Purpose To compare the prevalence of angle closure among siblings of patients with open angles (OAs), suspect angle closure (PACS), and either primary angle closure (PAC) or PAC glaucoma (PACG).
Design Cross-sectional, clinical study.
ParticipantsA total of 303 South Indian sibling pairs, including 81 OA probands, 143 PACS probands, and 79 PAC/PACG probands.
Methods Probands and siblings underwent a clinical examination, including gonioscopy by a masked grader, applanation tonometry, slit-lamp biomicroscopy, optic nerve evaluation, and A-scan ultrasonography. Probands and siblings were classified into 1 of 3 groups based on the phenotype of the more severely affected eye: OA, PACS, or PAC/PACG. Multivariable regression models were used to estimate the odds of prevalent angle closure in PACS or PAC/PACG siblings compared with OA siblings.
Main Outcome Measures Prevalence and relative prevalence of angle closure and PAC/PACG among OA, PACS, and PAC/PACG siblings.
Results Mean sibling age was 49.7±8.7 years, and 56.6% of siblings were females. Angle closure was more prevalent in both PACS siblings (35.0%) and PAC/PACG siblings (36.7%) compared with OA siblings (3.7%; P < 0.001). There was PAC/PACG present in 11.4% of PAC/PACG siblings compared with 4.9% of PACS siblings (P = 0.07) and 0% of OA siblings (P = 0.002). In multivariable models adjusting for sibling age and sex, the odds of angle closure was 13.6 times greater in angle closure (PACS or PAC/PACG) siblings compared with OA siblings (95% confidence interval [CI], 4.1-45.0; P < 0.001). Sibling angle-closure risk was also greater in female (odds ratio [OR], 2.3; 95% CI, 1.3-4.0; P = 0.005) and older siblings (OR, 1.5 per 10-year increment; 95% CI, 1.1-2.0; P = 0.02). Siblings of PAC/PACG probands had a 2.3-fold greater odds (95% CI, 0.8-6.5) of having PAC/PACG compared with siblings of PACS probands, although the association was not significant (P = 0.13).
Conclusions In the South Indian population screened, siblings of angle-closure patients had a >1 in 3 risk of prevalent angle closure, whereas siblings of PAC/PACG patients had a >10% risk of prevalent PAC/PACG. Screening siblings of angle-closure patients is likely to be of high yield in finding undetected angle closure.
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