The cornea is a thin, clear, spherical layer of tissue on the surface of the eye that provides a window for light to pass through. In a healthy eye, the cornea bends or refracts light rays to help them focus precisely on the retina in the back of the eye.
There are many diseases that can affect the cornea, causing pain or loss of vision. Disease, infection or injury can cause the cornea to swell (called “edema”) or degrade (become cloudy and reduce vision).
Treatment for corneal disease can take many forms, depending on the underlying problem as well as the patient’s preferences. Some conditions may resolve on their own and many can be treated with medication. In other cases, a corneal surgery may be necessary in order to prevent blindness or restore a severely damaged eye.
Some common corneal conditions include:
- Keratoconus – a progressive eye disease in which the normally round cornea thins and begins to bulge into a cone-like shape. In patients with keratoconus, the cone-shaped cornea deflects light and causes distorted vision.
- Fuch’s Dystrophy – an inherited eye disease that causes the cells in the innermost layer of the cornea to deteriorate, leading to distorted vision and corneal swelling. As these cells continue to deteriorate, fluid will continue to build up and vision will worsen. Once these cells are lost, they do not grow back.
- Pterygium – a benign growth of the conjunctiva (the lining of the white part of the eye) that grows on to the cornea and partially covers the iris (colored part of the eye). Patients with a pterygium often first notice the condition because of the appearance of a lesion on their eye or because of dryness, itchiness, irritation, tearing, and/or redness.
Penetrating Keratoplasty (PKP)
Standard corneal transplant surgery was first developed over one hundred years ago, and the 90% success rate reported today is based on numerous refinements to this basic technique. Corneal transplants may be necessary for patients whose vision is severely impaired due to scarring, swelling, hereditary conditions, complications from prior eye surgeries, or a cornea with an abnormal curvature that cannot be treated with specially fitted contact lenses. Corneal transplants are the most common and successful transplant surgeries performed in the United States, with over 40,000 procedures done each year. With PKP, the full thickness of the host cornea is removed as a disk and replaced with a donor cornea that is sutured into place with stitches that are smaller than a human hair. These donor corneas are provided by eye banks throughout the United States and are carefully reviewed to check for viruses and clarity before being released for transplantation.
Descement Stripping Automated Endothelial Keratoplasty (DSAEK)
This newer corneal procedure was first proposed in the 1950s, but did not become a widespread technique until the early 2000s. It is not an appropriate technique for all patients with corneal disease. However if it is indicated, it can significantly reduce the time to full visual recovery. This is primarily done for patients with a condition called Fuch’s dystrophy.
The DSAEK technique involves making a small 5 mm incision into the cornea. Then, the diseased posterior cells of the cornea (endothelium) are removed and replaced with pre-cut donor corneal cells. An air bubble, instead of sutures, is used o keep the graft in place.
Deep Anterior Lamellar Keratoplasty (DALK)
This is the newest type of corneal surgery that preserves the patient’s posterior cornea and replaces only the diseased or scarred anterior portion of the cornea. This surgery theoretically reduces the risk of rejection and corneal transplant failure.
Dr. Liston is fellowship trained to perform PKP, DSAEK, and DALK procedures. He will take the time to educate you on the best course of action for your individual needs.
Phototherpeutic Keratectomy (PTK)
Phototherapeutic Keratectomy is an advanced laser procedure used to treat corneal abnormalities such as scar tissue or an irregular corneal surface that causes blurry vision or discomfort of the eye. PTK offers patients a safer, less invasive alternative than older manual techniques and helps them achieve the results they desire. During the PTK procedure, the eye is numbed with anesthetic eye drops. The surgeon then removes the superficial layer of the cornea (epithelium), while a laser reshapes the cornea to your unique specifications. A bandage contact lens is placed on the eye to protect the cornea. The epithelium heals within a few days and naturally covers the treated area.
Corneal Cross-Linking (CXL)
Cross-Linking is a minimally invasive outpatient procedure that ocmbines the use of UVA light and riboflavin eye drops to add stiffness to corneas which have been weakened by disease or refractive surgery. Cross-linking, which has been performed in Europe since 2003, is considered the standard of care around the world for keratoconus and corneal ectasia following refractive surgery. Our practice is proud to offer patients the first and only therapeutic products for corneal cross-linking which have been FDA approved to treat progressive keratoconus. This approval offers an effective treatment for patients who, until recently, had to options to limit the progression of this sight-threatening disease.
For information on the FDA approved corneal cross-linking procedure for the treatment of keratoconus and corneal ectasia following refractive surgery, visit www.avedro.com