The authors present a prospective cohort study of adult patients with a cyclo-deviation and associated diplopia due to have strabismus surgery during a five-year period. Two groups were formed depending on the type of surgery required whether this was targeted at the cyclo-deviation or a vertical deviation. The Adult Strabismus-20 (AS-20) questionnaire was completed pre- and postoperatively. Significant differences are reported between the patients and a control group without strabismus; the latter scores are similar to other controls reported in the literature. Significant improvement was seen within the patient group following surgery especially in the functional subscale, with bigger changes reported in the patients who had their cyclo-deviation targeted during surgery. No objective measurements of strabismus are presented by the authors in this paper. The authors conclude that they believe there is a requirement for a symptom specific vision-related quality of life measure for cyclo-deviation to aid earlier diagnosis and plan future research to develop such a measure.