Abstract
Purpose:
To assess the retinal thickness of diabetic patients with no diabetic retinopathy (NoDR), mild to moderate retinopathy (MMDR), severe non-proliferative retinopathy (SNPDR), and proliferative retinopathy (PDR) with reference to the normal retinal thickness distribution measured with iVue SD-OCT.
Methods:
Diabetic subjects were enrolled in 3 primary care clinics according to IRB approved study protocol. Diabetic subjects over age 18 with informed consent were enrolled. 3-field color fundus photos and Retina Map scans with iVue SD-OCT were acquired for each eye of subjects. Normal retinal thickness distribution was established by iVue SD-OCT normative database (NDB) study. The iVue NDB subjects were enrolled in 5 ophthalmology and optometry sites following IRB approved study protocol. 2 certified graders determined diabetic retinopathy and macular edema levels based on EyePACS grading protocol, masked to the OCT test results. The retinal thickness parameters for this study are central sub-field retinal thickness (CSF) and computed macular volume (CMV). Descriptive statistics were generated and box-plots were provided for the OCT measurements distribution for each sub group.
Results:
Analysis included 901 with NoDR, 449 MMDR, 37 SNPDR, 14 PDR subjects, and 457 normal subjects from the iVue NDB for OCT measured central 1mm retinal thickness (RT_1mm), central 3 mm retinal volume (Volume_3mm), and central 5 mm retinal volume (Volume_5mm). RT_1mm in patients with diabetes is not significantly thicker than normal thickness. Less severe levels of retinopathy are associated with significantly thinner RT_1mm thickness (p<0.05). Subgroups based on ME grading consisted of 1409 not ME, 41 ME but not centrally involved, and 155 ME centrally involved subjects. Presence of hard exudates within 1.5mm of foveola is associated with statistically significant increase in central thickness (p<0.05). In the not ME group, some cases exhibited very thick retina by OCT; examining the OCT images revealed severe edema which was not detected in the fundus photo grading.
Conclusions:
Comparison of OCT parameters among nondiabetic subjects and diabetic subjects with varying levels of retinal disease will help to assess the clinical utility of OCT for DR and DME detection. Further analysis is needed to take into consideration other factors, such as gender, age, duration of diabetes, and coexisting retinal disease.
Keywords: 499 diabetic retinopathy •
498 diabetes •
550 imaging/image analysis: clinical