The authors developed a diplopia questionnaire using a data-driven, quality-of-life correlated scoring algorithm that allows clinicians to assess diplopia severity on the basis of patient report, assigning a numeric score from 0 (no diplopia) to 100 (diplopia everywhere and always). Numeric scoring of this patient-reported outcome could have a broad application for assessing diplopia severity and treatment outcomes.
They write that of the various methods available for assessing diplopia severity, a previous diplopia questionnaire has been shown to be rapid and simple, with specific advantages over a diplopia field plotted on a Goldmann perimeter. The original questionnaire assessed diplopia in seven positions of gaze using three response options (never, sometimes, always). However, patients sometimes requested additional response options, specifically “rarely” and “often,” when this original questionnaire was used in clinical practice. The purpose of this study was to develop a revised questionnaire, and then an optimal scoring algorithm, and to evaluate the test–retest reliability of the new instrument.
For this new questionnaire they added “rarely” and “often” categories so that for each question, the patient could select from one of five responses: “never,” “rarely,” “sometimes,” “often,” or “always.” They also removed the question, “can you get rid of it?” (diplopia) because it was sometimes confusing to the patient and added complexity to the potential scoring algorithms.
To optimize questionnaire scoring, 147 adults with diplopic strabismus of all forms completed both the questionnaire and the Adult Strabismus-20 (AS-20) health-related quality-of-life questionnaire. The 10-item AS-20 function subscale score (scored 0 – 100) was defined as the gold standard for severity. A range of weights was assigned to the responses and the gaze positions (from equal weighting to greater weighting of primary and reading ).
The questionnaire showed excellent test–retest reliability, and excellent responsiveness to surgery, with a mean score change of 51 ± 34.
The authors conclude that this new questionnaire is a useful patient-reported outcome measure that can be used to assess diplopia severity in both clinical and research settings, and may be useful for evaluating changes over time and with treatment.