A corneal transplant is a routine surgical procedure that replaces a damaged cornea with a healthy one from a donor.
The cornea is the thin, transparent membrane that sits in front of the iris and pupil of the eye. The cornea allows a person to see by focusing light that enters the eye.
Corneal disease is one of the leading causes of blindness in the world.
In 2014, more than 47,000 people in the United States had corneal transplant surgery.
This article outlines some of the reasons people may need a corneal transplant. We also discuss the different surgical procedures and what people can expect from the surgery.
A corneal transplant is a surgical procedure that involves removing all or part of a damaged cornea and replacing it with healthy corneal tissue from a donor.
The type of corneal transplant a person receives will depend on which layer of the cornea is damaged, as well as the extent of the damage.
The cornea consists of five layers:
- The epithelium: This is the outermost layer of the cornea. It helps to protect the cornea and focus light.
- Bowman’s layer: A very thin layer that sits between the epithelium and the stroma.
- Stroma: This layer helps to strengthen the cornea.
- Descemet’s membrane: A very thin layer that separates the stroma from the endothelium.
- Endothelium: The innermost layer of the cornea. Cells in this layer work as a pump to drain fluid out of the stroma.
The ultimate aim of corneal surgery is to improve a person’s sight or alleviate eye pain.
Injuries to the cornea may be minor or severe. Minor injuries, such as small scratches, usually heal on their own. However, deeper injuries can cause scarring and problems with vision.
A surgeon may perform corneal surgery to treat severe corneal injuries or corneal dystrophies.
Corneal dystrophies are eye diseases that affect the cornea.
Treating corneal dystrophies
Examples of corneal dystrophies include:
Keratoconus is a disease that causes thinning and bulging of the cornea.
In keratoconus, the cornea becomes cone shaped and no longer focuses light correctly. This can cause a person’s vision to become blurred or distorted.
Usually, prescription glasses or contact lenses can treat keratoconus. However, some people may require surgery to correct vision problems.
Keratoconus typically begins developing when a person is in their late teens or early 20s.
Fuchs’ dystrophy is a disease that causes the endothelial cells in the innermost layer of the cornea to degenerate. As the cells degenerate, they become less efficient at pumping fluid out of the cornea. The cornea then swells and thickens, causing vision to become cloudy or hazy.
According to the American Academy of Ophthalmology (AAO), Fuchs’ dystrophy may develop in a person’s 30s or 40s. However, a person may not experience vision problems until their 50s or beyond.
Lattice dystrophy and map-dot fingerprint dystrophy
Lattice dystrophy (LD) and map-dot fingerprint dystrophy (MDFD) are two different types of corneal dystrophy that can cause corneal erosion. This is where the epithelial cells in the outermost layer of the cornea detach from the Bowman’s layer, below.
According to the AAO, corneal erosion is a painful condition that can result in blurred or hazy vision.
A person will meet with their surgeon prior to the corneal transplant surgery.
During this consultation, the surgeon will conduct an eye examination. They will also want to discuss the person’s medical history, including any medications they are taking.
In some cases, a surgeon may suggest stopping or reducing certain medications before the surgery.
People should arrange for a friend or family member to collect them from the hospital on the day of the surgery.
A person will not be able to drive immediately following corneal transplant surgery, as it may affect their vision. They can also be groggy from general anesthesia.
The most common type of corneal transplant is a keratoplasty. There are two types of keratoplasty procedure, namely, penetrating keratoplasty or endothelial keratoplasty.
Either keratoplasty procedure may involve general anesthesia or local anesthesia. If a person has a procedure under local anesthesia, their surgeon will also provide a sedative to help them relax.
A penetrating keratoplasty (PK) is a procedure that replaces all layers of the cornea.
The surgeon will begin by opening up the eyelids to expose the eye. They will then use stitches or a device called a scleral fixation ring to prevent the eye from moving during the procedure.
The surgeon measures the person’s cornea to determine the appropriate size of the donor’s corneal button. The corneal button is the tissue that will replace the recipient’s cornea.
The surgeon will sew the donor’s corneal button onto the recipient’s eye. They will then cover the eye with a pad or plastic shield.
Descemet’s membrane endothelial keratoplasty
A Descemet’s membrane endothelial keratoplasty (DMEK) is one of several types of endothelial keratoplasties.
A DMEK replaces the endothelium of the cornea. Again, the surgeon may use stitches or a scleral fixation ring to prevent eye movement.
The surgeon makes several incisions in the person’s cornea. They then remove the failing endothelium and the attached Descemet’s membrane (DM), leaving the healthy layers of the cornea intact.
The surgeon removes the innermost layers of the donor’s corneal tissue, taking only the healthy endothelium and its attached DM.
Next, the surgeon inserts these layers beneath the healthy layers of the recipient’s cornea through the incisions they made earlier.
The surgeon will inject a bubble of sulfur hexafluoride into the incision site. This is to make sure that the donor’s Descemet’s membrane sticks to the recipient’s eye.
Corneal transplants are an outpatient surgery, which means people can go home the same day as their surgery. They will need to arrange transport to and from the hospital, as they cannot drive themselves home after the surgery.
People may receive general anesthesia to put them to sleep for the duration of the surgery.
Otherwise, surgeons will inject local anesthesia into the eye. This means that a person will be awake for the surgery but will not feel pain.
People will also receive sedatives while under local anesthetic, which will help them to relax.
Doctors will ask for a follow-up appointment the day after the surgery to check how the eye is healing.
Following surgery, a person should follow their doctor’s advice regarding caring for the eye at home. This will include:
- using the eye drops their doctor prescribes
- avoiding rubbing or putting pressure on the eye
- keeping the eye covered
Recovery time is dependent on the type of transplant procedure. It can take up to 1 year for the eye to fully recover.
A doctor will be able to advise on when a person can resume their normal activities.
According to a report by the Healthcare Costs and Utilization Project (HCUP), in 2007, the average cost of an outpatient corneal transplant procedure was $13.119. A doctor or surgeon will be able to provide the latest costs and figures.
Costs may vary according to:
- the state or hospital where the procedure occurs
- the type of health insurance a person has
- the doctor who performs the surgery
Every surgery carries risks of complications. Some of the potential complications are below:
The most dangerous complication of corneal transplant surgery is tissue rejection. This complication arises if the body identifies the donor cornea as a foreign object and tries to get rid of it.
It is important to seek medical attention immediately if any symptoms of tissue rejection occur. These symptoms include:
- eye pain
- sensitivity to light
- red eyes
- cloudy or hazy vision
Below are some factors that could increase the risk of tissue rejection.
The donor cornea
The main factors that affect donor tissue rejection are human leukocyte antigen (HLA) incompatibilities and blood type incompatibilities.
HLAs are a set of proteins in the body that regulate the immune system.
The type of antigens and antibodies that make up a person’s blood determine their blood type.
If the donor HLA or blood type is incompatible with those of the recipient, the recipient is more likely to reject the donor tissue.
Health of the recipient
Certain preexisting conditions can increase a person’s risk of an immune reaction. Some of these conditions include:
- herpes keratitis, which is a viral infection of the eye
- uveitis, or inflammation of the structures in the middle of the eye
- atopic dermatitis, which is a chronic inflammatory skin condition
Age of the recipient
According to a 2017 review, younger people are more likely to reject a corneal transplant, compared to older people. This is partly due to the fact that younger people tend to have more robust immune responses.
Other complications that may occur following a corneal transplant include:
The above conditions can result in long-term damage if a person does not seek treatment. They should contact a doctor immediately if they experience pain, vision problems, or other concerning symptoms following a corneal transplant.
A doctor may treat surgical complications with medication or further surgery.
Corneal transplants are usually very successful. A 2017 review notes that 70% of people who have this surgery have a functioning cornea 5 years later. This success rate drops to 50% after 15 years.
To increase the success rate of a corneal transplant, people should follow the advice of their healthcare team.
A person may need a corneal transplant to help restore their sight following a corneal injury or disease. A corneal transplant involves replacing all or part of the damaged cornea with corneal tissue from a donor.
There are a number of complications that can arise as a result of a corneal transplant. The most common complication is tissue rejection. Other complications include infection, retinal detachment, and glaucoma.
People should see a doctor immediately if they develop concerning symptoms following a corneal transplant. If complications arise, a doctor may need to prescribe medicine or schedule follow-up surgery.