Fuch's Endothelial Dystrophy
What is Fuch’s Endothelial Dystrophy (FED)?
Fuch's endothelial dystrophy (FED) is an inherited disease that affects the two innermost layers of the cornea, causing a gradual deterioration in vision over many years. The treatment options have dramatically improved over recent time. It is now possible to restore your eyesight, with a Descemet's Membrane Endothelial Keratoplasty (DMEK), directly replacing the affected cells with donor cells. People with minor deterioration affecting only the central cornea may be suitable for a Primary Descematorhexis, avoiding the need for a transplant.
Mr Darcy is a specialist high volume corneal transplant surgeon who will assess your eyes and offer a bespoke treatment plan.
Overview of Fuch’s Endothelial Dystrophy?
Fuch's endothelial dystrophy (FED) is an inherited disease that affects the cornea. The cornea is part of the durable outside layers of the eye that protect the delicate inside contents. It is a transparent window allowing light in, while also maintaining the strength. Any loss of transparency due to scarring or waterlogging of the cornea causes blurring of the vision, by preventing a sharp focus of light forming on the retina.
The cornea has five separate layers. FED affects the two innermost layers (called the Endothelium and Descemet's). Together these layers are thin (12-20µm), much smaller than a human hair (30-181µm). They make up about 4% of the total corneal thickness. The endothelium is very important for maintaining the water balance and clarity of the cornea. Formed as a series of tightly-packed cells, the endothelial cells behave similarly to a dam wall, preventing the fluid that fills the eye escaping and waterlogging the cornea. These cells function as a pump, continuously removing any excess liquid from the cornea. Their action is similar to bilge pumps found on boats, which continuously pump water out of the hull, keeping it afloat. We are typically born with around 4000 cells per square millimetre. This number gradually decreases with age, so that by the age of 40, we have about 3000 cells per square millimetre and only 2000 per square millimetre by the age of 80.
As endothelial cells are lost, the neighbouring cells shuffle along and swell to fill the gaps (diagram 4 – 700 cells). This movement maintains the integrity of the dam wall, but the reduction in the number of cells reduces the overall pumping power. The cornea can remain relatively dehydrated and clear until a critical number of cells remain; this is usually around 500-700 cells/mm2. Analogous to a boat, the hull remains dry with the loss of only a few pumps. As more are lost a puddle gradually starts to collect on the floor. In the eye, this initially causes blurring of vision, typically occurring first thing in the morning. With mild swelling, the windscreen wiper effect of blinking is enough to clear this excess fluid. We are all used to waking with blurred vision that resolves within a few seconds after rousing. Overnight we stop blinking, and the windscreen wiper effect is lost. Restarting blinking in the morning clears the vision.
As more pumps are lost the cornea becomes increasingly swollen, taking longer and longer to clear each morning. Eventually, the 'ship sinks' and the waterlogging and blurring remain throughout the day.
Q&A about Fuch’s Endothelial Dystrophy
How is Fuch's Endothelial Dystrophy treated? +
It is an excellent time to be diagnosed with FED. New treatment options have dramatically improved outcomes so that, in the majority of cases, we can fully restore your vision. FED does not require treatment until your vision becomes affected. At the point your eyesight is affected we will advise you of your best treatment option.
When does Fuch's Endothelial Dystrophy need treatment? +
Treatment is only required when FED affects your vision. This point varies between people and is dependent upon: an individual's visual needs, their job, hobbies, night driving requirements etc. There are two common initial symptoms; blurring of vision in the mornings that gradually clears throughout the day, or increasing difficulties driving at night.
Is everybody suitable for DMEK? +
Most people who need an endothelial transplant are suitable for DMEK surgery. Mr Darcy specialises in complex cases and will advise you of your options.
What is the difference between DMEK and DSAEK? +
DMEK is an iteration of DSAEK with many benefits, including improved visual outcomes and lower graft rejection rates. DMEK only replaces the affected endothelium and Descemet's like-for-like. In contrast, DSAEK also transplants some stroma, increasing the thickness of the graft.
What if I am not suitable for DMEK? +
DMEK has recently superseded Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK). DSAEK similarly uses donor cells to replace your affected endothelial cells. DSAEK is still an excellent option for some people, with good visual outcomes.
Who is suitable for Primary Descematorhexis? +
We reserve Primary Descematorhexis for FED that only affects the central cornea. You must also have good endothelial cell counts at the edge of the cornea. We will advise you if this is an option available to you.
How does Primary Descematorhexis work? +
Stage 1 Surgery - Mr Darcy removes the centrally affected Descemet's and endothelium.
Stage 2 The Restorative Phase - Your remaining endothelial cells shuffle along and swell to fill in the gap created during surgery. You will be given specialist drops to help your cells migrate during this process.
I have Fuch's Endothelial Dystrophy and cataract. Should I have a combined procedure? +
The endothelial cells in FED have accelerated programmed cell death, meaning the number of cells decreases more rapidly than a person without FED. The rate of endothelial cell loss varies between people with FED, related to an individual's genetics.
Any surgery inside the eye causes the loss of some endothelial cells. When performing cataract surgery alone, we use special techniques to minimise this, protecting the endothelium. Cataract surgery alone can result in ongoing swelling in the cornea, which will impede your vision and can adversely affect any future DMEK surgery. We recommend a specialist assessment before having cataract surgery. We will guide you whether a combined procedure is more appropriate - DMEK plus cataract.