Purpose: To compare glaucoma conversion rates in patients with ocular hypertension (OH) with and without pseudoexfoliation. Design: Cohort study, based on 32 918 screening participants. Participants and Controls: Ninety- eight patients with OH and pseudoexfoliation and 98 matched controls. Main Outcome Measure: Perimetric glaucoma conversion. Methods: Apopulation- based glauco- ma screening of elderly citizens of Malm , Sweden, was conducted between 1992 and 1997 to recruit participants for the Early Manifest Glaucoma Trial. Screening participants with intraocular pressure (IOP) between 24 and 32 mmHg and pseudoexfoliation were compared to controls among other screening participants without pseudoexfoliation but matched for baseline IOP, age, and gender, and the 2 groups were invited to a reexamination. Computerized visual field tests were performed to identify persons with manifest glaucoma. Visual acuity, refraction, IOP, and central corneal thickness were also measured. Results: After a mean of 8.7 years (range: 6.3- 11.4),54 of 98 patients (55.1% ) with pseudoexfoliation at the baseline examination and 27 of 98 patients (27.6% ) without pseudoexfoliation had developed glaucoma. The risk ratio was 2.0 (P< 0.0001). Conclusion: The glaucoma conversion rate was twice as high in patients with OH and pseudoexfoliation as in control patients matched for IOP, age, and gender. Thus, pseudoexfoliation was a strong independent risk factor for glaucoma in patients with OH. Purpose: To compare glaucoma conversion rates in patients with ocular hypertension (OH) with and without pseudoexfoliation. Design: Cohort study, based on 32 918 screening participants. Participants and Controls: Ninety- eight patients with OH and pseudoexfoliation and 98 matched controls. Outcome Measure: Perimetric glaucoma conversion. Methods: Apopulation-based glaucoma screening of elderly citizens of Malmö, Sweden, was conducted between 1992 and 1997 to recruit participants for the Early Manifest Glaucoma Trial. Screening participants with intraocular pressure (IOP) between 24 and 32 mmHg and pseudoexfoliation were compared to controls among other screening participants without pseudoexfoliation but matched for baseline IOP, age, and gender, and the 2 groups were invited to a reexamination. Computerized visual field tests were performed to identify persons with manifest glaucoma. Visual acuity, refraction, IOP, and central corneal thickness were also measured. Results: With a mean of 8.7 years (range: 6.3-11.4), 54 of 98 patients (55.1%) with pseudoexfoliation at the baseline examination and 27 of 98 patients (27.6%) without pseudoexfoliation had developed glaucoma. The risk ratio was 2.0 (P <0.0001). Conclusion: The glaucoma conversion rate was twice as high in patients with OH and pseudoexfoliation as in control patients matched for IOP, age, and gender. Thus, pseudoexfoliation was a strong independent risk factor for glaucoma in patients with OH.