While the majority of corneal transplants are given to adults, a considerable number of teens, children and even infants sometimes need to have the treatment but are replacement corneas suitable for younger eyes?
A team of Australian researchers, led by Dr Keryn Williams, tracked success rates and visual outcomes in 640 young transplant patients who received new corneas between 1985 and 2009. The results from the 25-year study were published in an issue of the Ophthalmology journal.
Dr Williams"s research group found that the highest rate of transplant success had occurred in adolescent patients treated for keratoconus. In recipients aged between 13 and 19, more than 85 per cent of transplants were carried out for this reason.
Keratoconus is a disorder of the cornea the clear, outer surface of the eye which focuses incoming light. It is said to affect one in 2,000 people in Britain and across the world.
A person who has the condition may at first notice symptoms during puberty, in their late teens or early 20s. Vision will usually become blurry or distorted, while the eyes themselves begin to feel irritated by bright light.
As the symptoms of keratoconus worsen, the cornea often becomes much thinner than normal and can eventually take on a cone-shaped appearance which makes seeing clearly near impossible.
Usually, both eyes will be affected often to varying degrees and in some cases the symptoms gradually get worse and worse for as many as ten or 20 years.
For most patients, surgery will only be considered where less intrusive treatments, such as glasses or contact lenses, have failed.
In Dr Williams"s study, the corrective procedure was considered successful if the young person"s vision was significantly improved and only if their new corneas remained healthy and functional for at least ten years after the operation.
Within this keratoconus subgroup, 75 per cent of adolescents achieved 20/40 vision or better, though some required glasses, contact lenses or vision-correcting surgery. But 90 per cent still had a healthy pair of corneas for their ten-year follow-up examination.
Dr Williams commented: "Vision improvement was substantial for children of all age groups in whom grafts succeeded and we can safely assume this had a significant positive impact on their social and educational development.
From the available pre-surgery vision records, we know that before their transplants most kids had 20/200 vision [defined as legally blind] and after surgery, 60 to 80 percent of them attained 20/40 or better and maintained this improvement for up to 15 years," she added.
The Australian scientists also tracked the outcomes for infants and older children. With a rather alarming success rate of just 50 per cent, the under-fives age group fared by far the worst.
Dr Williams and her team suggested that this may have been related to the illnesses that made the transplants necessary in the first place. Many of the infants had severe developmental disorders that it is thought may have had an impact on the outcomes of their surgery.
Youngsters aged between five and 12 received their corneal transplants for a whole host of reasons and enjoyed success rates that just about matched the adults treated for similar conditions.
However, less than 40 per cent of transplant patients in the infant age group had healthy and functional corneas when examined 16 years after their surgery. By contrast, around 70 per cent in the 5-12 years subgroup still had a working set of corneas 22 years post-transplant.
The researchers based their findings on data from the Australian Corneal Graft Registry. Since this information was collected from a huge number of surgeons and varied hospital settings, Dr Williams says that it gives a "real world" demonstration of transplant success.
by Alexa Kaczka