Purpose: It is known that even after visual loss, younger patients with Leber's hereditary optic neuropathy (LHON) can recover vision. The purpose of this study was to determine the mean age at onset for LHON patients with and without visual recovery who carried the 11778 mutation, and to determine the pattern of central vision recovery.
Methods: Thirty-five LHON patients with the 11778 mutation of mitochondrial DNA who had visited the Keio University Hospital between 1980 and 1999 and were followed for 2 to 20 years, were the subjects of this retrospective study. The patients who had recovered vision were tested by Goldmann perimetry, Humphrey perimetry, and landmark-driven fundus microperimetry with a scanning laser ophthalmoscope (SLO). The fixation status was assessed by SLO microperimetry.
Results: Nine of the 35 patients (14 of 70 eyes) demonstrated a recovery of visual acuity to better than 0.3 in at least one eye. The mean age of disease onset was 15.9 +/- 4.6 years in patients with visual recovery and 25.5 +/- 8.9 years in patients without visual recovery. This difference in the mean age at onset was significant (P =.0001; Welch t-test). These 9 patients (14 eyes) showed fenestrated central scotomas in testing by Humphrey 10-2 threshold and SLO microperimetry. The nasal side of the central visual fields had a higher sensitivity than the temporal side in 7 of the 9 patients in Humphrey 10-2 threshold testing. Areas insensitive to 0 dB were detected on the nasal side of the central retina in these patients by SLO microperimetry, and fixation stability was related to the degree of clinical visual acuity.
Conclusion: The LHON patients with the 11778 mutation and a younger age of onset were more likely to show visual recovery. The findings made by perimetry suggest that the nerve fiber bundles in the nasal field (retina temporal to the fovea) may have a greater potential to recover function in LHON patients.