ObjectiveTo observe the changes in choroidal thickness in type 2 diabetes patients with diabetic retinopathy (DR). MethodsA total of 227 eyes from 150 type 2 diabetes patients were enrolled in this study. The patients included 67 males (89 eyes) and 83 females (138 eyes). The mean age was (65.6±8.0) years, and the mean diabetes duration was (12.4±6.5) years. All the patients were examined for best corrected visual acuity (BCVA), diopter, slit lamp ophthalmoscopy, indirect ophthalmoscopy and spectral domain optical coherence tomography (SD-OCT) examination. The patients were divided into non-DR (NDR group, 99 eyes), non-proliferative DR (PDR) without macular edema (ME) group (NPDR/ME-group, 64 eyes), non-PDR with ME group (NPDR/ME+ group, 5 eyes), PDR without ME group (PDR/ME-group, 25 eyes), PDR with ME group (PDR/ME+ group, 5 eyes) according to the Early Treatment Diabetic Retinopathy Study. The ones having a history of pan-retinal photocoagulation (PRP) were classified as PRP-DR. Age-matched normal subjects were enrolled as the control group. Sub-foveal choroidal thickness (SFCT) was measured by SD-OCT with enhanced depth imaging (EDI). ResultsMean SFCT was (310.2±54.8), (251.1±81.4), (262.5±83.2), (286.2±76.8) and (327.4±83.1) μm respectively in control, NDR, NPDR/ME-, PDR/ME-and PRP-DR groups. Mean SFCT decreased significantly in NDR and NPDR/ME-group (t=2.754, 2.140; P < 0.05). Mean SFCT in PDR/ME-group was thicker than that in NDR (t=-2.114, P < 0.05). Mean SFCT in PRP-DR group was thicker than that in PDR/ME-group (U=271.500, P < 0.05). ConclusionSFCT decreased during the early course of diabetics and increased significantly as the severity worsened from NDR to PDR, and increased in the early duration after PRP treatment.