Study of changes in choroidal thickness with severity of diabetic retinopathy and diabetic macular edema in type 2 diabetic patients

Abstract

: Diabetic retinopathy (DR) is one of the long-term microvascular complications of Diabetes mellitus. Chronic hyperglycemia cause microvascular abnormalities to both retina and choroid. Optical coherence tomography (OCT) is a non-invasive fundus imaging modality, which plays a vital role in revealing the pathogenesis and development of retinal–choroidal diseases.This prospective observational study included 128 eyes of 64 subjects diagnosed with type 2 diabetes and out of 128 eyes, 113 (88%) eyes were found to have DR. Collected data included age, gender, duration of diabetes, glycemic control, comprehensive ocular examination, fundus photography, and CT measurement on OCT.Mean age in the study group was 53.71 ± 9.37 years (45–70 years). Out of 113 eyes, 19 (17%) eyes were diagnosed as mild NPDR, 21 (19%) eyes had moderate NPDR, 36 (31%) eyes had severe NPDR and 37 (33%) eyes had PDR. The average SFCT in MILD NPDR was 310 ± 14.70 μm at 95% CI (1.86), MODERATE NPDR was 316 ± 17.97 μm at 95% CI (2.70), SEVERE NPDR was 326.02 ± 14.05 μm at 95% CI (4.59) and PDR was 298.55 ± 18.75μm at 95% CI. (1.41). The presence of DME significantly affects average SFCT. It was observed that choroidal thickness tends to increase as the severity DR with DME progress.The average SFCT was thicker in patients with increase in severity of DR, and then SFCT decreased in patients with PDR. As the severity of NPDR increased from mild to moderate to severe NPDR, there was increase in sub foveal choroidal thickness. (p<0.05). PDR showed decrease in sub foveal choroidal thickness in comparison to NPDR which is highly statistically significant. p=0.01 (p<0.05). The presence of DME significantly affects average SFCT (p<0.05). It was observed that choroidal thickness tends to increase as the severity DR with DME progress. Thus, Choroidal thickness measurement can help in assessment of DR pathogenesis.