Axial Length and Myopic Macular Degeneration Prevalence among Chinese-Americans: The Chinese American Eye Study (CHES)

Abstract

Purpose : To investigate the quantitative and qualitative association of axial length (AL) and prevalence of myopic macular degeneration (MMD) among Chinese- Americans.

Methods : The CHES is population-based cross-sectional study on self-identified Chinese- Americans, aged 50 years and older. Participants underwent an interview, clinical exam, ophthalmic exam; and stereoscopic fundus photography. MMD was assessed in a masked manner by an expert grader. A modified version of the Meta-Analysis for Pathologic Myopia (META-PM) was used to define MMD that included presence of tessellation, diffuse and patchy chorioretinal atrophy, atrophic macula, lacquer cracks, choroidal neovascularization, and Fuch’s spots. Multiple logistic regressions was used and odds ratios and 95% Confidence intervals [OR, (95% CI)] were calculated to examine the association of MMD and axial length. Other socio-demographic, clinical and ocular predictors of MMD were tested as potential confounders and effect-modifiers. Final model included AL, age and sex. To assess the qualitative nature of the relationship between the predictors and MMD, we performed locally weighted (Lowess) regression with slope calculations on the Lowess fitted curves for each consecutive unit of AL.

Results : Out of the 1523 myopes in CHES, 490 (32.2%) had MMD. After adjusting for age, sex and severity of myopia, AL was statistically significantly associated with MMD prevalence [OR=2.6 (2.4, 3.0) per each mm longer AL]. Lowess analysis was suggestive of a minimal difference in predicted prevalence of MMD between 20-25 mm of AL. From 25 mm onwards, there was substantially higher MMD prevalence for longer AL (slope_24-25=0.09 vs slope_25-26=0.27). All participants with an axial length of 31 or more had evidence of MMD. The results were similar when the analysis was repeated for males and females, separately.

Conclusions : In this cohort of Chinese- Americans, longer axial length was an independent risk factor for prevalent MMD. Eye care providers should be aware that Chinese Americans with axial lengths higher than 25 mm have a substantially high risk of having MMD and therefore, should consider conducting detailed retinal exams or referring patients to a retina specialist for evaluation.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.