Cornea & External Disease
What is Corneal Dystrophy?
Corneal dystrophy is an inherited eye condition that affects the delicate inner layer of the cornea called the endothelium. The endothelium functions as a pump-like mechanism which constantly removes fluids from the cornea to maintain clarity of vision. Gradually over time, patients with corneal dystrophy lose these endothelial cells. Once lost, they do not grow back. Instead, the remaining cells begin to spread out to fill in the empty spaces. The pump becomes less efficient causing the cornea to swell and cloud over reducing visual acuity.
What Causes Corneal Dystrophy?
Slightly more common in women than men, corneal dystrophy often develops between the ages of 30 and 40 and is an inherited condition which can be controlled but not cured. It typically affects both eyes.
What are the Symptoms?
Common symptoms include hazy vision that is often more noticeable in the morning, fluctuating vision, glare, light sensitivity and a sandy, gritty sensation in the eyes.
How is Corneal Dystrophy Diagnosed?
Corneal dystrophy is detected by examining the cornea with a slit lamp microscope which magnifies the endothelial cells thousands of times. The ongoing progression of the disorder is monitored with pachymetry testing to measure the thickness of the cornea. Specular microscopy is also used to monitor the number, density and quality of the endothelial cells.
What are the Treatment Options?
Medications are used to control blurred vision that results from corneal swelling. Salt solutions in the form of drops and ointments are also prescribed to draw fluid from the cornea and reduce swelling and improve vision. Surgical intervention is indicated when the vision deteriorates to the point that ability to function normally is impaired. At this point, a corneal transplant may be indicated.
Patients whose cornea has become cloudy because of disease may be able to regain useful vision with a corneal transplant (keratoplasty). Corneal transplant is the most successful of all tissue transplants that are available in the United States.
The corneal tissue needed for a transplant is usually readily available through an Eye Bank because of advances in Eye Banking Technology. All corneal tissue for transplant is tested thoroughly to make sure it is safe for transplantation.
Corneal transplant is for patients who have lost vision due to corneal disease or injury.
What to Expect the Day of Surgery
On the day of surgery you will arrive at Thomasville Surgery Center 20 to 30 minutes prior to your procedure. You will be checked in and given a sedative to help you relax. The anesthesia provider will prepare the eye by performing a muscle block for the surgical eye. An eyelid holder (speculum) will be placed in the eye to keep the eye open while the surgery takes place.
Your diseased cornea will be removed with an instrument called a trephine which is used to measure and cut the specific amount of cornea the doctor wants to remove. The donor cornea will also will be cut with a trephine to match what was used for your cornea.
The surgery is painless and done on an outpatient basis. The operation may take from one to two hours. You will remain at the center for a short recovery period after the procedure is finished. You will then be allowed to return home where you will be expected to relax for the rest of the day. You may experience some discomfort for a couple of days, but eye drops and pain medication can be used to minimize this discomfort.
As with most surgeries everyone heals differently, but most patients may resume normal activities within a few days. Lifting, bending and straining should be avoided for several weeks as the cornea heals. To help protect the eye while it heals you will be asked to wear a shield, glasses or sunglasses.
The healing process may take a few months to a year. During this time you will continue to use eye drops as directed by your doctor.
Following corneal transplant some patients may experience a return of best vision within a few months, for others it may be as much as one year. As with any transplant there is always the risk of rejection. The risk of rejection of the tissue is rare, but it is very important that you contact your physician if signs of rejection occur. (Redness, pain, sensitivity to light or decrease in vision)
The rate of success for corneal transplant depends largely on the reason for having the procedure done. For example, corneal transplant for degeneration after a cataract surgery or keratoconus has a higher success rate than for those performed because of a chemical burn or a previous failed graft.
Descemet’s Stripping Automated Endothelial Keratoplasty
DSAEK is a new procedure that can help some patients who previously would have required a full thickness corneal transplant (Penetrating Keratoplasty). As with a full thickness transplant, DSAEK also requires the use of a donor cornea. Instead of replacing the whole cornea DSAEK replaces only the diseased posterior section of the cornea. DSAEK requires minimum sutures, allows a faster visual recovery, less discomfort and reduces the risk of sight threatening complications.
The cornea is the clear portion of the front of the eye. It helps bend and focus light on the retina at the back of the eye. In order for vision to be clear, the cornea must be clean and clear. Corneal disease can cause the cornea to become cloudy, preventing light from passing through clearly.
What to Expect the Day of Surgery
You will be asked to arrive 30 minutes to one hour prior to surgery. You will be checked in and given a sedative to relax you. You will then be prepared for surgery. Once the eye is numb a sterile drape will be placed, and an eyelid holder (speculum) will be placed to hold the eye open for the doctor during surgery. A small incision will be made so the surgeon can strip away the diseased Descemet’s membrane and endothelial cells. Next, the bottom 10 – 20% of a donor cornea with healthy Descemet’s membrane and endothelial cells will be inserted through the incision. After the donor graft is placed an air bubble will be used to hold the new portion of cornea in place.
Immediately following the surgery you will be taken to the recovery area where you will remain flat for about an hour to allow the air bubble to continue to press the tissue into place. Before you leave a patch will be placed over the eye. Antibiotic eye drops will be used for a week or so to help prevent infection. A mild steroid eye drop will be used for at least a year to help prevent rejection.
The day after surgery you should be able to resume your normal activities. DSAEK allows your vision to improve within a few weeks compared to a full thickness transplant which could take months or years. This allows the doctor to do DSAEK on the other eye within months instead of a year or more.
The goal of any vision restoration procedure is to improve your vision. Usually most patients will begin seeing better within 6-8 weeks. However, we cannot guarantee that you will have the results you desire. As with any transplant there is a risk of rejection of the donor tissue. If rejection does occur it is possible to have the procedure repeated.