Objective To evaluate the association between baseline measurements of iris thickness at three positions and change in anterior segment biometric parameters after prophylactic laser peripheral iridotomy (LPI). Design Prospective clinical cohort study. Participants Fifty-two eyes of 52 nonglaucomatous subjects with anatomically narrow angles. Methods Anterior segment optical coherence tomography images captured before and after LPI were analyzed using customized software, the Zhongshan Angle Assessment Program. Differences in preoperative and postoperative measurements for anterior segment biometric parameters were compared by paired Student’s t-tests. Multivariate linear regression models, adjusted for age, sex, ethnicity, and preoperative pupil diameter, were used to examine the association between the baseline measurements of iris thickness at three positions and the change in anterior segment biometric parameters after LPI. Main Outcome Measures Baseline iris thickness measured at 750μm (IT750) and 2000μm (IT2000) from the scleral spur and maximal iris thickness (ITM). Changes in iris curvature (ICURV) and trabecular–iris space area at 500μm (TISA500) and 750μm (TISA750) from the scleral spur after LPI. Results ICURV significantly decreased, while TISA500 and TISA750 significantly increased following LPI (all P<0.0001). Lower baseline IT750 was significantly associated with greater postoperative increases in TISA500 and TISA750 (both P<0.05). Lower baseline IT2000 and ITM were significantly associated with greater postoperative decrease in ICURV (both P<0.05). Conclusion Our results showed that lower baseline measurements of iris thickness are associated with greater decrease in ICURV and increases in TISA500 and TISA750 after LPI. This suggests that eyes with thinner irides undergoing LPI were more likely to exhibit greater magnitude of change in terms of flattening of the iris convexity (i.e., ICURV) and widening of the anterior chamber angle (i.e., TISA500 and TISA750).

Our results showed significant opening of the anterior chamber angle width after LPI and demonstrated an inverse association between baseline and LPI-induced opening of the anterior chamber angle width, such that eyes with a more crowded anterior chamber angle undergoing LPI had a greater magnitude of increase in anterior chamber angle width after the procedure.

In this study, regardless of ethnic classification, subjects who received cataract surgery by phacoemulsification experienced a significant postoperative decrease in intraocular pressure and increases in angle opening distance, anterior chamber depth, anterior chamber volume and angle recess area. The percent changes in postoperative outcomes did not differ significantly by ethnicity.

Optic disc size was significantly smaller in Caucasian compared to the other ethnic groups. Optic disc size differences among non-Caucasian ethnic groups were not significant.

The aim of the study was to explore the correlation between central corneal thickness (CCT) and the degree of myopia in Taiwanese adults. A total of 528 individuals were enrolled to undergo myopic laser refractive surgery from January 2004 to December 2006. Preoperative CCT was measured using the Orbscan corneal topography system and refractive status was determined by cycloplegic spherical equivalent. The relationship between CCT and refractive error was investigated by interindividual and intraindividual analyses. Participants had a mean age of 34.8 ± 7.3 years, and 79.9% were female. The mean refractive error was -7.27 ± 2.96 diopters and the mean CCT measurement was 560 ± 35 μm. CCT revealed that there was no association with age. However, CCT was significantly (p = 0.012) less in females than in males. The CCT also showed no significant association with refractive error (p = 0.49). Among the 67 participants with myopic anisometropia, the mean difference between both eyes was 3.09 ± 1.06 diopters. There was no association between the intereye CCT difference and refractive error (p = 0.57). The results remained the same after adjusting for age and sex. In conclusion, there was no correlation between CCT and the degree of myopia among adults in Taiwan. These data might contribute to the ongoing discussion about the role of CCT in the higher incidence of development and progression of glaucoma in myopic individuals.

Purpose To investigate the association between ultrasound energy, expressed as cumulative dissipated energy, and changes in intraocular pressure following uncomplicated cataract surgery by phacoemulsification. Methods In this prospective study, nonglaucomatous subjects underwent cataract surgery by phacoemulsification. Intraocular pressure was compared by clustered linear regression at four separate time points: preoperative, 1 day, 1 month, and 3 months after cataract surgery. Changes in intraocular pressure were evaluated as a function of cumulative dissipated energy using univariate and multivariate clustered linear regression models, which adjusted for sex, ethnicity, age, axial length, spherical equivalent, mean preoperative Shaffer gonioscopy grade of all four quadrants, cataract grade, preoperative intraocular pressure, central corneal thickness, and use of both eyes in the same subject. Results One hundred and sixty one eyes (89 Asian, 49 Caucasian, 12 African, and 11 Hispanic) from 116 nonglaucomatous subjects were analyzed. The 161 eyes included 81 right and 80 left eyes. The 89 Asian eyes included 46 Chinese, 35 Filipino, and 8 Vietnamese. Preoperative intraocular pressure was 14.9±3.2 mmHg. Postoperative intraocular pressure significantly increased to 16.0±4.9 mmHg at 1 day (P=0.037) and decreased to 12.4±3.1 and 12.3±3.0 mmHg at 1 and 3 months, respectively (both P<0.0001). Intraocular pressure changes at 1 day, 1 month, and 3 months did not demonstrate significant associations with cumulative dissipated energy measurements in either univariate or multivariate clustered linear regression analyses (all P>0.05). Conclusions The amount of ultrasound energy delivered to the eye during phacoemulsification, expressed as cumulative dissipated energy, was not associated with postoperative changes in intraocular pressure.

PurposeTo investigate the association between hypothyroidism and glaucomatous disease.MethodsThis cross-sectional study included all subjects above the age of 40 years from two nationwide surveys: the 2008 National Health Interview Survey (NHIS) as well as the 2007 and 2008 National Health and Nutrition Examination Survey (NHANES). The presence or absence of glaucoma, thyroid disease and other demographic and health-related information including comorbidities was ascertained via interview. Blood samples were collected from NHANES subjects and analyzed for thyrotropin (TSH).ResultsA total of 13,599 and 3,839 NHIS and NHANES participants respectively were analyzed to assess for a possible relationship between self-reported glaucoma, and self-reported hypothyroidism as well as self-reported thyroid disease. The unadjusted odds ratio (OR) for NHIS showed a significant association between self-reported glaucoma and self-reported hypothyroidism (OR 1.46, 95% confidence interval [CI] 1.07-1.99). Multivariate logistic regression analysis adjusted for age, gender, race, comorbidities, and health-related behavior, however, showed no association between self-reported glaucoma and hypothyroidism or thyroid disease in both surveys (OR 1.60, 95%CI 0.87-2.95 for NHIS; OR 1.05, 95%CI 0.59-1.88 for NHANES).ConclusionA previously reported association between hypothyroidism and glaucomatous disease was not confirmed in two large U.S. health survey populations. While such an association was noted in the univariate analysis for the NHIS survey, such a relationship was not found in the multivariate analysis after adjustment for potential confounding variables.

Background To compare anterior segment biometric parameters between Caucasians and Chinese before and after laser peripheral iridotomy (LPI). Design Prospective clinical cohort study Participants Caucasian and Chinese primary angle closure suspects. Methods Anterior segment optical coherence tomography images captured before and after LPI were analyzed to measure anterior segment biometric parameters. Paired Student’s t-tests were used for within-ethnic group comparisons. Univariate and linear mixed-effects regression models were used for between-ethnic group comparisons. Main Outcome Measures angle opening distance (AOD500, AOD750); angle recess area (ARA750); iris thickness (IT750, IT2000, ITM); iris curvature (ICURV); anterior chamber area (ACA); anterior chamber volume (ACV); and anterior chamber width (ACW). Results Caucasians had significantly greater preoperative ARA750, ACW, and ICURV and lower preoperative IT2000 compared to Chinese (P<0.05). Ethnic differences in preoperative AOD500, AOD750, IT750, ITCM, ACA, and ACV were insignificant (P>0.05). Significant postoperative increases in AOD500, AOD750, ARA750, ACA, ACV, and ACW along with significant postoperative decrease in ICURV were observed within both ethnic groups (P<0.05). However, the amount of LPI-induced changes in AOD500, AOD750, ARA750, ACA, ACV, ACW, and ICURV did not differ between the two ethnic groups (P>0.05). Conclusion Both Caucasian and Chinese demonstrated opening of anterior chamber angle width (AOD500, AOD750, ARA750), expansion of anterior chamber dimensions (ACA, ACV, ACW), and flattening of iris convexity (ICURV) after LPI. Although certain aspects of anterior segment anatomy differed between Caucasians and Chinese preoperatively, they did not translate into significant ethnic differences in the amount of LPI-induced changes in the anterior segment biometric parameters.