Retinal thickness in people with diabetes and minimal or no diabetic retinopathy: Heidelberg Spectralis optical coherence tomography.

PURPOSE: To evaluate macular thickness in people with diabetes but minimal or no retinopathy using Heidelberg Spectralis optical coherence tomography (OCT).
METHODS: In a multicenter, cross-sectional study of mean retinal thickness, on Spectralis OCT in the nine standard OCT subfields, spanning a zone with 6-mm diameter, center point, and total retinal volume were evaluated. Central subfield (CSF) thickness was evaluated for association with demographic and clinical factors. Stratus OCT scans also were performed on each participant.
RESULTS: The analysis included 122 eyes (122 participants) with diabetes and no (n = 103) or minimal diabetic retinopathy (n = 19) and no macular retinal thickening on clinical exam. Average CSF thickness was 270 ± 24 μm. Central subfield thickness was significantly greater in males relative to females (mean 278 ± 23 μm vs. 262 ± 22 μm, P < 0.001). After adjusting for gender, no additional factors were found to be significantly associated with CSF thickness (P > 0.10). Mean Stratus OCT CSF thickness was 199 ± 24 μm.
CONCLUSIONS: Mean CSF thickness is approximately 70 μm thicker when measured with Heidelberg Spectralis OCT as compared with Stratus OCT among individuals with diabetes in the absence of retinopathy or with minimal nonproliferative retinopathy and a normal macular architecture. CSF thickness values ≥ 320 μm for males and 305 μm for females (~2 SDs above the average for this normative cohort) are proposed as gender-specific thickness levels to have reasonable certainty that diabetic macular edema involving the CSF is present using Spectralis measurements.