Choroidal Thickness Mapped in Type 1 and Type 2 Diabetes using 3D-1060nm-Widefield-OCT

Abstract

Purpose: : To map choroidal thickness (ChT) in healthy subjects and patients with diabetes with and without retinopathy using a 3D-1060nm-Widefield-OCT.

Methods: : Forty-two type2 (41-82 years, 11 female), and sixteen type1 diabetic subjects (25-49 years, 5 females) were imaged by 3D-1060nm-OCT performed over 36ºx36° field of view. Axial length, body mass index, plasma glucose and blood pressure measurements were recorded. Eyes were graded according to a modified ETDRS (without retinopathy (NDR), microaneurysms, exudates, clinically significant macula edema) and 18 eyes from 18 healthy age and axial eye length matched control subjects (35-79 years, 11 female). The ChT at the subfoveal location and ChT-maps between retinal pigment epithelium and the choroidal/scleral-interface, were generated and statistically analyzed.

Results: : ChT mapping of all diabetic type2 patients demonstrated central and inferior thinning compared to healthy eyes (unpaired t-test P<0.001). In type1 eyes, the choroid showed a trend of decreased thickness when retinal pathology was present. Subfoveal ChT (mean±SD) for healthy eyes was 351±80µm; significantly thicker than all NDR type2 (n=15) with 210±59µm but not NDR type1 (n=10) with 390± 64µm (ANOVA P<0.001,Tukey P<0.001).

Conclusions: : 3D-1060nm-Widefield-OCT has shown that the central choroid is thinner in all type2 diabetic eyes regardless of disease stage when compared to type1 and healthy controls. In contrast to the conventional assessment of pathological thickness change in several locations, thickness maps allow determination of the choroid thickness status over the extent of the imaged area and are therefore a more insightful clinical biomarker than choroidal thickness values alone.

Keywords: choroid • diabetes