Alterations in the Choroidal Sublayers in Relationship to Severity and Progression of Diabetic Retinopathy: A Swept-Source OCT Study

Erica W T Kung; Victor T T Chan; Ziqi Tang; Dawei Yang; Zihan Sun; Yu Meng Wang; C H Chan; Michael C H Kwan; Jian Shi; Carol Y Cheung

doi:10.1016/j.xops.2022.100130

Alterations in the Choroidal Sublayers in Relationship to Severity and Progression of Diabetic Retinopathy: A Swept-Source OCT Study

Ophthalmol Sci. 2022 Feb 25;2(2):100130. doi: 10.1016/j.xops.2022.100130. eCollection 2022 Jun.

Authors

Affiliation

¹ Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China.

Abstract

Purpose: To examine the association of baseline choroidal sublayers metrics with the risk of diabetic retinopathy (DR) progression over 2 years, with adjustment for confounding factors that affect choroidal measurements.

Design: Prospective, observational cohort study.

Participants: One hundred three eyes from 62 patients with diabetes mellitus (DM).

Methods: Patients were followed up at 6-month intervals for at least 2 years. Choroidal metrics including choroidal area, choroidal thickness (CT), and choroidal vascularity index were measured for both (1) the choriocapillaris plus Sattler's layer and (2) the Haller's layer within the subfoveal and parafoveal region. Cox proportional models were constructed to estimate the relationship between baseline choroidal metrics and DR progression, adjusted for intereye correlation, established risk factors (i.e., duration of DM, glycated hemoglobin [HbA_1c] level, body mass index [BMI], use of insulin, and mean arterial blood pressure [MABP]) and confounding factors of choroidal measurements (i.e., age and axial length). Additional predictive value of choroidal metrics was assessed using the C-statistic.

Main outcome measures: Hazard ratios (HRs) calculated by Cox proportional hazards model to demonstrate the associations between baseline choroidal metrics and DR progression.

Results: After adjusting for age, axial length, and intereye correlation, choroidal metrics in Haller's layer at baseline that were associated with a higher risk of DR progression included increases in subfoveal choroidal area (HR, 2.033; 95% confidence interval [CI], 1.179-3.505; P = 0.011), subfoveal plus parafoveal choroidal area (HR, 1.909; 95% CI, 1.096-3.326; P = 0.022), subfoveal CT (HR, 2.032; 95% CI, 1.181-3.498; P = 0.010), and subfoveal plus parafoveal CT (HR, 1.908; 95% CI, 1.097-3.319; P = 0.022). These associations remained statistically significant after additionally adjusting for duration of DM, HbA_1c level, BMI, use of insulin, and MABP. Addition of these choroidal metrics significantly improved the discrimination for DR progression when compared with established risk factors alone (e.g., duration of DM and HbA_1c; increase in C-statistic ranged from 8.08% to 9.67% [P < 0.05]).

Conclusions: Eyes with a larger choroidal area and CT in Haller's layer at baseline were associated with a higher risk of DR progression over 2 years.

Keywords: BMI, body mass index; CI, confidence interval; CSI, choroid–sclera interface; CT, choroidal thickness; CVI, choroidal vascularity index; Choroid; DM, diabetes mellitus; DME, diabetic macular edema; DR progression; DR, diabetic retinopathy; Diabetic choroidopathy; Diabetic retinopathy; HR, hazard ratio; HbA1c, glycated hemoglobin; MABP, mean arterial blood pressure; NPDR, nonproliferative diabetic retinopathy; PDR, proliferative diabetic retinopathy; SS, swept-source; Swept-source OCT; VA, visual acuity; VEGF, vascular endothelial growth factor.