Cornea
The cornea is a clear dome shaped structure at the front of the eye. Along with the lens of the eye, the cornea focuses light onto the retina to facilitate vision. Both the shape and the clarity of the cornea are essential to its function. Corneal diseases affect either the shape or clarity of this structure, resulting in challenges with vision.
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At Glacier Eye Clinic, Dr. Mark Jessen is a trained subspecialist in corneal disease, refractive surgery (LASIK), and anterior segment surgery. Dr. Jessen provides a full range of medical and surgical care for conditions affecting the cornea, ocular surface, iris, and lens in order to treat disease as well as optimize or even enhance vision. If you have questions about, or have been diagnosed with, a corneal condition please call our clinic for additional information or to schedule an evaluation.
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Keratoconus

In keratoconus, the shape of the cornea is altered. Over time, the cornea becomes thin and steepens, or protrudes forward into the form of a cone. This change of shape causes light entering the eye to be poorly focused. As keratoconus progresses, vision declines, the cornea can become scarred, and patients may experience painful episodes of swelling known as corneal hydrops.

Management of keratoconus focuses on two objectives: preventing progression and optimizing vision. The major risk factor for and even cause of keratoconus is eye rubbing. Ceasing to rub and apply pressure to the eye is essential. In many cases, a procedure known as crosslinking is performed to stop progression. Rehabilitation of vision may require glasses or specialty contact lenses. In some cases, a device called Intacs is used to help flatten the cornea to improve vision in glasses or assist with the fit of contact lenses. In severe cases of keratoconus, a corneal transplant may be required.

Other conditions similar to keratoconus also require monitoring and care. These include pellucid marginal degeneration and ectasia, or weakening, after prior corneal surgery.

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Corneal Collagen Crosslinking

In cases of progressive keratoconus crosslinking can often stop progression by stiffening the cornea. At Glacier Eye Clinic, we perform FDA approved corneal collagen crosslinking. In this office-based procedure eye drops containing riboflavin, a common vitamin (B2), are instilled into the eye. Then, a UV light source is used to cause a photochemical process in the cornea. This process leads to additional links between proteins in the cornea to provide strength and stiffness. The increased stiffness typically halts the progressive thinning and shape change of the cornea. If you would like to learn more about crosslinking or see if you are a candidate, please contact our office.

Fuchs Corneal Dystrophy

Fuchs dystrophy affects approximately 4% of the population over age 40. Fuchs is a disease that affects the inner layer of corneal cells, known as endothelial cells. These cells help maintain clarity of the cornea by pumping fluid out of the cornea and back into the eye. In Fuchs, these pump-like cells decrease in number and the adjacent layer of the cornea, known as Descemet’s membrane, thickens.

Healthy corneal endothelial cells.

Fuchs dystrophy with loss of endothelial cells.

These changes lead to blurry vision, difficulty with nighttime vision, and glare. Patients may notice foggy vision in the morning that clears as the day progresses or general visual decline. Once Fuchs impacts the vision a corneal transplant is typically required. Typically, only the inner layers need to be transplanted, such as in a DMEK or DSEK (see below).
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Corneal Transplantation

The cornea consists of 5 different layers and is the most commonly transplanted tissue in the body. In the past, corneal transplantation always required the entire cornea to be replaced. While such transplants are still done, we are now often able to replace only the affected or diseased layers. Each eye is unique and determining which transplant is best requires thorough evaluation by a cornea specialist.

This type of transplant is also known as a “full thickness” transplant. In this procedure all 5 layers of the cornea are removed. The donor cornea used for transplantation then also consists of all 5 layers, providing a complete or full thickness transplant.

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Many corneal diseases only affect the innermost linings of the cornea. The most common of these conditions is Fuchs Corneal Dystrophy but there are others. Typically in these cases only the inner lining of cells needs to be replaced. A DMEK transplant replaces the least amount of corneal tissue relative to other transplantation techniques.

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A DSEK is also a transplant of the inner layers of the cornea. It differs from DMEK in that a small amount of the middle layer of the cornea is also added to the transplant. The additional tissue increases the thickness of the transplant, which can be helpful in certain circumstances.
A DALK procedure is similar to a PKP or full thickness transplant with one important difference. This procedure leaves the innermost layer of the patient’s own cornea intact while replacing the outer layers. This can help decrease the risk of rejection of the transplant tissue. Not all patients that are candidates for a full thickness transplant or PKP are candidates for DALK.

Other Corneal Conditions

Many other conditions can affect the cornea, thereby reducing vision. Infection, scarring, tumors, and  inflammation may present in the cornea alone or secondary to other systemic medical conditions. At Glacier Eye Clinic we will do our best to assist you in diagnosing, treating, and coordinating with your other medical doctors to take care of your vision.

Additional information about the cornea and corneal disease may be found on the National Eye Institute website.

National Eye Institute