Retinal fixation in Diabetic Macular Edema

Abstract

Abstract Purpose: Diabetic macular edema (DME) determines central retinal sensitivity reduction with a functional correlate to increased macular thickness. Data about fixation are controversial. The aim of this study was to determine fixation characteristics in diabetic patients with or without clinically significant macular edema (CSME). Methods: 120 consecutive diabetic patients (165 eyes) underwent best corrected visual acuity (BCVA) determination (ETDRS charts), and a complete ophthalmologic examination. Diagnosis and classification (focal, diffuse and cystoid) of CSME were made on 30 degrees stereo retinal photographies (field 2 of ETDRS) and fluorescein angiography and OCT. The presence and site of hard exudates was evaluated. Retinal fixation and macular sensitivity were investigated with an advanced, automatic microperimeter (MP1, Nidek Technologies, Italy). Macular thickness and foveal neuroretinal detachment were determined by Optical Coherence Tomography (OCT Stratus, Zeiss Humphrey Instruments, Germany). Results: Of 141 examined eyes 24 (17.14%) had focal CSME, 37 (26.43%) had diffuse CSME, 51 (36.43%) cystoid CSME, 29 (17.6%). Mean BCVA was 0.6+0.36 logMAR. There was no significant correlation between the type of edema and the site and the stability of fixation (P>0.05). Fixation was eccentric or unstable in case of subfoveal hard exudates (Site P=0.032; Stability P= 0.0113). The presence subfoveal neuroretinal detachment did not significantly influence fixation pattern (P>0.05). Conclusions: Retinal fixation patterns in DME vary diferently based on clinical characteristics of foveal involvement. Fixation may be often located in areas undergoing laser treatment. The functional impact of focal photocoagulation should be investigated also from the fixation point of view