Nociplastic pain among individuals with chronic ocular surface pain: One cause for "pain without stain"?

Abstract

Chronic ocular surface pain (COSP) refers to interrelated symptoms such as burning, aching, and irritation and can occur as an isolated condition or comorbid with numerous ocular disorders, including dry eye syndrome Treatments for COSP are largely aimed at the ocular surface and modulating pain arising from damaged corneal nerves; however, the average impact of these treatments on COSP are low to absent. A potential explanation for this is that, in a subset of patients with COSP, individuals have amplified and/or dysregulated neural signaling and sensory processing within the central nervous system (CNS). As in other chronic pain conditions, this might be the pathogenic mechanism primarily responsible for maintaining pain - a phenomenon now referred to as nociplastic pain. The key clinical features of nociplastic pain include symptoms out of proportion to signs, regional or widespread pain, the presence of other chronic pain conditions, and non-pain CNS mediated symptoms (e.g., sleep disorders). We provide an overview for eye care clinicians of nociplastic pain and delineate the emerging evidence for the presence of nociplastic pain among some individuals with COSP. We highlight gaps in our current understanding of nociplastic pain in COSP and provide clinicians with specific tools that may aid in the assessment and management of nociplastic pain.

Keywords: Central nervous system; Chronic overlapping pain conditions; Dry eye; Neuropathic ocular pain; Nociplastic pain; Ocular pain.