Abstract--This article reviews the instrument development process and synthesizes current research findings for three low-vision and blind rehabilitation outcomes measures developed in the Department of Veterans Affairs (VA). The examined measures include the Blind Rehabilitation Service Functional Outcomes Survey, the Functional Assessment of Self-Reliance on Tasks, and the VA Low Vision Visual Functioning Questionnaire. We examined vision rehabilitation literature using two fundamental measurement criteria to compare and contrast the instrument development process and research findings for the three measures. Our findings suggest the three measures need refinement to meet the two criteria and proposed measurement standards for instruments in this field. Advanced development goals for the instruments are identified. Measures that meet the specified and proposed measurement criteria will help establish an evidence-based system and guide practice at the VA and in the field.
Key words: aging, blind rehabilitation outcomes, clinician ratings, low-vision outcomes, measurement, outcomes assessment, psychometrics, Rasch model, self-report ratings, visual impairment.
This article reviews the instrument development process and synthesizes current research findings for three low-vision and blind rehabilitation outcomes measures developed in the Department of Veterans Affairs (VA). A recent article by Robert Massof discusses the measurement of visual disability over the past 20 years , but this article reports on the state of vision rehabilitation outcomes measurement as it pertains to efforts supported by the VA Rehabilitation Research and Development (RR&D) Service and the VA Blind Rehabilitation Service (BRS). This review provides a historical overview of the impetus for developing the outcomes measures, an examination of the instrument development process, and a synthesis of the research findings based on a contemporary psychometric analytic approach.
We examined low-vision and blind rehabilitation literature, VA RR&D Service project reports, and related conference abstracts and presentations to assemble a historical synopsis of instrument development efforts. From the synopsis, we identified three VA low-vision and blind rehabilitation outcomes measures and examined them for differences and similarities in the following areas: purpose of the instrument, content prioritization, content selection and item generation, item responses, field testing, and administration time and approach. We then evaluated research findings for the three instruments. Our efforts to synthesize the findings were somewhat restricted by the lack of designated standards for evaluating an instrument in this field. We therefore chose to apply the following two fundamental measurement criteria that most psychometricians believe outcomes instruments should satisfy to ensure optimal measurement properties :
1. A low-vision and blind rehabilitation outcomes measure must reliably discriminate between the different levels of functional ability imposed by visual impairment. This criterion mandates that outcomes measures capture functional ability across the broadest array of functional domains. Instruments that meet this criterion will be able to measure patients' visual functioning across the continuum of services provided by the VA BRS.
2. A low-vision and blind rehabilitation outcomes measure must be sensitive to or able to reliably detect change across time for all levels of visual functioning.
These criteria merely reiterate two measurement properties--an instrument must discriminate both between and within veterans and do so accurately over time .
Department of Veterans Affairs Blind Rehabilitation Program For more than five decades, the leadership, programs, and principles established within the VA BRS have contributed significantly to raising the level of quality services for severely visually impaired veterans in the United States and abroad. …