The Effects of Botulinum Toxin A on Neuropathic Ocular Pain Management

Abstract

Purpose : Ocular pain can be driven by both nociceptive and neuropathic mechanisms. Botulinum toxin has been investigated as a potential therapeutic for patients with a neuropathic contributor to pain. This study was performed to evaluate the impact of botulinum toxin A (BoNT-A) on neuropathic ocular pain (NOP) and identify predictive factors for patient outcomes.

Methods : Retrospective study of 27 individuals (52±11 years; 44% male; 82% White; 44% Hispanic) with NOP symptoms (wind/light sensitivity, pain persistence despite treatments targeting the ocular surface) who received ≥1 session of BoNT-A based on a modified migraine protocol. Clinical parameters were recorded as available. Demographics and pain questionnaires were analyzed using Chi-Square with Phi coefficients and multivariable logistic regression.

Results : 19 individuals reported improvement (mild 19%, moderate 30%, or marked 22%) in ocular pain after BoNT-A. Factors positively correlated with pain improvement included the presence of any autoimmune mediated condition (phi=0.42, p=0.03), throbbing pain prior to injection (phi=0.42, p=0.03), presence of conjunctivochalasis in either eye (phi=0.57, p=0.04), and bilateral pain prior to injection (phi=0.44, p=0.02). Factors negatively associated with pain improvement included self-reported allergies (phi=-0.43, p=0.02) and unilateral pain prior to injection (phi=-0.44, 0.02).When combined in a multivariable forward stepwise logistic regression model, throbbing pain, autoimmune mediated conditions, conjunctivochalasis, and allergies remained in the model.

Conclusions : The majority of individuals with NOP reported some degree of improvement in ocular pain after BoNT-A. Pain improvement was moderately positively correlated with autoimmune mediated conditions, throbbing pain sensation, conjunctivochalasis, and bilateral eye pain. These metrics may be useful in predicting which patients respond better to BoNT-A injection and help provide more tailored pain therapies.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.