Donor Corneas: How Old is Too Old?

Tissue transparency is the top feature that distinguishes the eye from other anatomic organs. In the healthy eye the central retina (macula) receives crisply focused light rays transmitted through the clear vitreous, that passed through the clear lens, that had crossed the watery aqueous inside the anterior chamber, that originally entered the eye through the transparent cornea. So, anything that clouds the visual pathway interferes with good eyesight.

Think of the cornea like the windshield of the car. It is a transparent barrier that blocks the wind and filters the oncoming light. If the windshield is dirty, scratched or cracked the driver will have significant problems operating the car due to poor visibility, right? And so it is with the cornea, a very efficient mechanical and optical barrier. Swelling, scarring or other changes to the cornea lead to profound vision changes.

Depending on the diagnosis the eye surgeon may recommend corneal transplantation. The medical term is penetrating keratoplasty. The diseased, cloudy cornea is replaced with healthy, transparent cornea. Nearly 40,000 such procedures are performed every year in America.

Just like heart transplants, donor corneas come from cadavers. The majority are harvested from the local medical examiner's morgue, typically from young people who died from non-natural causes (motor vehicle fatalities, shootings, accidents, etc.) It appears intuitive that younger eyes would make for better donor tissue - but new research refutes that notion.

In a published series of 1000 corneal transplant procedures patients (all 60 years and older) were divided into two groups: those with donor corneas aged 12-65 years and donor corneas older than 65.

So, did donor age make a difference? After five years both groups had similar favorable outcomes - 86% successful transplantation.

Now, let's turn the tables.

Note that in this study all of the recipients were seniors, so most won't need a replacement cornea to last more than 20 years or so. On the other hand, a 30-year-old cornea transplant recipient will need a graft that can survive 50+ years. How would they do receiving the cornea from a 75-year-old donor? We don't know that answer today, but some experts suggest that so long as the donor cornea is healthy age should not matter. More studies will be needed to test that theory.

REFERENCE: Ophthalmology April 2008, pages 620-626.

Related Topics:

• WebMD Video: Corneal Transplant Surgery
• Decide NOW to be an Eye Donor

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