Abstract
Purpose :
Individuals with neuropathic ocular pain (NOP) have poor response to conventional topical therapies targeting the ocular surface. Common descriptors of NOP such as chronic pain, burning sensation, photoallodynia, and hyperalgesia to wind elucidate somatosensory dysfunction. We performed a prospective, open, single-arm pilot study without randomization to quantify changes in chronic ocular pain and corneal nerve density in sub-basal plexus after long-term use of trigeminal nerve stimulation (TNS).
Methods :
During January-December 2021, seven subjects with NOP were identified as candidates for daily 20-minute TNS sessions at home for six months. Participants gave subjective scores on a 0-10 scale to questions evaluating severity of pain, dryness, burning sensation, sensitivity to light and wind before and after a 20-minute in-clinic TNS trial. The same questions and scale were used to monitor changes in symptom severity monthly. In vivo confocal microscopy (IVCM) was performed prior to initiating TNS therapy and measurements were repeated every two months to quantify changes in corneal nerve density for a total of six months.
Results :
Paired t-tests were performed comparing baseline measurements vs. in-clinic TNS trial, response at three and six months. In-clinic TNS trial showed overall decrease in symptom severity. Reduction of ocular pain and sensitivity to wind were statistically significant (p=0.014 and p=0.048, respectively). Follow up at three months, maintained the same trend with an important decline in wind hyperalgesia (p = 0.002). 6 month follow up showed a clinically significant reduction in ocular pain of 24% (p = 0.025) and decrease in wind sensitivity by 18% (p= 0.019). IVCM did not show changes in corneal nerve density in the subbasal plexus.
Conclusions :
Six months of TNS therapy significantly reduces chronic ocular pain and wind hyperalgesia exhibiting its potential use as adjunctive therapy for NOP. TNS does not modify corneal nerve density.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.