Comparative study of experimental choroidal neovascularization by optical coherence tomography and histopathology

To study the development, progression, and regression of experimental choroidal neovascularization (CNV) by correlating the cross-sectional images from sequential optical coherence tomography (OCT) with histopathologic sections of the same retinal regions.

Laser photocoagulation was performed in the posterior pole of the eye of 4 rhesus monkeys to induce CNV. Funduscopy, fluorescein angiography (FAG), and OCT were performed on day 1 and weekly for 13 weeks. Histological serial sections of CNV tissue were compared to corresponding OCT images.

In the developmental stage of CNV, the CNV was observed by OCT as a nodular high reflex area continuing from the highly reflective retinal pigment epithelium (RPE). Histopathological studies showed that the CNV was composed of tightly packed proliferated RPE and immature vascular endothelial cells. In the active stage, OCT revealed a thick multi-layered high reflex area under the sensory retina. This high reflex area corresponded with the CNV membrane that consisted of newly formed blood vessels with wide vascular lumens and proliferated spindle-shaped RPE cells. In the regressive stage, OCT revealed a dome-like, white-colored highly reflective layer continuing from the RPE layer with moderate reflection beneath the layer. Histopathologically, the neovascular tissue was enveloped by mono-layered, cuboidal-shaped RPE cells with melanin granules.

Optical coherence tomography images clearly demonstrated the positional relationship between the CNV and the RPE. Optical coherence tomography imaging provides information on the CNV which complements conventional examinations by funduscopy and FAG.