Using two large national surveys, researchers found the percentage of older adults who said they needed help performing daily tasks because of severe vision problems fell from 3.5 percent in 1984 to 1.7 percent in 2010. Those whose poor eyesight made it difficult to read or make out certain objects declined from 23 percent in 1984 to 10 percent in 2010.

"There are many possible explanations" for the significant decline in impaired vision said the study's lead author, Dr. Angelo Tanna, of the Northwestern University Feinberg School of Medicine in Chicago. "Improved techniques for cataract surgery may be a major driving force," he said.

Changes in nutrition and lifestyle over the decades may also be reducing the rates of other eye diseases, Tanna told Reuters Health in an email.

Previous research has linked reductions in the number of people who smoke to lower risks of vision loss due to macular degeneration, he explained. In addition, better glucose control among diabetics could lower the same risk for diabetic retinopathy.

The new study was published in the journal Ophthalmology.

Blindness or low vision affects 3.3 million Americans over age 40, according to the National Eye Institute. As the population ages, the number of Americans with major eye diseases is projected to increase substantially by 2020.

To gauge whether eye disease is indeed on the rise in older Americans, Tanna's team analyzed data from two large surveys, covering more than 100,000 adults, conducted yearly or every few years between 1984 and 2010.

Participants answered questions about problems related to their eyesight and how it affected their daily lives. One of the surveys focused just on severe vision impairments that limited a person's ability to perform basic functions, such as bathing or shopping, without help. The other survey asked about both severe impairments and less severe problems that interfered, for example, with seeing the letters in newsprint.

The researchers found little change in the rates of severe vision problems in middle-aged adults.

Among people over the age of 65, however, the number who said they needed help with daily activities due to poor eyesight declined by almost 46 percent in one survey and 59 percent in the other between 1984 and 2010.

When it came to less severe visual impairments, far fewer adults of all ages reported trouble in 2010 than in 1984. Over that period, the number of working age and older adults who struggled to read decreased by about 60 percent.

The research "illustrates the enormous advances in ophthalmology over the last 30 years," said Dr. James Tsai, chair of ophthalmology at Yale University School of Medicine in New Haven.

"People can regain vision right away after cataract surgery," he said. In other eye diseases, advanced treatments can stop or slow the progression of vision loss, he added.

As a result, "fewer people are going blind from diabetic retinopathy, glaucoma and macular degeneration," said Tsai, who was not involved in the new study.

In its report, Tanna's team noted that in addition to better therapies for eye diseases, "a more mundane contributing factor" may be the possible greater use of glasses and contact lenses or possibly even refractive surgery (such as Lasik).

Although study participants self-reported poor vision, which is less precise a measure of vision loss than a standardized eye exam, the survey findings reflect how the impairment affects daily lives, the authors remarked.

Future studies should further investigate what's behind the decrease in vision problems to identify the most effective strategies "to improve the health of the population and individuals' quality of life" they concluded.

SOURCE: bit.ly/N8PAVA Ophthalmology, online June 8, 2012.

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