Correlating Confocal Microscopy, Molecular Features And Disparity Between Symptoms And Signs As An Important Method Of Diagnosis In Patients With Ocular Pain.

Ocular pain can have varied severity and causes and in some cases can have a lot of discordance between symptoms and signs. This makes both the diagnosis and treatment difficult. Understanding the possible causes for this, helps the clinician in their approach to management. Increased nociception and neuropathy are two important causes for discordance and can be studied using tear fluid molecular factors and confocal microscopy features of cornea. Our study aims to correlate In Vivo Confocal Microscopy (IVCM) features and tear factors in patients with ocular surface discomfort.

Narayana Nethralaya, Bengaluru,Karnataka ,India

IVCM images, Ocular Surface Disease Index (OSDI) score and Tear Film Breakup Time(TBUT) from 132 subjects (264 eyes) were analyzed for dendritic cell density (DCD), sub-basal nerve plexus (SBNP) features and microneuroma-like features. 13 soluble factors were measured using multiplex Enzyme Linked Immunosorbent Assay(ELISA) in tears from 72 subjects (86 eyes). Clinical features of discordance between signs and symptoms were correlated with IVCM  and tear molecular factors.

Patients with overall higher OSDI score had higher DCD(p<0.05) suggesting increased inflammation in these eyes. Among these the patients with discordant pain had increased tear Interlukin IL-17A (pro-nociceptive) and reduced Vascular Endothelial Growth Factor-A (VEGF-A) (anti-nociceptive) levels (p<0.05) suggesting an altered balance of nociception in these eyes. Micro-neuromas were significantly associated in patients with more symptoms than signs. 

Patients with symptoms out of proportion to signs showed higher micro-neuromas, dendritic cells and altered tear nociceptive factors. Understanding this discrepancy can make diagnosis and management easier and give clinicians the opportunity to offer targeted therapy.