Purpose: To quantify the impact of the mode of administration (MOA) on scores of the Vision Impairment in Low Luminance (VILL) questionnaire.
Methods: The VILL questionnaire was implemented using different MOAs (paper, interview, electronic), in addition to a demographical survey of adult participants recruited at an outpatient eye clinic, with the initial MOA being either paper or interview. Polytomous Rasch models were used to generate person measure scores for the three subscales of the VILL questionnaire (reading, VILL_R; mobility, VILL_M; and emotional, VILL_E). Measures of agreement among the different MOAs were calculated (self-administered paper/interview, self-administered paper/self-administered electronic, and interview/self-administered electronic). An age-matched analysis was performed to control for the impact of the initial MOA, administration interval, visual acuity, and self-reported hearing difficulties.
Results: We included 309 participants (mean age, 63 ± 14 years; 61% female). Intra-class correlation coefficients were 0.930, 0.919, and 0.799 for paper versus interview assessment; 0.951, 0.959, and 0.916 for paper versus electronic; and 0.967, 0.955, and 0.907 for interview versus electronic assessment (VILL_R, VILL_M, and VILL_E, respectively). Mean differences were 0.35, 0.41, and 1.74 logits; 0.32, 0.18, and 0.68 logits; and 0.08, 0.22, and 0.63 logits, respectively. None of the mentioned factors significantly affected the results (corrected P ≥ 0.11).
Conclusions: Paper, interview, and electronic MOAs of the VILL can be considered equivalent. Reporting across the main MOAs of self-administration (paper) and interviewer-administration was unaffected by better eye visual acuity and self-reported hearing difficulties.
Translational relevance: The results support use of the VILL questionnaire with flexible modes of administration.