Morphological retinal characteristics of patients with low vision due to diabetic macular edema

Abstract

Background: The World Health Organisation (WHO) defines low vision as a best corrected visual acuity (BCVA) in the better eye between ≥0.5 logMAR and ≤1.3 logMAR. In diabetic macular edema (DME) the correlation between retinal morphology and function is not completely understood in patients with advanced visual impairment. Objective: The aim of the study was to describe the pathomorphological similarities of DME in patients with low vision and to correlate them with clinical parameters. Material and methods: Optical coherence tomography (OCT) and fluorescence angiography (FA) images were graded according to the SAVE protocol and correlated with BCVA, cataract grade and clinical parameters in order to elucidate joint features. Results: Out of a total collective of 65 patients 24 had low vision and 18 of these 24 patients (75%) showed typical signs of atrophic edema according to SAVE protocol criteria (SAVE group 4); however, 6 patients were afflicted with less progressive forms of DME but still suffered from low vision. Common pathomorphological findings were a discontinuity of the ellipsoid zone (EZ; n = 18), loss of pseudosepta (n = 7), layer-disrupting cysts (n = 7) and hard exudates (n = 10). Conclusion: It is suggested that a disruption of the EZ, loss of pseudosepta and layer-disrupting cysts are signs of an advanced chronic DME causing low vision. A definition of characteristic pathomorphological patterns of chronic damage in OCT is important for a possible treatment discontinuation in the clinical routine.