OBJECTIVES: The three-item Vision Correction Scale (VCS) assesses the extent to which a respondent uses vision correction (e.g., glasses, contact lenses, or magnifying glass) at near, intermediate, and far distances in the seven days prior to assessment. The goal of the current study is to evaluate the psychometric performance of VCS scores using clinical study data.

METHODS: A total of 510 adults with bilateral cataracts underwent intraocular lens (IOL) replacement in a prospective, subject-masked, randomized, two-arm, parallel-group study. Subjects completed the VCS at five study visits (two pre- and three post-surgery) and VCS scores were evaluated with respect to reliability (internal consistency and test-retest) and construct-related validity (using correlational and known-groups methods). Additional assessments supporting the analysis included a self-reported eight-item Vision Disturbance Scale, five-item IOL Replacement Satisfaction Scale, single-item Patient Global Impression of Change and Clinician Global Impression of Change, and the Early Treatment Diabetic Retinopathy Study chart results converted to LogMAR scores as indicators of visual acuity at near, intermediate, and far distances.

RESULTS: Contributing to the present results were data from 271 subjects (n=187 female, 69.0%) who were mostly white (n=261, 96.3%) and between the age of 45 and 88 years (M=68.3, SD=7.3). Alpha coefficients across timepoints (α from 0.71-0.82) and intraclass correlation coefficients (ICC) from the two pre-surgery visits (ICC=0.784) and from one post-surgery visit (assessed one hour apart; ICC=0.950) indicate acceptable score reliability. Pearson correlation coefficients among VCS items and between VCS item and total scale scores and other assessments, and comparative analysis using known-groups methods, support the construct-related validity of the assessment, though variable results for the VCS Item 3 (far distance) were observed.

CONCLUSIONS: Results indicate that the VCS is capable of producing scores that are reliable and valid among patients who have undergone IOL replacement surgery for cataracts.