Long term effects of cataract eye surgery

23 April 2013

Research into cataract surgery has revealed the potentially damaging long-term effects of lens removal.

In New Zealand, cataract surgery is estimated to be performed at a cost of about $60 million a year. Due to an increasingly ageing population cataract surgeries have become the most common surgical procedure.

At the same time, an increase in life expectancy means there is a longer time in which damage to other eye tissues may happen after cataract surgery.

“It’s very important to consider the long term effects of lens removal on the health of other eye tissues,” says Sir Charles Hercus Health Research fellow Dr Julie Lim, from the Department of Optometry at The University of Auckland. She is working with doctoral researcher, Ankita Umapathy who has a University of Auckland doctoral scholarship and a Hope Foundation Scholarship.

“It is our hypothesis that cataract surgery may eliminate the lenticular glutathione (GSH) reservoir, causing a reduction in GSH availability to avascular tissues in the front of the eye,” she says. “This may increase their susceptibility to oxidative stress and the incidence of subsequent eye diseases.”

“We propose that the lens, by acting as a GSH reservoir, is part of an integrated system to protect eye tissues from oxidative damage and the removal of this source of GSH will increase the exposure of eye tissues to oxidative stress,” she says.   “

This will result in a higher incidence of ocular damage and vision loss in cataract patients than presently seen today,” says Dr Lim.  “Given the large increases in cataract patient numbers the resultant eye diseases will invariably create a heavy burden on the hospital systems and economy.”

“There is growing evidence that persistent damage to tissues of the eye can occur several years after removal of the lens during cataract surgery.”

“It follows that providing an extra source of GSH after cataract surgery may provide a long term solution to maintaining eye health in the elderly,” says Dr Lim.

Experiments now underway will determine whether the lens normally supplies GSH to other tissues of the eye. Depending on the outcome of those experiments, they will then investigate whether GSH supplementation after surgery would be beneficial or not.  If it is, then GSH could be added during surgery via eye drops.

“It may be that after cataract surgery to protect long term eye health, GSH eye drops could be administered daily, for example to help protect vulnerable eye tissues from oxidative damage,” says Dr Lim.

Age-related eye diseases such as macular degeneration, cataract and glaucoma are the leading causes of blindness worldwide. An increasingly aging population means the incidence of these diseases is expected to escalate.

Eye tissues are constantly exposed to irradiation and high metabolic activity that require them to possess high levels of antioxidant protection, says Ankita Umapathy.  As people age their natural internal antioxidants such as GSH decline making tissues in the front of the eye vulnerable to oxidative stress.

“Of all the eye tissues, the lens has the highest concentration of GSH, at higher levels than even those found in the kidney and liver (which are traditionally thought to be actively involved in setting circulating GSH levels in the plasma).”

Like the liver and kidney, the lens is thought to serve as a reservoir of GSH for the anterior tissues of the eye such as the cornea, says Ms Umapathy.

For more information contact:

Suzi Phillips Media Relations Advisor The University of Auckland s.phillips@auckland.ac.nz Mob 021 416 396 Phone +64 9 373 7599 ext 87383