Anatomic Classification of Choroidal Neovascular Membranes Using High–Speed Fourier–Domain Optical Coherence Tomography

Abstract

Purpose: : To utilize high–speed Fourier–domain OCT to image choroidal neovascular membranes (CNV) and to attempt to classify the membranes as either sub–RPE (type 1), subretinal (type 2) or combined, and to determine whether the fluorescein angiogram appearance correlates with the anatomic location of the CNV.

Methods: : Thirty patients diagnosed with active choroidal neovascular membranes on fluorescein angiography were imaged with a high–speed Fourier–domain OCT system built at the UC Davis Medical Center. Axial data was acquired by the use of two superluminescent diodes as light sources, with axial resolutions of 6µm for SLD1 ( 840@50nm), and 3.5 µm for SLD2 (890@150nm). The lateral resolution was calculated to be in the range of 10 to 15 µm for most of our subjects. A set of 100 B–scans were acquired for each patient covering 6 x 6 x 2 mm volume of retina (lateral x lateral x depth). The membranes were then localized in relation to the RPE in order to classify the lesions as either sub–RPE (type 1), subretinal (type 2) or combined. This anatomic classification was then compared to the fluorescein angiographic appearance in order to determine whether or not a correlation could be found.

Results: : High–speed Fourier–domain OCT was successfully able to localize the CNV in all of the cases imaged. The majority of choroidal neovascular lesions imaged were found to be sub–RPE. A strong correlation was not found between fluorescein angiographic appearance and anatomic classification.

Conclusions: : High–speed Fourier–domain optical coherence tomography offers an alternative non–invasive modality to image and anatomically classify CNV, which may aid in the study of this entity and its treatments. Fluorescein angiography cannot be used reliably to determine the anatomic location of CNV.

Keywords: choroid: neovascularization • imaging/image analysis: clinical