The goal of this clinical trial is to understand what effect a cold treatment with an investigational device, ETX-4143, has on the anatomical structures and the inflammatory response of the surface of the eye in those people who suffer from chronic ocular surface pain (COSP). The trial will also tell us more about the safety of this investigational device. The main questions this study aims to answer are:
* What anatomical changes happen to corneal surface nerves after treatment with ETX-4143 * What changes in inflammatory mediators and cell response take place after treatment with ETX-4143
Researchers will obtain images of the corneal surface nerves for analysis using a confocal microscope and collect tear bio samples for analysis.
Participants will:
* Be screened for having chronic ocular surface pain * Will be treated with ETX-4143 cold treatment for 4 minutes * Fill out a weekly questionnaire on eye pain for 12 weeks * Be seen in the clinic 2 weeks, 6 weeks, and 12 weeks after treatment to have images of the corneal surface taken, and to collect a tear bio sample
Documented symptoms of COSP pain for at least 3 months
A score of ≥5 on the single question COP-Q Eye Pain Severity Module
Able to obtain sufficient quality corneal in-vivo confocal microscopy images
Less than 50% improvement in VAS Eye Pain score after topical 0.5% proparacaine hydrochloride at screening
Subjects with clinically significant corneal scarring that could limit the confocal microscopy
Insufficient number of corneal nerves to permit Fun-IVCM imaging