Uses for Donated Eye Tissue

Being an organ donor is a very worthy and noble act which can greatly enhance if not save the life of someone in need of an organ. As morbid as it may seem, human eyes are routinely “harvested” at the time of death for those with organ donor wishes.

Eye transplantation? Currently it is impossible to transplant an eye from one person to another for two main reasons. The first is rejection as the immune system of the patient receiving the eye will immediately perceive the donor eye as being a foreign body which must be attacked just as an invading bacteria, virus, or a sliver under your skin. The immune system acts as your body’s protector and there is no way to “rewrite” its programming. This is the same response as with other organ transplants in which the patient must have a genetically closely matching donor, preferably a blood relative. Medications to suppress the immune system must then be used ongoing to prevent rejection of the new tissues.  This can lead to increased susceptibility to various infections and other complications. The second and most difficult problem with transplanting an eye is the optic nerve which connects the eye to the brain and will be severed in the procedure. The optic nerve is central nervous tissue which, similar to your spine, cannot be repaired or reattached once severed.

Most individual tissues within the eye will have the same limitations. For example, your retina which is susceptible to retinal detachment, macular degeneration, and other diseases is also central nervous tissue which cannot be replaced with donor tissue.

So that leaves only tissues within the eye which have no blood supply (carries immune response) and no central nervous tissue which is limited to the clear front of the eye called the cornea. The cornea gets all of its oxygen from the air as blood vessels within the cornea would reduce its transparency and not allow light to enter the eye. Very beautiful and unique tissue in the body. The cornea also has only peripheral nerve endings (pain!) which can sometimes regenerate. Corneas are removed from donor eyes and frozen at the time of “passing.”  They are stored at a couple degrees above freezing and are viable for transplanting for up to two weeks.

The donated corneas are used most commonly for replacement of corneas damaged by trauma, scarring, infection or diseases of the cornea such as keratoconus  Fuch’s Dystrophy and other corneal disorders. A corneal transplant is an invasive procedure used only when the cornea is damaged or scarred to the point of severe vision loss. Recovery time for a corneal transplant can takes months or years and vision is rarely 20/20 even with corrective lenses. Although the cornea has no blood supply, the immune system is very smart and rejection rates for corneal transplants can be as high as 20%. New procedures (endothelial keratoplasty) involving transplantation of only the innermost layer of the cornea can be used in Fuch’s Dystrophy and offers a much better visual outcome but requires a very skilled surgical hand to perform the procedure.