Risk factors for optical coherence tomography-assessed center-involving diabetic macular edema in a South Indian population

Abstract

Purpose : To determine the risk factors for center-involving diabetic macular edema (ciDME) and increased central subfield thickness (CST) assessed by optical coherence tomography (OCT) in South Indian patients with type 2 diabetes (T2D).

Methods : For this cross-sectional analysis, patients with T2D were recruited prospectively at Sankara Nethralaya Main Hospital in Chennai, South India. Both eyes of each patient were imaged with color fundus photographs (Daytona Plus Panoramic Ophthalmoscope – P200T, Optos), which were graded for presence or absence of clinically significant macular edema (CSME), and structural OCT (Cirrus HD-OCT, Model 5000). Exclusion criteria included having significant ocular disease that prevented obtaining gradable images. Demographic and clinical data were recorded. Blood was drawn for lipid, hemoglobin A1c, and genetic testing, and a urine sample was taken to measure albuminuria. CSTs were recorded from OCT retinal thickness maps of both eyes, and only the eye with the higher CST for each patient was used for analyses. ciDME was defined as being present if CST was ≥ 290 µm in women and CST was ≥ 305 µm in men. Scans demonstrating other macular pathology that could influence CST such as epiretinal membrane were excluded. Multivariate analyses were done using stepwise logistic regression to assess the effect of covariates on ciDME and CST.

Results : Of participants with gradable OCT scans (N=483), 88 had ciDME and 395 had no ciDME. The concordance between OCT assessment of ciDME and fundus photograph assessment of CSME was 89.6%. In multivariate regression with imputation, participants with ciDME were more likely to be younger, men, have a longer duration of diabetes, lower triglycerides and have albuminuria (p<0.028 for all comparisons). Examining CST as a continuous outcome in multivariate regression, it was found that a higher CST was associated with male sex (p=1.22 x 10^-5) and albuminuria (p=1.09 x 10^-3).

Conclusions : OCT analysis quantitates and refines risk factors for DME, and validates observations from previous studies that have assessed DME by fundus photography alone. By clearly assessing the demographic and clinical risk factors for DME, it will be possible to better identify genes associated with the disease through ongoing genetic analyses of the collected DNA samples from these patients.

This is a 2021 ARVO Annual Meeting abstract.