Sep. 29, 2011 Glaucoma is the second leading cause of blindness worldwide. Although it can be treated, new research shows Canadians may not be doing enough to protect themselves. According to a new study by Lawson Health Research Institute's Dr. Cindy Hutnik, many Canadian glaucoma patients are not screened until the disease has reached moderate or advanced stages.
Glaucoma is known as the "silent thief of sight." It slowly and irreversibly destroys the optic nerve -- so slowly, in fact, that many people don't realize they have glaucoma until it reaches advanced stages. To maintain eye health, preventive screening is vital. Yet despite a spectrum of known risk factors, it appears many Canadians are not checking for them.
In a multi-centre study, Hutnik and her colleagues examined the risk factors shared by 404 newly diagnosed patients across 18 Canadian locations. Each was assessed for demographic information, medical history, and ocular family history, as well as a complete eye exam. Results were largely consistent with the international standards, confirming older age, structural abnormalities and deterioration, and high intraocular pressure as leading glaucoma risk factors. In a surprising twist, however, 48% of these new diagnoses -- nearly half -- were already at moderate to advanced stages.
It is not clear why Canadians are not screening for glaucoma earlier. Researchers suspect the slow disease progression may not project the same urgency as, for example, a broken limb. The additional cost of screening, which is not covered by OHIP, may also be a deterrent. Researchers have even suggested that available screening measures may not be sensitive enough to detect the complex spectrum of risk factors at early stages. While investigation continues, Dr. Hutnik urges Canadians to keep a close eye on the situation.
"Almost half to two-thirds of your optic nerve is dead before you even get a visual field defect," she explains. "If you're late getting your clinical screening test, the nerve has been dying for a long time and once it's dead, it's dead. You can only prevent it from getting worse."
Dr. Hutnik is an Associate Scientist at Lawson's Centre for Clinical Investigation and Therapeutics, and a Physician at the Ivey Eye Institute at St. Joseph's Health Care London. She is also a Professor in the Departments of Ophthalmology and Pathology at The University of Western Ontario, and an Adjunct Professor in the Department of Chemistry & Biochemistry and the University of Windsor.
Funding for the study was provided by Pfizer Canada Inc.
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- Yvonne M. Buys, Paul Harasymowycz, Rania Gaspo, Kenneth Kwok, Cindy M. L. Hutnik, Pierre Blondeau, Catherine M. Birt, Robert L. G. Piemontesi, Lisa F. Gould, Mark R. Lesk, Iqbal K. Ahmed. Comparison of Newly Diagnosed Ocular Hypertension and Open-Angle Glaucoma: Ocular Variables, Risk Factors, and Disease Severity. Journal of Ophthalmology, 2012; 2012: 1 DOI: 10.1155/2012/757106
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