Vision-specific quality-of-life research: a need to improve the quality.

w m a a i R i v g r a a R m m w i i a ( b S EARLY AS THE FOURTH CENTURY BC, THE IMPORtance of the concept of quality of life (QoL) has been debated by philosophers including Socrates, ristotle, and Royce. The interest in QoL has grown xponentially in the last century and a recent Medline earch using the term “quality of life” generated over 1 500 related articles. To date, “QoL” has become de igueur in ophthalmic outcomes research in order to omplement traditional and objective outcomes such as he measurement of visual acuity and intraocular pressure IOP). The patient’s perspective is important to fully nderstand the impact of ocular conditions and treatment ptions. From a clinician’s point of view, for example, the se of eye drops may be effective in managing IOP, but it ay well result in side effects with impact on the patient’s oL when the patient is queried. The need for patient-reported information has produced a lethora of questionnaires (commonly called instruments) hat assess psychometric constructs. This has, however, reulted in a confusing choice for the would-be investigator. ery often a construct such as “vision functioning” is confused ith “vision-specific QoL.” Vision functioning, commonly asessed using the Visual Functioning Index-14 (VF-14), easures visual disability or vision-related activity limitation ssociated with vision-dependent tasks such as reading, drivng, and shopping. Vision-related QoL is a complex trait that ncompasses vision functioning, symptoms, emotional welleing, social relationships, concerns, and convenience as they re affected by vision. Vision-related QoL instruments are herefore better able to provide a complete assessment of the mpact of ocular conditions and the effectiveness of treatment n other critical components of QoL. Currently, traditional psychometric methods remain the referred techniques used in patient-based outcome measures n ophthalmology. Examinations of scale reliability, validity, nd responsiveness are desirable, although few studies in phthalmology have reported all these properties. Reliability