Lifetime Risk of Visual Impairment Resulting from Glaucoma in Patients Initially Followed up for Elevated Intraocular Pressure.

PURPOSE: To report the lifetime risk of visual impairment resulting from glaucoma in patients originally followed up in a 10-year prospective randomized study initiated in 1981 to assess patients with elevated intraocular pressure (IOP). DESIGN: Retrospective patient chart review. PARTICIPANTS: Data on deceased patients who initially were followed up prospectively in the randomized controlled study and thereafter were followed up in ordinary clinical practice were collected until the end of 2017. Inclusion in the original study required an untreated IOP of 22 mmHg or more and 1 or more risk factors for glaucoma. METHODS: Visual impairment, low vision, and blindness were defined according to the World Health Organization criteria. All eyes that became visually impaired were registered, including the date and cause of the impairment; the cumulative incidence of visual impairment corrected for competing risks was calculated; and the Kaplan-Meier method was used to analyze the importance of risk factors present at baseline for 1 eye per patient. MAIN OUTCOME MEASURES: The proportion of patients who became bilaterally visually impaired because of glaucoma, the cumulative incidence of glaucoma-related visual impairment in at least 1 eye, and potential baseline risk factors for visual impairment caused by glaucoma. RESULTS: Seventy-seven of 90 patients (86%) included in the initial randomized study were deceased at the end of 2017. Four patients were lost to follow-up during the clinical follow-up. Of the 77 patients, 7 (9%) became bilaterally visually impaired and 2 of those 7 became bilaterally blind because of glaucoma. The cumulative incidence of glaucoma-induced visual impairment in at least 1 eye increased from 0.00 after 5 years to 0.22 (95% confidence interval [CI], -0.01 to 0.67) after 30 years. The cumulative incidence of glaucoma blindness in at least 1 eye increased from 0.00 after 5 years to 0.17 (95% CI, 0.10-0.54) after 30 years. No specific risk factor significantly increased the risk of visual impairment caused by glaucoma. CONCLUSIONS: Although the investigated patients showed elevated IOP and at least 1 additional glaucoma risk factor (i.e., they were high-risk patients), only a relatively small proportion of the patients with glaucoma demonstrated visual impairment.

Predicting undetected glaucoma according to age and IOP: a prediction model developed from a primarily European-derived population.

PURPOSE: To model prediction of undetected glaucoma in a predominantly white population, based on intraocular pressure (IOP) and subject age. METHODS: In 1992-1997, a population screening for glaucoma was performed at Malmö University Hospital where individuals between 55-79 years of age (n = 46 614) living in Malmö, were invited to a free eye health examination. Recently examined patients were not invited (n = 4117). IOP and age were recorded for all screened subjects. Subjects who screened positive were further examined to establish or reject a glaucoma diagnosis. We performed multiple regression analysis of the combined effect of age and IOP on the likelihood of undetected glaucoma. RESULTS: In all, 32 918 subjects attended the screening (77.5% of invited), 22 218 women and 11 700 men, while 9579 refrained from participation. Glaucoma was diagnosed in 406 subjects. The proportion of subjects with glaucoma increased exponentially with increasing IOP and older age. Still, the majority of subjects with glaucoma (57%) had ≤IOP 21 mmHg. The predicted rate of undetected glaucoma was low, <5%, for subjects with IOP <25 mmHg, but rose rapidly with higher IOP, reaching 81% in the group with IOP >35 mmHg and age 75-79 years. The model fit well to the data (R2  = 0.97). CONCLUSION: We created a model estimating the combined effect of IOP and age on the likelihood of undetected glaucoma. The model may facilitate case-finding in European-derived populations. Despite the important impact of IOP on the risk of glaucoma, a large proportion of subjects with undetected glaucoma had IOP ≤ 21 mmHg.