Psychometric Validation of a Short-Form Spanish Low Vision Quality of Life Questionnaire (SF-SLVQOL) Using Rasch...

Area of Science:

• Ophthalmology
• Psychometrics
• Health Outcomes Research

Background:

• The original Spanish Low Vision Quality of Life Questionnaire (SLVQOL) is effective but time-consuming.
• Developing a shorter version is crucial to reduce patient burden and improve efficiency.

Purpose of the Study:

• To develop and validate a short-form version of the SLVQOL (SF-SLVQOL) using Rasch analysis.
• To ensure the SF-SLVQOL maintains psychometric robustness and measurement precision in Spanish-speaking populations with visual impairment.

Main Methods:

• Rasch analysis (Partial Credit Model) was used to systematically reduce items from the original SLVQOL data (n=365).
• Item reduction was guided by point-biserial correlations and misfit statistics.
• The resulting SF-SLVQOL was evaluated for validity (structural, criterion, construct), reliability (internal consistency, test-retest), and differential item functioning.

Main Results:

• The 6-item SF-SLVQOL demonstrated excellent unidimensionality and internal consistency (Cronbach's alpha = 1.00).
• High criterion validity (r=0.95) and convergent validity with NEI VFQ-25 (r=0.69) were confirmed.
• The SF-SLVQOL showed significant known-groups validity and acceptable test-retest reliability (ICC=0.753).

Conclusions:

• The SF-SLVQOL is a psychometrically sound, brief instrument for assessing vision-related quality of life.
• It reduces administration time by 76% compared to the original SLVQOL.
• This efficient tool is suitable for clinicians and researchers working with Spanish-speaking populations experiencing visual impairment.