Development and psychometric evaluation of beliefs about the orthokeratology lens compliance scale (BOLCS): Based on the theory of planned behavior

Purpose: Non-adherence to standard wear, care, and follow-up procedures is a major risk factor for contact lensrelated complications. The effectiveness of orthokeratology largely depends on the wearer's adherence. However, a deficiency in scales capturing adherence beliefs pertinent to orthokeratology exacerbates the lack of guidance for effective intervention strategies. The purpose of this study is to develop and evaluate the psychometric properties of a new scale based on the Theory of Planned Behavior that assesses the level of adherence among ortho-k wearers. Methods: This study involved three stages following the STROBE checklist: (1) developing initial scale items based on the Theory of Planned Behavior, a literature review, and a qualitative study; (2) evaluation of content and face validity; (3) psychometric testing on 296 participants. Item analysis, based on Classical Test Theory, assessed the overall consistency, reliability, and validity of the scale. Results: The final 37-item Beliefs about the Orthokeratology Lens Compliance Scale (BOLCS) comprises 11 dimensions. The Cronbach's alpha coefficients for each dimension ranged from 0.560 to 0.798. The folded half reliabilities were 0.845, and the combined reliabilities ranged from 0.676 to 0.793, indicating strong reliability. Item-level CVI (I-CVI) and scale-level CVI/average (S-CVI/Ave) values, assessed by the panel, ranged from 0.71 to 1 and 0.954, respectively. Exploratory and confirmatory factor analyses supported a factor structure consistent with the theoretical model. Conclusions: The scale's construction adhered to a standardized process, yielding preliminary validation results with satisfactory reliability and validity.