May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
Factor Analysis With Varimax Rotation Confirms the Construct Validity of the Amblyopia and Strabismus Questionnaire
Author Affiliations & Notes
  • E. S. Van de Graaf
    Erasmus Medical Center, Rotterdam, The Netherlands
    Ophthalmology,
  • G. W. van der Sterre
    Erasmus Medical Center, Rotterdam, The Netherlands
    Ophthalmology,
  • J. Passchier
    Erasmus Medical Center, Rotterdam, The Netherlands
    Medical Psychology & Psychotherapy,
  • H. van Kempen-du Saar
    Ophthalmology, Waterland Hospital, Purmerend, The Netherlands
  • C. W. N. Looman
    Erasmus Medical Center, Rotterdam, The Netherlands
    Public Health,
  • J. Felius
    Pediatric Eye Research, Retina Foundation of the Southwest, Dallas, Texas
  • H. J. Simonsz
    Erasmus Medical Center, Rotterdam, The Netherlands
    Ophthalmology,
  • Footnotes
    Commercial Relationships  E.S. Van de Graaf, None; G.W. van der Sterre, None; J. Passchier, None; H. van Kempen-du Saar, None; C.W.N. Looman, None; J. Felius, None; H.J. Simonsz, None.
  • Footnotes
    Support  Prof. Henkes Foundation, Foundation Ondersteuning Oogheelkunde 's-Gravenhage, Foundation Blindenhulp, and Ooglijders Foundation
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 2578. doi:
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      E. S. Van de Graaf, G. W. van der Sterre, J. Passchier, H. van Kempen-du Saar, C. W. N. Looman, J. Felius, H. J. Simonsz; Factor Analysis With Varimax Rotation Confirms the Construct Validity of the Amblyopia and Strabismus Questionnaire. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2578.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : The Amblyopia and Strabismus Questionnaire (A&SQ) was previously developed to assess quality of life in amblyopia and/or strabismus patients. Factor analysis, preliminarily reported at ARVO 2005, was now repeated with Varimax rotation to verify that the questions of the A&SQ correlated in an ordered manner to all components of quality of life of such patients.

Methods: : Responses on the A&SQ from 3 groups were analyzed: healthy controls (n=53), amblyopia and strabismus patients (n=72) and a historic cohort of amblyopes who were born between 1962-1972 and occluded between 1968-1974 (n=173). The correlations among the responses on the 26 A&SQ questions within the 5 domains: fear of losing the better eye, problems with distance estimation, visual disorientation, diplopia and social contact & cosmetic problems were examined by Principal Component Analysis on the correlationmatrix (PCA). Distribution of questions along the factors derived by PCA was examined by orthogonal Varimax rotation.

Results: : Data from 296 respondents were analyzed. PCA provided that 6 factors (cutoff point eigenvalue >1.0) accumulatively explained 70.5% of the variance. Orthogonal Varimax rotation provided that 4 out of the 5 domains of the A&SQ showed an unidimensional separation on 4 factors (factor loadings >0.50), i.e. the questions within these domains did not require a rearrangement. In the one multidimensional domain: distance estimation, the questions pertaining to near distance estimation separated on the one remaining factor whereas the questions relating to far distance estimation separated on the other. The 6 factors explained 33.7% (soc contact & cosm), 10.3% (dist est at near), 8.7% (dipl); 7.2%(vis disor); 6.3% (fear loosing better eye) and 4.3% (dist est at dist) respectively of the response variance.

Conclusions: : The very high explained variance in the A&SQ scores and the factors found by the PCA confirmed the a priori hypothesized dimensions of this HRQOL instrument.

Keywords: amblyopia • quality of life • strabismus 
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