Measurement of Symptoms Pre- and Post-treatment of Dry Eye Syndromes.

: Valid assessment of dry eye syndrome symptoms is essential for diagnosis and for making treatment decisions and monitoring responses to treatment. Notwithstanding the desirability of being able to measure across several assessment domains to gauge the influence of symptom burden on the quality of life, the time-consuming nature of such assessments may make them unsuitable for routine clinical use. This review of symptom assessment methods examines the relative merits of visual analogue and Likert scales. Also examined are ways in which symptoms can be influenced by comorbid diseases and associated medications, and how the validity of assessing treatment efficacy could be compounded by natural progression of a dry eye syndrome apart from either favorable, neutral, or adverse responses to treatment. Follow-up assessments may also be biased by patient expectations. How validity of responses could be improved by the instructional use of a demonstration scale is described and illustrated. Personal instruction is suggested for patients anticipated to have age- or language-related difficulties but for some patients instruction could be successfully self-directed. A comparison of methods used to monitor dry eye syndrome treatment has allowed recommendations to be made for a method of using visual analogue scales which incorporates features which have been demonstrated to be advantageous in previous studies. The continuous nature of a visual analogue scale allows for smaller changes to be recorded with associated better discriminating capacity. More powerful statistical analysis of findings is possible when using visual analogue scales. Reference to previous assessment scores and exactly the same scale anchors improve the reliability of measurements of change in symptoms over time.