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Cataract is leading cause of global blindness
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LONDON – Cataract remains the leading cause of blindness worldwide, while age-related macular degeneration has become the leading cause of blindness in developed countries, said Hugh R. Taylor, AC, MD, speaking here at the Moorfields Bicentenary meeting.
Dr. Taylor, an internationally known ophthalmic epidemiologist, said glaucoma and diabetic retinopathy are among the other leading causes of blindness.
Dr. Taylor outlined some of what is known historically about the causes of blindness. He said that in the late 1800s, in European countries such as Germany, 40% of blindness was caused by corneal disease and trauma. By the late 1950s and early 1960s, in England and Wales, 23% of blindness was attributed to cataract, 10% to diabetes and 26% to AMD.
“Those are similar figures to those from the United States,” he said.
In its latest data, the World Health Organization has identified cataract as the overall leading cause, responsible for 42% of blindness, he said.
The WHO estimates that currently about 37 million people in the world are legally blind and 124 million suffer from low vision.
There is currently a backlog of about 20 million cataract surgeries worldwide, Dr. Taylor said.
“We have a relatively low rate of cataract surgery here in Europe – around 1,000 per 1 million residents,” Dr. Taylor said. “To cope adequately with demand, it should hover around 3,000 surgeries per 1 million residents.”
As a comparison, he said, in the United States the figures range from 2,000 surgeries per 1 million residents in rural areas to as many as 6,000 surgeries per 1 million residents in urban areas.
In addition to an increase in the number of cataract surgeries performed, Dr. Taylor said, “there has to be a quality outcome.” He noted that in Southeast Asia, for example, about 30% of people undergoing cataract surgery have a postoperative visual acuity of 6/60, a level of visual acuity that is considered legal blindness in some countries.
On a worldwide scale, Dr. Taylor said, among the causes of blindness, glaucoma and AMD are less preventable, while refractive error and cataract are more preventable.
He said the prevalence of trachoma has dramatically declined – from about 15% of all world blindness in 1995 to 4% 2002.