The cornea is one of the many essential components of the eye that enable us to see distinctly. It is a clear dome shaped membrane that covers the front of the eye and forms the most powerful part of the overall focusing mechanism acting as the outermost lens.
The cornea itself is made up of five layers:
• The epithelium at the very front – very smooth and sensitive to touch, this layer prevents infection and dirt
• Bowman’s layer – a very thin barrier layer
• The stroma – this is not really just a layer since it makes up 90 per cent of the cornea thickness. It is mainly water with some collagen fibres which give strength and allow focussing
• Descemet’s layer – another very thin barrier layer
• The endothelium – this layer is extremely thin and performs the function of a pump or filter, ensuring the correct amount of water is in the stroma. If this layer fails to function, then cornea can swell up and become cloudy, leading to Fuchs dystrophy.
So what is Fuchs Dystrophy?
The Austrian ophthalmologist Ernst Fuchs was the first to identify one of several eye disorders including corneal clouding now known as Fuchs’ dystrophy, having been shortened form the original endothelial dystrophy.
Dystrophy refers to the condition of tissue or cells wasting away. Fuchs’ realised the endothelial layer can degenerate and become thick and cloudy, so much so that the cornea changes shape and ceases to function as an efficient focussing mechanism.
Once established, the condition steadily worsens, to the extent that vision is totally lost; the only recourse is a corneal transplant.
Who gets it?
Whilst the condition is relatively rare, anyone is prone to developing the disorder, however those people with a family history are most at risk. If one of your parents have the condition, then there is a 50% chance of inheriting – fortunately if you do NOT have the condition then you will not pass it on.
As far as groups of people are involved, Fuchs’ dystrophy is found in men more than women and in those aged over fifty.
What are the symptoms?
• Cloudy or foggy type vision, but only in the mornings at first
• Vision becoming worse in the afternoons as time progresses
• Seeing a halo effect around lights and sensitivity to their glare
• Increasing eye pain
• The cornea having a cloudy appearance and very small blisters may appear on the epithelial layer (called bullous keratopathy), the layer at the front of the cornea.
Testing for Fuchs’ Dystrophy
Several eye tests can be carried out to assist in diagnosis, including the basic optometrist’s eye tests to establish if vision is deteriorating over time. Along with the basic tests a glare test can be used to assess if light affects those results.
Other more specific tests include the use of a slit lamp to establish whether or not there are any irregularities in the endothelial layer at the back of the cornea, a corneal pressure test and a corneal thickness test.
The corneal thickness test is important as it tells the optometrist if any swelling has begun – a sure sign something is amiss.
What can be done prior to transplant?
There are a few things that can be tried in order to slow down development before a transplant is finally necessary:
• Eye drops can be prescribed to reduce the amount of water in the cornea.
• A few times a day it’s a good idea to dry the eyes, not with tissues or a towel, but with a hairdryer! Obviously it’s necessary to be careful – hold the drier blowing only warmish air from side to side with the arm fully extended.
• Try wearing soft contact lenses
The final action – a corneal transplant
Years ago it was common practice to transplant a complete donor cornea.
Innovative surgical techniques now make it possible for up to three recipients to benefit from the kind action of one donor.
A single cornea can be utilised to act as tissue for different eye locations and instances, with transplants occurring on the same day.
For example in the case of a person suffering from Fuchs’ dystrophy it’s only the rear endothelial layer than need to be removed and replaced; the procedure is called a “Descemet stripping automated endothelial keratoplasty” – or fortunately for us – DSAEK. This procedure is quite complex and must be performed by an expert corneal surgeon.
The outcome for corneal transplant recipients is very good. In cases where there is some rejection, then a management protocol can usually be implemented to make the transplant work.
And after a transplant?
Years of free of any further symptoms are normally expected