The Toronto epidemiology glaucoma survey: a pilot study

Objective: To evaluate the prevalence of undetected glaucoma in a Toronto population. Design: A cross-sectional survey. Participants: Toronto residents aged 50 years or older. Methods: Telephone calls were randomly made to Toronto residents. Those who indicated they did not have glaucoma were invited to the Toronto Western Hospital for a comprehensive ophthalmic assessment, including best corrected visual acuity testing, applanation tonometry, pachymetry, gonioscopy, disc assessment, frequency doubling technology, and Heidelberg retinal tomography. Patient suspected to have glaucoma were asked to return for further evaluation, including a 24-2 Humphrey automated visual field test, repeat Heidelberg retinal tomography, repeat disc assessment, and possibly a diurnal tension curve. The diagnosis of glaucoma was made based on standardized criteria modified from those used by the Rotterdam Study and Foster and associates. Results: Among 975 eligible respondents, 73 (7.5%) stated that they had glaucoma. Of the remaining 902 negative respondents, 271 booked clinical appointments, and 180 completed the clinical assessment; their mean age was 61.6 years. Of the participants, 7 (3.9%) were diagnosed with glaucoma: 5 (2.8%) had primary open-angle glaucoma (3 with low-pressure and 2 with high-pressure glaucoma); 1 had (0.6%) chronic angle-closure glaucoma; and 1 (0.6%) had pseudoexfoliation glaucoma. A further 8 (4.4%) participants were classified as probably having open-angle glaucoma and 33(18.3%) as being suspected to have glaucoma. Narrow angles were found in 27 participants (15%), and 37 (20.6%) had family histories of glaucoma. Conclusion: The prevalence of undetected glaucoma appears to be high in Toronto. Further studies involving larger numbers of participants are required to confirm this finding.