Prevalence of cataract type in relation to axial length in subjects with high myopia and emmetropia in an Indian population

Abstract

Purpose: To compare the prevalence of different types and densities of age-related cataract in subjects with high myopia and emmetropia in an Indian urban clinic-based population.

Design: Prospective, observational, clinic-based case-control study.

Methods: An observational case-control study of 800 healthy eyes was undertaken at Iladevi Cataract & IOL Research Center, Ahmedabad, India. Subjects with high myopia (axial length [AXL], > or = 26.0 mm; n = 400 eyes) and those with emmetropia (AXL, 21.0 to 23.99 mm) were examined (n = 400 eyes). The type of cataract was categorized as: nuclear, cortical, or posterior subcapsular cataract (PSC). Nuclear density was measured based on the Emery and Little classification.

Results: In all the age groups (40 years of age or more), nuclear cataract was encountered more often in subjects with high myopia (odds ratio, 3.8; 95% confidence interval, 2.9 to 5.2; P < .001); PSC and mixed cataracts were encountered frequently in subjects with emmetropia (P < .001). Prevalence of nuclear cataract was higher in subjects with high myopia with increasing AXL when compared with other types of cataract (P < .001). In all the age groups, the nuclear density was significantly higher than grade 3 in subjects with high myopia when compared with those with emmetropia (P < .001 in those younger than 70 years; P = .003 in those older than 70 years).

Conclusions: Nuclear cataract was associated strongly with high axial myopia. The density of the cataract was higher in the high myopia group. No association was observed between PSC or cortical cataract and high axial myopia.