What is Fuchs' Dystrophy?
Fuchs' endothelial dystrophy is a progressive disease of the corneal endothelial cells that leads to clouding of the cornea and eventual reduction in vision.
The endothelial cells of the cornea are a specialised single layer of cells on the back surface of the cornea that pump water out of the cornea. This keeps the cornea thin and clear. Endothelial cells do not have the ability to regenerate and hence if they are damaged the cornea gradually begins to swell with water, making it hazy and leading to loss of vision. Patients with Fuchs' may notice this as foggy vision, particularly in the morning when you wake up. This can be like looking through a misted window. Typically, vision begins to improve toward the end of the day, but this may not happen in advanced cases.
A baby is born with roughly 4000 endothelial cells per square millimetre. In an 80-year-old without Fuchs' dystrophy the endothelial cell count is usually between 1500-2500 per square millimetre. This reduction in cell numbers is normal and happens because of ageing. The cornea remains clear even up to around 800 cells per square millimetre. In a patient with Fuchs' there is an accelerated rate of cell loss, such that a 50 years old may have less than 500 cells per square millimetre. In addition, endothelial cells in Fuchs patients are abnormal and can accumulate abnormal proteins resulting in small bumps on the back of the cornea called guttata. These changes can result in symptoms of glare and haloes around bright lights and a decrease in the quality of vision.
Whilst early signs of Fuchs' dystrophy can be detected by an eye surgeon even in patients in their thirties, it is relatively uncommon for patients to become symptomatic and require surgery till they are in their fifties.
Fuchs' dystrophy occurs as a result of abnormal genes that affects the function of endothelial cells. Not all of these are well understood yet. Whilst Fuchs' can be expressed by different generations of the same family, it can also commonly occur sporadically where there is no previous family history. Inheritance of the Fuchs' gene is also variable and the fact that you have Fuchs' doesn't always mean that your offspring will express Fuchs' endothelial dystrophy.
Medical Treatment of Fuchs' Dystrophy
During the early stage of Fuchs dystrophy when swelling of the cornea is still mild, your doctor may prescribe you sodium chloride (salt) drops or ointment. By increasing the salt content of the tears water is drawn out of the cornea by osmosis.
Salt drops do not cure Fuchs' Dystrophy and simply delay the need for surgery in early cases.
Surgery for Fuchs' Dystrophy
Fuchs' dystrophy ultimately leads to increasing loss of corneal endothelial cells leading to increasing difficulty with vision. This can range from constantly blurred vision to glare and haloes around bright lights at night. When the patient reaches this stage they usually require a surgical operation to replace endothelial cells in the cornea - endothelial transplantation. Endothelial transplantation may be combined with cataract surgery. Mr Angunawela is one of the few UK surgeons that performs the latest endothelial specific small incision transplant operations - DSAEK and DMEK. It is no longer considered modern practice to perform full thickness corneal transplantation (PK) for Fuch's dystrophy. To read more about surgery click here