Topography of Diabetic Macular Edema by Retinal Thickness Analyzer (RTA) and Optical Coherence Tomography (OCT) Compared to Fluorescein Angiography

Abstract

Abstract: : Purpose: To compare the amount and pattern of fluorescein leakage in diabetic macular edema with the retinal thickness maps obtained by retinal thickness analyzer (RTA) and optical coherence tomography (OCT). Methods: A consecutive series of 30 eyes from 30 patients with diabetic macular edema was included. On fluorescein angiography (FA) the macula was analyzed divided in 10 subfields as defined by the EDTRS. The amount and source of leakage for each field were determined. Retinal thickness was measured by OCT and RTA maps in each of those 10 fields and compared to the FA grading. Results: Foveal retinal thickness on OCT was most influenced by the overall FA leakage, which was the only significant covariate on multivariate analysis. The source and amount of leakage was highly significantly correlated with retinal thickness topography in the four peripheral fields (r=0.54, p=0.002). The mean amount and source of leakage in those fields between 1500 and 3000µm from the foveal center also showed the highest correlation with central foveal thickness on OCT (r=0.46, p=0.01). Similar results were obtained by RTA when excluding ischemic cases (r=0.44, p=0.04). For both instruments the FA leakage within the central foveal fields<1500µm did not correlate significantly with retinal thickness. Automated measurements of central foveal thickness by OCT and RTA were highly correlated to each other (r=0.73, p<0.001), but were not correlated for the peripheral fields. Overall OCT measurements correlated higher with FA. Conclusions: OCT and RTA thickness measurements can be used to identify patients for further examination. FA leakage in the outer EDTRS fields correlates best with central thickness and retinal thickness topography.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • diabetic retinopathy • imaging/image analysis: clinical