Patient-Reported Spectacle Independence Questionnaire (PRSIQ): Development and Validation

Purpose: To develop a questionnaire quantifying spectacle independence following cataract surgery.

Design: Questionnaire design and validation study.

Methods: A literature review, expert clinical interviews, and patient interviews were undertaken to develop a patient-reported questionnaire assessing spectacle independence. Draft items were assessed and revised in a series of cognitive interviews where the instructions, recall period, and response categories were evaluated for understandability and consistency. The final draft items were evaluated in 2 quantitative studies. Confirmatory factor analyses, including item response theory calibration, were performed; reliability estimates were obtained; and validity analyses of the resulting scores were carried out.

Results: Qualitative research demonstrated that patients often considered themselves spectacle independent yet, when probed, it was determined that the respondent actually wore correction for certain activities. Moreover, despite what the respondents claimed about needing to wear correction and their actual use of correction, there were various levels of function reported when carrying out activities at several different distances without the use of correction. Using the qualitative results, the Patient-Reported Spectacle Independence Questionnaire (PRSIQ) was developed to assess spectacle independence via items that assess what patients say and do, and how they function at various distances. All quantitative analyses (eg, discriminant and convergent validity correlations, known-groups analyses) conform to predictions and support the use of the PRSIQ as a measure of spectacle independence.

Conclusions: The PRSIQ is a patient-reported measure assessing spectacle independence following cataract surgery. The analyses conducted provide evidence for the use of the PRSIQ total score as a measure of spectacle independence.