Structure and function of the cornea
The cornea is a transparent “porthole” that not only protects the eyeball, but also fulfils an essential optical function: together with the crystalline lens, it allows images to be focused on the retina. It is covered with an epithelium which, when damaged, causes painful ulceration because the cornea is strongly innervated.
Pathologies of the cornea
The transparency of the cornea is its main characteristic. The loss of transparency can and is related to infection, trauma, genetic pathologies.
- Herpetic keratitis Herpes, which is often cutaneous and benign, is of much greater concern when it affects the eye, mainly located in the cornea. Fortunately nowadays, local antiviral treatments are more and more effective, curative but also preventive when there are known triggering factors (sun exposure). The severity of herpes keratitis remains mostly represented by recurrences.
- Infectious keratitis Infectious contamination of the cornea can be secondary to trauma or to particularly dreaded germs: staphylococci, pneumococci, etc… affecting contact lens wearers in particular. Amoebic keratitis is a recent phenomenon affecting people who use running water to care for their lenses.
Corneal injury due to broken glass (glasses, windshield) is the most common accident. The most dramatic cause of trauma is chemical burns, mainly caused by alkaline products (soda, battery liquid). In such a situation, it is essential to immediately rinse the eye abundantly by passing the injured person’s face under a tap to avoid intraocular penetration of the chemical agent. As a precautionary measure, protection by goggles is essential when handling any chemical product.
- Corneal endothelial dystrophy is a common cause of loss of corneal transparency. Degeneration of this layer in people over 50 years of age causes corneal edema requiring corneal transplantation.
- keratoconus is a frequent dystrophy, often familial, in which the cornea becomes conical, treated with great success by corneal transplantation.
The corneal graft
When the cornea loses its transparency, there are currently few treatment options other than corneal grafting called keratoplasty. Thanks to the “Établissement Français des Greffes”, created in 1994, the possibilities of corneal transplantation are improved. The diseased cornea is replaced by a human cornea taken from a corpse. The cornea was previously placed for three weeks in a preservation system in order to check its quality and to ensure that the donor did not present any transmissible pathology. Unfortunately, the real problem still lies in the lack of donors. Yet the re-placement of the cornea of a blind person by the cornea of a deceased person remains a fine example of human solidarity comforted by science, generosity and human skill. Is there greater communion than this?