Supported by grants from the Foundation Ondersteuning Oogheelkunde ‘s-Gravenhage, the Foundation Blindenhulp, the Ooglijders Foundation, and the Foundation Nederlands Oogheelkundig Onderzoek.
The Amblyopia and Strabismus Questionnaire (A&SQ) was previously developed to assess quality of life (QoL) in amblyopia and/or strabismus patients. Here, factor analysis with Varimax rotation was employed to confirm that the questions of the A&SQ correlated to dimensions of quality of life (QoL) in such patients.
Responses on the A&SQ from three groups were analyzed: healthy adults (controls) (n = 53), amblyopia and/or strabismus patients (n = 72), and a historic cohort of amblyopes born between 1962-1972 and occluded between 1968–1974 (n = 173). The correlations among the responses to the 26 A&SQ items were factor-analysed by Principal Component Analysis (PCA). As the development of the A&SQ was intuitive-deductive, it was expected that the pattern of correlation could be explained by the five a priori hypothesized dimensions: fear of losing the better eye, distance estimation, visual disorientation, diplopia, and social contact and cosmetic problems. Distribution of questions along the factors derived by PCA was examined by orthogonal Varimax rotation.
Data from 296 respondents were analyzed. PCA provided that six factors (cutoff point eigenvalue >1.0) accumulatively explained 70.5% of the variance. All A&SQ dimensions but one matched with four factors found by Varimax rotation (factor loadings >0.50), while two factors pertained to the fifth dimension. The six factors explained 33.7% (social contact and cosmetic problems); 10.3% (near distance estimation); 8.7% (diplopia); 7.2% (visual disorientation); 6.3% (fear of losing the better eye); and 4.3% (far distance estimation), together 70.48% of the item variance.
The highly explained variance in the A&SQ scores by the factors found by the PCA confirmed the a priori hypothesized dimensions of this QoL instrument.
Mangione CM, Lee PP, Gutierrez PR, Spritzer K, Berry S, Hays RD (2001) Development of the 25-item National Eye Institute Visual Function Questionnaire. Arch Ophthalmol 119:1050–1058 PubMed
Carlton J, Karnon J, Czoski-Murray C, Smith KJ, Marr J (2008) The clinical effectiveness and cost-effectiveness of screening programmes for amblyopia and strabismus in children up to the age of 4-5 years: a systematic review and economic evaluation. Health Technol Assess 12(25):iii,xi–194
Simonsz-Tóth B et al (2007) Visusevaluierung in einer historischen Kohorte von 137 okkludierten Patienten, 30–35 Jahre nach Ende der Okklusionsbehandlung (Evaluation of visual acuity in a historic cohort of 137 patients treated for amblyopia by occlusion 30–35 years ago). Klin Monatsbl Augenheilkd 224:40–46. doi: 10.1055/s-2006-927209PubMedCrossRef
Ford BL (1983) An overview of hot-deck procedures. In: Madow WG, Ollein I, Rubin DB (Eds) Incomplete data in sample surveys. New York Press, New York, pp 185-207
Armitage P, Berry G, Matthews JNS (2001) Statistical methods in medical research, 4th edn. Blackwell Publishing Inc, Oxford, pp 456–464
Jongman RHG, Ter Braak CJF, Van Tongeren OFR (eds) (1995) Data analysis in community and landscape ecology. Cambridge University Press, Cambridge
Weih LM, Hassell JB, Keeffe J (2002) Assessment of the Impact of Vision Impairment. IOVS 43(40):927–935
Sabri K, Knapp CM, Thompson JR, Gottlob I (2006) The VF-14 and psychological impact of amblyopia and strabismus. IOVS 47(10):4386–4389
- Construct validation of the Amblyopia and Strabismus Questionnaire (A&SQ) by factor analysis
Elizabeth S. van de Graaf
Hanneke van Kempen-du Saar
Casper W. N. Looman
Huibert J. Simonsz
- Graefe's Archive for Clinical and Experimental Ophthalmology
Incorporating German Journal of Ophthalmology
Print ISSN: 0721-832X
Elektronische ISSN: 1435-702X
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