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Importance: There is limited literature on lifestyle and health factors related to primary open-angle glaucoma amongst Asians., Background: This study evaluated the association of primary open-angle glaucoma with smoking, health and ocular factors amongst Chinese Singaporeans., Design: Case-control study., Participants: The study used 711 primary open-angle glaucoma patients from a Singapore hospital and 2788 population-based controls., Methods: Subjects underwent clinical examination and completed a questionnaire with details on family history of glaucoma, comorbidities, smoking and alcohol consumption. Glaucoma cases were subclassified as normal or high-tension glaucoma according to their untreated intraocular pressures., Main Outcome Measures: The association of various health and lifestyle factors, with normal-tension and high-tension glaucoma was evaluated., Results: Using multiple logistic regression, primary open-angle glaucoma was associated with older age (odds ratio 1.12 per year older; 95% confidence interval 1.10-1.15; P < 0.001), family history of glaucoma (odds ratio 7.86; 95% confidence interval 4.48-13.79; P < 0.001), higher intraocular pressure (odds ratio 1.75 per 1 mmHg; 95% confidence interval 1.64-1.87; P < 0.001) and thinner central corneal thickness (odds ratio 1.01; 95% confidence interval 1.01-1.02; P < 0.001). Myopes were more likely to have primary open-angle glaucoma (P < 0.001). A current smoking habit was protective against normal-tension glaucoma (odds ratio 0.30; 95% confidence interval 0.10-0.92; P = 0.035)., Conclusions and Relevance: Older age, family history of glaucoma, higher intraocular pressure, thinner central corneal thickness and myopia were significantly associated with primary open-angle glaucoma amongst Chinese Singaporeans., (© 2017 Royal Australian and New Zealand College of Ophthalmologists.)

Purpose: To characterize an optical coherence tomography (OCT)-derived parameter, Bruch's membrane opening-minimum rim width (BMO-MRW), and its association with demographic and clinical parameters in normal Chinese subjects., Methods: Right eyes of 466 consecutive healthy subjects from a population-based study of Singaporean Chinese underwent Cirrus OCT imaging. The retinal internal limiting membrane (ILM) and BMO were automatically delineated using the built-in Cirrus algorithm. The standard 36 interpolated radial B-scans (72 BMO points, 5° increments) of each optic nerve head were manually extracted from the central circle (3.46-mm diameter). We used Matlab to measure the shortest distance from the BMO points to the ILM. Associations of BMO-MRW with demographic and clinical parameters were evaluated using marginal general estimating equations analysis., Results: There was a slight preponderance of male subjects (50.9%), with a mean age of 54.8 ± 7.63 years. Mean BMO-MRW was 304.67 ± 58.96 μm (range, 173.32-529.23 μm), which was highly associated with OCT-derived disc area (DA) (β = -91.78, P < 0.001) and rim area (RA) (β = 194.31, P < 0.001), followed by spherical refractive error (SRE) (β = -2.23, P = 0.02) and retinal nerve fiber layer (RNFL) thickness (β = 0.5, P = 0.04), after adjusting for the associated factors such as age, sex, intraocular pressure (IOP), and vertical cup-disc ratio (VCDR)., Conclusions: Disc area and RA had the strongest association with BMO-MRW, followed by SRE and RNFL thickness. The availability of this normative database will facilitate optic nerve head assessment using the BMO-MRW parameter in Chinese subjects.

Purpose: To evaluate the acceleration of pupil constriction (APC) in response to illumination using video anterior segment optical coherence tomography (AS-OCT) in angle closure and normal eyes., Methods: This was an observational study of 342 Chinese subjects. Iris and angle changes in response to illumination were captured with real-time video recordings of AS-OCT and analyzed frame by frame. APC was calculated using a quadratic function, fitting pupil diameter to a time series. APC was divided into two vector components: acceleration of pupil block (APB) acting perpendicular to the lens surface and acceleration of iris stretch (AIS) acting toward the iris root., Results: Of 342 eligible patients, 306 (89.5%) were available for analysis; of whom 136 (41.7%) had angle closure. After adjusting for age, sex, baseline pupil diameter, and iris thickness, APC was significantly lower in angle closure eyes (0.61 mm/s(2)) than in open-angle eyes (0.90 mm/s(2)) (P < 0.0001) as was AIS (0.58 mm/s(2) vs. 0.89 mm/s(2)) (P < 0.001). APB was significantly higher in angle closure eyes compared to open-angle eyes (0.14 mm/s(2) vs. 0.09 mm/s(2)) (P < 0.001). After adjusting for age and sex in logistic regression, the magnitude and direction of all vector parameters were significantly associated with presence of angle closure., Conclusions: Angle closure eyes have smaller AIS and larger APB in response to illumination as measured using AS-OCT videography. This shows that, comparatively, the iris of angle closure eyes stretches less and develops a more convex configuration in response to illumination.

Objectives: To evaluate corneal hysteresis (CH) and intraocular pressure (IOP) measured by the Ocular Response Analyzer in Chinese subjects with primary angle-closure glaucoma (PACG), assess their relationship with Goldmann applanation tonometry (GAT) measurements, and compare this with subjects with primary open-angle glaucoma (POAG) and normal controls., Methods: In this prospective observational study, consecutive subjects with PACG and POAG without prior intraocular surgery were enrolled from glaucoma clinics. Normal subjects were recruited from an ongoing population-based study. One eye of each subject underwent standardized ocular examination and IOP measurement by GAT and the Ocular Response Analyzer. Corneal hysteresis and corneal-compensated IOP were compared between groups., Results: Of the 443 subjects recruited, 131 had PACG, 162 had POAG, and 150 were normal. Corneal hysteresis was lower in PACG (9.1 mm Hg; 95% confidence interval [CI], 8.7 to 9.4 mm Hg) and POAG (9.5 mm Hg; 95% CI, 9.2 to 9.5 mm Hg) eyes compared with control eyes (10.4 mm Hg; 95% CI, 10.1 to 10.6 mm Hg; P < .001 for both), with no difference (P = .16) in CH found between PACG and POAG eyes. After adjusting for age, sex, and IOP measurement by GAT, CH persisted to be lower only in eyes with PACG in comparison with control eyes (9.4 vs 10.1 mm Hg; P = .006). Eyes with POAG had lower CH than control eyes but the difference was not statistically significant (9.6 vs 10.1 mm Hg; P = .06)., Conclusions: Corneal hysteresis was lower in eyes with glaucoma. After adjusting for age, sex, and IOP measurement by GAT, a persistently lower hysteresis was noted in eyes with PACG compared with other groups.

Purpose: To investigate the association of lens parameters-specifically, lens vault (LV), lens thickness (LT), and lens position (LP)-with angle closure., Design: Prospective, comparative study., Participants: One hundred two Chinese subjects with angle closure (consisting of primary angle closure, primary angle-closure glaucoma, and previous acute primary angle closure) attending a glaucoma clinic and 176 normal Chinese subjects with open angles and no evidence of glaucoma recruited from an ongoing population-based cross-sectional study., Methods: All participants underwent gonioscopy and anterior-segment optical coherence tomography (AS OCT; Carl Zeiss Meditec, Dublin, CA). Customized software was used to measure LV, defined as the perpendicular distance between the anterior pole of the crystalline lens and the horizontal line joining the 2 scleral spurs, on horizontal AS OCT scans. A-scan biometry (US-800; Nidek Co, Ltd, Tokyo, Japan) was used to measures LT and to calculate LP (defined as anterior chamber depth [ACD] +1/2 LT) and relative LP (RLP; defined as LP/axial length [AL])., Main Outcome Measures: Lens parameters and angle closure., Results: Significant differences between angle-closure and normal eyes were found for LV (901±265 vs. 316±272 μm; P<0.001), LT (4.20±0.92 vs. 3.90±0.73 mm; P = 0.01), LT-to-AL ratio (0.18±0.04 vs. 0.16±0.03; P<0.001), ACD (2.66±0.37 vs. 2.95±0.37 mm; P<0.001), and AL (22.86±0.93 vs. 23.92±1.37 mm; P<0.001), but no significant differences were found for LP (4.76±0.51 vs. 4.90±0.54 mm; P = 0.34) or RLP (0.21±0.02 vs. 0.20±0.02; P = 0.14). After adjusting for age, gender, ACD, LT, and RLP, increased LV was associated significantly with angle closure (odds ratio [OR], 48.1; 95% confidence interval [CI], 12.8-181.3, comparing lowest to highest quartile), but no association was found for LT (OR, 1.78; 95% CI, 0.76-4.16), LP (OR, 1.94; 95% CI, 0.59-6.31), or RLP (OR, 2.08; 95% CI, 0.66-6.57). There was low correlation between LV and LT (Pearson's correlation coefficient [PCC], 0.17), between LV and RLP (PCC, 0.08), or between LV and LP (PCC, 0.2)., Conclusions: Eyes with angle closure have thicker lenses with greater LV compared with normal eyes. The LV, which represents the anterior portion of the lens, is a novel parameter independently associated with angle closure after adjusting for age, gender, ACD, and LT., (Copyright © 2011 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)