What is the cornea?
If we envision our eye as a photography camera system, the cornea serves as the focusing mirror. This front layer of the eye acts as a transparent «window» to the external environment. It is the most refractive surface of the eye, and its structure influences the journey of light rays towards the posterior segment (retina: the light – sensitive back layer of the eye).
Which are the anatomical components of the cornea?
The cornea consists of the following layers:
- Epithelium
- Bowman’s membrane
- Corneal stroma
- Descemet’s membrane
- Endothelium
What exactly is corneal transplantation (keratoplasty surgical procedure);
The cornea, being exposed to the external environment when the eyelids are open, is susceptible to injuries and infections. Apart from injuries and infections, various factors such as cloudiness, ulcers, diseases like keratoconus or ectasias, hereditary and genetic conditions as well as dystrophies, can dramatically affect vision via major alterations in the cornea.
When the corneal structures undergo significant changes due to the mentioned factors, and the cornea or a portion of it needs to be replaced, corneal transplantation (keratoplasty surgical procedure) becomes a viable solution. It involves the surgical intervention of replacing the damaged cornea with a graft, obtained from a compatible donor through eye banks. This is a highly intricate surgical procedure and the graft is sutured with fine stitches.
Which are the modern corneal transplantation techniques?
The primary methods of corneal transplantation include:
- Penetrating Keratoplasty (PKP) or full – thickness corneal transplantation: This technique involves the complete replacement of the affected pathological cornea (the entire thickness)
- Deep Anterior Lamellar Keratoplasty (DALK) or partial – thickness corneal transplantation: This method selectively replaces only specific parts – tissues of the damaged cornea.
- Posterior Lamellar Keratoplasty or Endothelial Keratoplasty, including Descemet’s Stripping Endothelial Keratoplasty (DSEK), Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) and Descemet Membrane Endothelial Keratoplasty (DMEK). Posterior Lamellar Transplantation is applied when the damage is located through the posterior layers of the cornea (endothelium).
- Keratoprosthesis: When an artificial cornea replaces the pathological one, serving as a solution for severe corneal conditions that have caused irreversible damage.