New Treatments for Fuchs’ Dystrophy
It seems that every year gets better and better for patients with Fuchs’ Dystrophy. Treatment options have greatly improved over the past 10 years, with surgery becoming less invasive, recovery time faster and visual results better. Beyond surgery it appears more and more likely that medical options for the condition will one day be available, removing the need for surgery altogether.
What is Fuchs’ Dystrophy?
Fuchs’ dystrophy is a condition affecting the innermost layer of the cornea, the clear window at the front of the eye. This layer is referred to as the endothelium. It is a densely packed sheet of hexagonal cells with a special function- to pump fluid. To nourish the cornea, fluid constantly drifts into it from within the eye. The endothelium must pump it back inside, creating a cycle, preventing the cornea from swelling and keeping it clear. Without a healthy endothelium the cornea swells and vision is lost.
In Fuchs’ dystrophy the endothelium slowly degenerates, forming clumps called “guttata”. On their own these guttata can cause blur or scatter light to produce glare. If too many form, the ability of remaining healthy cells to pump fluid is reduced and swelling begins. The earliest sign of this may be blurry vision first thing in the morning that takes more than a few minutes to clear.
Figure 1 a cornea with Fuchs’ dystrophy. The grey haze centrally is created by guttata
Figure 2 The front of the eye- side view- the cornea is the clear dome shaped “window” at the front
Figure 3 the endothelium is the layer of cells on the inside of the cornea
Figure 4 looking from the bottom up, these cells are densely packed and hexagonal
What Causes Fuchs’ Dystrophy
Most agree that Fuchs’ is a genetic condition, but there are several genetic defects that have been linked to the condition thusfar. It may be that what we recongise as Fuchs’ dystrophy is the final stage common to several genetic problems in the endothelium.
How is it treated?
Until recently, the only accepted therapies for Fuchs’ dystrophy were drops aimed at drying out the swollen cornea, or if the condition was severe, replacing the whole of the central cornea with a cornea from an organ donor- a penetrating graft or keratoplasty. Recovery from this surgery was long, with visual results variable.
Pioneering work by Dr. Gerret Melles in the Netherlands led to the discovery that selective replacement of only the back layers of the cornea was possible through keyhole surgery. If a part of your car engine is damaged, we replace that part, not the whole engine. Similarly if only the endothelium is damaged it makes perfect sense to remove only this damaged layer and replace it with the same layers from an organ donor. We call this “endothelial keratoplasty”. This has been the greatest recent revolution in corneal surgery.
Initially we removed endothelium and replaced it with the inner 20% of the donor cornea. This procedure was called a “DSEK”. Compared with the older style penetrating keratoplasty this immediately improved predictability of visual results and recovery times. Most corneal surgeons are now progressing to offer “DMEK”- in which only the endothelial cells and their supporting membrane (the innermost 2% of the corneal thickness) is transplanted. This further improves visual results and recovery times, occurring through a keyhole incision half the size used for DSEK. Instead of the 16 stitches we used to place for a penetrating keratoplasty, it seems we are now down to only 1.
Figure 5 DMEK graft on first day after surgery, the air bubble seen is used to “squeeze” the graft in position
What is coming next?
Recently a patient from Sydney Eye Hospital was observed to heal her cornea after removal of the diseased endothelial layer without the need for a corneal graft at all. This is leading to further research at the Eye Hospital to determine if all cases of Fuchs’ dystrophy need a graft to restore clear vision. Elsewhere in the world medical therapies and injections are being trialled.
It is a good time to be a Fuchs’ patient!
Click here To read an interview with Dr. Moloney on Fuchs’ Dystrophy”.