Psychometric Properties of Scales for Assessing the Vision-related Quality of Life of People with Low Vision: A Systematic Review.

OBJECTIVE: To synthesize information on the psychometric properties of scales used to assess vision-related quality of life in people with low vision. METHODS: A systematic review was conducted. The Cochrane Library, Embase, PubMed, Bireme and Epistemonikos databases were consulted in July 2020. Eligibility assessment of abstracts and full texts was performed independently by two investigators.A standardized template was used for data extraction regarding study design, scale and version, clinical condition of participants, and psychometric properties measured, using database-specific controlled vocabulary terms for low vision and keywords for vision-related quality of life and validity. Data was synthesized considering two approaches for scales validations, Classical Test Theory and Rasch Analysis. RESULTS: A total of 53 articles were included in our analysis. In total, 40 studies evaluated the NEI VFQ scale, four evaluated the IVI scale, two evaluated the VA LV VFQ instrument and seven validated the LVQOL scale. This review found that the VRQoL NEI VFQ, IVI, LVQOL and VA LV VFQ-48 scales have adequate psychometric properties, with good internal consistency, when assessed using the CTT approach. The NEI VFQ scale also showed adequate test-retest reliability and adequate construct and content validity. The NEI VFQ and LVQOL scales showed inadequate items and multidimensionality when Rasch analysis was used. The IVI scale showed potential for assessing change in HRQoL after providing interventions to patients with low vision. CONCLUSIONS: Many questionnaires exist to measure vision-related quality of life in people with low vision, but the psychometric properties of the questionnaires are variable.

Rasch Validation of the LVQOL Scale.

AIM: This study proceeds to rigorously examine and validate the Low Vision Quality-of-Life Questionnaire (LVQOL) on a Greek population of ophthalmic patients employing Rasch measurement techniques. METHODS: It is a prospective observational study of 150 cataract patients and 150 patients with other ophthalmic diseases, all followed longitudinally for a period of two months pending surgical or other corrective therapy, after which they were administered the LVQOL for a second time. RESULTS: The original 25-item LVQOL demonstrated high reliability and validity, excellent measurement precision and ordered response category thresholds. A small number of items carry an acceptable level of measurement error while three items had some differential functioning for gender, Age and underlying disorder that did not exceed the established thresholds. CONCLUSIONS: This validation study is the first to employ Rasch measurement to examine the validity of the LVQOL and it supports its use with no changes to the original structure. The LVQOL can be employed in a large range of ophthalmic diseases and reliably assess improvements in quality-of-life following phacoemulsification surgery or any other intervention.

Comparison of Quality of Life Questionnaires in Patients with Low Vision

Objectives: To compare the quality of life assessed by the Low Vision Quality of Life Questionnaire (LVQOL) and National Eye Institute Visual Function Questionnaire (NEI VFQ-25) in patients with low vision. Materials and Methods: A total of 64 consecutive patients who presented to the Ankara University Low Vision Rehabilitation Department for the first time were included in the study. Patients aged 18 or older who had a best-corrected visual acuity of less than 20/60 or a visual field of equal to or less than 20° from the fixation point in the better eye were included. After examination, the patients were asked to complete the LVQOL and NEI VFQ-25 questionnaires. Results: A very strong correlation was found between the total scores of the two questionnaires. A strong correlation was found between the "distance vision" subscale score of LVQOL and "distance activities" subscale score of NEI VFQ-25. There was also a strong correlation between the "reading and fine work" subscale score of LVQOL and "near activities" subscale score of NEI VFQ-25. There was a weak correlation between the LVQOL total score and visual acuity. There were moderate negative correlations between age at disease onset and the total scores of the two questionnaires. Conclusion: Both the LVQOL and NEI VFQ-25 are able to quantify the quality of life of individuals with low vision and it is possible to compare the studies carried out with these two questionnaires which are validated in Turkish.