A corneal transplant involves the replacement of an irregularly shaped, or opaque cornea with a donor cornea. Corneal transplants are performed on patients with deformed corneas (eg. Keratoconus), opaque corneas (such as Fuch’s dystrophy) or scarred corneas (after a serious infection or after an accident). Several medical terms are used for corneal transplants, of which keratoplasty is the most common. The designation stems from the Greek word for cornea: keratos.
The cornea is the transparent spherical tissue that covers the front of the eye. It is the primary refractive component of the eye. A change in the shape or in the clarity of the cornea can seriously influence the eyesight. During surgery, usually only the central part of the cornea is replaced. After successful surgery, eyesight can gradually revert back to normal, however rigid contact lenses or scleral lenses are often required in order to regain perfect sight.
Scleral lenses and contact lenses
If, after recovering from surgery, the cornea still remains too irregularly shaped, then glasses will not be sufficient as an aid in regaining eyesight. A contact lens, however, does serve this purpose. The goal of a contact lens fitting subsequent to a corneal transplant is to regain eyesight and find a lens that is suitable for and tolerated by the eye.
Considering the fact that standard rigid contact lenses do not fit irregularly shaped corneas, special lens designs were developed for eyes after undergoing corneal transplant surgery. A temporary solution would be the ‘piggy-back’system, whereby a rigid lens is placed on top of a soft lens in order to improve eyesight. In cases where corneal rigid gas-permeable lenses are capable of improving vision, but cannot be tolerated, scleral lenses may be the answer.
The condition of the cornea needs to be monitored regularly. For this to be achieved, close cooperation between optometrist and ophthalmologist is essential. It is important to carry out routine examinations during this period. For this reason, it is most important to consult a practice with sufficient experience in the medical application of contact lenses.