Washington, Nov 16 (IANS): A donor's age may have no impact on the outcome of corneal transplants, a study in the US journal Ophthalmology said Friday.

Corneas from 71-year-old donors are likely to remain as healthy as those from donors half that age 10 years after their transplant, Xinhua cited from the study, funded by the US National Institute of Health (NIH).

The study of 663 participants found that the transplant success rates for corneas from donors aged 12 to 65 and aged 66 to 75 after 10 years was similar at 77 percent and 71 percent respectively.

However, when the investigators separated the donors into smaller age groups they found some differences.

The success rate remained steady at 75 percent for the vast majority of donors aged 34 to 71. But it increased to 96 percent for donors aged 12 to 33 and decreased to 62 percent for donors aged 72 to 75.

Surgeons often seek the youngest corneal tissue available regardless of patient age.

Historically, some surgeons set extremely restrictive upper age limits, the NIH said in a statement, adding that when the study began in 2000 many surgeons would not accept corneas from donors over 65.

"Our study supports continued expansion of the corneal donor pool beyond age 65," said study co-chair Edward Holland, professor of ophthalmology at the University of Cincinnati.

"We found that transplant success rates were similar across a broad range of donor ages," said Holland, who is the director of the Cornea Service at the Cincinnati Eye Institute.

The cornea is the clear window that allows light into the eye and helps focus it. Scarring, swelling or other damage to the cornea can lead to blurred vision. Such damage can occur after injuries or infections, from inherited conditions, or as a complication of cataract surgery.

A corneal transplant is performed when decreased vision or discomfort from corneal damage cannot be corrected with lenses or medication. It involves removing a portion of the damaged cornea and grafting corneal tissue from a deceased donor in its place.

More than 46,000 corneal transplants were performed in the US last year, the NIH said.

In addition, eye banks in the US exported about 20,000 corneas to other countries in 2012, an increase of 7 percent over 2011.