MORPHOLOGICAL FINDINGS IN THE VISUAL-SYSTEM IN A CASE OF LEBERS HEREDITARY OPTIC NEUROPATHY

We examined the retina, optic nerve, optic tract, extraocular muscles, and peripheral nerves of a woman known to have the 11778 primary muta tion of Leber's hereditary optic neuropathy (LHON). Overall, the resul ts indicated a striking loss of retinal ganglion cells and axons. The optic nerve and tract were shrunken and atrophic, showing little evide nce of inflammatory changes. On morphometry, axon counts in the optic nerve were found to be 95% below those in age-matched controls, with s till greater loss in the optic tract. Electron microscopy of the optic nerves disclosed that the axons contained aggregations of neurofilame nts having a relative paucity of microtubules, as well as an abundance of small organelles, including multivesicular bodies and myelin loops . Mitochondrial profiles in the extraocular muscles were present in un usually high numbers and contained abnormal cristae. These findings su ggest a noninflammatory involutional process of degeneration primarly affecting the retinal ganglion cell and its axon; axoplasmic statis at the ultrastructural level, possibly as a consequence of decreased axo nal transport due to insufficient production of ATP by impaired mitoch ondria; a probable compensatory increase of mitochondria in the extrao cular muscle; and possibly a relative sparing of nongeniculate retinof ugal axons. (C) 1994 Wiley-Liss, Inc.