Prevalence of Angle Closure in Siblings of Patients With Primary Angle-closure Glaucoma

Purpose: To determine the frequency of angle closure in siblings of patients with primary angle-closure glaucoma (PACG). Methods: In this cross-sectional observational study, siblings of consecutive patients with PACG underwent a comprehensive ophthalmologic examination, including slit-lamp biomicroscopy, measurement of intraocular pressure, stereoscopic optic nerve head examination, and dynamic gonioscopy. Ultrasonic pachymetry was obtained in all subjects; peripapillary retinal nerve fiber layer thickness measurement by optical coherence tomography and standard achromatic perimetry were performed in subjects with angle closure, categorized as primary angle-closure suspect (PACS), primary angle closure (PAC), and PACG, or any suspicion of glaucoma in the presence of open angles. Results: Overall, 95 siblings from 47 families with at least 1 subject affected with PACG participated in the evaluations; 55 (57.9%) individuals were categorized within the spectrum of angle closure, including 34 (35.8%) subjects with PACS, 7 (7.4%) individuals with PAC, and 14 (14.7%) cases of PACG. Nine (9.5%) individuals with open angles demonstrated other abnormal features, these included 3 (3.2%) subjects with suspicious discs, 5 (5.3%) cases of primary open-angle glaucoma, and 1 patient (1.1%) with normal-tension glaucoma. The remaining 31 individuals (32.6%) had no evidence of glaucoma. Conclusions: Our findings indicate familial segregation of angle closure. Siblings of PACG patients are at high risk for the condition, such that two thirds of them demonstrate clinical findings related to glaucoma. These observations suggest a hereditary basis for angle closure; therefore, siblings of patients affected with angle closure should undergo targeted screening for glaucoma.