Corneal Diseases & Surgeries
The cornea is the front clear covering of the eye, overlying the iris, or the colored part of the eye. It is the first part of the eye that light passes through and is responsible for the majority of the focusing power of the eye (even more than the lens). As a result, your ability to see clearly is significantly affected by changes in the cornea. Just like any other tissue in the body, the cornea is susceptible to inflammation (called keratitis), infections, degenerations, inherited diseases, and trauma:
- Abrasion, or scratch, resulting from trauma or occurring spontaneously
- Pterygium, a growth from the conjunctiva (overlying the white part of the eye) onto the clear cornea, which can cause redness, irritation and decreased vision, treated by surgical removal
- Superficial punctate keratitis, or inflammation on the superficial cornea, from contact lens wear, viral infections, or occurring spontaneously
- Ulcer, or infection, occurring from contact lens wear, surgery, or other causes
- Viral keratitis, most commonly due to herpetic eye disease (including shingles) or adenovirus infection
- Inherited corneal dystrophies, including:
- Keratoconus, an inherited dystrophy, causing progressive thinning of the cornea with loss of vision, in some cases eventually requiring a corneal transplant
- Fuchs dystrophy, causing swelling in the cornea with loss of vision, sometimes requiring corneal transplantation
- Map-Dot-Fingerprint (MDF) dystrophy (or Epithelial Basement Membrane dystrophy), leading to irritation and poor vision and treated with minor procedures
Some common cornea procedures include pterygium removal, superficial keratectomy (polishing the superficial part of the cornea to remove diseased tissue), and various forms of corneal transplantation. The cornea is also the site of surgery when LASIK or PRK are performed to correct for nearsightedness, farsightedness, and astigmatism.
Corneal transplantation is performed for diseases of the cornea causing significant vision loss. It is one of the most common transplant procedures in all of medicine. Corneal transplantation involves the replacement of a diseased or scarred cornea with a donated one. [Any individual may request to be an organ donor, and if so, may also request to donate their corneas to help the eyesight of another individual.] When the cornea becomes cloudy, light cannot penetrate the eye to reach the light-sensing retina. Poor vision or even blindness may result. In corneal transplant surgery, the surgeon removes part or all of the central portion of the cloudy cornea and replaces it with a clear cornea.
The success rate of a corneal transplant in an otherwise healthy eye is close to 95%. This is the highest success rate of any organ transplant surgery. Corneal transplantation has restored sight to many who would have been blinded permanently by corneal injury, infection, or inherited corneal disease or degeneration.
There are various options for corneal transplantation. If your entire cornea is diseased, the standard penetrating keratoplasty is your only option. If your corneal disease only involves the superficial part of the cornea, you may be eligible for an anterior lamellar keratoplasty. If the disease involves just the posterior portion, known as the endothelial cell layer, resulting in corneal swelling, you may be a candidate for posterior lamellar, or endothelial, keratoplasty. Other less common procedures include epikeratoplasty