What are the symptoms?
A healthy cornea is clear and bright, however, in advanced Fuchs’ dystrophy, the cornea can become hazy and dull due to swelling which affects your quality of vision. Typical symptoms include:
- Foggy vision, particularly in the morning when you wake up
- Glare and haloes around bright lights
- Typically, vision begins to improve toward the end of the day but this may not happen in advanced cases
While 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 until they are in their fifties.
What are the causes?
Some reduction in endothelial cells is normal and happens because of ageing. A baby is born with roughly 4000 endothelial cells per square millimetre, whilst an 80-year-old without Fuchs’ dystrophy has an endothelial cell count usually between 1500-2500 per square millimetre. The cornea remains clear even up to around 800 cells per square millimetre. However, 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.
Fuchs’ dystrophy occurs as a result of abnormal genes that affect 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.