Correlation of the Area of Leakage in Fluorescein Angiography and Retinal Thickness in Optical Coherence Tomography in Diabetic Macular Edema

Abstract

Purpose: : To correlate the area of leakage in fluorescein angiography (FA) and of retinal thickening in spectral domain optical coherence tomography (SD OCT) in diabetic macular edema.

Methods: : Fifteen eyes of 15 patients with untreated diabetic macular edema were examined using FA as well as SD OCT at the same time (Spectralis OCT©, Heidelberg Engineering). Late phase (5-10min) FA images and OCT raster scans were further analyzed regarding the area of leakage and the area of retinal thickening. All planimetric measurement was performed using the program ImageJ © (National Institutes of Health). Retinal thickening was defined as a retinal thickness bigger than 300 µm.

Results: : ImageJ and Spectralis OCT allowed for direct correlation of the area of leakage and retinal thickening. In all patients the area of fluorescein leakage was significantly smaller than the corresponding area of retinal swelling in SD OCT. This was true for minute 5 FA images as well as for minute 10 images. The area of dye leakage was restricted to characteristic morphologic changes, such as formation of cysts of variable dimension and only to a lesser extent to diffuse swelling. Large microaneurysms were clearly identified as a source of plasma and dye leakage leading to a corresponding retinal swelling.

Conclusions: : SD OCT is a valuable tool to determine not only morphologic, but also patho-physiologic intra-retinal changes following the break-down of the blood-retina barrier in diabetic maculopathy. Therefore, in several cases this technique can replace FA examinations with its possible systemic side effects.

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