Abstract
PurposeTo culturally and linguistically adapt the Convergence Insufficiency Symptom Survey (CISS) to Spanish and assess the psychometric performance of the new version through Rasch analysis and classical test theory methods.MethodsThe Spanish version of the CISS (CISSVE) was completed by 449 subjects (9–30 years old) from the general population. The validity and reliability of CISSVE were assessed through Rasch statistics (precision, targeting, item fit, unidimensionality, and differential item functioning). To test construct validity, we calculated the coefficients of correlation between the CISSVE and the Computer-Vision Symptom Scale (CVSS17) or Warwick–Edinburgh Mental Well-Being Scale (WEMWBS). We determined test–retest reliability in a subset of 229 subjects. We used differential item functioning (DIF) to compare the CISSSVE and the CISS after administering the CISS to 216 English children.ResultsAfter applying exclusion criteria, the responses of 420 participants (mean age, 18.62 years; female, 54.95%) revealed good Rasch model fit, good precision (person separation = 2.33), and suboptimal targeting (–1.37). There was some evidence of multidimensionality, but disattenuated correlations between the Rasch dimension and a possible secondary dimension were high, suggesting they were measuring similar constructs. No item bias according to gender or age was detected. Spearman's correlation was 0.34 (P < 0.001) for CISSVE–CVSS17 and non-significant for CISSVE–WEMWBS. The limits of agreement for test–retest reliability were 9.67 and –8.71. Rasch analysis results indicated no difference between CISS and CISSVE.ConclusionsAccording to our results, CISSVE is a valid and reliable tool for measuring the symptoms assessed by CISS in Spanish people 9 to 30 years of age.Translational RelevanceCISSVE can measure convergence insufficiency symptoms in Spanish-speaking subjects.
Highlights
Convergence insufficiency is one of the most common abnormalities of binocular vision
According to our results, CISSVE is a valid and reliable tool for measuring the symptoms assessed by Convergence Insufficiency Symptom Survey (CISS) in Spanish people 9 to 30 years of age
Of the questionnaires completed by 449 participants, responses to 429 questionnaires were used in the Andrich’s rating scale model (RSM) analysis implemented in Winsteps
Summary
Convergence insufficiency is one of the most common abnormalities of binocular vision. The first version of this questionnaire consisted of 13 items and assessed the frequency of each symptom using a four-option response scale.[3] In 2003, a revised version was introduced[1] that included two more items and a new response scale with five choices: never, infrequently, sometimes, fairly often, and always This new version made the tracking of changes during therapeutic interventions more sensitive.[1] The 15-item version of the CISS (hereafter CISS) is a frequently used outcome measure in binocular vision research and has been used to assess convergence insufficiency (CI) symptoms in various clinical groups from the ages of 8 to 30 years,[1,2,4] where subjects with symptomatic CI had a significantly higher CISS score than others with normal binocular vision. To our knowledge, no data have been reported regarding its
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