Cornea Transplant & DSAEK

The Cornea

The cornea is the clear front window of the eye. It covers the colored iris and the round pupil. While passing through the cornea, light is focused so we can see.

Unhealthy Corneas and Vision

If a patient has an injured or diseased cornea, it can become scarred or swollen, losing its clarity and smoothness. Because of scars, swelling or an irregular shape, the cornea can scatter or distort light, resulting in blurred vision or glare.

When is a Corneal Transplant Needed?

If your vision cannot be corrected satisfactorily with eyeglasses or contact lenses or a painful swollen cornea cannot be relieved by medications or special contact lenses.

Keratoconus, a steep curving of the cornea, Fuchs' dystrophy, a hereditary corneal failure, scarring after infections or injury are just some of the reasons for a corneal transplant.

Deciding on a Corneal Transplant

When you and your doctor decide on a corneal transplant, your name is put on a list at the local eye bank. Before a cornea is released for transplant, the eye bank tests the human donor for the viruses that cause hepatitis and HIV. The cornea is carefully checked for clarity.

Surgery is often done on an outpatient bases. Local anesthesia is most often used, depending on your age, medical condition and eye disease. During the procedure, the diseased or injured cornea is carefully removed from the eye. The new donor cornea is sewn into place.

Your doctor will decide when to remove the sutures, depending upon the health of your eye and rate of healing. Usually, it will be one year before all sutures are removed, but this varies depending on the technique used for your procedure. Often sutures are left in place permanently.

Can Complications Occur?

Corneal transplant surgery is the most common and successful of all transplant surgery 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, most rejections can be stopped with minimal injury.

Warning signs of rejection are:

• Persistent discomfort
• Light sensitivity
• Redness
• Change in vision

Corneal transplants can be repeated, usually with good results. The overall rejection rates, however, for repeated transplants are higher than for the first transplant. Vision may continue to improve up to a year after surgery.

A successful corneal transplant requires care and attention on the part of both patient and physician. No other surgery, however, has so much to offer the patient when the unhealthy cornea is deeply scarred or swollen.

DSAEK: The Sutureless Corneal Transplant

DSAEK (Descemet Stripping Automated Endothelial Keratoplasty) is a new option for patients with corneal edema who require corneal transplantation. 

 

 

 

 

 

 

 

 

 

 

 

 

This procedure has several advantages over traditional corneal transplant surgery which include:

• Faster visual recovery
• Less astigmatism created since there are no sutures
• Suture related complications are essentially eliminated
• Eye is much stronger and more resistant to injury since only the diseased tissue, rather than the entire cornea, is replaced.
• Surgery time is quicker
• Chance of rejection is reduced significantly
• Procedure can be combined with cataract surgery
• There is little or no change in the refractive error since the patient's cornea is left intact

In order to understand this new procedure one must understand the conditions and pathology that lead to corneal edema.

The back cellular layer, or posterior layer, of the cornea is called the endothelium and is responsible for maintaining the clarity of the cornea by pumping excess fluid from the cornea. The endothelium has a finite number of cells; that is these cells are unable to be replaced once they are damaged or die. Certain conditions can cause loss of these finite cells (endothelial cell loss) leading to corneal edema and vision loss.  Irreversible corneal edema occurs when the endothelial cell loss occurs to such an extent that fluid can no longer be pumped from the cornea and the cornea swells preventing light from being focused on the retina.

There are two main conditions that result in irreversible endothelial cell loss:

Pseudophakic Bullous Keratopathy - Corneal Edema

This is a condition in which one's cornea has become permanently swollen (corneal edema) following a cataract and intraocular lens implant procedure. The cells that line the back inside surface of the normally crystal clear 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.

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, severe inflammation following the operation, intra-operative bleeding, or a predisposing disease called 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.

Fuchs' Endothelial Dystrophy

The normally crystal clear cornea has a layer on its inside surface called the endothelium. The purpose of this layer of cells is to pump water out of the cornea keeping it crystal clear and thin. Normally, as we age, these cells can become thick and fat. When the ophthalmologist looks at your eye through the slit lamp microscope, these cells can be detected and are termed guttata. Guttata are part of the normal aging process of the corneal endothelium.  Fuchs' endothelial dystrophy was first described more than 100 years ago. It is a process in which guttata occur throughout the entire back surface of the cornea and appear one to three decades earlier than is normally expected.

In Fuchs' endothelial dystrophy, as the guttata increase in size and numbers, fluid begins to accumulate within the cornea. Patients develop blurry or foggy vision in the morning, see halos around lights early in the morning, are unable to read in the early part of the day, etc. As the day goes on and the cornea dehydrates on its own, it becomes clearer and thinner and the patient's vision improves. As the process of Fuchs' endothelial dystrophy progresses, the swelling of the cornea persists further on into the day until eventually the vision never clears.

Surgical Treatment of Pseudophakic Bullous Keratopathy & Fuch's Endothelial Dystrophy using the DSAEK procedure:

In both pseudophakic bullous keratopathy and Fuch's dystrophy, only the corneal endothelium is diseased.  The remaining layers of the cornea are usually normal and healthy. Until recently, the treatment of choice in patients with corneal edema from endothelial cell loss was a corneal transplant operation (penetrating keratoplasty). This involves replacing the entire cornea using a full thickness donor cornea.  Recently a new procedure was developed to treat this condition called DSAEK.  DSAEK stands for Descemets' Stripping Automated Endothelial Keratoplasty. In this procedure, the damaged endothelium is removed from the patient's eye and replaced with a partial thickness piece of donor cornea containing a healthy endothelium (posterior graft). 

This procedure is done through a sutureless incision and therefore results in a faster visual recovery.  Most patients recover useful vision within three months of surgery compared to a full thickness corneal transplant that may take up to a year or longer to achieve the same level of vision.  Dr. Ahdoot no longer recommends performing a standard corneal transplant on most patients with pseudophakic bullous keratopathy or Fuch's dystrophy unless they have significant corneal scarring.

Complications of the DSAEK Procedure:

The posterior graft can dislocate and may need to be repositioned or replaced.  In some instances a regular corneal transplant may need to performed.