For many, the thought of a deceased partner, child or sibling having their eyes removed for donation is disturbing. Yet for those in need of a corneal transplant, this gift of sight provides a new chance to live a fulfilled life. Optometrists are in a powerful position to diffuse the fears surrounding eye donations and encourage greater support for eye banking.
Each year around the world, the quantum of eyes collected from people who have died outnumbers all of the other organs and tissues collected from deceased people for transplantation purposes.
Yet still more are needed because similarly, the number of corneal transplants performed each year exceeds the number of other transplants that use donated tissues or organs from deceased individuals.
In Australia and New Zealand alone, approximately 1,800 corneal transplants are performed each year. Success rates – at about 95 per cent – are high and many transplants will last for up to 20 years.
Each year around the world, the quantum of eyes collected from people who have died outnumbers all of the other organs and tissues collected from deceased people for transplantation purposes…
There are even stories of people who’ve had their transplant for more than 30 years. Apparently one young girl with keratoconus had a corneal transplant back in 1952. While it’s difficult to determine the absolute truth, the donor was reportedly in their 80s. That cornea didn’t fail until 2005 – so the cornea was about 130 years old.
The primary reason for corneal transplantation in Australia and New Zealand is keratoconus – the degenerative disease, which causes the cornea to thin and change in shape. As a result, sufferers experience distorted vision, multiple images, streaking and sensitivity to light.
Bullous keratopathy, which occurs as a result of cataract surgery is another common reason for corneal transplant. However, with the arrival of new surgical procedures, such as phaco-emulsification, this disease has reduced.
Various inherited dystrophies, such as Fuch’s, as well as penetrating eye diseases caused by trauma, can also eventually require corneal transplants.
Giving The Gift of Life
While patients waiting on corneal transplants do not face the same life threatening conditions as those waiting on transplants for a liver, heart or kidney, the day-to-day challenges can be immense. For those who are well progressed in the disease process – seeing less than 6/60, or with only a perception of light – the ability to work, live independently and enjoy quality of life is eroded.
However, thanks to modern transplant procedures, a transplant can restore vision to 6.9.66, and in doing so, lift the burden for the individual, family, friends and the health system at large.
Demand Continues
With so many corneal transplants required every year, Graeme Pollock, Director of the Lions Eye Donation Service at the Centre for Eye Research (CERA), says there is a constant need to find more donors.
“We are fortunate to have adequate supplies of corneas to fulfil scheduled surgical procedures across Australia and New Zealand, but with such a high demand for corneal transplants each year, it doesn’t take much to change the balance. The need for donors is ever present,” he said.
Dr. Pollock said that generally all corneal transplantations are done on a scheduled surgery basis and about 95 per cent of surgeries go ahead because there is a cornea available. Impressively and thanks to the availability of donor corneas, in the past 25 years, every emergency corneal procedure in Australia has been completed within 24-48 hours.
More Donations Needed
While Australia is far from being a world leader when it comes to donating organs for transplant, we are one of the top countries in the world for transplant surgery and for the quality of life achieved post transplant. Fortunately for those who require a corneal donation, we tend to donate more eyes than any other organ.
Dr. Pollock says the reason we have a good eye donation rate is simply because medically, there are less complications and restrictions for donor eyes, compared with other organs or tissues.
“The medical exclusion criteria and the circumstances in which you die is much, much wider for eye donors. For example, with organ donation, only people who die in an intensive care unit can donate organs. Of those, only a small proportion will meet the necessary criteria – due to their disease or circumstances of their death.
“With eyes, it generally doesn’t matter what circumstances the donor dies in –
a car accident, cancer… the eyes can still be donated.
Overcoming Donor Resistance
With that in mind, it’s hard to imagine why we don’t have even more eyes to donate. After all, in the U.S.A., 25 per cent of all donated corneas are given to other countries, such as India, where the needs are vast.
Dr. Pollock says its all about perception – some people may be reluctant to donate or agree to their family members donating eyes because the concept of eyes being removed from a loved one is more confronting than the concept of other organs or tissues being removed.
“It’s much easier for people to imagine what people look like without eyes. But the reality doesn’t match the imagination… When you donate your eyes, your eyelids are shut – so from an external point of view, there is no change.”
In fact of all donations, eyes are the ones you are least likely to notice. “Eye donation is the only organ or tissue donation that does not require a skin incision – nothing needs to be sewn up,” said Dr. Pollock.
With sophisticated storage techniques, some of the eye banks in Australia and New Zealand are now able to keep donated eyes for up to four weeks. This enables them to be transported around the country and even across the Tasman to meet fluctuating demand.
Regulatory Implications
While supply is a small problem for the Eye Bank, one of the greatest issues that impacts its ability to meet demand and invest in development is government regulation. Dr. Pollock estimates that one third of the Bank’s expenses are related to meeting regulations.
In Australia and New Zealand, eye and tissue banking is subject to the same regulatory and reporting processes as those faced by large pharmaceuticals. The difference, Dr. Pollock says, is that those pharmaceutical companies are large and able to make a profit from their operations. That profit can be used to further research and remunerate stakeholders. Eye and tissue banking is not for profit. Continued research, development, donation, storage and distribution of eyes for transplant purposes rely on continued government funding and public donations.
“The expenses involved in the regulatory process are extraordinarily high and the number of man hours devoted to meeting regulations high as well…
“In my opinion, you need regulations and standards, but you need a proper, scaled approach based on scientific evidence and scaled according to risk. For eyes in particular, the risk is miniscule.”
He estimates that one eye costs the eye bank AUD$2,000 to handle. By the time hospitals, surgery and materials are taken into account, the cost of a corneal transplant is in the vicinity of AUD$10,000.
Success is High
Straightforward corneal transplants to treat diseases such as keratoconus usually achieve a 90 per cent success rate after one year and an 80 per cent success rate five years later. However treatments for more complex conditions, such as trauma or Fuch’s dystrophy, can be less successful. For example, after five years, the success rate in patients who have had transplants as a result of alkali burns, stands at only 25 per cent.
“One of the reasons that the cornea was the first form of transplant over 100 years ago, was because the cornea is immunoprivileged – which means it doesn’t reject in the same way other organs do,” said Dr. Pollock.
“However, as soon as you have a lot of inflammation – or blood vessels across the cornea – the risks of rejection can be high.
Dr. Pollock said the problem for scientists is that because there is no blood supply to the cornea, corneal rejection doesn’t fit models of other organ rejection. Consequently, available immunosuppressants are not as effective on the cornea as they are on other organs.
New Possibilities for at Risk Transplants
However new technologies and procedures are opening doors for patients at greater risk.
“While straightforward corneal transplants for keratoconus don’t require tissue typing, research has shown that transplants that involve inflammation may be more successful when tissues are appropriately and accurately matched,” said Dr. Pollock.
“The ability to store donated eyes for up to four weeks and new Polymerase Chain Reaction (PCR) technology that enables much more accurate tissue typing will give us the capabilities and time required to match tissues.”
New surgical procedures are also being performed on patients with diseases in
the posterior section of the eye.
“The donor cornea is cut down to 150 microns which contains the endothelial cells… similar to a cataract operation, the surgeon goes in sideways to remove the diseased layer. Instead of transplanting the whole thickness of the cornea, they simply transplant a tiny layer and it goes to work,” said Dr. Pollock.
While the procedure is more difficult than a standard corneal transplant, according to surgeons in the United States, vision is better because it is a thinner graft.1
At the same time, research continues into stem cell therapies that could one day obviate the need for corneal transplants.
“Research is being done here at CERA and there are exciting prospects – all the cells that constitute a cornea can be grown in vitro,” said Dr. Pollock.
“However, some of the issues include the ability to grow them reliably in good numbers and also the delivery mechanism – how do you get a mono layer of cells grown in a lab onto the cornea, and get them to continue to grow? So, yes, that technology is running along, the whole area of bioengineering continues to gallop ahead… but I hesitate to put any time frame on that. And, even if it gets to the point where we are able to grow corneas, you still have the issue that somewhere along the line, someone needs to donate.”
Reference
1. www.alancarlsonmd.com/helping-patients-understand-recent-advances-in-corneal-transplantatio
