Extract:
People diagnosed with CFS/ME consistently report that they experience vision-related symptoms associated with their illness and some of these reports are being verified experimentally. 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), includes four vision-related items: eye pain, sensitivity to bright lights, unable to focus vision and/or attention, loss of depth perception. For each item, respondents rate the symptom fre-quency along with the associated severity/ bother on a 5-point scale. Here, we report DSQ vision-related item responses for 59 individuals (39 women, 20 men) who, after completing the DSQ, met its criteria for diagnosis of CFS/ME. Respondents were aged 22–69 years (mean=46 years; SD=11). All reported that they had no history of eye disease. Ethical approval was granted by the National Research Ethics Service and The School of Psychology Ethics Committee, University of Leicester.
Responses on each item revealed that vision-related problems were frequently experi-enced, the most frequent being sensitivity to bright lights (92%) followed by being unable to focus vision and/or attention (88%) and eye pain (86%). Loss of depth perception (61%) was least frequent. The more frequent the symptom, the greater the apparent severity/bother (figure 1).
We explored each set of four items (frequency and severity) to consider whether they could be used to provide overall frequency and severity assessments of vision-related symptoms. Such a consider-ation would help with the standardised assessment and establishment of norm data relating to visual-related symptoms asso-ciated with ME/CFS within and across populations. We considered the factor struc-ture of the frequency and severity data separ-ately, and found that parallel analysis suggested one factor on each occasion, with all factor loadings (0.34 to 0.83) above the criteria of 0.32.
αCoefficients for the scales exceeded the acceptable criteria ofα=0.70; frequency,α=0.72; severity,α=0.71. Factor scores for both sets of items shared a correl-ation of r=.88, p<0.001; therefore sharing 64% of the variance, suggesting the two measures share a very close relationship. No significant differences were found for the factor scores for sex (frequency, t=−1.44,p=0.155; severity, t=−1.43, p=0.160), nor was there a significant correlation for age (frequency, r=−0.04, p=0.777; severity, r= −0.06, p=0.652).
In summary, responses of individuals with CFS/ME to the visual items included in the DSQ indicated that they experienced frequent and often severe vision-related symptoms associated with their illness.
These findings are in agreement with those of previous self-report studies 1–3 and recent experimental evidence for problems related to visual attention in those with CFS/ME.
They add to an emerging body of evidence that vision-related symptoms represent a significant clinical feature of CFS/ME that may provide insights into its aetiology and prove useful in its diagnosis.
As such, they warrant further experimental study and should not be overlooked by CFS/ME diagnosticians.
Vision-related symptoms as a clinical feature of chronic fatigue syndrome/myalgic encephalomyelitis? Evidence from the DePaul Symptom Questionnaire, by Claire V Hutchinson, John Maltby, Stephen P Badham, Leonard A Jason, in British Journal of Opthalmology, 1 November 2013
