Probability of blindness from glaucoma drops by half, say researchers

A comparative long-range study by Mayo Clinic ophthalmology researchers shows that the probability of blindness from glaucoma 20 years after diagnosis has dropped by half in the last generation. The findings appear online in the "in press" section of the journal Ophthalmology.

The researchers examined the medical records of all residents of Olmsted County, Minnesota, age 40 or above, diagnosed with glaucoma between 1981 and 2000. They compared this with similar data from a previous study of patients diagnosed between 1965 and 1980, using the same resource, the repositories of the Rochester Epidemiology Project.The findings: While the incidence of glaucoma in the population has not changed, the probability of going blind in at least one eye due to glaucoma dropped by half, from 25.8 percent in the earlier study, to 13.5 percent in the later period. As well, the annual incidence of glaucoma-caused blindness in the population has dropped by more than half.

"This is a testament to the skill and effort of the researchers, physicians and other care providers working in eye care over that period," says Arthur Sit, M.D., Mayo Clinic ophthalmologist and senior author of the study. "Our improved understanding of glaucoma, along with better treatment and management of patients seem to have had this impact. Still, much research and public education remains to be performed. A 14 percent blindness rate from a common eye disease is hardly ideal."

Dr. Sit discounted early diagnosis as a factor in the dramatic shift, noting that the age of first diagnosis for glaucoma patients has not changed. The study also has its limitations. While it reflects virtually every case of glaucoma in the study county, the population over the period was roughly 90 percent white and does not necessarily reflect more diverse communities.

There is no early warning sign of glaucoma, other than loss of peripheral vision, which most people fail to notice. Dr. Sit urges regular eye appointments as the best way to diagnose the condition.