Vision Impairment, Ocular Conditions, and Vision-specific Function: The Singapore Malay Eye Study
Received 24 December 2007; received in revised form 6 April 2008; accepted 1 May 2008. published online 26 June 2008.
Objective
To validate the VF-11, a vision-specific function scale and determine the relationship among vision impairment, ocular conditions, and vision-specific functioning in an Asian Malay population.
Design
Population-based cross-sectional study.
Participants
Persons aged 40 to 80 years of Malay ethnicity in Singapore.
Methods
Of the 3280 participants, 3267 answered the VF-11 scale. Participants underwent an extensive and standardized examination procedure, which included visual acuity testing. Sociodemographic and medical data were recorded using a standardized questionnaire. Rasch analysis was initially used to validate the VF-11 and determine its measurement characteristics. Analyses were performed to explore the relationship between the overall functioning score and the presenting unilateral and bilateral vision and ocular conditions using linear regression models.
Main Outcome Measure
Vision-specific functioning score.
Results
The mean presenting visual acuity values in the better and worse eyes were 0.21 (±0.23) and 0.36 (±0.27) logarithm of the minimum angle of resolution, respectively. Some 46.4% of participants had some form of visual impairment in either eye, and 1.8% of participants had severe visual impairment in both eyes. By using Rasch analysis, it was shown that a modified VF-11 is a unidimensional, reliable, and valid scale to assess vision-specific functioning in this population. Participants with unilateral or bilateral visual impairment had significantly lower vision functioning scores. The independent association between severe vision loss in one or both eyes and functioning was considered to be clinically meaningful. Eye conditions were not independently associated with overall visual function with bilateral visual impairment in the model with the exception of glaucoma (P<0.05 and β = −1.08). Compared with people with normal vision, people with mild/moderate visual impairment were 1.6 (95% confidence intervals [CI], 1.2–2.2; P = 0.01) and 2.2 (95% CI, 1.6–3.0; P = 0.007) times more likely to have moderate and poor vision function, respectively. Similarly, participants with severe visual impairment were 3.5 (95% CI, 1.1–12.7; P<0.001) and 13.6 (CI, 4.0–45.4; P<0.001) times more likely to have moderate and poor vision function, respectively.
Conclusions
Presenting unilateral and bilateral vision impairment is significantly associated with poor vision-specific functioning across the spectrum of mild to severe vision impairment in this Asian Malay population.
Financial Disclosure(s)
The authors have no proprietary or commercial interest in any materials discussed in this article.
Available online: June 26, 2008.
1Centre for Eye Research Australia, University of Melbourne, Australia
2Department of Pharmacy, National University of Singapore, Singapore
3Centre for Vision Research, University of Sydney, Australia
4Department of Community, Occupational and Family Medicine, Yong Loo Lin School of Medicine, National University of Singapore
5Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore
6Singapore Eye Research Institute, Singapore National Eye Centre
Correspondence: Ecosse Lamoureux, PhD, Centre for Eye Research Australia, Department of Ophthalmology, University of Melbourne, 32 Gisborne St, East Melbourne, Victoria, 3002, Australia
Manuscript no. 2007-1643.
Financial Disclosure(s): The authors have no proprietary or commercial interest in any materials discussed in this article.
ABSTRACT