Purpose: The aim of the study reported here was to assess choroidal thickness (CT) and central macular thickness (CMT) in patients with diabetic retinopathy.
Materials and methods: A total of 151 eyes from 80 patients from the retina department of Istanbul Training and Research Hospital who had type 2 diabetes mellitus with diabetic retinopathy were studied retrospectively in this cross-sectional research. Patients were divided into three groups: mild-moderate nonproliferative diabetic retinopathy without macular edema (NPDR), mild-moderate nonproliferative diabetic retinopathy with macular edema (DME), and proliferative diabetic retinopathy (PDR). In addition, 40 eyes of 20 healthy individuals comprised a control group. Choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroid/sclera junction at 500-μm intervals up to 1,500 μm temporal and nasal to the fovea. The CMT measurement was obtained for each eye. Serum hemoglobin A1c (HbA1c) levels were measured.
Results: The study included 191 eyes, comprising 151 eyes of 80 patients and 40 eyes of 20 healthy individuals. Of the 151 patient eyes, 61 had NPDR, 62 had PDR, and 28 eyes had DME. There was no statistically significant difference in age between the groups (P>0.05). In both the PDR and DME groups, the CT was statistically significantly decreased compared with the control group (P<0.001, P<0.001 for the PDR and DME groups, respectively). The mean CMT in the DME group was increased significantly compared with both the NPDR and PDR groups (P<0.001, P<0.001, respectively). In all three groups, serum HbA1c levels were found to be increased significantly compared with the control group (P=0.000). We found a statistically weak-moderate negative correlation between central macular and foveal CT (r=-289, P=0.000). There was a statistically strong correlation between CMT and HbA1c levels (r=0.577, P=0.483) and a statistically weak-moderate negative correlation between the central CT and HbA1c levels (r=-0.331, P<0.001).
Conclusion: Diabetes changes the CT. CT was found to be significantly decreased in the DME and PDR groups.
Keywords: choroidal thickness; diabetic retinopathy; optical coherence tomography.