Question

I have ME/CFS and 2 years ago I had to move to varifocal glasses. I had my eyes tested in April and had to return those glasses as I needed a different prescription. I have had them retested today, and needed another prescription. The optician said that my prescription seems to change as my condition fluctuates. What is happening to eyesight as a result of ME/CFS and is there any research in this area? I get a lot of migraines and I think this is because of the problems I have with my vision.

Answer

Problems relating to vision are quite commonly reported in a range of neurological conditions such as Alzheimer's and Parkinson's disease. Some of these symptoms may be related to what is termed cortical hyperexcitability – in other words, parts of the brain involved with visual messages become over sensitive. There is currently very little information in the medical literature about visual symptoms in ME/CFS but these problems are frequently discussed and may have a significant impact on the quality of everyday life. Some people, for instance, stop driving, or find reading or watching television to be a problem.

The visual symptoms that people with ME/CFS often report include:

• increased awareness or sensitivity to bright light,
• visual or reading fatigue,
• difficulty with focussing on images and following moving images,
• vision related headaches after reading,
• pain in or around the eye,
• dry and/or itchy eyes (dry-eye syndrome).

From a research point of view, Dr Claire Hutchinson (University of Leicester) and colleagues have carried out a number of tests to see if these symptoms can be objectively measured and confirmed. Using a group of people with ME/CFS, along with a control group, she described some of the investigations she has conducted:

• cortical excitability,
• visual attention and the ability to ignore irrelevant background information,
• eye movement and the ability to track/follow objects.

Some of the results were published in 2018 (below). They indicate that basic eye movements to simple static targets are less accurate in people with ME/CFS and that moving eyes for even short periods of time induces eye-movement fatigue. This type of ophthalmological testing has helped to confirm that people with ME/CFS have a range of problems related to visual attention that are consistent with their self-reported symptoms.

Research

“The objective of this study was to determine vulnerability to pattern-related visual stress in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). A total of 20 ME/CFS patients and 20 matched (age, gender) controls were recruited to the study. Pattern-related visual stress was determined using the Pattern Glare Test.

Participants viewed three patterns, the spatial frequencies (SF) of which were 0.3 (low-SF), 2.3 (mid-SF), and 9.4 (high-SF) cycles per degree (c/deg). They reported the number of distortions they experienced when viewing each pattern. ME/CFS patients exhibited significantly higher pattern glare scores than controls for the mid-SF pattern. Mid-high SF differences were also significantly higher in patients than controls.

“These findings provide evidence of altered visual perception in ME/CFS. Pattern-related visual stress may represent an identifiable clinical feature of ME/CFS that will prove useful in its diagnosis. However, further research is required to establish if these symptoms reflect ME/CFS-related changes in the functioning of sensory neural pathways.”

C Hutchinson et al. Increased Vulnerability to Pattern-Related Visual Stress in Myalgic Encephalomyelitis | November 2015

“Myalgic encephalomyelitis (ME) is a devastating disorder marked by debilitating fatigue. It not well understood and its diagnosis is controversial. It is very important therefore that significant clinical features are investigated. Visual symptoms in ME represent a group of distinct, quantifiable, clinical features that could significantly improve diagnosis and provide insights into underlying pathology. The purpose of the present study was therefore to explore the effect of ME on spatial windows of visibility using the spatial contrast sensitivity function.

“Contrast sensitivity was determined for stationary luminance-defined sinusoidal gratings spanning a five-octave range of spatial frequencies (0.5 to 16 c/deg) in a group of 19 individuals with ME and a group of 19 matched (age, gender) controls. Compared to controls, the ME group exhibited a restricted spatial window of visibility for encoding stimulus contrast. This was characterised principally by a contrast sensitivity deficit at lower spatial frequencies and a narrower bandwidth. Our findings suggest that contrast sensitivity deficits may represent a visual marker of ME, and be indicative of abnormal visual processing at the level of the retina and in the cortical and subcortical visual pathways.”

C Hutchinson et al. Restricted Spatial Windows of Visibility in Myalgic Encephalomyelitis (ME) | January 2018

People with ME/CFS report vision-related reading difficulty, although this has not been demonstrated objectively. Accordingly, we assessed reading speed and acuity, including crowded acuity and acuity for isolated words using standardized tests of reading and vision, in 27 ME/CFS patients and matched controls.

We found that the ME/CFS group exhibited slower maximum reading speed, and had poorer crowded acuity than controls. Moreover, crowded acuity was significantly associated with maximum reading speed, indicating that patients who were more susceptible to visual crowding read more slowly. These findings suggest vision-related reading difficulty belongs to a class of measurable symptoms for ME/CFS patients.

C Hutchinson et al. Visual Aspects of Reading Performance in Myalgic Encephalomyelitis (ME) | August 2018