Abstract
Purpose:
To evaluate the prevalence of myopia and to assess ocular biometric parameters in subjects with primary angle closure.
Methods:
The study recruited 460 subjects, which included 152 primary angle closure suspects (PACS), 80 primary angle closure (PAC), 174 primary angle closure glaucoma (PACG) and 54 subjects with acute primary angle closure (APAC). A-scan biometry (US-800; Nidek Co, Ltd, Tokyo, Japan) was used to obtain measurements of anterior chamber depth (ACD), axial length (AL), lens thickness (LT) and vitreous length (VL). Refraction was measured with an autorefractor (Canon RK-5 Auto Ref-Keratometer; Canon Inc. Ltd., Tokyo, Japan), and refractive status was categorized as myopia (<-0.50D), emmetropia (-0.50D to +0.50D) and hyperopia (>+0.50).
Results:
The mean age of the subjects was 65.6 years (SD ±8.8), 64.8% were female and the majority of subjects were Chinese (92%). Amongst all subjects with angle closure, 23% had myopia and 51.1% had hyperopia. Overall, 9.6% of angle closure subjects had moderate and high myopia (<-2.0D). The lowest proportion of myopic patients was in the PACS sub-group (10.5%). While the myopic angle closure subjects had statistically longer AL (p=0.02 and p<0.001) and VL (p= 0.03 and p<0.001) than the emmetropic and hyperopic subjects, there was no statistical difference in ACD (p=0.44) and LT (p=0.46) between the different refractive status groups.
Conclusions:
Almost a quarter of subjects with angle closure were myopic with 9.6% having moderate to high myopia. Myopic angle closure may be mediated through a shallow anterior chamber as ACD did not vary with refractive status, but myopic angle closure subjects had longer VL and AL. We advocate gonioscopy in all patients irrespective of refractive status, as a significant proportion of angle closure patients may be myopic.
Keywords: 420 anterior chamber •
605 myopia