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Yingke He, Mani Baskaran, Tin A. Tun, Arun K. Narayanaswamy, Tin Aung; Changes In Anterior Segment And Angle Configuration Over Four Years In A Cohort Of Singaporean Subjects With Open Angles. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3265.
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To prospectively assess changes in angle configuration and anterior segment parameters measured by anterior segment optical coherence tomography (Visante ASOCT, Carl Zeiss Meditec, Dublin, CA) over four years in a cohort of Singaporean subjects with open angles.
339 open angle subjects aged >50 without ophthalmic symptoms were recruited from a community-based clinic. All subjects underwent gonioscopy and ASOCT imaging at baseline and four years later. Gonioscopic angle closure was defined as the presence of Shaffers’ grading ≤1 for three or more quadrants. Horizontal ASOCT images were analyzed for the following measurements: angle opening distance (AOD) at 750μm from the scleral spur; trabecular-iris space area (TISA) at 750μm; iris area (IAREA), iris thickness (IT) at 2000μm, iris curvature (ICURV), anterior chamber depth (ACD), anterior chamber area (ACA), anterior chamber volume (ACV) and lens vault (LV).
Of the 339 subjects, 204 subjects (61%) had high quality ASOCT images at baseline and at Year 4. The mean age of study subjects at follow up was 63.9(SD 6.4) years; 53.7% were female and 86% were Chinese. Overall, from baseline to Year 4, there was decrease in mean Shaffer grade, ACD, AOD750, TISA750, IT2000, and IAREA in both nasal and temporal quadrants (p<0.05). There was an increase in ICURV (in the temporal quadrant) as well as LV compared to baseline (p<0.05). 19 out of 204 patients (9%) were found to have developed gonioscopic angle closure at the 4-year follow-up visit. Subjects who developed angle closure had lower mean Shaffer grade, ACD, AOD750, TISA750, ACA and ACV but higher LV and temporal ICURV (all p<0.05) at baseline, compared to those whose angles remained open.
In this cohort of open angle subjects followed-up over four years with ASOCT, there was a significant decrease in angle width, iris area and thickness, but increase in temporal iris curvature and lens vault. Almost 10% of subjects developed gonioscopic angle closure over this period; those who developed angle closure had smaller angle and anterior segment measurements but thicker LV at baseline.
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