Evaluating choroidal neovascularization in exudative age-related macular degeneration by fluorescein angiography combined with frequency-domain optical coherence tomography

Abstract

Objective To evaluate the diagnostic value of Heidelberg retinal angiography(HRA) combined with optical coherence tomography (OCT) to detect neovascularization (CNV) in exudative age-related macular degeneration (AMD) patients. Methods This is a cross-sectional study of a series of clinical cases. AMD diagnosis was established by international standard vision chart, Slit lamp microscope, direct or indirect ophthalmoscope examination. A total of 50 eyes (42 cases) of exudative AMD received HRA and frequency domain OCT scan. All 50 eyes received fundus fluorescein angiography (FFA) and frequency-domain OCT simultaneously, and among them 15 eyes also received indocyanine green angiography (ICGA) at the same time. FFA and ICGA were carried out by conventional methods, CNV was localized by real-time Localization technology of frequency domain OCT. In the radial and grid-like section from the areas with strong fluorescence, image acquisition settings are 7 μm fault for each frame, 30° intervals for radialsection, 10 vertical and 10 horizontal scan lines for grid-like section. CNV can be divided into 4 types (typical CNV, partial typical CNV, occult CNV, CNV scarring) according to their boundaries demonstrated in FFA. Based on the features of the OCT images, there were 3 types of integrated image (sub-RPE type, sub-retinal type and mixed type). Results CNV was detected in all 50 eyes. There were 4 eyes (8%) of typical CNV, 11 eyes (22%) of partial typical CNV, 32 eyes (64 %, including 27 eyes of RPE detachment and 5 eyes of passive late leakage) of occult CNV and 3 eyes (6%) of CNV scarring. There were 4 eyes (8%) of sub-RPE type (CNV under the RPE light band) , 16 eyes (32%) of sub-retinal type(interrupted light band of RPE and choroid capillary layer) and 30 eyes (60%) of mixed type of integrated image. Conclusion The image integration technology of the HRA and frequency domain OCT system provide a valuable tool to classify and measure CNV, which will benefit the clinical treatment of AMD patients. Key words: Macular Degeneration/ diagnosis; Choroidal Neovascularization/ diagnosisTomography, optical coherence; Fluorescein angiography; Diagnostic imaging