Fuchs' corneal dystrophy also referred to as Fuchs’ endothelial dystrophy or simply Fuchs’ dystrophy disorder affects the cornea, which is the front surface of the eye. The disease leads to vision problems.
Definition & Facts
Fuchs' corneal dystrophy is a degenerative eye disease in which the innermost layer of cells in the cornea (the endothelium) go through fairly extreme changes. The endothelium is responsible for keeping the cornea clear by maintaining the proper amount of fluid. Excess fluid can cause swelling, so the endothelium also acts as a necessary pump. When the endothelium ceases to function properly, the corneas become cloudy and swollen which causes a gradual decline in vision.
Fuchs' corneal dystrophy usually affects older adults over the age of 50, though eye doctors can sometimes detect signs earlier in young adults. Research trends show that it is more common among women than men and that children have a 50 percent chance of inheriting the disease from their parents.
Symptoms & Complaints
- Hypersensitivity to light
- Eye pain
- Foggy or blurred vision
- Seeing colored halo shapes surrounding lights (illusory palinopsia)
- Difficulty seeing in dim lighting and/or at night
- Poor vision upon initially awakening that may improve later in the day
- The sensation that something is in the eye socket
The disease typically develops over distinct two stages. The first stage may involve mild or no symptoms at all. During this early stage, the corneal swelling is usually limited to the morning, as keeping the eyes shut while sleeping prevents moisture from evaporating; vision thus tends to get better throughout the day.
Once the disease progresses to the second stage, however, vision no longer improves throughout the course of the day. Pain and hypersensitivity to light develop in this stage, and adverse climate conditions tend to worsen the symptoms.
If the disease progresses without proper treatment, scarring (often permanent) can form at the center of the cornea. Although the discomfort and irritation will lessen with scarring, a film will form over the cornea, reducing vision.
Causes of Fuchs’ corneal dystrophy are often genetic in nature. Some cases are caused by a mutation in the COL8A2 gene though in other cases, particularly those that manifest later in life, the specific mutations are unknown. Fuchs' corneal dystrophy can be an autosomal dominant disorder in how it is inherited from one generation to the next.
The genetic basis of the disease is complex and may be one of several factors. Family members can be affected to highly variable degrees and, sometimes, no symptoms or diagnoses ever occur. Fuchs’ dystrophy can also occur without a previous family history, as the genetic mutation can occur spontaneously. In many cases the cause of the disease is unknown or idiopathic.
Diagnosis & Tests
When visiting the optometrist or ophthalmologist, patients experiencing symptoms or those with a genetic predisposition may undergo a variety of tests to determine whether or not they have Fuchs’ dystrophy. The various and comprehensive tests will generally measure the clarity, thickness, and shape of the cornea in order to examine the structure and function of the endothelium.
The first and most simple measure taken is a visual acuity test, where patients will be asked to read letters and numbers off a chart from various distances. Using an instrument called a slit-lamp, the doctor will conduct a detailed examination of the cornea under high magnification to check for any changes, no matter how subtle, in the appearance of the endothelium. He or she will also perform a corneal cell count at this time.
A pachymetry is another test that may be used to measure the thickness of the cornea and detect any swelling associated with the disease. Finally, a corneal pressure test involves the doctor using drops to numb the eyes before using a pressure-gauging instrument. From a clinical perspective, the earliest signs of Fuchs’ dystrophy are tiny drop-like lesions in the endothelium (called guttata) and a reduced number of endothelial cells. These signs may be detected through the above-mentioned tests.
Treatment & Therapy
The doctor-approved treatment route for Fuchs’ corneal dystrophy will depend entirely on the stage of the disease. For patients lucky enough to receive treatment in the early onset, vision can often be improved greatly by removing the excess water from the cornea. This can be done using hypertonic eye drops that are made with 5% sodium chloride, but in some cases doctors may recommend glaucoma drops instead.
As the disease progresses to the second stage, more severe treatment methods will be required. For patients experiencing painful corneal abrasions and very poor vision, a full-thickness corneal transplantation (also called a penetrating keratoplasty) may be necessary.
Another type of transplant, deep lamellar endothelial keratoplasty (DLEK), involves replacing the endothelium and leaving the original, upper layers of the cornea untouched. This treatment has shown fewer risks than a traditional penetrating keratoplasty, but it may not be the appropriate choice for all cases. An advanced form of DLEK called femtosecond laser-assisted Descemet's stripping endothelial keratoplasty (FS-DSEK) has also been developed in recent years and has shown promising results in the treatment of the disease.
Prevention & Prophylaxis