Dry eye symptoms and signs in United States Gulf War era veterans with myalgic encephalomyelitis/chronic fatigue syndrome.
Sanchez, Victor, Kim, Colin K, Locatelli, Elyana V T et al. · Clinical & experimental ophthalmology · 2024 · DOI
Quick Summary
Researchers studied eye dryness and discomfort in Gulf War veterans with ME/CFS and compared them to veterans without the condition. They found that people with ME/CFS reported significantly more eye pain and dryness symptoms, even though physical examination of their eyes showed similar amounts of tear production and surface damage as the control group. This suggests that the eye pain experienced by ME/CFS patients may come from causes beyond just dry eyes.
Why It Matters
Dry eye and ocular pain are common but underrecognized symptoms in ME/CFS. This study provides objective evidence that these symptoms are real and distinct from typical dry eye disease, which could help validate patient experiences and potentially lead to better diagnostic criteria and treatment approaches tailored to ME/CFS-related eye problems.
Observed Findings
ME/CFS group reported OSDI dry eye scores of 48.9 compared to 19.1 in controls (p<0.001).
ME/CFS group reported neuropathic eye pain (NPSI-E) scores of 23.0 compared to 6.5 in controls (p<0.001).
Ocular surface parameters measured on slit lamp examination were generally similar across all three groups (ME/CFS, intermediate fatigue, and controls).
Blood markers of inflammation showed no significant differences between ME/CFS and control groups.
Intermediate fatigue group reported symptoms intermediate between ME/CFS and control groups across most measures.
Inferred Conclusions
Ocular pain in ME/CFS involves mechanisms beyond ocular surface dysfunction, potentially including central sensitization or neuropathic pain pathways.
Eye symptoms in ME/CFS warrant clinical attention as a distinct manifestation separate from primary dry eye disease.
The symptom-sign mismatch suggests standard ophthalmologic examinations may inadequately capture the ocular pathology in ME/CFS.
Remaining Questions
What specific neurological or pain processing mechanisms drive the disconnect between reported eye symptoms and objective clinical findings in ME/CFS?
Do ocular symptoms improve with ME/CFS-targeted treatments, and if so, would this support a common underlying mechanism?
What This Study Does Not Prove
This study does not establish the cause of increased ocular pain in ME/CFS—it only demonstrates that symptoms exceed what physical eye examination would predict. It cannot prove whether ocular pain is a primary ME/CFS feature or a secondary manifestation. The cross-sectional design prevents conclusions about whether eye symptoms develop before, after, or alongside ME/CFS onset.