Medicine and medical procedures have developed in leaps and bounds. It is extraordinary how far we have come, even in the last few decades. For instance, transplants, which have been discussed and attempted for centuries, could almost be considered routine, with close to 47,000 transplants (lungs, kidneys, livers, hearts) performed in 2023.
Interestingly, what has yet to be performed with entirely successful outcomes is a transplant of a complete eyeball. The eye is an incredibly complex organ that is connected to the brain via the optic nerve. In order for us to see, the optic nerve sends signals from the eye to the brain, which then interprets these as images. The optic nerve, which is thin and small, measures about 3.3cm to 5.6cm long and contains more than a million tiny nerve fibres. If these fibres are damaged or cut (as in the case of a transplant), they cannot be reattached, so signals from a transplanted eye cannot be sent to the brain. While a whole eye transplant has been successfully performed in 2023 (on military veteran Aaron James), unfortunately, vision has not been restored.
However, it is possible to transplant parts of an eye. A corneal transplant is the most common, and it is necessary in cases where the cornea has been injured or damaged from a condition or disease. Greek physician Galen (130-200 AD) is said to be the first person to develop the concept of corneal transplantation; however, no reports of him actually attempting this have been found. The first successful human corneal transplant was performed over a century ago in 1905 by Eduard Zirm.
The other kinds of eye transplants include eyelash transplants, where lashes may be lost due to injury, burns, or other medical conditions, as well as eyelid and tear duct transplants. Doctors use part of a human placenta, the amniotic membrane, as a bandage to heal the sclera, conjunctiva, or cornea in amniotic membrane transplants. There is also the potential for treating conditions like age-related macular degeneration or Stargardt’s disease by replacing damaged retinal cells with healthy cells, grown using human stem cells.
With the incredibly high demand for donor corneas, scientists have been researching the use of animal corneas in human transplants. Pigs and sharks have been found to have corneas most similar to humans.
While there is no doubt that we are going to see great developments in the medical industry in the years to come, restoring or repairing sight is likely to be a significant focus of many scientists. For now, we’ll just have to wait and see.
