Ocular neuromodulation as a novel treatment for retinitis pigmentosa: identifying rod responders and predictors of visual improvement.

PURPOSE

To evaluate the safety and efficacy of ophthalmic nerve stimulation (ONS), combined with ascorbic acid (AA) in the treatment of retinitis pigmentosa (RP).

METHODS

Forty participants with RP were enrolled in a prospective open-label single-armed intervention. Patients with non-syndromic RP; aged ≥ 4 years, with BCVA ≥ 20/400 were included. All participants were treated with bilateral ONS sessions combined with intravenous administration of AA for two weeks. The primary efficiency endpoint was the change in scotopic vision at 6 months, assessed using 10-item, 100-point, Low Luminance Questionnaire (LLQ-10). The secondary efficiency points included BCVA and contrast sensitivity. Rod responders were defined by ≥ 25 points increment of LLQ-10 score at 6 months' visit.

RESULTS

Ocular neuromodulation therapy significantly improved low luminance vision, BCVA, and contrast sensitivity in patients with RP (p ≤ 0.05). At 6-month visits, 60% of patients were identified as rod responders. The mean change in LLQ-10 score was (46.35 ± 16.81 point) in rod responders versus (4.9 ± 7.6 point) in non-responders (p < 0.0001). A clinically significant improvement of BCVA (≥ 0.2 logMAR unit) and contrast sensitivity (≥ 0.3 log unit) were demonstrated in 50% of the right eyes of rod responders.

CONCLUSION

Ocular neuromodulation significantly improved night vision, BCVA, and contrast sensitivity. Determinants of rod responders include the duration of night blindness, stage of the disease, and thickness of ganglion cell layer at baseline. Two therapeutic scenarios were recognized; an early disease-modifying intervention that restores night vision and a late cone rescue intervention that improves/maintains central vision.