The objective of this study was to determine vulnerability to pattern-related visual stress in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). 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 3 patterns, the spatial frequencies of which were either 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 spatial frequency 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. It may, after additional, more thorough investigation, provide insight into ME-related changes in the sensory neural pathways of the brain.

People with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (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 measureable symptoms for ME/CFS patients.

Foot drop is observed when significant weakness of the dorsiflexor muscles of the foot and ankle result in a distinctive gait abnormality. In this, patients excessively flex the knee and hip to lift high the affected foot so as to avoid the dragging of the toes across the ground producing a characteristic 'steppage gait' pattern [37]. Normal dorsiflexion of the foot is achieved through the use of the muscles of the anterior compartment of the lower leg.