Avaliação da Visão Funcional (AVIF) para crianças de dois a seis anos com baixa visão: exame de confiabilidade e de validade

Abstract

The AVIF-2 to 6 years is a method of Functional Vision Assessment for children with low vision. It was developed by a Physical Therapist and an Occupational Therapist from the Childrens Low Vision Clinic at the São Geraldo Hospital (Clinics Hospital, at UFMG - Federal University of Minas Gerais). In this study, the psychometric characteristics (reliability and validity) of the AVIF-2 to 6 years were analysed, as well as the capacity of this test to differentiate between various levels of visual response.After conducting a debate among a panel of professionals from different areas regarding the appropriateness of the items to be tested, the AVIF-2 to 6 years was applied to 40 children from two to six years of age, 20 of which had low vision and 20 without low vision. The children with low vision and with normal neurological results were observed at the Childrens Low Vision Clinic. The children without low vision and with normal development, according to the Denver II, were selected from twopublic daycare centres. The two groups were the same in terms of age, gender and socioeconomic status. The data were compared between these groups and between the different subgroups of age and visual acuity level. The inter-rater and test-retest reliability for the seven categories and for the 47 items of the AVIF-2 to 6 years, as well as the internal consistency of the items, were also tested. The analyses weredone using the following tests: chi-square, Kruskal-Wallis, Mann-Whitney, Pearson Linear Correlation, Intra-class Correlation, Weighted Kappa Coefficient and Cronbachs Alpha. There were differences of statistical significance (p < 0.05) between the total score of AVIF-2 to 6 years and those of the categories of visual fixation, visual tracking, confrontation visual field, eye-hand coordination and movement within surroundings, with the best responses for the children in the control group. There no difference of statistical significance only in the categories of contrastsensitivity on flat surfaces and colour vision. In the analysis of test-retest reliability of the seven categories (visual fixation, visual tracking, confrontation visual field, eyehand coordination, contrast sensitivity on flat surfaces, movement within surroundings and colour vision), six of them exhibited the Intra-class Correlation Coefficient with moderate to excellent values (between 0.40 and 1.00). For the movement within surroundings category, this coefficient was 0.37. Testing for inter-rater reliability, only the category of confrontation visual field exhibited the Intraclass Correlation Coefficient with a value below 0.40. The Weighted KappaCoefficient, applied to the 47 items of the AVIF-2 to 6 years, had poor results (equal to or lower than 0.40) for some items of visual tracking (test-retest), confrontation visual field (test-retest and inter-rater) and movement within surroundings (testretest). There was also low reliability in the stacking blocks item for test-retest. All of the other items exhibited Weighted Kappa Coefficient values above 0.40. Furthermore, the movement within surroundings category was the only one thatobtained low internal consistency, which can be related to the small number of items in this category. On the other hand, in the contrast sensitivity on flat surfaces category there was excessive agreement, indicating item redundancy. The AVIF-2 to 6 years demonstrated potential to differentiate between various levels of functional vision. Further studies will focus on increasing the reliability of some items until the test is ready for clinical use.