Morphological features of choroidal neovascular membranes in age-related macular degeneration complicated by high pigment epithelial detachment

Aim. To study the morphological features of choroidal neovascular membranes in patients with wet age-related macular degeneration, complicated by high pigment epithelial detachment. Methods. The study enrolled 10 patients with wet age-related macular degeneration, who underwent vitrectomy with choroidal neovascular membranes removal, including 4 patients with occult choroidal neovascularization and 6 patients with classic choroidal neovascular membrane. Results. Histologic pattern consisting of pigmented epithelium cells layer with Bruch’s membrane, fibrovascular membrane, photoreceptors segments layer and, in some of the cases, choroid fragments, was discovered in tissue specimens of patients with classic choroidal neovascular membrane. Histologic pattern of choroidal neovascular membrane in patients with occult choroidal neovascularization also consisted of pigment epithelium cells layer with Bruch’s membrane, fibrotic neovascular membrane itself and photoreceptors segments layer. Pigment epithelium cell layer, in contrast to the control group, had apparent signs of hyperplasia. Average thickness of pigment layer of the retina was 16.08±4.64 μm in patients with high pigment epithelial detachment, by 30% higher compared to the control group (11.22±3.38 μm, р <0.05). Mean Bruch’s membrane thickness was 6.7±0.19 μm in the main group, which also exceeded the similar values in the control group (5.7±3.8 μm, р <0.05). Histochemical studies revealed qualitative differences between the study groups in the levels of collagen types I and III. Glycosaminoglycans, in contrast, were detected only in the group with classic choroidal neovascular membrane. Conclusion. In patients with occult choroidal neovascular membrane complicated by high pigment epithelial detachment, Bruch’s membrane thickening was found due to collagen type 1 deposits on the outer surface, which caused a local hydrodynamics alterations and influences the bioavailability of medications.

age-related macular degeneration, high pigment epithelium detachment, choroidal neovascular membrane