Visual function in chronic Leber's hereditary optic neuropathy during idebenone treatment initiated 5 to 50 years after onset

Abstract

Purpose: Leber's hereditary optic neuropathy (LHON) is a mitochondrial disease characterized by a subacute and progressive impairment and subsequent degeneration of retinal ganglion cells (RGCs). In most cases, it results in optic nerve atrophy and permanently reduced visual acuity (VA). Idebenone has recently been approved in Europe for treating LHON. However, published clinical data has only focused on efficacy in patients within the first years after disease onset. The present study is the first to evaluate possible effects of idebenone treatment in patients with LHON when initiated after more than 5 years from disease onset.

Methods: Oral treatment with idebenone 300 mg tid was started in seven patients 5 to 51 years after LHON onset. All patients had genetically confirmed primary LHON mutations (m11778G>A, m14484T>C, and m13051G>A). Visual function of all fourteen eyes was tested every 3 months using logarithmic reading charts and automated static threshold perimetry. The obtained clinical data were analyzed retrospectively using a multivariate analysis for VA and the Wilcoxon signed-rank test for visual field data.

Results: Before treatment, VA was 0.78 ± 0.38 logMAR (range 0.24 to 1.50 logMAR). During the first year of therapy, VA improved significantly by an average of - 0.20 ± 0.10 logMAR or 10 ± 5 ETDRS letters (P = 0.002; VA range 0.06 to 1.30 logMAR). Seven of fourteen eyes showed an improvement of 2 or more lines. Visual field mean deviation increased from - 8.02 ± 6.11 to - 6.48 ± 5.26 dB after 12 months, but this change was not statistically significant (P = 0.056).

Conclusions: The increase in VA of patients who have had LHON for more than 5 years observed soon after start of treatment may not constitute a coincidental spontaneous recovery. We hypothesize that the treatment response in chronic LHON was the result of a reactivated signal transduction in surviving dysfunctional RGCs. The results of this study indicate a beneficial effect of idebenone on improvement of visual function in LHON patients with established optic atrophy.

Keywords: Idebenone; Leber’s hereditary optic neuropathy; Medical treatment; Mitochondrial disease; Optic nerve; Vision.