Sibling Risk of Narrow Angles in Asian Patients With Primary Angle Closure Glaucoma or Acute Primary Angle Closure

Abstract

Purpose: : To ascertain the recurrence and relative risk of having narrow drainage angles in siblings of subjects with primary angle closure glaucoma (PACG) or acute primary angle closure (APAC)

Methods: : This prospective study examined siblings of 72 Singaporean probands with newly diagnosed PACG/APAC. All subjects underwent an ophthalmic evaluation that included slit lamp examination, stereo-biomicroscopic disc evaluation and gonioscopy; as well as A-scan biometry and imaging with ultrasound biomicroscopy (UBM) and the anterior segment optical coherence tomography (AS-OCT). An angle was classified as narrow if the posterior (usually pigmented) half of the trabecular meshwork could be seen for less than 180 degrees of the angle circumference with confirmation on AS-OCT. The sibling recurrence and relative risk of having narrow angles compared to the general population were calculated.

Results: : 190 sibling pairs including 72 probands were examined. Of these, 43 pairs had both siblings unaffected, 49 pairs had both siblings affected, 76 pairs had sibling one affected but not sibling two and 22 pairs had sibling two affected but not sibling one. The sibling recurrence risk for having narrow angles was 38% (95% Confidence Interval: 15%-61%) while the sibling relative risk for narrow angles was 5.85 (95% Confidence Interval 2.36-9.32)

Conclusions: : Siblings of patients with PACG/APAC have a 40% probability of having narrow angles. Siblings of individuals with PACG/APAC are 5.85 times more likely to have narrow angles than the general Singaporean population. This data provides further evidence of a genetic basis to PACG/APAC and suggests a targeted screening strategy amongst family members may be useful to identify patients at risk of PACG/APAC

Keywords: clinical (human) or epidemiologic studies: risk factor assessment