Measuring the outcomes of ophthalmic healthcare: low vision rehabilitation

Abstract

The measurement of health status and medical outcomes is becoming a major requirement for all providers of healthcare services. There is a need to measure the outcomes of healthcare, not only to demonstrate the effectiveness of care, but also to assess the relative (and possibly competing) worth of different forms of care. At the same time, there is a growing awareness of the limitations of clinical outcomes in contrast to those measured by patients themselves. There is, therefore, considerable interest in the use of generic and disease specific ‘Quality of Life’ (Qol) instruments. Within ophthalmic healthcare, clinical outcomes include, for example, measures of visual function or the gradings of images of ocular structure. Other outcome measures used may include specific disease scales or indices, including questionnaire measures of visual disability (e.g. the VF14, ‘Activities of Daily Vision Scale’ and TyPE scales, designed to assess the impact of cataract and cataract surgery on self-rated visual disability). In contrast to disease specific measures, generic measures are designed to provide an overall measure of an individuals health status. These measures are classified into profile measures (e.g. the SF36) or indices (e.g. the Rosser index or the EuroQol). There have been a number of studies which have evaluated the effectiveness of low vision rehabilitation, although these have mainly been small cross sectional surveys which have used a single definition of ‘success’, including for example, the visual acuity/visual performance achieved with the LVA or the usage of the LVA. More recently questionnaire approaches have been used to measure ‘success’, but as with clinical outcomes, the validity and reliability of the outcomes used has not been established. Given the considerable scale of the low vision population and the current debate about optimal models of low vision care, there is a pressing need to (1) define an appropriate set of outcome measures and (2) carry out randomised controlled trials comparing the effectiveness and cost-effectiveness of different forms of care. If we as clinicians fail to inform the debate about appropriate outcomes in ophthalmic healthcare, this may result in such care being incorrectly valued by others.