Chronic fatigue syndrome (CFS) or myalgic encephalomyelitis (ME) is a debilitating disorder, affecting at least 250 000 people in the UK. Marked by debilitating fatigue, its aetiology is poorly understood and diagnosis controversial. A number of symptoms overlap with other illnesses with the result that CFS/ME is commonly misdiagnosed. It is important therefore that significant clinical features are investigated. People diagnosed with CFS/ME consistently report that they experience vision-related symptoms associated with their illness1–⇓3 and some of these reports are being verified experimentally.4 Although vision-related symptoms may represent a significant clinical feature of CFS/ME that could be useful in its diagnosis, they have yet to be included in clinical guidelines.

A recently developed, standardised measure designed to assess core CFS/ME symptoms, The DePaul Symptom Questionnaire (DSQ),5 includes four vision-related items: eye pain, …