Does an Eye Transplant Replace the Whole Eye?
With over 37 million people around the world suffering irreversible vision loss, being able to transplant an entire eye to a new person seems like a great solution.
Although eye transplants are performed, this procedure does not involve the entire eye. Instead, there are parts of the eye that can safely be transplanted to a different person, and most eye transplants are actually corneal transplants.
Whole-eye transplants (WET) are both experimental and controversial, but medical researchers are working on this technology.
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Millions of people around the world suffer vision loss that is irreversible, so eye doctors have worked to replace parts of the eye for centuries. While whole-eye transplants are currently not feasible, some parts of the eye can be successfully replaced with donor tissue. (Learn More)
Corneal transplants are the most common and successful form of eye tissue transplant. When someone refers to an eye transplant, they usually mean corneal transplant. (Learn More) However, there are some other types of eye tissue transplants, a few of which are still in development. (Learn More)
Thanks to advances in organ donation and transplantation, the understanding of eye transplants is improving. Researchers hopes that whole eye transplant will become feasible in a decade. (Learn More)
Like any surgery, there are risks to eye tissue transplants, but these forms of surgery, particularly corneal transplants, can be life-changing for the recipient. (Learn More)
What Is a Corneal Transplant?
Corneal transplants are the most common form of transplant to improve vision. This form of surgery has been performed for more than a century, and it has a great record for success.
The cornea is the clear tissue on the front of your eye, over your pupil. It is necessary for clear vision, and if it becomes misshapen, damaged, or cloudy, you will not be able to see well. During a cornea transplant, a donor cornea that is clear replaces an unhealthy cornea.
- Penetrating keratoplasty (PK): This is the older form of corneal transplant, but it works well and is still performed often. During the transplant, you will most likely be awake with local anesthesia. Your doctor will remove a small piece of your cornea, and the donated tissue will replace what was removed, then sutured or stitched into place.
- Lamellar keratoplasty (LK): With LK, the inner and outer layers of the cornea are replaced rather than all layers as with PK. There are a few different techniques used in LK, which depend on how the donor tissue is prepared. All approaches to LK have a faster recovery time and fewer complications after the operation.
At your follow-up visit, your eye doctor will remove stitches if they are present and examine your eye for any potential complications.
Full recovery and vision return take about a year because it takes a long time for new tissues to integrate with your eye and for the swelling in the area to go down. You may still need glasses, contact lenses, or a laser surgery like LASIK to change refractive errors, but you will be able to see clearly thanks to the new cornea.
There are risks to both forms of cornea transplant. The main complication would be rejection of donor tissue. Your doctor may prescribe drugs to ease the body into working with this new tissue.
The following are other risks associated with corneal transplants:
- Infection in the eye
- Glaucoma, or high eye pressure that leads to retinal damage
- Loss of vision
- Scarring on the surface of the eye that clouds vision
- Swelling of the cornea
Other Eye Transplant Surgeries
Other types of eye transplant procedures, some of which are still in the early stages, include:
- Amniotic Membrane Transplantation (AMT). This is a well-established surgery. The amniotic membrane is replaced to treat problems affecting the sclera, the outer layer or “white” of the eye, and the conjunctiva, the clear tissue covering the white part of the eye.
- Eyelash transplants. Eyelashes do not need to be long to be effective, but they are an important part of the eye’s overall system, helping to maintain the microbiome. If eyelashes are lost due to injury, burns, medical conditions, or radiation treatment, they can be replaced with transplant surgery.
- Tear duct replacement. This procedure is still in its early phases, but in 2010, French eye surgeons transplanted eyelids with tear ducts as part of a full-face transplant. Eyelids with tear ducts have also been part of other transplants in the past few years. For people who suffer problems with clogged or insufficient tear ducts, this transplant could change how their eyes manage moisture.
- Retinal pigment epithelium transplant. Some early retinal cell testing has been very successful. In clinical trials, researchers have used human stem cells to create retinal pigment epithelial (RPE) cells, which can be beneficial for those suffering from macular degeneration or other conditions that involve degradation and loss of cells in the retina.
Whole Eye Transplant Is Still Experimental
According to the National Eye Institute (NEI) in 1977, the difficulties presented by transplanting the entire eye included:
- Keeping proper blood circulation in the transplanted eye during and after the operation.
- Immune system rejection of foreign tissue.
- Cutting the optical nerve and incorporating that into another person’s optic nerve.
As surgery techniques improve, the first two issues are being managed in different ways in different organ transplants. Nerve regeneration techniques are becoming more available to assist with connecting a new optic nerve.
In 2016, a team of surgeons aimed to perform a whole eye transplant, but studies conducted on laboratory mice and other animals found that cell growth was an important issue. Essentially, convincing cells not to die off completely and to regenerate when they were placed in a new environment was the crux of the problem.
While a WET has still not been conducted successfully yet, there is hope that within a decade, this technology will become possible.
Eye Surgery Success and Risks
Most vision loss is associated with age. Cataracts, macular degeneration, diabetic retinopathy, and glaucoma are all associated with being at least 40 years old and progressing to vision loss between 60 and 70 years old. Because older adults are more likely to have progressive vision loss, surgery is riskier because that age group does not heal as fast from procedures and will have more complications with anesthesia.
Corneal transplants tend to have a high rate of success. Other forms of eye transplant are still newer and experimental, so their rates of success are not well-known.
As with any surgery, there are risks of complications later, but many people benefit from corneal transplants.
Ethical Considerations for Whole-Eye Transplantation. (2016). Journal of Clinical Ethics.
What Parts of the Eye Can Be Transplanted? (April 3, 2018). American Academy of Ophthalmology (AAO).
Corneal Transplant. (August 28, 2018). MedlinePlus.
Sclera. (March 28, 2016). American Academy of Ophthalmology (AAO).
Conjunctiva. (March 28, 2016). American Academy of Ophthalmology (AAO).
An Audacious Vision: Researchers Aim for the First Human Eye Transplant Within the Decade. (November 23, 2016). STAT: Health.