Rasch Validation of the LVQOL Scale.

Abstract

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.