Choroidal thickness in type 2 diabetes mellitus patients using spectral domain optical coherence tomography

To measure the choroidal thickness in patients with type 2 diabetes mellitus and its comparison to healthy age-matched individuals. This prospective comparative study conducted at departments of Ophthalmology, Shri B.M. Patil Medical College, Hospital and Research Centre, Vijayapura. Study included 192 patients, 96 with diabetes and 96 age-matched controls. Data acquired comprised demographics, a thorough eye examination, fundus photography and spectral domain optical coherence tomography measurements of choroidal thickness using enhanced depth imaging. Mean age was 60.17±7.727 years with male predominance in both cases and controls. The mean duration of diabetes was 5.67±3.39 years. Positive correlation was noted between duration of diabetes and severity of retinopathy (p = 0.001). 21 patients did not have any evidence of diabetic retinopathy, while 75 patents had features of non-proliferative diabetic retinopathy, of which (31) had mild, (21) moderate, (12) severe and (11) with proliferative diabetic retinopathy. Mean choroidal thickness of controls was 327.308±18.945 microns, as compared to thinner choroids 295±15.082 microns in cases without retinopathy and 271 ± 36.122, 242 ±30.048, 193±15.748 microns in mild, moderate, severe non-proliferative diabetic retinopathy respectively and 191.492± 23.834 microns in proliferative diabetic retinopathy. Statistically significant differences were noted on comparing choroidal thickness between controls and cases (p = 0.001). Choroidal thickness was maximum in control group with a p value of <0.001, while cases showed overall thinner choroids with increasing severity of retinopathy. Thinnest choroids were observed in patient with proliferative diabetic retinopathy. Choroidal thickness can be used as a non-invasive prognostic bio marker for diabetic retinopathy.