Classification of diabetic macular edema cases based on optical coherence tomography images and evaluation of morphological features

OBJECTIVES: This study aimed to classify DME morphologically using optical coherence tomography (OCT) and to assess the impact of selected OCT biomarkers on DME subtypes. METHODS: OCT images of patients with DME categorized into three groups as diffuse macular edema (dME), cystoid macular edema (CME) and cystoid degeneration (CD). Presence of subretinal fluid (SRF), disorganization of inner retinal layers (DRIL), ellipsoid zone (EZ) damage, external limiting membrane (ELM) damage, exudates, hyperreflective dots (HRD), epiretinal membrane (ERM) and vitreomacular traction (VMT) were evaluated. The effect of OCT findings on DME type was examined and factors affecting visual acuity were evaluated in this retrospective, cross-sectional study. RESULTS: 746 eyes of 538 patients were evaluated and 55.1% were in the CME group, 40.6% in dME and 3.8% in the CD group. It was observed that the integrity of ELM and EZ was impaired in 11.58% and 11.09%, respectively. When SRF, DRIL, HRD, exudates, VMT and ERM were examined, the rates of 16.7%, 19.23%, 28.83%, 54.40%, 2.76% and 15.8% were obtained, respectively. The CD group had the weakest visual acuity, while the dME group had the greatest (P < 0.001). While SRF, HRD, and exudates were most common in CME; DRIL, ELM and EZ damages were most common in the CD group (P < 0.001). CONCLUSION: The group with the lowest visual acuity and the most damage to the outer retinal layers is the CD group. Presence of SRF, DRIL, HRD, exudate and ERM are also among the reasons that decrease visual acuity in DME.