What is Fuchs’ Endothelial Dystrophy?
Fuchs’ Endothelial Dystrophy (FED) is a common condition of the cornea which typically presents from middle age. The cornea must be clear and appropriately curved for good vision. A normal cornea is kept clear by the back surface membrane (endothelium) that contains cells that pump excess water out of the cornea. These endothelial cells cannot replicate or repair themselves and become fewer with age. In FED, the endothelial cells are abnormal and fail to pump out water adequately causing a loss of corneal clarity as the cornea becomes progressively waterlogged and opaque.
What are the symptoms?
The earliest symptom of FED is glare. As the corneal becomes waterlogged, patients typically report misty vision on waking which initially resolves after a short period each day. However, with the passage of time, the duration gets longer and longer until it is permanent.
What is the treatment?
Medical (non-surgical) treatment is generally not very effective. Hypertonic saline drops are available to try to draw water out of the cornea but in significant disease this does little to dry out the cornea. Less elegant but more effective is the use of a hair-drier held at arm’s length and used to dehydrate the cornea by a wind-evaporation effect.
As the disease progresses, surgery is required in the form of a corneal transplant or corneal graft. A full thickness corneal transplant known as a penetrating keratoplasty (PK) used to be the standard of care. However, modern management is in the form of a partial thickness corneal transplant known as an “endothelial keratoplasty or EK. The advantage of this surgery is that only the diseased layer of the cornea is replaced, with less graft rejection and more rapid restoration of vision without the need for difficult glasses.
This can be either a Descemet’s Stripping Endothelial Keratoplasty (DSEK), a modification called DSAEK (where the A indicates a step has been automated) or a Descemet’s Membrane Endothelial Keratoplasty (DMEK) which is now the preferred procedure. DMEK is a challenging procedure, as the donor graft is a membrane that rolls up into a scroll and has to be unfolded the right way up inside the recipient’s eye, and then made to stick on in the right place! Invented in Holland, it is a better procedure than a PK for endothelial disease in general and FED in particular.
A recently innovation is Descemetorrhexis Without Endothelial Keratoplasty (DWEK) or Descemetorrhexis Only (DO). This relatively new technique harnesses the regenerative capacity of the peripheral corneal with just the central affected zone being removed without a subsequent corneal transplant. This evolving technique has shown early promise and could reduce the future demand for corneal transplantation.