Choroidal neovascularization in long-standing case of Vogt-Koyanagi-Harada disease.

The eyes in a case of Vogt-Koyanagi-Harada disease (VKH) with long-standing uveitis for 26 years after the onset were studied histopathologically. It was found that typical granulomatous inflammation was persistent in the uveal tract and the choroidal neovascularization occurred in the peripheral fundus accompanied by proliferation of the retinal pigment epithelial cells (RPE). Some of the new vessels under the pigment epithelium extended into the vitreous. It was concluded that the ocular inflammation of VKH was essentially granulomatous even in this long-standing case. Disappearance of choroidal melanocytes, existence of epithelioid cells containing pigment granules, and accumulation of lymphocytes and plasma cells in the lesion indicated that the inflammation was an autoimmune reaction against uveal melanocytes, although the trigger initiating the disease remains unknown. It was further concluded that the peripheral fundus as well as the peripapillary and macular areas was a predilected site for choroidal neovascularization in chronic uveitis. The choroidal neovascularization may develop in such a way that the uveal inflammation damages the Bruch's membrane and choriocapillaris and consequently causes retinal ischemia, thus stimulating the endothelium of the choriocapillaris and the overlying RPE to proliferate. There is a close relation between choroidal neovascularization and proliferation of RPE. Choroidal neovascularization may cause reactive proliferation of the RPE and vice versa.