A new patient reported outcome measure for refractive surgery: preliminary results
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First Author: A.Frings GERMANY
Co Author(s): M. Lundström G. Rubin B. Allan
To create a concise, practical, on-line, self-administered, self-archiving, and self-scoring PRO questionnaire for routine clinical use in refractive surgery.
Moorfields Eye Hospital, London and UCL Institute of Ophthalmology, London
360 refractive surgery patients comprising 120 preoperative, 120 post laser vision correction, and 120 post refractive lens implantation cases completed the trial questionnaire using Google Forms to archive responses directly in relation to 4 domains: eye comfort, quality of vision, functional freedom, and emotional well-being. Each scale had 10 items and 4 response categories. Contextual information on spectacle dependence for near, intermediate and distance vision; and overall satisfaction was also collected. Standard validation techniques including Rasch scaling and principal component analysis were then used to grade ordering of categories, dimensionality, measurement precision, item fit, differential item functioning, and targeting.
We observed ceiling effects and a poor fit to the Rasch model for eye comfort, quality of vision, and functional freedom scales - with most refractive surgery patients sampled reporting few problems in these areas. After Rasch scaling, a 7-item emotional wellbeing scale was unidimensional, with satisfactory performance against other validation criteria.
Further study is required to determine whether a single gateway item designed to filter out patients with no problems will improve the validation performance of our visual quality, comfort, and functional freedom scales. Further study is also required to examine repeatability and sensitivity to change for our 7-item emotional wellbeing scale.