Corneal Edema refers to the swelling of the cornea. Endothelial cells on the inner surface of the cornea are responsible for actively pumping fluid out of the cornea in order to keep the cornea clear. Endothelial cells cannot be replaced if they become injured and die.
When the cells become compromised through disease (see Fuchs’ corneal dystrophy), trauma, or repeated surgical procedures involving corneal incisions, the cells decrease in number, and as a whole, function less efficiently. When this occurs, fluid builds up in the cornea, resulting in swelling of the cornea and subsequently hazy/blurred vision.
Current treatments include the application of saline drops and/or ointment. In more severe cases surgical replacement of the entire cornea or, more recently, just the inner endothelial layer is required.
- 5% sodium chloride drops and ointment are hypertonic saline drops and ointment that help reduce corneal edema by helping to draw fluid out from the cornea.
The cornea has 5 layers:
- Bowman’s layer
- Descemet’s membrane
- PKP – (Penetrating Keratoplasty) The replacement of the entire cornea, all 5 layers, with a donor cornea. This treatment is no longer commonly used to treat corneal edema or Fuchs’ corneal dystrophy.
- DSEK – (Descemet’s Stripping Endothelial Keratoplasty), which is a partial corneal transplant, involves replacing only part of the stromal layer along with Descemet’s membrane and inner endothelial layer. This process leaves most of the patient’s own healthy cornea intact, allows for faster healing, and minimizes the chance of graft failure.
New treatments include DMEK (similar to DSEK), and DALK (for deep corneal scars and keratoconus), which are the next evolution of endothelial transplantation.
DMEK – (Descemet’s Membrane Endothelial Keratoplasty), involves replacing only Descemet’s membrane and the inner endothelial layer. The absence of stromal transplantation allows for better post-op visual acuity when compared to DSEK. The drawback to DMEK is the fact that it is a more challenging surgery. The transplanted layer is very thin and hard to handle, thus damaging the transplant during the procedure is a very real risk.