A corneal transplant is a surgical procedure that replaces the cornea or part of the cornea with corneal tissue from a donor eye. This is done usually when some type of corneal failure has occurred.
Some types of corneal transplants include penetrating keratoplasty (traditional), DSAEK, and DALK. It should be noted that sometimes even after a corneal transplant, good vision may be limited if there has been severe scarring or if the body rejects the transplant.
DSAEK is a partial thickness corneal transplant procedure in which only the diseased inner cell layer of the cornea is replaced. The inner layer of the cornea is lined by cells (endothelium) that serve to pump fluid out of the cornea and keep it clear and thin. These cells can be damaged by prior surgery, inflammation, or by a condition known as Fuchs’ Dystrophy. As endothelial function declines the cornea swells and becomes cloudy, decreasing vision. If swelling becomes severe, blisters (bullae) can develop on the cornea and cause pain and infection. As these conditions progress, surgery is often required to help with pain or improve vision.
Compared to full thickness corneal transplants, there are many advantages to DSAEK. Since 95% of the corneal structure is unchanged, patients tend to have much less astigmatism and a much stronger cornea. Healing usually takes a few weeks and is much quicker than healing of a full thickness transplant.
Occasionally the donor tissue comes loose and requires repositioning and the placement of a second air bubble. Once the graft has been attached for a few days, there is no risk of dislocation at a later point. In some patients with severe corneal swelling, scarring is present that may limit best possible vision even though the swelling resolves.
The corneal specialist measures your eye and the donor cornea tissue is cut to the appropriate size for your eye. A small incision is made in your cornea (much like cataract surgery) and the diseased endothelial cell layer is carefully removed. The donor tissue is then introduced into the eye and an air bubble is used to apply it to the back of the cornea. The air bubble remains for 1-2 days helping to keep the donor tissue in place. Surgery generally takes less than 30 minutes and you are able to return home. A protective eye shield is kept in place until Dr. Foster sees you the next day.
Initially the vision will be quite blurry but will clear over the first several weeks. The eye may be red, sore, light-sensitive, and watery for the first week or two after surgery. During the first 24 hours after surgery, Dr. Foster will ask you to keep your eye looking at the ceiling as much as possible to help graft adherence. It is also very important not to rub or touch the eye for the first few weeks.
Steroid eye drops are used to help the eye heal after surgery and prevent graft rejection for the long term. The risk of graft rejection is typically 5% or less but is high enough that long-term drops (usually once a day) are required. Dr. Foster will keep a close watch over your healing process and will customize an anti-rejection regimen appropriate for you.
With a traditional, ‘full thickness’ corneal transplant surgery, a circular portion is removed from the center of the diseased cornea. A matching circular area is removed from the center of a healthy, clear donor cornea, and is then sutured into place, replacing the diseased one. With the advancement of DSAEK corneal transplant, the treatment has now gone from close to a year recovery to about a six-week recovery with the newer techniques
There are several common conditions that affect the most superficial layer of corneal cells, the epithelium. These conditions include recurrent corneal erosion (RCE), band keratopathy, Salzmann’s nodular degeneration and epithelial basement membrane dystrophy (EBMD). These conditions can interfere with vision and even cause significant pain and gritty sensation, due to a rough and irregular ocular surface.
If ocular lubricants fail to improve the pain or vision, a procedure known as Lamellar Keratectomy or LK can be beneficial. The Eye Associates is one of the few practices in the country skilled in Deep Anterior Lamellar Keratoplasty or DALK.
During the procedure, the surgeon anesthetizes the eye with drops or ointment removes then removes the top 95% of the cornea and replaces it with healthy donor tissue. Patients keep their own healthy endothelial cells and the eye maintains greater strength with a lower risk of rejection than ‘full thickness’ transplants. A soft contact lens is placed that minimizes discomfort after the procedure. This remains in place until it is removed by the corneal surgeon. In a few days, a stronger, healthier cell layer will replace that which was removed. Some scratchiness and irritation is normal for a few days after the procedure until the surface has healed.
Many keratoconus patients are candidates for this modern corneal transplant technique because the inner layer of corneal cells (endothelium) is healthy.
Even with these modern techniques, a transplanted cornea heals slowly. It can take up to a year for good vision after corneal transplantation. While a corneal transplant will relieve the symptoms of keratoconus, it may not provide you with flawless vision and often rigid contact lenses are still required to see your best. However, of all conditions requiring corneal transplants, keratoconus has the best prognosis for clear vision.
Today’s patients are benefiting from research and an expanded set of tools for treating difficult conditions, and the use of amniotic membrane tissue is a good example of that. The innate healing properties of the tissue make it ideal for faster healing and tissue regeneration. It is especially helpful in the treatment of corneal diseases and degeneration. The amniotic membrane contains specialized proteins and growth factors that diminish inflammation, prevent drying, aid tear stability and accelerate healing.
Eyes treated this way usually experience less pain, less inflammation, less scarring and heal more quickly. Some of the eye conditions that we treat with the tissue are chemical burns, pterygiums, conjunctivochalasis, corneal defects, and dry eyes, just to name a few.
It is the part of the placenta that protects the baby with its natural therapeutic properties. The tissue is donated by consenting mothers after cesarean section births. The mothers have been tested for health issues prior to donation, and have made an informed decision to help others. The tissue bank is regulated by the FDA and quality control testing.
AmbioDisk™ is a sutureless, dehydrated amniotic membrane allograft utilized for the safe and effective treatment of ocular surface diseases and disorders in the office setting. 5-year shelf life with simple room temperature storage.
PROKERA® is made by clipping a piece of amniotic membrane tissue in between two rings made out of a clear, flexible material.