Progression of Visual Field Defects in Leber Hereditary Optic Neuropathy: Experience of the LHON Treatment Trial

Abstract

To describe the visual fields of patients with Leber hereditary optic neuropathy (LHON), a maternally inherited disorder characterized by bilateral, often sequential vision loss, before and during progressive visual deterioration. Prospective longitudinal follow-up of serial visual fields in patients enrolled onto an open-label, nonrandomized pilot study of topical brimonidine purite as prophylactic treatment after first eye involvement in LHON. Nine molecularly confirmed primary mutation patients with LHON with monocular vision loss for less than six months and normal visual function in the other eye were followed prospectively for up to two years. Visual fields were performed on automated perimetry at baseline and on many follow-up visits. Despite normal visual acuity at baseline in all patients, seven patients had some minimal changes in the central visual field of the second eye. All patients had subsequent deterioration of visual acuity, mean deviation, and foveal sensitivity in their second eye. The earliest pattern of abnormality was typically a cecocentral defect enlarging to become a central defect, often with a superior or inferior predilection. The visual field defects in the two eyes of any given patient were remarkably similar. LHON may be a bilateral condition at onset more frequently than appreciated. Automated static perimetry of the "normal" eye may reveal subclinical findings that typically worsen rapidly over weeks to months to similar central scotomatous damage. Quantitative automated static perimetry is helpful in elucidating the natural history of LHON and in understanding the underlying pathology and pathophysiology of this disease.