More than just the “window to the eye,” the cornea is a complex, multi-layer structure that is responsible for focusing light for vision. Located at the front of the eye, it is highly susceptible to unfavorable environmental conditions such as low humidity, excessive UV light, and wind.
The three most common corneal conditions are:
Keratoconus is a condition where a portion of the cornea is abnormally steep and irregularly shaped. Because the cornea is the “clear window” allowing light into the eye, any irregularities can make vision blurry.
Visual changes from keratoconus are occasionally mild, but severe disease may cause thinning and scarring along the visual axis. The progressive shape and power changes in a cornea with keratoconus can make vision very blurry. Light sensitivity, sudden pain, and corneal swelling are all common in severe keratoconus. It is important to note that the right and left eye can be affected differently.
Early keratoconus can be treated with glasses or soft contacts. As the disease progresses, gas permeable or newer therapeutic contact lenses may be needed to obtain the best vision. Astigmatism-reducing therapies, such as corneal inserts (Intacs), have helped many patients find greater comfort and improved vision using contact lenses.
If contact lenses cannot adequately correct the abnormal corneal shape, collagen crosslinking may be considered. This cornea-strengthening procedure is the only means to stop progressive bulging in certain corneas. If crosslinking is not possible, cornea transplants are a next step.
Full-thickness and partial-thickness cornea transplants have been time-tested remedies for keratoconus. By replacing the irregular cornea with a sutured donor cornea, a relatively normal curvature can be restored.
Conditions that affect the cornea and conjunctiva are considered disorders of the ocular surface. Dry eye, blepharitis, epithelial basement membrane dystrophy, conjunctivochalasis, and ocular allergy are some of the most common ocular surface problems.
Most conditions related to ocular surface disease exhibit some degree of irritation or foreign body sensation. Redness, blurry vision, light sensitivity and tearing are common. If you are experiencing any of these symptoms, it is a good idea to make an appointment.
Treatment is tailored to the underlying cause of each condition. Medical therapy is usually enough for milder disease. Artificial tears are routinely helpful. Occasionally surgical treatment is warranted when conservative measures fail, including Superficial Keratectomy, the insertion of Punctal Plugs, or a Keratoprosthesis.
Conditions that affect the underside of the cornea are known as endothelial disorders. Unhealthy corneal endothelium may create glare or blur due to increased thickening or irregular reflections of the corneal tissue. The most common of this group of diseases is Fuchs Dystrophy.
Some patients with endothelial dystrophy note more pronounced morning blurry vision. Family history is often an indicator of Fuchs Endothelial Dystrophy.
Medication can help patients with milder endothelial disorders. Advanced disease necessitates a cornea transplant for best vision. Traditional cornea transplants are used for those with severe disease and other abnormalities of the front of the eye.
DSEK (Descemet Stripping Endothelial Keratoplasty) and DMEK (Descemet Membrane Endothelial Keratoplasty) are preferred surgical techniques. Dr. Harvey has been performing DSEK since 2005, helping pioneer small-incision surgery to selectively transplant the underside of the cornea.