Lens Power, Axial Length-to-Corneal Radius Ratio, and Association with Diabetic Retinopathy in the Adult Population with Type 2 Diabetes

Abstract

Purpose: To calculate crystalline lens power and to determine the relationship between ocular biometry and diabetic retinopathy (DR) in an adult population with type 2 diabetes mellitus (T2DM).

Design: Cross-sectional, population-based study.

Participants: Patients with T2DM from the Beixinjing community, Changning district, Shanghai.

Methods: Random clustering sampling was used to identify adults with T2DM in the Beixinjing community. Spherical equivalent (SE) was determined by subjective refraction that achieved the best corrected vision. Axial length (AL), corneal power (CP), and anterior chamber depth (ACD) were measured using the IOLMaster. Diabetic retinopathy and diabetic macular edema (DME) were assessed according to the international DR classification.

Main outcome measures: The crystalline lens power was calculated using the Bennett-Rabbetts formula. The AL-to-corneal radius ratio (AL/CR ratio) was defined as the axial length divided by the mean corneal radius of curvature.

Results: A total of 4011 eyes of 2057 subjects with T2DM were included in the analysis. In multivariate logistic models adjusting for age, sex, duration of diabetes, glycosylated hemoglobin A1c, serum creatinine, body mass index, systolic blood pressure, and cataract, after categorizing values into quartiles, there were trend associations between lens power and any DR (P = 0.01), between AL/CR ratio and any DR (P = 0.02), and between AL and any DR (P = 0.03), between lens power and moderate DR (P = 0.02), and between AL and moderate DR (P = 0.02); eyes with higher AL/CR ratio were less likely to have any DR (odds ratio [OR], 0.43; 95% confidence interval [CI], 0.24-0.78; P = 0.01 per 1 increase) and moderate DR (OR, 0.44; 95% CI, 0.21-0.93; P = 0.03 per 1 increase), eyes with longer AL were less likely to have any DR (OR, 0.88; 95% CI, 0.81-0.95; P = 0.002 per millimeter increase) or moderate DR (OR, 0.89; 95% CI, 0.80-0.98; P = 0.02 per millimeter increase), and eyes with higher SE were more likely to have any DR (OR, 1.08; 95% CI, 1.03-1.13; P = 0.003 per diopter increase).

Conclusions: In persons with T2DM, lens power, AL/CR ratio, and AL were associated with the presence of any DR and moderate DR. These findings suggested that globe elongation plays a major role in protective effects against DR, with contributions from lens power and other refractive components.