What is it?
Corneal transplantation, also known as transfixing keratoplasty, is a surgical procedure in which a diseased or damaged cornea is replaced with one from a recently deceased donor who has no known disease that could affect the viability of the tissue. The cornea is the transparent part of the eye opposite the iris and pupil. The operation is performed by ophthalmologists, i.e. doctors specializing in eye diseases.
What is the cornea?
The cornea is the primary transparent tissue of the eyeball. It allows light rays to converge on the crystalline lens and thus on the retina. It is composed of three main cell layers, as well as two membranes. It is extremely thin (500 µm at its center), which makes it extremely fragile and prone to numerous diseases and injuries. What’s more, it has no blood vessels to maintain its transparency, which deprives it of the nutrients that the cornea must draw from the tears spread in a thin film over the entire surface of the eye by the blinking of the eyelids.
Who’s at risk?
Corneal trauma is one of the main reasons for consulting ophthalmic emergency departments. Do-it-yourselfers or “Sunday” gardeners who don’t take every precaution are the first to be affected.
What are the symptoms?
What all corneal injuries have in common is intense pain, which usually raises the alarm:
- It is immediately intense when a foreign body is embedded in the cornea and lasts at least until it is removed by the ophthalmologist;
- But it occurs several hours after exposure to ultraviolet light without sufficient protection, and is often accompanied by photophobia (difficulty in tolerating light). Reduced vision can also occur, particularly after severe chemical or physical burns, or after a blow that has affected other structures in the eye. This is often a sign of seriousness;
- Watching a solar eclipse unprotected, even for a few seconds, can cause serious retinal burns. At the time, it’s painless, which is why it’s worth prolonging the viewing period. But in the hours or days that follow, vision deteriorates and straight lines appear distorted. Unfortunately, these problems do not always regress. What’s more, retinal burns are a risk factor in the long-term development of macular degeneration (AMD), the leading cause of blindness in the elderly.
How is corneal trauma diagnosed?
Ophthalmoscope examination of the cornea and fluorescein testing are essential.
Who to consult? As a general practitioner is not equipped to assess the integrity of a cornea, you should immediately see an ophthalmologist as a matter of urgency. If yours isn’t available, go straight to the nearest emergency room, as there’s usually an ophthalmologist on call 24 hours a day. If the injury is related to a chemical that has been sprayed into the eye, remember to take the bottle with you so that the doctor knows what it is;
What does the assessment involve? Examination of the cornea with an ophthalmoscope, after instilling a drop of fluorescein, reveals any erosion, bleeding or ulceration. In the event of shock, and if there is any doubt that other internal structures of the eye have been affected, the ophthalmologist may perform a fundus examination.