Outer retinal thickness and correlation with visual acuity in patients with diabetic macular edema

Quick Fire Free Paper Session 04PURPOSE: To investigate the correlation of outer retinal thickness (distance between the retinal pigment epithelium and the external limiting membrane) and visual acuity in patients with diabetic macular edema. SETTING: Department of Ophthalmology, University of Hong Kong METHODS: Eyes with conditions other than DME, and conditions that would render media unclear for OCT scans were excluded. Each subject was assessed by a Snellen visual acuity chart, and OCT scan using the Heidelberg Spectralis (Heidelberg, Germany). The scanned images were then analyzed with the software provided by Heidelberg (Heidelberg Explorer). The hyper-reflective lines in the outer retina were identified, and the distance between the external limiting membrane (ELM) and the retinal pigment epithelium (RPE) was measured using the built-in caliber. Those with disruption of the ELM at the fovea were excluded from further analysis. A P value <0.05 was considered statistically significant. RESULTS: A total of 108 eyes of 108 subjects were recruited, but 30 (27.8%) were excluded due to disruption of the ELM, resulting in 78 eyes for analysis. The mean age was 58.1±11.5 years. 51 of them were male (47.2%). Mean refractive error was -1.3±2.5 dioptres. The mean SnellenVA was 0.51±0.18. Mean total retinal thickness (TRT) at fovea was 398.0±74.3mm. Mean outer retinal thickness (ORT) at fovea was 115.7±35.6mm. When both the TRT and ORT were compared against VA, both had P