The Development of an Instrument to Measure Quality of Vision: The Quality of Vision (QoV) Questionnaire


PURPOSE: To develop an instrument to measure subjective quality of vision: the Quality of Vision (QoV) questionnaire.

METHODS: A 30-item instrument was designed with 10 symptoms rated in each of three scales (frequency, severity, and bothersome). The QoV was completed by 900 subjects in groups of spectacle wearers, contact lens wearers, and those having had laser refractive surgery, intraocular refractive surgery, or eye disease and investigated with Rasch analysis and traditional statistics. Validity and reliability were assessed by Rasch fit statistics, principal components analysis (PCA), person separation, differential item functioning (DIF), item targeting, construct validity (correlation with visual acuity, contrast sensitivity, total root mean square [RMS] higher order aberrations [HOA]), and test–retest reliability (two-way random intraclass correlation coefficients [ICC] and 95% repeatability coef- ficients [Rc]).

RESULTS: Rasch analysis demonstrated good precision, reliability, and internal consistency for all three scales (mean square infit and outfit within 0.81–1.27; PCA _60% variance explained by the principal component; person separation 2.08, 2.10, and 2.01 respectively; and minimal DIF). Construct validity was indicated by strong correlations with visual acuity, contrast sensitivity and RMS HOA. Test–retest reliability was evidenced by a minimum ICC of 0.867 and a minimum 95% Rc of 1.55 units.

CONCLUSIONS: The QoV Questionnaire consists of a Rasch tested, linear-scaled, 30-item instrument on three scales providing a QoV score in terms of symptom frequency, severity, and bothersome. It is suitable for measuring QoV in patients with all types of refractive correction, eye surgery, and eye disease that cause QoV problems.

Investigative Ophthalmology & Visual Science, November 2010, Vol. 51, No. 11
Submitted for publication 8 February 2010; revised 12 April and 5 May 2010; accepted 5 May 2010.

Colm McAlinden1,2, Konrad Pesudovs3, and Jonathan E. Moore2,4
1 School of Biomedical Sciences, University of Ulster, Coleraine, United Kingdom;
2 Cathedral Eye Clinic, University of Ulster, Belfast, Northern Ireland, United Kingdom;
3 NH&MRC (National Health and Medical Research Council) Centre for Clinical Eye Research, Department of Optometry and Vision Science, Flinders Medical Centre and Flinders University of South Australia, Bedford Park, South Australia, Australia;
4 Mater Hospital, Belfast Health and Social Care Trust, Belfast, Northern Ireland, United Kingdom.


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