Prevention of primary angle‐closure glaucoma in Asia

Focused research is needed to reduce the prevalence of glaucoma in Asi

Associations between Narrow Angle and Adult Anthropometry: The Liwan Eye Study

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Reproducibility of Anterior Chamber Angle Measurements Obtained with Anterior Segment Optical Coherence Tomography

PURPOSE. To evaluate the reproducibility of anterior chamber (AC) angle measurements obtained using anterior segment optical coherence tomography (AS-OCT). METHODS. Patients with suspected glaucoma and those with glaucoma, ocular hypertension, or anatomically narrow angles were recruited from the glaucoma service at the National University Hospital, Singapore. All subjects underwent imaging of the nasal, temporal, and inferior AC angles with an AS-OCT prototype under standardized dark and light conditions. For short-term reproducibility analysis, a single observer acquired two sets of images followed by a third set of images acquired by a second observer. The interval between sessions was 10 minutes. For long-term reproducibility analysis, a single observer acquired two sets of images at least 24 hours apart. Images were measured using custom software to determine the AC depth (ACD), angle opening distance at 500 m (AOD 500 ), angle recess area at 500 m (ARA 500 ), and trabecular-iris space area at 500 m (TISA 500 ). The intraclass correlation coefficient (ICC) was calculated as a measure of intraobserver and interobserver reproducibility. RESULTS. Twenty eyes of 20 patients were analyzed for shortterm reproducibility, and 23 eyes of 23 patients were analyzed for long-term reproducibility. AC depth measurement demonstrated excellent reproducibility (ICC 0.93-1.00) in both dark and light conditions. For the nasal and temporal quadrants, all AC angle parameters demonstrated good to excellent shortterm (ICC 0.67-0.90) and long-term (ICC 0.56 -0.93) reproducibility in both dark and light conditions. In the inferior quadrant, reproducibility was lower in all categories of analysis and varied from poor to good (ICC 0.31-0.73). CONCLUSIONS. AS-OCT allows quantitative assessment of the AC angle. The reproducibility of AC angle measurements was good to excellent for the nasal and temporal quadrants. The lower reproducibility of measurements in the inferior quadrant may be unique to this prototype due to difficulty in acquiring high-quality images of the inferior angle. Further assessment of the commercially available AS-OCT is needed to clarify this finding. (Invest Ophthalmol Vis Sci

Primary angle closure glaucoma in East Asia: educational attainment as a protective factor.

PURPOSE: To examine the relationship between education, other risk factors and incident primary angle closure glaucoma (PACG). METHOD: Glaucoma was excluded in a group of 4597 Mongolian volunteers in 1999. After 6 years, 1892 traced participants had full ophthalmic examination, dilated disc photographs and agreed to complete a questionnaire on socio-economic status. PACG was diagnosed using both structural and functional evidence from objective grading of paired disc photographs, follow up visual fields and clinical examination. Ophthalmic examination included van Herick grading, Goldmann intraocular pressure (IOP), gonioscopy, lens opacity grading and dilated disc examination. Central anterior chamber depth, lens thickness and axial length were recorded using ultrasound A scan mounted on a slitlamp. Education level was assessed using national census categories. RESULTS: PACG was diagnosed in 29 participants (6 year incidence = 1.53%, 95% confidence interval (CI) = 1.03-2.19%). In univariate analysis, risk factors for incident PACG included presence of refractive error, narrow van Herick grading of ≤15%, narrower average Shaffer grading, higher IOP, larger cup disc ratio and lower levels of education. In multivariate analysis, adjusted for age, sex, Shaffer grading, refractive error and IOP, those with no formal education were approximately 7 times more likely to develop PACG compared to those with >8 years of formal schooling (OR = 7.27, 95% CI = 2.73-19.38). CONCLUSIONS: People with lower levels of education have a higher risk of incident PACG, independent of age, sex, IOP and axial length

Changes in anterior segment morphology in response to illumination and after laser iridotomy in Asian eyes: an anterior segment OCT study

10.1136/bjo.2006.113654British Journal of Ophthalmology91111485-148

Randomised controlled trial of screening and prophylactic treatment to prevent primary angle closure glaucoma.

AIMS: To determine if screening with an ultrasound A-scan and prophylactic treatment of primary angle closure (PAC) with laser peripheral iridotomy (LPI) can reduce the incidence of primary angle closure glaucoma (PACG) in Mongolia. METHODS: A single-masked randomised controlled trial was initiated in 1999. 4725 volunteer Mongolian participants ≥ 50 years old from the capital Ulaanbaatar or the rural province of Bayankhongor were recruited, of which 128 were excluded with glaucoma. 4597 were randomly allocated to the control, no-screening arm or screening with ultrasound central anterior chamber depth (cACD), with the cut-off set at < 2.53 mm. 685 screen-positive participants were examined and angle closure was identified by gonioscopy in 160, of which 156 were treated with prophylactic LPI. Primary outcome of incident PACG was determined using both structural and functional evidence from objective grading of paired disc photographs from baseline and follow-up, objective grading of follow-up visual fields and clinical examination. RESULTS: Six years later, 801 (17.42%) participants were known to have died, and a further 2047 (53.92%) were traced and underwent full ophthalmic examination. In an intention to treat analysis using available data, PACG was diagnosed in 33 participants (1.61%, 95% CI 1.11% to 2.25%), of which 19 were in the screened group and 14 in the non-screened group (OR 1.29, 95% CI 0.65 to 2.60, p = 0.47), indicating no difference between groups. CONCLUSIONS: We were not able to identify a reduction in the 6 year incidence of PACG after screening with cACD < 2.53 mm and prophylactic treatment of PAC