AIDS-RELATED OPTIC NEUROPATHY - A HISTOLOGICAL, VIROLOGICAL AND ULTRASTRUCTURAL-STUDY

Background: Clinical and histopathological evidence of optic nerve axo nal loss has been reported in AIDS patients without retinitis. The stu dy was carried out to investigate the possible involvement of HIV-infe cted cells in the development of optic nerve degeneration. Methods: Op tic nerves were obtained from eight AIDS patients and four normal cont rols. These nerves were morphologically and immunohistochemically anal yzed. Additionally, using PCR amplification techniques, the retina and optic nerve samples obtained from three HIV-seropositive patients and one control were examined for the presence of HIV and cytomegalovirus antigens. Results: We noted various stages of axonal degeneration in the optic nerves obtained from AIDS patients in whom there was an abse nce of retinal findings. Characteristic glial changes involving hypert rophic astrocytes, vacuolated oligodendrocytes, and mononuclear phagoc yte series cells were also seen in the AIDS optic nerves. HIV DNA was present in at least four of five optic nerves but in only one of five retinas. Control specimens were each negative for all cytomegalovirus and HIV antigens. Conclusions: Degeneration in the optic nerve may be mediated by HIV-infected macrophages rather than by direct viral infec tion of neurons. Axonal degeneration due to AIDS at the level of the o ptic nerve can occur independently of retinal infection.