Fuchs' Dystrophy
Fuchs’ Corneal Dystrophy (FCD) is an inherited condition that affects the inner layer of the cornea but no other part of the eye. It is not linked to any general health diseases and is an isolated ocular abnormality.
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What is Fuchs' Dystrophy?
Fuchs’ Corneal Dystrophy (FCD) is an inherited condition that affects the inner layer of the cornea but no other part of the eye. It is not linked to any general health diseases and is an isolated ocular abnormality.
The cornea is the transparent dome that forms the front, outer protective coat of the eye. The cornea is comprised of collagen, the same material that forms the white globe of the eye or sclera. The collagen strands are specially arranged in sheets oriented and spaced relative to those above and below and tightly packed together to result in clarity and transparency of the tissue. Any disruption of this arrangement leads to loss of transparency and therefore loss of vision.
The front of the eye is full of nourishing fluid called aqueous humour that soaks through the inner layer of the cornea hydrating it. This would lead to corneal swelling but for a layer of cells called the corneal endothelium which actively pumps the fluid back out, into the eye. This keeps the cornea at the correct thickness and therefore maintains transparency. We are born with a finite number of these cells, between 5000 and 6000 cells in each square millimeter of tissue but we lose them gradually throughout life and they are irreplaceable. Under normal circumstances we have more than sufficient numbers of cells to maintain corneal clarity for our lifetime unless they are lost through disease or injury.
Symptoms of Fuchs' Dystrophy
In the early stages of the condition there may be no symptoms but the first symptom is typically blurred vision on waking that gradually clears throughout the morning. This is because overnight when the eyelids are closed, fluid cannot evaporate from the surface of the eye leading to hydration of the cornea which is slow to clear because of the reduced cell count.
Later stages of FCD are characterized by the cornea taking longer to clear and vision gradually becoming more blurred. As cells tend to be lost toward the centre of the cornea, this increases the impact of the condition on vision. Eventually, the fluid will form microscopic blisters which migrate through the cornea and may break at the surface of the eye, this is called bullous keratopathy.
Symptoms of FCS include:
- Grittiness or the feeling of a foreign body in the eye
- Photosensitivity or increased sensitivity to light or glare
- Increasingly blurred, central vision
- Variation with environmental conditions. Symptoms worsen in humid environments e.g. after taking a shower or bath
- Pain in bullous keratopathy
Diagnosis of Fuchs’ Dystrophy
Diagnosis of FCD is often made on clinical examination as there may be characteristic findings of droplet-like deposits or corneal guttata visible on the endothelium, visible swelling of the cornea or blisters at the surface. These findings can be investigated further using elevation topography or ultrasound scanning to accurately measure the corneal thickness or by specular microscopy to image or count the cells directly.
Treatment of Fuchs’ Dystrophy
There is no cure for FCD and many people will not require specific treatment if they do not have significant symptoms as there are no medical treatments that can slow down the progress of the condition.
Non-invasive treatments includes the use of a hair dryer used at arms-length to blow warm or cold air (not hot) across the cornea and dry it, or the use of 5% NaCl (five percent sodium chloride) eyedrops which also have a drying effect on the cornea by drawing fluid out of it by osmosis.
If symptoms worsen to significantly impact vision then corneal transplant surgery may be required.
Fuchs’ Dystrophy FAQ’s
If you do not have an affected parent, the prevalence of the condition is between 4 – 10% and higher in European countries relative to other areas of the world. If your mother or father had FCD you will have an approximately 50:50 chance of developing the condition. FCD is more common in women than men in the typical late-onset disease.
This is a condition where the same symptoms as for FCD are experienced but the cause is mechanical loss of endothelial cells often following cataract surgery. Both PBK and FCD can co-exist in the same eye. The treatment of PBK is the same as for FCD.
Yes. Extra precautions should be taken if you are due to undergo cataract surgery to protect the endothelium as far as possible. However carefully cataract surgery is performed, endothelial cell loss will occur to a greater of lesser extent so the possibility of corneal decompensation or swelling should be addressed prior to surgery.
Yes, lubricating drops will help to keep the eye comfortable and will not worsen FCD. Symptoms of FCD are usually worse in the morning when using sodium chloride 5% eyedrops or a hairdryer at arm’s length to dry the cornea is most effective. Symptoms of DED are usually worse in the evening when lubricating drops will be of greater benefit although symptoms will vary according to particular circumstances.
As the condition progresses vision does continue to deteriorate so that severe visual loss will result unless corneal transplant surgery is performed. Even in advanced cases however, because the retina and optic nerve are not affected sight will not be totally lost.
