Change in subfoveal choroidal thickness in diabetes and in various grades of diabetic retinopathy

BACKGROUND: To evaluate subfoveal choroidal thickness (SFCT) change in diabetes and in various grades of diabetic retinopathy (DR) in comparison to age-matched healthy subjects. METHODS: This prospective observational study included 100 eyes of diabetic patients without DR (group D), 100 eyes with DR (group R), and 100 eyes of healthy subjects (group N). The assessment included demographics, duration of diabetes, comprehensive ocular examination, fundus photography with/without fundus fluorescein angiography, spectral domain optical coherence tomography with enhanced depth imaging to assess SFCT. RESULTS: The SFCT was comparable between groups N (310.65 ± 37.34 µm) and D (308.48 ± 30.06 µm; P = 0.60), but was significantly lower in R (296.52 ± 21.41 µm; P < 0.01). The SFCT was significantly lower in proliferative DR (n = 36; SFCT = 284.56 ± 21.09 µm) as compared to non-proliferative DR (n = 64; SFCT = 303.25 ± 18.59 µm; P < 0.001). The SFCT had moderately negative correlation with severity of DR (R = − 0.50; P < 0.01). The difference in SFCT when compared with normal subjects was significant only in severe/very severe non-proliferative DR (294.47 ± 15.65 µm; P < 0.01) and in proliferative DR (284.56 ± 21.09 µm; P < 0.01). There was a negative correlation of SFCT with the duration of diabetes (R = − 0.41; P < 0.01). CONCLUSION: SFCT decreases with increasing duration of diabetes. The decrease is significant after the onset of severe DR, and is proportionate to the severity of DR.