Correlation between optical coherence tomographic patterns and visual acuity in eyes with diabetic macular edema

Abstract

Purpose The aim of the present study was to investigate the correlation between different features of optical coherence tomography, macular thickness, and visual acuity (VA) in patients with diabetic macular edema. Patients and methods In total, 168 eyes with clinically significant diabetic macular edema were included in the study. Best-corrected VA was measured and converted to the logarithm of the minimum angle of resolution (logMAR). Optical coherence tomography was carried out and morphology at the presumed fovea was used to classify eyes into four groups: group I, in which the eyes had only noncystoid sponge-like diffuse retinal thickening (DRT); group II, in which the eyes had DRT with cystoid macular edema (CME); group III, in which the eyes had DRT with serous retinal detachment (SRD); and group IV, in which the eyes had DRT with CME and SRD in the same eye. Retinal thickness at the central fovea [center point thickness (CPT)], average macular thickness (AMT), and the height of the cystoid space and the SRD at the fovea were measured. Results DRT was found alone in 65% of the eyes, CME in 16%, SRD in 13%, and CME and SRD in 6%. Mean logMAR was 0.68 with DRT, 1.16 with CME, 0.89 with SRD, and 1.05 with CME and SRD. Mean CPT was 299 μm in DRT, 573 μm in CME, 354 μm in SRD, and 483 μm in CME and SRD, whereas mean AMT was 309 μm with DRT, 374 μm with CME, 344 μm with SRD, and 390 μm with CME and SRD. There was a positive significant correlation between logMAR and CPT in DRT (0.357, P = 0.001), whereas the correlation was less in CME, SRD, and CME and SRD (0.373, P = 0.087; 0.463, P = 0.053; and 0.082, P = 0.847; respectively). The positive correlation between logMAR and AMT was significant in DRT, CME, and SRD but not in CME and SRD (0.314, P = 0.002; 0.605, P = 0.003; 0.646, P = 0.004; and 0.327, P = 0.429, respectively). The height of the SRD was positively correlated with logMAR (0.516, P = 0.028), whereas the correlation between the height of the cystoid space in CME and logMAR was less (0.360, P = 0.099). Conclusion DRT was the most common feature. CME had worst visual outcome and greatest CPT and AMT. In DRT, worse VA correlated more with CPT than with AMT, whereas in CME and SRD, correlation of VA was more with AMT than with CPT. VA correlated with height of lesion in eyes with SRD but not with CME. The height of cystoid space correlated with CPT but not with AMT, whereas the height of SRD correlated with both CPT and AMT.