The cornea is the clear, round window of tissue that covers the iris and lens of the eye. There are five layers to the cornea, the innermost being the endothelium (read about corneal anatomy here). This layer is made of a sheet of endothelial cells and is essential in keeping the cornea clear. They accomplish this by working as a pump to keep a regulated amount of water in the stroma (the middle layer of the cornea).
However, in a diseased state like Fuchs’ corneal dystrophy, the cornea can be cloudy, interfering with the ability of the cornea to focus light as it enters the eye. This can result in blurred, clouded vision that can diminish our ability to see clearly.
What is Fuchs’ Corneal Dystrophy?
Fuch’s corneal endothelial dystrophy (“Fuchs’”) is a progressive disease that affects the inner most layer of the cornea, the endothelium. Specifically, for reasons that are not fully understood yet, it causes reduced number of endothelial cells (the only cells that exist on the endothelium) and dysfunction of the remaining cells with cellular debris that causes glare.
The remaining cells then are forced to pump harder in order to keep the cornea clear. However, at a certain point, these cells can no longer keep up and the fluid starts to build up within the stroma, causing a swollen cornea. This leads the clouding of the cornea and the blurred vision. Over time, Fuchs’ tends to progress and worsen slowly. Eventually, it can lead to scarring and increased (though treatable) loss of vision. It can cause blistering of the cornea (bullae) which can be painful. Again, however, most of the time this condition is treatable with medical and surgical therapies.
Who Is At Risk?
Fuchs corneal dystrophy tends to first present in the 3rd to 6th decade of life, and happens somewhat more frequently in women. It develops in both eyes at about the same rate. Often, there is no genetic pattern that Fuchs follows. However, it can occur earlier in one’s adulthood and can run in families (it can be inherited). There is a 50% chance of a parent passing it on to their children if they themselves inherited it from their parents.
Often, the first time that this disease will show up is right after any intraocular surgery, such as cataract surgery. Although the surgery can go well and the patient can have no symptoms before surgery, these already ‘sick’ endothelial cells end up not being able to handle the microscopic trauma of the surgery. Hence, there can be a significant reduction in the number of functioning endothelial cells – even more than in a regular cataract surgery in a non-Fuchs’ patient, due to the pre-existing weakness of these cells. Hence, patients with a history of Fuchs’ dystrophy may be at a greater risk of corneal edema after ocular surgery as they have fewer healthy, functioning endothelial cells.
What are the Signs of Fuchs’ Corneal Dystrophy?
At first, a person with Fuchs’ dystrophy will awaken with blurred vision that will gradually clear during the day. This occurs because the cornea is normally thicker in the morning; it retains fluids during sleep that evaporate during the day when the eyes are open while we are awake. As the disease worsens, this swelling will remain constant and reduce vision throughout the day.
Other symptoms can include:
- Glare around light sources or objects
- Halos around objects
- Blurred / hazy / cloudy vision
- Trouble with night driving
- Decreased contrast sensitivity (colors look washed out)
- Pain in the eye (if blisters/bullae present)
Often, the symptoms may be mild overall, with slightly more blurring & glare in the morning, which clears as the day progresses. However, once the disease progresses, the vision can be blurry throughout the day. The speed of progression is variable, anywhere from a few years to 20 years, before the symptoms worsen.
How is it Diagnosed?
Your ophthalmologist can use different techniques to examine your corneas to see if you may have Fuch’s Dystrophy. These examinations can include: slit lamp examination; pachymetry to measure the thickness of the cornea; specular microscopy to actually count the cells and see their morphology; anterior segment OCT (optical coherence tomography); etc. After these data points are combined, your physician will be able to tell if the symptoms you are experiencing are due to Fuchs’ or some other disease, as many other conditions can mimic these symptoms.
This disease can be treated medically in its earliest stages, but often requires surgery such as a Descemet’s Stripping (Automated) Endothelial Keratoplasty (DSEK / DSAEK) or corneal transplant to restore your vision.
Medical management includes topical hypertonic drops, the use of a hairdryer to dehydrate the normal tear film, and therapeutic soft contact lenses. Drops can be used to draw out the fluid in the cornea and decrease the swelling. In using a hairdryer, the patient is instructed to hold a hairdryer at an arm’s length or directed across the face, to dry out the epithelial blisters. This can be done two or three times a day. Finally, a contact lens can be used to help bandage the blisters, but this is typically a temporary measure.
Definitive treatment, however, is surgical. It can either take the form of a corneal transplantation (penetrating keratoplasty, PKP), or a Descemet’s Stripping (Automated) Endothelial Keratoplasty (DSEK / DSAEK). You can find out more about these procedures on our other educational pages.