What is the GPI?
Glaucoma is a chronic eye disease characterised by progressive damage to the optic nerve and consequent restriction of the field of vision. The condition does not reduce length of life but is associated with impaired health status and health related quality of life. The Glaucoma Profile Instrument (GPI) is a six-dimension disease specific patient reported outcome instrument for use as a measure of health outcome. Responses provide a simple descriptive health profile and a single index value of health status, the Glaucoma Utility Index (GUI).
How was the GPI developed?
Full details are provided in the publication by Burr and colleagues. In brief, using qualitative methods, six key aspects of glaucoma health were identified. These were near vision tasks, treatment effects both in and around the eye and effects on general health, illumination, mobility, and visual judgement for activities of daily living. These were refined to six dimensions of health status: central and near vision, lighting and glare, mobility, activities of daily living, eye discomfort and other possible effects of glaucoma and its treatment. Each dimension has four levels: no difficulty, some difficulty, quite a lot of difficulty and severe difficulty. The final instrument is the GPI, available for download both as the questionnaire and a guide for the respondent.