What is the cornea?
The cornea is the clear tissue that covers the lens at the front of the eye and has three main layers. Light is transmitted into the eye through the cornea onto the light sensitive retina which sends nerve impulses to the brain that are then perceived as sight.
Corneal dystrophies, traumatic injury, severe infections, subsequent scarring and many diseases of the eye can lead to the cornea losing its ability to transmit light, causing impaired vision or blindness.
The cornea is privileged when compared to other organs and tissues of the body in that it does not have any blood supply. This isolation from the immune system allows corneas to be transplanted without the routine need for tissue matching with the recipient and the high risk of rejection as seen in other organ transplants.
What is a cornea graft/transplant?
If the cornea is damaged from disease or injury the eye can be repaired by removing the damaged cornea and transplanting a healthy cornea from a donor.
During the transplant, the defective cornea is replaced by an identical sized piece of healthy corneal tissue and is held in place with sutures that are painless and nearly invisible.
Grafts can be full thickness, which means they have replaced all three layers of the cornea or can be a partial thickness graft where they only replace the layers which are affected.
Generally the patient is awake and sedated for the procedure and can go home the same or the next day. The proceduce generally takes one to two hours.
The term graft and transplant seem to be interchangable.
What to expect during recovery?
Total cornea transplant recovery time can be up to a year or longer. Depending on the type of transplant you have, your vision may be blurry for the for the first few months while your eye gets used to its new cornea. In some cases your vision may not return until after all of the stitches are removed.
As your vision improves, you gradually will be able to return to your normal daily activities. Heavy exercise and lifting are prohibited until your eye has stabilised, this may be weeks or months. You should be able to return to work within a week after surgery, however, in some cases people do not return to work or school for six to 12 months depending on your job and how quickly your vision improves.
Steroid eye drops will be prescribed for several months to help your body accept the new corneal graft, as well as other medications to help control infection, discomfort and swelling. You should keep your eye protected at all times by wearing a shield or a pair of eyeglasses so that nothing inadvertently bumps or enters your eye.
If stitches were used in your surgery, they usually are removed three to 18 months post-surgery, depending on the health of your eye and the rate of healing. Adjustments can be made to the sutures surrounding the new corneal tissue to help reduce the amount of astigmatism resulting from an irregular eye surface. The curve of the new cornea is unlikely to exactly match the curve of your cornea so you will be left with a degree of myopia (nearsightedness) and astigmatism. The aim is to have vision corrected by glasses or contact lenses.
After your eye has fully healed and all stitches have been removed, you may be eligible to undergo laser eye surgery to remove any astigmatism.
As with any type of surgery, always follow the instructions of your eye surgeon to help minimize corneal transplant complications and expedite healing.
For a more detailed account of my recovery and what you might expect please refer to Medical Information sheet 2 - What to expect in the first month.
What type of graft did I have?
I had a full thickness lamellar graft. Generally people seem to get the middle of their cornea replaced, but as you can see from my cover photo, my graft is a banana shape and only the bottom part of my cornea was replaced. I have over 20 stitches in my eye which I can feel all the time.
My surgeon performed some additional work on my eye to help reshape it as the diseased cornea had caused my eye to droop.
Unfortunately I'm one of the unlucky ones who has to wait until the stitches are removed before I'll know if I have regained any sight. My recovery time is expected to be about 18 months. It will be 12 months before my first stitches are removed and then the remaining stitches will be removed at my doctors discretion over the next 2-3 months. It will then take up to three months for my eye to settle into place and get used to seeing through my new cornea. My graft was performed in April 2015, by December 2016 we will know how much sight I have regained.
I work in an office using a computer all day and found that the computer light burned my graft and the low vision from my 'good' eye wasn't very strong, so my Doctor has me working 20 hours per week for the first 12 months and it will be reviewed once we see how much vision I regain.
Cornea graft rejections
Cornea transplants are performed routinely and have a reasonable success rate. In fact, cornea grafts are the most successful of all tissue transplants.
Complications of a corneal transplant can be significant and can include cornea graft rejection, eye infection and problems associated with the use of stitches.
Rejection of the donor tissue is the most serious complication after a corneal transplant and occurs in 5 to 30 percent of patients. Transplant rejection is when your body's immune system detects the donor cornea as a foreign body and attacks and tries to destroy it.
Recognizing the main warning signs of corneal transplant rejection is the first step to preventing graft failure. These can be remembered using the acronym RSVP:
Extreme Sensitivity to light
Rejection signs may occur as early as one month or as late as several years after surgery. Your eye doctor will prescribe medication that can help reverse the rejection process. If detected early, the graft will be successful 9 out of 10 times, according to the Cornea Research Foundation of America.
Should your graft fail, corneal transplant surgery can be repeated. While repeat surgery generally has good outcomes, overall rejection rates increase with the number of corneal transplants you have.
History of cornea transplants
The first corneal transplant was performed in 1906, and it was only after the widespread availability of antibiotics in the 1950s which saw the establishment of eye banks. Until the 1960s, donated corneas were stored in moist chambers for up to two days. In the 1970s eye banks were able to store corneas for longer periods by keeping them in a liquid media, which contained basic nutrients and antibiotics and stored in a fridge at four degrees Celsius.
(Information sourced from Lions NSW Eye Bank Australia and AllAboutVision.com).
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Medical Info Information Sheet #1 2015