Long-Term Trigeminal Nerve Stimulation as a Treatment for Ocular Pain

Objectives: Ocular pain symptoms (e.g., hypersensitivity to light and wind, "burning" sensations) can be debilitating and difficult to treat. Neuromodulatory therapies targeting sensory trigeminal and central pain pathways may help treat chronic ocular pain refractory to traditional therapies. The current study evaluates the long-term effects of a trigeminal neurostimulator (TNS) on ocular pain.

Materials and methods: Retrospective review of 18 individuals at the Miami Veterans Affairs Eye Clinic with chronic, severe ocular pain who were prescribed and used TNS at home for ≥3 months. The primary outcome measures were 1) ocular symptom intensity over a 24-hour recall period (dryness, pain, light sensitivity, wind sensitivity, burning; rated on 0-10 scales) captured pre-TNS and at monthly follow-up intervals and 2) side effects. The frequency and duration of TNS was a secondary outcome measure.

Results: The mean age of the population (n = 18) was 57.5 years (range, 34-85 years) with a male majority (67%). Two individuals discontinued use due to lack of efficacy and one due to confounding health issues. Initial mean weekly frequency of TNS use was 3.7 ± 1.9 sessions of 25.8 min at month 1 and 2.7 ± 2.3 sessions of 28.0 min at month 6. At six months, pain intensity (↓ 31.4%), light sensitivity (↓ 36.3%), wind sensitivity (↓ 32.6%), and burning sensation (↓ 53.9%) were all decreased compared to baseline (p < 0.01 for all); greater decreases in ocular pain were noted in individuals with migraine (n = 10) than those without migraine (n = 8). No significant change was noted in mean dryness scores. Fifteen subjects experienced sedation with TNS use, persisting throughout the follow-up visits. No other adverse effects were communicated by any subjects.

Conclusion: Our study suggests TNS is a safe, adjunctive treatment option in individuals with severe, chronic ocular pain. Individuals demonstrated gradual, continual improvement in pain symptoms over time within a multimodal approach.