The Ocular Pain Assessment Survey and In Vivo Confocal Microscopy as Valuable Tools in the Diagnosis and Management of Patients with Corneal Neuropathic Pain

Abstract

Purpose : Quality of life (QOL) in patients with corneal neuropathic pain (CNP) can be greatly diminished due to the high impact of this condition on patients' daily activities. Diagnosis and management of these patients are challenging due to the lack of clinical signs on slit-lamp examination. This study was designed to assess new tools for the diagnosis of patients with CNP utilizing in vivo confocal microscopy (IVCM) and a novel quantitative pain questionnaire, the Ocular Pain Assessment Survey (OPAS) and the utility of the combination of these in the management of patients with CNP.

Methods : This is a cross-sectional, single-center study, including 18 patients with the diagnosis of CNP who had completed the OPAS questionnaire. IVCM was performed for the central cornea of all patients. Two masked observers analyzed three representative IVCM images of the subbasal corneal nerve layer for the density of microneuromas (injured nerves that develop enlarged terminal sprouts), nerve density, dendritiform cell (DC) density and morphology (DC field). IVCM data were correlated with results of OPAS questionnaire utilizing Pearson’s correlation test. A p-value <0.05 was considered statistically significant.

Results : The mean age of patients was 54.7±14.8 years (Male/female ratio: 5/13). On IVCM, 100% of patients presented microneuromas (density 6.35±0.66 neuromas/mm²). This presence of microneuromas correlated positively with the severity of ocular pain at the day of the visit and during the last two weeks (R=0.530 and 0.501, p=0.02 and 0.04 respectively), and eye pain affecting overall QOL (R=0.566, p=0.02). DC field on IVCM (mean 185.5±123.2 µm²), a sign of immune activation showed significant correlation with eye pain during the last two weeks (R=0.523, p=0.03). Nerve density (mean 11.37±6.93 mm/mm²) correlated with the presence of associated factors such as redness, burning, sensitivity to light and tearing (R=0.567, p=0.02).

Conclusions : The OPAS questionnaire provides a novel tool in the quantitative assessment of CNP patients' symptoms. Microneuromas on IVCM may potentially serve as a diagnostic marker for CNP. The combination of IVCM for assessment of signs and OPAS for assessment of symptoms s may serve as valuable tools in the management of patients with CNP.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.