N Weinreb, Linda M Zangwill, Felipe A MedeirosAbstract:Purpose To examine the relationship between glaucomatous structural damage and ability to divide attention during simulated driving. Design Cross-sectional Observational study. Methods setting: Hamilton Glaucoma Center, University of California San Diego. patient population: Total of 158 subjects from the Diagnostic Innovations in Glaucoma Study, including 82 with glaucoma and 76 similarly aged controls. Observation Procedure: Ability to divide attention was investigated by measuring reaction times to peripheral stimuli (at low, medium, or high contrast) while concomitantly performing a central driving task (car following or curve negotiation). All subjects had standard automated perimetry (SAP) and optical coherence tomography was used to measure retinal nerve fiber layer (RNFL) thickness. Cognitive ability was assessed using the Montreal Cognitive Assessment and subjects completed a driving history questionnaire. main outcome measures: Reaction times to the driving simulator divided attention task. Results The mean reaction times to the low-contrast stimulus were 1.05 s and 0.64 s in glaucoma and controls, respectively, during curve negotiation ( P P = .025), respectively, during car following. There was a nonlinear relationship between reaction times and RNFL thickness in the better eye. RNFL thickness remained significantly associated with reaction times even after adjusting for age, SAP mean deviation in the better eye, cognitive ability, and central driving task performance. Conclusions Although worse SAP sensitivity was associated with worse ability to divide attention, RNFL thickness measurements provided additional information. Information from structural tests may improve our ability to determine which patients are likely to have problems performing daily activities, such as driving.
Amod Gupta - One of the best experts on this subject based on the ideXlab platform.
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correlation between retinal nerve fiber layer thickness and central corneal thickness in patients with ocular hypertension an optical coherence tomography study
American Journal of Ophthalmology, 2006Co-Authors: Sushmita Kaushik, Jamyang Gyatsho, Rajeev Jain, Surinder Singh Pandav, Amod GuptaAbstract:Purpose To correlate the retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) parameters measured by optical coherence tomography (OCT) with central corneal thickness (CCT) measurements in patients with ocular hypertension (OHT). Design Observational cross-sectional study. Methods setting: Tertiary care referral teaching institute. study population: Fifty-one eyes of 51 patients with OHT and 35 eyes of 35 normal subjects. Both groups were stratified into thin (CCT ≤555 μm) and thick (CCT >555 μm) cornea subsets. Ocular hypertensives were further stratified by CCT into ≤555 μm, 556 to 588 μm, and >588 μm subsets. Observation Procedure: RNFL thickness (average, superior average, and inferior average) and ONH parameters were measured by OCT. CCT was measured by ultrasonic pachymetry. main outcome measures: Correlation between CCT and OCT measurements of RNFL and ONH parameters. Results In the OHT group, CCT correlated significantly with all three RNFL measurements (Pearson's coefficient r = 0.412, 0.484, and 0.380, respectively) but with only four ONH parameters (cup-to-disk area ratio, cup area, rim area, and horizontally integrated rim width; r = −0.459, −0.283, 0.421, and 0.436, respectively). The RNFL in ocular hypertensives with CCT ≤555 μm was significantly thinner than in those with thick corneas (analysis of variance, post hoc Bonferroni comparisons, P 555 μm were similar. Conclusions Ocular hypertensives with CCT ≤555 μm may represent patients who have either very early undetected glaucoma or an inherent structural predisposition to glaucomatous damage. This may in part explain the higher risk of these patients for progression to glaucoma.
Kwun Yee T Poon - One of the best experts on this subject based on the ideXlab platform.
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Recent Statin Use and Cataract Surgery
American Journal of Ophthalmology, 2011Co-Authors: Donald S. Fong, Kwun Yee T PoonAbstract:Purpose To investigate whether the statin class of drugs reduces the risk of cataract extraction. Design Case-control study. Method setting: Kaiser Permanente Southern California, which provides prepaid healthcare for 3.2 million residents by 6000 physicians. patient population: Eligible patients were those who had 5+ years of continuous enrollment in 2009. Cases were 13 982 patients who underwent cataract surgery in their first eye in 2009. Controls were the 34 049 patients who had an eye examination, but did not undergo cataract surgery or have a diagnosis of cataract in their medical record. Observation Procedure: The primary source of data to assess cataract surgery, treatment with statins, and other risk factors is the electronic database of Kaiser Permanente. main outcome measure: Use of the statin class of drug. Results Patients who had cataract surgery were older, were more likely to be white, and appeared to have more coronary artery disease but less diabetes. The proportion of statin users appeared to be greater among those with cataract surgery (64.3%) compared to those without a diagnosis of cataract or cataract surgery (55.5%). After adjustment for age, sex, race, smoking status, diabetes, and coronary artery disease, longer-term statin use was found to be protective against cataract extraction (OR: 0.93, P = .02), while shorter-term use was associated with cataract surgery (OR: 1.11, P Conclusion The current study finds that recent longer-tem statin use was protective against cataract surgery in younger patients (50-64 years of age), while shorter-term use was associated with an increased risk of surgery. One strength of the current study is information on the large number of incident cases of cataract extraction and the electronic database on drug use. Additional studies will be needed to understand the difference in effect between longer- and shorter-term users of statins.
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Recent Statin Use and Cataract Surgery
American Journal of Ophthalmology, 2011Co-Authors: Donald S. Fong, Kwun Yee T PoonAbstract:Purpose To investigate whether the statin class of drugs reduces the risk of cataract extraction. Design Case-control study. Method setting: Kaiser Permanente Southern California, which provides prepaid healthcare for 3.2 million residents by 6000 physicians. patient population: Eligible patients were those who had 5+ years of continuous enrollment in 2009. Cases were 13 982 patients who underwent cataract surgery in their first eye in 2009. Controls were the 34 049 patients who had an eye examination, but did not undergo cataract surgery or have a diagnosis of cataract in their medical record. Observation Procedure: The primary source of data to assess cataract surgery, treatment with statins, and other risk factors is the electronic database of Kaiser Permanente. main outcome measure: Use of the statin class of drug. Results Patients who had cataract surgery were older, were more likely to be white, and appeared to have more coronary artery disease but less diabetes. The proportion of statin users appeared to be greater among those with cataract surgery (64.3%) compared to those without a diagnosis of cataract or cataract surgery (55.5%). After adjustment for age, sex, race, smoking status, diabetes, and coronary artery disease, longer-term statin use was found to be protective against cataract extraction (OR: 0.93, P = .02), while shorter-term use was associated with cataract surgery (OR: 1.11, P Conclusion The current study finds that recent longer-tem statin use was protective against cataract surgery in younger patients (50-64 years of age), while shorter-term use was associated with an increased risk of surgery. One strength of the current study is information on the large number of incident cases of cataract extraction and the electronic database on drug use. Additional studies will be needed to understand the difference in effect between longer- and shorter-term users of statins.
Achim Langenbucher - One of the best experts on this subject based on the ideXlab platform.
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Changes in corneal power and refraction due to sequential suture removal following nonmechanical penetrating keratoplasty in eyes with keratoconus.
American journal of ophthalmology, 2006Co-Authors: Achim Langenbucher, Berthold SeitzAbstract:Purpose: To assess the changes in corneal power and refraction due to sequential suture removal after penetrating keratoplasty (PK). Design Retrospective consecutive case series. Methods setting: Clinical practice. study population: We studied 67 phakic keratoconus eyes (central excimer laser trephination, primary keratoplasty, graft/recipient diameter 8.1/8.0 mm; double running suture) in this longitudinal study. main outcome measures: Zeiss keratometry (equivalent power (KEQ), astigmatism (KAST)), corneal topography (equivalent power (TEQ), astigmatism (TAST)) and subjective refractometry (spherical equivalent (SEQ), refractive cylinder (RAST)) were assessed with sutures in place (interval 1), with one suture out (interval 2), and with all sutures out (interval 3). Observation Procedure: Corneal power and refraction was decomposed into vector components and the changes were derived between time stages. Results The mean follow-up period was 3.9 ± 1.7 years. At interval 1, the axes of KAST/TAST/RAST were almost randomly distributed. At interval 2, the with/against the rule component of KAST/TAST/RAST decreased slightly and the oblique component increased significantly, so that the axes tended to have a preferred oblique direction. At interval 3, the with/against the rule component of KAST/TAST/RAST increased slightly and the oblique component decreased significantly, so that the with/against the rule component exceeded the oblique component by approximately 23%/28%/25%. Median KEQ/TEQ/SEQ changed by 0.64/0.62/−1.11 diopters (interval 1 to interval 2) and by −0.85/−0.90/1.56 diopters (interval 2 to interval 3). Conclusions As a result of removal of the first running suture, corneal astigmatism as well as the refractive cylinder tend to oblique axes. As a result of removal of the second running suture, the final corneal astigmatism and refractive cylinder tend to orientation axes with/against the rule.
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Spontaneous long-term changes of corneal power and astigmatism after suture removal after penetrating keratoplasty using a regression model.
American journal of ophthalmology, 2005Co-Authors: Achim Langenbucher, Gottfried O. H. Naumann, Berthold SeitzAbstract:Purpose To assess the diagnosis-based spontaneous long-term changes in corneal power and refraction with a regression model in the all-sutures-out time period following non-mechanical penetrating keratoplasty (PK). Design Retrospective non-randomized clinical trial. Methods setting: Clinical practice. study population: 147 eyes [47 Fuchs dystrophy (FD); 100 keratoconus (KC)] were studied after suture removal in this retrospective longitudinal study. main outcome measures: Zeiss keratometry [equivalent power (KEQ) and astigmatism (KAST)], corneal topography analysis [equivalent power (TEQ) and astigmatism (TAST)], and subjective refractometry [spherical equivalent (SEQ) and refractive cylinder (RAST)] were assessed in at least three up to 16 ophthalmologic examinations in the all-sutures-out time period. Observation Procedure: The time course of each target variable was analyzed in a longitudinal manner (time interval ≥ 12 months) separately for each patient with a linear regression model. Results Post-keratoplasty follow-up ranged from 31 months to 10.3 years. In the linear regression model, the annual change in FD/KC showed an increase/a decrease in KEQ (0.29 ± 0.50/−0.63 ± 0.46 diopters, P = .02) and an increase/a decrease in TEQ (0.37 ± 0.54/−0.69 ± 0.49 diopters, P = .04) corresponding to a decrease/an increase in SEQ (−0.31 ± 0.47/0.63 ± 0.43 diopters, P = .02). KAST/TAST/RAST showed a minimal annual decrease (−0.06 ± 0.41/−0.05 ± 0.45/−0.06 ± 0.41 diopters) in FD but an increase in KC (0.46 ± 0.41/0.51 ± 0.43/0.46 ± 0.38 diopters) ( P = .05/0.06/0.12). Conclusions In the follow-up after post-keratoplasty suture removal, patients with FD/KC tend to develop a spontaneous myopic shift (steepening of the cornea)/hyperopic shift (flattening of the cornea). In contrast with those with FD, patients with KC should be counseled on the fact that astigmatism may increase again over time after suture removal.
