Enhanced depth imaging optical coherence tomography in type 2 diabetes

Purpose. To investigate the changes in macular choroidal thickness in eyes with various stages of diabetic retinopathy, using enhanced depth imaging optical coherence tomography (EDI OCT). Methods. Sixty-three consecutive diabetic patients-who presented without diabetic retinopathy (NDR); with diabetic retinopathy (nonproliferative diabetic retinopathy NPDR]) and no clinically significant macular edema (CSME-); or with NDPR and clinically significant macular edema (CSME+)-underwent EDI OCT. Twenty-one age- and sex-matched healthy subjects (21 eyes) also underwent EDI OCT. Results. A total of 63 eyes of 63 consecutive diabetic patients (26 female 41.2%]; mean age 65 ± 9 years, range 48-83 years) were included in the analysis. Mean best-corrected visual acuity was 0.13 ± 0.25 LogMAR (range 0-1). Mean CMT was 272.5 ± 16.2 μm in 21 NDR eyes, 294.5 ± 23.5 μm in 21 NPDR/CSME- eyes, and 385.6 ± 75.1 μm in 21 NPDR/CSME+ eyes. There was no difference in mean subfoveal choroidal thickness among each diabetic group (238.4 ± 47.9 μm NDR], 207.0 ± 55.9 μm NPDR/CSME-], 190.8 ± 48.4 μm NPDR/CSME+]; P = 0.23). The mean subfoveal choroidal thickness was significantly reduced in each diabetic group compared with the control group (309.8 ± 58.5 μm, P < 0.001). Conclusions. In diabetic eyes, there is an overall thinning of the choroid on EDI OCT. A decreased choroidal thickness may lead to tissue hypoxia and consequently increase the level of VEGF, resulting in the breakdown of the blood-retinal barrier and development of macular edema.