Weak Correlation Between Retinal Thickness and BCVA in CSME Eyes of Patients With Diabetes Type 2

Abstract

Purpose: : To investigate the correlation between retinal thickness using high definition OCT (Cirrus OCT) and best-corrected visual acuity (BCVA) in eyes with clinically significant macular edema (CSME) in patients with diabetes type 2.

Methods: : Retinal thickness was measured with the Stratus OCT and the spectral domain high-definition Cirrus OCT. For the Stratus OCT, two measures were considered, the central point thickness and the 1000-µm diameter area. For the Cirrus OCT, the values considered were the 500- and the 1000-µm diameter areas. Eyes were classified as having or not having central foveal involvement by both stereocolor fundus photography and Stratus OCT central point thickness measurements.

Results: : Only moderate correlations were found between retinal thickness and BCVA values (|R| ranging from 0.479 to 0.537; p<0.05), although eyes with central foveal involvement showed higher correlations compared to eyes without central foveal involvement. A robust correlation was found only in 50% of the eyes. The increased resolution of Cirrus OCT allowed for a better separation of eyes without central foveal involvement showing clearly, in these eyes, no correlation between retinal thickness and BCVA (|R| ranging from 0.005 to 0.116; p>0.05).

Conclusions: : Values in the correlation between retinal thickness and BCVA vary widely in diabetic retinal edema, with only 50% of cases showing a robust correlation, indicating that OCT thickness measurements cannot be used as a surrogate for visual acuity changes.

Keywords: diabetic retinopathy • imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)