Abstract
Purpose: :
: Meibomian gland dysfunction (MGD) is a common cause of the signs and symptoms of dry eye, yet a symptom survey specific for MGD has not been developed. We assembled likely MGD survey items from several sources and undertook a preliminary evaluation using MGD subjects.
Methods: :
Subjects over age 18 were recruited and classified as the MGD dry eye subtype based on accepted tests (i.e., Schein questionnaire, NaFl tear break up time, NaFl corneal and/or rose bengal conjunctival staining, abnormal meibum and/or meibomian gland atrophy, and a normal Schirmer test). MGD questionnaire items were drawn from published and anecdotal sources. The preliminary instrument contained 24 items targeting the frequency and intensity of 12 symptoms. Possible responses were marked from 0 (never, or not intense) to 9 (all the time, or extremely intense). Rasch analysis was utilized for psychometric evaluation of the survey items.
Results: :
69 MGD subjects were enrolled and completed the survey. Sample severity levels, using the MGD Workshop scheme, were: none subclinical, 10 minimal, 43 mild, 16 moderate and none severe. Initial analysis found that 4 items were outliers according to INFIT and OUTFIT ZSTDs scores > 3 or < -3 and these items were removed. Final analysis for the remaining 20 items demonstrated an excellent fit to the Rasch model (e.g., for persons, INFIT MNSQ = 0.98; ZSTD = -0.2; OUTFIT MNSQ = 0.97; ZSTD = -0.3; items fit statistics were similar).
Conclusions: :
The MGD-specific items indicate the presence of MGD, although redundancies occurred with some items. Further evaluation will be directed at eliminating symptom overlap using statistical means in conjunction with clinical decisions relative to Rasch ranking. Future research is necessary to validate the refined instrument in an independent sample of various dry eye subtypes and normals to establish diagnostic efficacy (i.e., sensitivity, specificity, PPV etc.) in MGD.
Keywords: cornea: tears/tear film/dry eye • clinical (human) or epidemiologic studies: systems/equipment/techniques • clinical research methodology