A recent study published in the Journal of Clinical Medicine suggests that subthreshold electrical stimulation (SES) may offer a therapeutic benefit for patients with Leber's hereditary optic neuropathy (LHON). The single-arm, prospective, exploratory study investigated the efficacy of SES in improving visual function in ten male LHON patients.
The primary outcome measure focused on changes in LogMAR-converted best-corrected visual acuity (BCVA) from baseline to one week after the final SES session. Results indicated a statistically significant improvement, with the median LogMAR BCVA improving from 1.80 at baseline to 1.75 one week post-treatment (p = 0.042).
Visual Acuity and Field Improvements
Secondary outcome measures assessed BCVA at four and eight weeks post-SES, both showing significant improvements from baseline (p = 0.043 and p = 0.042, respectively). While critical flicker frequency (CFF) did not show significant differences across the group, individual responses varied, with some patients experiencing increases in CFF.
Visual field analysis revealed that the summed actual sensitivity at 52 measurement points doubled in half of the patients, indicating an expansion of the visual field. This improvement was statistically significant in the group that experienced the doubling of sensitivity (p = 0.01), while no significant change was observed in the other half (p = 0.312). One patient, despite stable LogMAR BCVA, experienced a decline in summed actual sensitivity, highlighting the variability in treatment response.
Impact of Age at Onset
Correlation analysis indicated a significant relationship between age at onset and treatment efficacy. Specifically, younger patients at disease onset tended to experience greater improvements in visual fields (r = -0.67, p = 0.03). This correlation was not observed with age at treatment or the duration between disease onset and SES initiation.
Study Details and Limitations
The study enrolled ten male patients with an average time from LHON onset to SES initiation of 154 months. The primary endpoint was the change in LogMAR BCVA, with secondary endpoints including CFF and visual field changes. Limitations include the small sample size and lack of a control group, warranting further investigation with larger, randomized controlled trials to confirm these findings and explore the underlying mechanisms of SES in LHON.
