Choroidal Thickness in Patients with Diabetic Macular Edema and its Correlation to Macular Thickness and Vision

Abstract

Purpose: To investigate the relationship between subfoveal choroidal thickness, central macular thickness, visual acuity and the presence of diabetic macular edema (DME) using spectral domain optical coherence tomography (SD-OCT). Methods:A prospective, nonrandomized case control study of 124 eyes was included in the study and divided into three groups: Group I: 56 eyes having NPDR without macular edema, Group II: 27 eyes having NPDR with DME, Group III: 41 eyes of normal healthy subjects. Central macular thickness (CMT) and subfoveal choroidal thickness (SFCT) were measured on the OCT images and statistically compared. Pearson correlation analysis used to evaluate the relationships between choroidal thickness, macular thickness and visual acuity. Results: A total of 124 eyes of 76 patients; mean age 52.56 ±8.91years were included in the study. Mean bestcorrected visual acuity LogMAR was better in the control group (0.20 ± 0.40) than diabetic groups (0.42 ± 0.40 in group I, 0.80 ± 0.45 in group II) and the difference was significant among the groups (P= 0.01). Mean CMT was thicker in DME group (374.63μm ± 105.43) than the other 2 groups (246.66± 24.85 μm in group I, 227.05 μm ± 21.97 in group III) and the difference was significant among the groups (P= 0.00). Mean SFCT was thinner in DME group (234.93 μm ± 42.68) than d the other 2 groups (246.41 μm ± 44.37 in group I, 250.20 μm ± 53.10 in group III) but the difference was not statistically significant (P= 0.41). A significant correlation was found between LogMAR and CMT in group II (r=0.391, P=0.044) indicating that the vision may decrease as the central macular thickness increases in diabetic groups. A weak inverse correlation was found between LogMAR and SFCT in all groups indicating that the vision may decrease as the choroidal thickness decrease. A weak negative correlation was found between CMT and SFCT in diabetic groups (r=-0.142 in group I, r=-0.152 in group II) indicating that the choroidal thickness may decrease as the central retinal thickness increases in diabetic groups. Conclusion: In diabetic eyes, there is an overall thinning of the choroid. SFCT is directly related to vision and macular thickness.