The increase was seen mostly in patients age 80 and up, and researchers say it's not clear what factors - related to the surgery or not - might explain the added risk.

A cataract is a clouding of the eye's lens, usually caused when proteins in the lens condense into clumps with age. Some studies, but not all, have suggested that cataract removal curbs older adults' risk of falls and bone breaks.

In the new study, researchers looked at records for more than 15,000 Australian adults who'd had a first-time cataract surgery.

Overall, 600 were hospitalized for a fall-related hip fracture or other injury - either during the year before or the year after the eye surgery. And the risk, it turned out, was greater in the year after.

There were 273 hospitalizations in the year before surgery, and 352 in the year after.

When the researchers accounted for some other factors - like a patient's age and other medical conditions - the risk of hospitalization was 27 percent higher in the year after cataract surgery.

The findings, reported in the Journal of the American Geriatrics Society, conflict with a U.S. study published just last month.

That study reviewed Medicare records for one million older Americans with cataracts. It found that those who had cataract surgery had a somewhat lower risk of breaking a bone in the following year, versus those who did not have surgery.

(See Reuters Health story of July 31, 2012 reut.rs/QtQx21).

But there are differences in the study groups that may help explain the conflicting findings, according to Lynn B. Meuleners, of Curtin University in Perth, Australia, who led the new study.

For one, she said in an email, her study looked at patients who'd had cataract surgery in only the "first eye." In Western Australia, where the study was done, people typically wait six months to a year to have their second eye treated, if needed.

Meuleners suspects that may be a factor in the higher fall risk after surgery. If people had "lopsided vision" after single-eye surgery, that might have made them more prone to falls.

"It may also have been due to wearing old glasses and having poor vision in the corrected eye because of the glasses, and poor vision in the other eye due to cataract," Meuleners explained.

"One would expect better vision if both eyes had successful cataract surgery in a short period of time - generally 2 to 6 weeks," Meuleners said. "Therefore, ‘both eye' patients may have lower risk of falls if vision is a risk factor."

The U.S. Medicare study, she noted, did not look separately at patients who'd had surgery in only one eye or had both eyes done with a short wait in between.

According to the U.S. National Eye Institute, the typical wait time between two cataract surgeries is four to eight weeks.

It seems logical that cataract surgery could prevent some fall-related injuries, since vision problems are considered a risk factor for older people's falls.

But so far, research findings have been mixed as to whether that's true.

One reason is that most studies, like the current one and the one in the U.S., have been observational. That means researchers look at medical records or self-reports from people who have undergone cataract surgery, or have not had it, and track their falls and injuries.

That approach has a number of limitations, though, and cannot prove whether cataract surgery, itself, affects the risk of falls and fractures.

Meuleners' team also lacked data on a number of factors that affect older people's fall risk - like their medication use, cognitive function and whether they had balance and mobility problems.

She said it's possible, for instance, that the surgery, or the sedatives used during the procedure, worsened certain health problems for some patients - especially the most elderly - noting that the post-surgery increase in fall risk was largely among patients age 80 and up.

All of those questions warrant further study, Meuleners said.

For now, she recommended that people having cataract surgery talk with their doctors.

"Elderly patients, in particular those 80 and up having ‘first eye' surgery, should discuss with their surgeon their visual aids requirements after surgery at the earliest possible time," Meuleners said.

She also suggested they discuss whether a sedative is necessary during surgery.

Then there is the question of when to have the second eye done, if needed.

"One would think that timely second eye surgery would be beneficial," Meuleners noted. "So careful consideration should be given to wanting (or needing) to postpone second eye surgery."

In the U.S., it's estimated that half of people who live to age 80 will develop cataracts or have cataract surgery. More than three million surgeries are done nationally every year, at a cost of $1,500 to $3,000 each.

SOURCE: bit.ly/NK5jNn Journal of the American Geriatrics Society, online August 6, 2012.

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