Corneal Diseases & Surgeries
The cornea is the domed clear covering at the front of the eye and is the first physical structure through which light passes. It is responsible for the majority of the focusing power of the eye. 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. These may include any of the following ailments:
- Abrasion, a 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, an inflammation on the superficial cornea cause by contact lens wear, viral infections, or a spontaneous occurrence
- Ulcer, an infection occurring from contact lens wear, surgery, or other causes
- Viral keratitis, a condition most commonly caused by herpetic eye disease (including shingles) or adenovirus infection
Inherited corneal dystrophies may include the following conditions:
- 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), as well as various forms of corneal transplantation. The cornea is also the site of laser eye surgery when LASIK (Laser-Assisted In-Situ Keratomileusis) or PRK (photo refractive keratectomy) are performed to correct for nearsightedness, farsightedness, and astigmatism.
Corneal transplantation is performed for diseases of the cornea that have resulted in significant vision loss. This type of transplant procedure is one of the most common. Corneal transplantation involves the replacement of a diseased or scarred cornea with a donated one. 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 approximately to 95 percent. 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.
The options for corneal transplantation vary. If your entire cornea is diseased, penetrating keratoplasty is the standard procedure. 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 only the posterior portion (known as the endothelial cell layer), resulting in corneal swelling, you may be a candidate for posterior lamellar, or endothelial, keratoplasty or a less common procedures, such as epikeratoplasty.