Enhanced depth imaging optical coherence tomography in type 2 diabetes

Purpose:To investigate the changes in choroidal thickness within the macula of eyes with various stages of diabetic retinopathy, using enhanced depth imaging optical coherence tomography (EDI OCT).Methods:Sixty-three consecutive diabetic patients without (NDR) or with diabetic retinopathy (non-proliferative diabetic retinopathy [NPDR] and no clinically significant macular edema [CSME-]; 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 65.4 ± 8.9 years, range 48-83 years) were included in the analysis. Mean BCVA was 0.13±0.25 LogMAR (range 0-1). Mean CMT was 272.47±16.24 μm in 21 NDR eyes, 294.52±23.51 μm in 21 NPDR/CSME- eyes, and 385.61±75.07 μm in 21 NPDR/CSME+ eyes. There was no difference in mean subfoveal choroidal thickness among each diabetic group (238.42±47.95 μm [NDR], 207.0±55.95 μm [NPDR/CSME-], 190.85±48.43 μm NPDR/CSME+; p=0.18). The mean subfoveal choroidal thickness was significantly reduced in each diabetic group compared with the control group (309.76±58.52 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 the development of macular edema.