Changing definition of glaucoma.

OBJECTIVE: The authors assess whether there has been a change in the definition of open-angle glaucoma (OAG) in peer-reviewed articles during the past 15 years.

METHODS: A literature review was conducted (via Medline) to identify all articles on OAG from the American Journal of Ophthalmology, Ophthalmology, and Archives of Ophthalmology for the years 1980, 1985, 1990, and 1995. One hundred eighty-two articles were reviewed to identify optic nerve, visual field, and intraocular pressure (IOP) criteria used to define glaucoma. Articles were classified and analyzed by study design, severity, and type of glaucoma.

RESULTS: Of the 182 articles, 120 (66%) included a definition of OAG. Among these, approximately 36% used both optic disc and visual field criteria, 13% used optic disc or visual field criteria, 26% used only visual field criteria, 20% used only IOP, and 5% used only optic disc criteria. In the 1980s, when both disc and/or field parameters were used in the definition, 74% of the publications used general qualitative statements such as "characteristic glaucomatous changes." In the 1990s, 34% of articles provided specific descriptions of the optic disc and 61% provided specific visual field criteria. A similar proportion of reviewed articles published in the 1980s (20.4%) and 1990s (19.7%) used IOP as its sole criterion for defining glaucoma. A significantly larger proportion of prospective studies (38/46; 83%) provided specific criteria to define glaucoma compared to cross-sectional (67/111; 60%) and retrospective studies (15/25; 60%).

CONCLUSION: There is a lack of consistency in how glaucoma is defined in current clinical research. Although recent studies provide more specific criteria, there is a need to obtain a consensus definition.