Purpose: To assess changes in choroidal thickness in type 2 diabetic patients with diabetic retinopathy (DR) and diabetic macular edema (DME) using enhanced-depth imaging spectral domain optical coherence tomography (EDI-OCT).
Methods: Among 235 eyes from 145 patients, 195 treatment-naïve eyes were divided into no DR, mild/moderate nonproliferative DR (NPDR), severe NPDR, proliferative DR (PDR), and 40 eyes having a history of laser panretinal photocoagulation (PRP) were classified as PRP-treated DR. Eyes with no ocular treatment (195 eyes) were divided according to the presence of and to the subtypes of DME. Subfoveal choroidal thickness (SFChT) and parafoveal choroidal thickness (PFChT) at 1500 μm were measured using EDI-OCT.
Results: Mean age was 62.6 ± 12.4 years, and mean duration of DM was 15.1 ± 7.2 years. Mean SFChT in groups with no DR (40 eyes), mild/moderate NPDR (47 eyes), severe NPDR (72 eyes), PDR (36 eyes), and PRP-treated DR (40 eyes) was 262.3 ± 68.4 μm, 244.6 ± 77.0 μm, 291.1 ± 107.7 μm, 363.5 ± 74.9 μm, and 239.9 ± 57.4 μm, respectively. Mean SFChT was significantly greater in eyes with PDR than in those with no DR (P < 0.01), mild/moderate NPDR (P < 0.01), or severe NPDR (P < 0.05). Mean SFChT decreased significantly in PRP-treated DR compared with PDR (P < 0.01). Eyes with DME (67 eyes) had a thicker subfoveal choroid than eyes without DME (128 eyes; P < 0.05) and, compared with cystoid or diffuse types, SFChT was thickest in subretinal detachment (SRD)-type DME (P < 0.05).
Conclusions: Choroidal thickness increased significantly as the severity worsened from mild/moderate/NPDR to PDR, and decreased in PRP-treated eyes. The subfoveal choroid was thicker in eyes with DME than in those without, and was thickest in eyes with SRD-type DME.
Keywords: choroidal thickness; diabetic macular edema; diabetic retinopathy.