[A new valid and reliable questionnaire of asthenopia: development and evaluation]

Objective: To design a valid and reliable questionnaire to determine various causes of asthenopia for use by clinicians and researchers. Methods: The items to be included in the first version questionnaire were selected based on its definition and literature review. The second version was improved from patients interviews and the Delphi method. In this phase, 17 experts, 97 patients [47 males, 50 females, age (34.42±14.62) years old] with asthenopia and 20 controls [9 males, 11 females, age (33.50±7.31) years old] were involved to generated item list. In the Validation phase, we conducted two round interview through 275 asthenopia patients [97 males,186 females,age (34.42±14.62) years old] and 49 controls [17 males,32 females,age (35.79±8.88) years old]for item reduction and questionnaire validity and reliability assessment. Exploratory factor analysis was performed to reduce items and derive the subscale that each item belongs to. Internal consistency was calculated for all resulting subscales, using Cronbach's α coefficient, spilt-half reliability and repeatability. The repeatability of the questionnaire was measured by Pearson correlation analysis. Results: Our initial questionnaire contained 52 symptoms and 2 self-evaluation questions. After the item reduction and assessment, 19 items were selected and classified into three domains through factor analysis. Cronbach α for the three subscales of this version was between 0.79 and 0.85, while for the complete questionnaire it was 0.90, with a spilt-half reliability of 0.80. Factor analysis showed the three components had eigenvalues>3 and these explained 54.3% of the variance. Conclusions: The 19-item asthenopia questionnaire has acceptable psychometric properties, making it a valid and reliable tool for ophthalmologists and optometrists to evaluate asthenopia as well as to seek causes. It has the potential to be used in clinical trials and outcome research. (Chin J Ophthalmol, 2021, 57:284-291).