Photophobia

Photophobia, also known as light sensitivity, is a symptom of abnormal visual intolerance to light. It can manifest as discomfort or pain. It occurs in ME/CFS as part of a range of sensitivities such as hyperacusis and misophonia (sound sensitivity), and allodynia. Photophobia also forms part of the wide range of ocular symptoms that occur in ME/CFS.

Prevalence

 * In 1995, Katrina Berne reported a prevalence of 65-90% for 'photosensitivity'.


 * In a 2001 Belgian study, 70.7% of patients meeting the Fukuda criteria and 75.8% of patients meeting the Holmes criteria, in a cohort of 2073 CFS patients, reported photophobia.


 * A 2013 study by Hutchinson, et al, using a patient population of 59 answering questions on the DePaul Symptom Questionnaire (DSQ) found that the most common vision-related symptom was sensitivity to bright lights with a 92% prevalence.

Symptom recognition
Photophobia is not a symptom required for diagnosis in any definition. In the Canadian Consensus Criteria (CCC), it appears under the section Neurological/Cognitive Manifestations and can be used to form a diagnosis. The International Consensus Criteria (ICC) also lists photophobia as a diagnostic criteria, under the section Neurosensory, perceptual and motor disturbances.


 * In the Holmes criteria, photophobia is an optional criteria for diagnosis, under the section Minor Symptom Criteria - Neuropsychologic Complaints.

No other definitions mention photophobia.



Notable studies

 * 2000, Ocular manifestations in chronic fatigue syndrome (Abstract)


 * 2013, Vision-related symptoms as a clinical feature of chronic fatigue syndrome/myalgic encephalomyelitis? Evidence from the DePaul Symptom Questionnaire (Abstract)

Possible causes
Photophobia can be caused by the pupil dilating rather than contracting when exposed to a light source. Pupil dilation is controlled by the sympathetic nervous system, which is usually hyper-responsive in people with ME/CFS due to an excess of excitatory neurotransmitters.

A magnesium deficiency can cause photophobia, and such deficiency is common in ME/CFS. This can be resolved with appropriate magnesium supplementation.

Some medications have photophobia listed as a side effect, notably benzodiazepines.

Photophobia can also often caused by illnesses that are common comorbidities of ME/CFS, such as migraine, fibromyalgia, dry eyes, idiopathic intracranial hypertension which can occur in Ehlers-Danlos syndrome, infectious mononucleosis (although this not common),  chiari malformation, dyslexia , and lyme disease.

Potential treatments
There are no treatments that specifically target photophobia. It is usually resolved by treating the underlying cause. Treatable causes of photophobia include magnesium deficiency, and when photophobia occurs as a side-effect of medication. If the photophobia is caused by a comorbid illness, treatment may help alleviate the symptom.

In the absence of successful treatment, discomfort can be ameliorated by avoiding bright lights, keeping curtains drawn, and wearing an eye mask or dark glasses. When going outside, wearing dark glasses or other special glasses and hats can help.

Learn more

 * A Girl Behind Dark Glasses


 * ME/CFS flares: what do they feel like and how to cope


 * Prize-winning Animation Released for Severe ME Day
 * Shedding Light on Photophobia
 * Wikipedia - Photophobia