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Cornea and External Disease

The cornea is the front surface of the eye. It is made up of multiple layers including the epithelium (surface), stroma (middle), and endothelium (back). It is important for the cornea to remain clear to allow for light to enter the eye unobstructed.

Why would I need a corneal transplant?

  • Scarring from infection or trauma
  • Eye diseases such as Keratoconus
  • Hereditary factors or corneal failure from previous surgeries
  • Thinning of the cornea and irregular shape
  • Complications from LASIK
  • Chemical burns on the cornea
  • Excessive swelling of the cornea
  • Pain from blistering on the cornea

Corneal transplantation involves replacing a diseased or scarred cornea with a clear healthy one, which is donated through a local or national eye bank. The cloudy cornea is removed with a cookie-cutter-like instrument and the new one is secured in its place with sutures. These sutures remain for months or even years until the eye heals properly. Eye drops to promote healing and prevent rejection will be needed for several months to years after the outpatient procedure.

  • The Gavin Herbert Eye Institute ophthalmologists have developed and pioneered the use of femtosecond lasers to make the incisions in cornea transplants. These incisions have been proven to reduce astigmatism and speed vision recovery.
  • Specialized corneal transplantation techniques, including endothelial keratoplasty (DSAEK or DMEK) and deep anterior lamellar keratoplasty (DALK) are all performed on a regular basis by eye surgeons at UCI Health’s Gavin Herbert Eye Institute.

Can complications occur?

Corneal transplant surgery is the most common and successful of all transplant surgeries today. Ophthalmologists perform more than 40,000 corneal transplants each year in the United States. Corneal Transplants are rejected 5% to 30% of the time.  The rejected cornea clouds and vision deteriorates. If treated promptly, then most rejections can be stopped and reversed with minimal injury. 

 

Depending on the reason for your corneal transplant, there are several approaches that your surgeon may suggest.

 

Conventional Keratoplasty

Conventional keratoplasty refers to a standard corneal transplant using a circular blade, known as a trephine, to create an incision. A conventional corneal transplant requires long periods of convalescence, sometimes upwards of 12 months for patients to enjoy good, stable vision.  The traditional corneal transplant procedure requires multiple sutures and a lengthy post-operative recovery period until one reaches their final refraction and ‘best spectacle-corrected vision.’

Femtosecond Laser Keratoplasty

Femtosecond laser keratoplasty is a corneal transplantation or grafting technique using a femtosecond laser, which was developed by the UCI Gavin Herbert Eye Institute ophthalmologists. This method uses an ultra-fast laser capable of pulsing more than 60,000 times per second to create a zigzag incision. This new technique results in a faster visual recovery and less astigmatism compared to conventional corneal transplantation methods. We are the leading center for Femtosecond Laser Keratoplasty in the nation. Depending on the reason for your surgery, this may be the best option for your corneal transplant.

Deep Anterior Lamellar Keratoplasty (DALK)

Deep Anterior Lamellar Keratoplasty is a special type of corneal transplant in which only the anterior (front) part of the cornea is transplanted. The back layer of your cornea is retained. DALK allows for less chances of corneal rejection. At the Gavin Herbert Eye Institute, we have pioneered the combined use of the femtosecond laser and the DALK technique to allow a customized partial layer corneal transplant with the added benefits of the laser. This may be an option for you depending on the reason for your corneal transplant.

Endothelial Keratoplasty (DSAEK or DMEK)

DSAEK (Descemet stripping automated endothelial keratoplasty) or DMEK (Descemet membrane endothelial keratoplasty), are specialized corneal transplantation techniques that replace only the back layer of the cornea. During these procedures, the damaged or diseased inner layers particularly the endothelium are removed and replaced with a sheet of healthy donor corneal cells. These types of transplants are performed in eyes in which the disease is limited to only the inner corneal layer.

Patients who have a corneal transplant done using these techniques have a short period of time after their surgery when they need to lay face up to allow the new cells to adhere to the back layer of their cornea. A gas or air bubble is used to accomplish this. Patients are able to resume their normal activities sooner than those requiring a full thickness corneal transplant. Additionally, suture related complications are essentially eliminated and there is minimal change in the refractive error since the front part of the patient’s cornea is left intact.

DSAEK and DMEK vary only based on the thickness of the donor tissue that is implanted.  DMEK is the latest evolution in endothelial keratoplasty and involves the thinnest possible transplanted tissue. Visual recovery is faster than in DSAEK and is the preferred option in eyes with less advanced disease. 

The Boston keratoprosthesis is an "artificial cornea" that is indicated in patients who are poor candidates for a traditional corneal transplant. Patients who have had multiple previously failed standard corneal transplants or those with severe ocular surface disease who are poor candidates for limbal stem cell transplants may be candidates for the Boston keratoprosthesis. This technology was developed in 1965 and has undergone multiple advances. It gained FDA clearance in 1992. The current model consists of a clear plastic optic which is assembled onto a cadaver corneal tissue. This complex is then transplanted onto the eye in a similar fashion to the traditional corneal transplant. Long-term care and maintenance are the keys to its success. The chronic use of a bandage contact lens and antibiotic drops have allowed the improved safety and long term viability of the artificial cornea.

Keratoconus is a non-inflammatory corneal condition in which the normal dome-shaped architecture of the cornea is distorted. The cornea progressively thins and the normal corneal contour becomes conical. Keratoconus is usually diagnosed in young people (puberty or late teens). It usually affects both eyes, generally with different severity. Keratoconus usually progresses for 10-20 years and then stabilizes. In the early stages, keratoconus causes blurring of vision, which can be treated with glasses or soft contacts. As the disorder progresses, hard contact lenses are generally needed to correct vision adequately. Depending on the severity of the condition, there are several therapeutic options including corneal collagen crosslinking (CXL), intrastromal rings (INTACS), conventional penetrating keratoplasty (corneal transplant), femtosecond laser-assisted keratoplasty (laser corneal transplant), and deep anterior lamellar keratoplasty using the femtosecond laser (nearly full thickness laser corneal transplant).

We are excited to be a leading center for the FDA-approved protocol of collagen crosslinking (CXL). CXL aims to halt or slow down the progression of keratoconus in the early or moderate stages to allow visual rehabilitation with glasses or contact lenses and delaying or altogether avoiding corneal transplantation. Corneal crosslinking combines the application of riboflavin eye drops with ultraviolet-A light. Together, these create a chemical reaction within the cornea to increase corneal strength and stability by inducing new crosslinks between or within collagen fibers. In clinical trials, crosslinking has been shown to halt the progression of keratoconus and ectasia and to enhance the biomechanical stability of the cornea. Crosslinking is now approved for use in the US.

The corneal surgeons at the Gavin Herbert Eye Institute are world leaders in the management of keratoconus and laser corneal transplantation.

Fuchs’ endothelial dystrophy causes the innermost or back layer of cells of the cornea (endothelium) to deteriorate over time. As these cells break down, the endothelium of the eye becomes unable to process and pump water from the body of the cornea, which causes the cornea to swell and become distorted.

As the cornea’s normal architecture changes, the patient’s vision becomes hazy and tiny blisters can form on the surface of the cornea. The blisters can be very painful if they burst.

Initial symptoms of Fuchs’ endothelial dystrophy include morning blurry vision that generally clears as the day progresses. This is due to the cornea retaining fluid as the patient sleeps, with the fluid then decreasing throughout the day. As the disease progresses, the swelling does not subside and the blurred vision continues throughout the day.

Initially, this disease can be treated with drops, but as the condition worsens, a corneal transplant may be required for visual rehabilitation. Patients with Fuchs’ dystrophy often do very well with a specialized type of corneal transplant: Endothelial Keratoplasty (DSAEK and DMEK).

This is a condition in which one's cornea has become permanently swollen (corneal edema) following cataracts and intraocular lens implant procedure. The cells that line the back inside surface of the cornea (the endothelium), for one of various reasons, have been injured permanently. The function of the endothelium is to pump water out of the cornea, keeping it crystal clear and thin. When injured, these cells can no longer perform this function. The fluid that circulates inside the eyeball seeps into the cornea, causing it to swell and to become cloudy. This condition is called pseudophakic bullous keratopathy and is similar to Fuchs' endothelial dystrophy

The causes of endothelial cell damage following cataract operations are multiple. They include physical trauma during the operation, such as difficulties in removing the cataract or inserting the intraocular lens, or severe inflammation following the operation, or intraoperative bleeding. A person may also have the predisposing disease, Fuchs' endothelial dystrophy, that makes the cornea prone to losing endothelial cells.

When one is afflicted with pseudophakic bullous keratopathy, the cornea is permanently swollen and no medications, spectacles, or contact lenses can improve the vision of a patient with this condition. Patients with pseudophakic bullous keratopathy often do very well with a specialized type of corneal transplant: Endothelial Keratoplasty (DSAEK and DMEK).

Severe ocular surface diseases are a group of disorders leading to corneal limbal stem cell deficiency. These include chemical or thermal burns of the eye, congenital diseases such as aniridia, immunological disorders such as Stevens-Johnson Syndrome (SJS) and ocular cicatricial pemphigoid, infectious diseases resulting in long term ocular surface scarring such as trachoma or herpetic eye disease, and other causes such as chronic contact lens wear. These all culminate in a deficiency of ocular surface stem cells which results in progressive neovascularization and clouding of the cornea. This leads to severe visual impairment and, ultimately, to blindness. Current advances in limbal stem cell transplant technology now allow the transplant of cadaver or living related stem cells onto the ocular surface and the regeneration of an optically clear cornea with resulting gain of vision. Depending on the etiology of the disease, living-related donor tissue, cadaver tissue, or a combination of both are transplanted onto the ocular surface to build the necessary micro environment required for ocular surface health and healing. The Gavin Herbert Eye Institute is one of only a handful of centers in the United States to offer this technology.

A pterygium, or surfer's eye, is a pinkish, triangular-shaped growth over the cornea. It develops slowly over a person’s life and are more commonly found in sunny climates among people ages 20 to 40. Occasionally pterygia grow large enough to cover the pupil or cause significant astigmatism that can impact vision. They can also cause significant inflammation and irritation.  Removal of a pterygium and placement of a graft is performed to restore a smooth ocular surface. 

Corneal infections can be caused by bacteria, fungi, viruses, or parasites.  They can result from contact lens wear, damage to the cornea by a foreign object, or a variety of other causes. Symptoms include pain and inflammation to the eye, reduced vision, and corneal discharge. Over time the infection can lead to corneal erosions and scarring. Minor infections can be treated with antimicrobial eye drops. In more serious cases, corneal transplantation may be required to restore vision.

Ocular herpes, or herpes eye infections, are caused by the type 1 herpes simplex virus. Herpes eye infections can be transmitted through close contact with a person who is experiencing an active herpes episode. There are several forms of ocular herpes. Herpes keratitis is a viral corneal infection that typically infects the epithelium, or top layer, of the cornea. In cases of stromal keratitis, the infection involves deeper levels of the cornea, and may lead to scarring and loss of vision. According to the National Eye Institute, stromal keratitis condition is one of the leading causes of corneal scarring in the United States. Another serious form of ocular herpes is iridocyclitis, which involves inflammation of the iris and surrounding tissues, causing severe light sensitivity, blurry vision, and red, painful eyes.

Symptoms of ocular herpes include inflammation of the cornea, cloudy or blurry vision, recurrent eye irritation and infections, eye sores, tearing, and discharge.

Treatment for ocular herpes depends on where the infection occurs. For more superficial cases, antiviral eye drops or oral medications may be used. Surgical treatments such as debridement or corneal transplants may be recommended for more serious cases.

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Whether you need a routine eye exam or care for complex vision problems, the internationally respected ophthalmologists at the UCI Gavin Herbert Eye Institute will provide you with the highest quality of care to treat your vision problems. 

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The UCI Gavin Herbert Eye Institute has locations in Orange at the UCI Medical Center, and also in Irvine on the UCI Campus.