Impact of botulinum toxin type A on ocular pain with neuropathic features

To investigate the impact of botulinum toxin type A (BoNT-A) on neuropathic/nociplastic ocular pain (NOP) and identify predictors of patient outcomes.

A retrospective study of individuals with NOP symptoms (light sensitivity, wind/air sensitivity, persistent pain despite dry eye treatment) who received ≥1 BoNT-A injection. Primary outcome measures included if (responders vs. non-responders) and to what degree (none vs. mild vs. moderate vs. marked) individuals experienced pain improvement 4-6 weeks post-injection. Demographics and clinical exam information was compared between the groups.

27 individuals received BoNT-A for NOP symptoms. 74 % (n = 20) reported an improvement in pain and were classified as responders. Among responders, the degree of benefit varied, with 25 % reporting mild, 45 % moderate, and 30 % marked pain improvement. Improvements in light sensitivity (37 %), wind/air sensitivity (33 %), and quality of life (QoL) (59 %) were reported by fewer individuals. 80 % of responders and 0 % of non-responders reported QoL improvements afer BoNT-A. In a multivariable model that examined predictors of response (none to marked, 0-3), the presence of fibromyalgia (FM) (β = 0.50; p = 0.004) portended a better response, while shooting pain (β = -0.47; p = 0.007) portended a worse response to BoNT-A, (full model r² = 0.53; p < 0.001). Degree of pain improvement significantly correlated with improvements in light sensitivity, wind/air sensitivity, and QoL (ρ range: 0.42-0.63; p < 0.05).

After BoNT-A, most individuals reported improved ocular pain and QoL, while fewer noted improved light and wind/air sensitivity. Some systemic and ocular factors predicted treatment response and may thus guide treatment.