This is a slowly progressive condition of the cornea causing blurring of vision. It is caused by a deficiency in the number of cells on the back of the cornea (decreased endothelial cell density). The function of these cells is to pump the cornea dry so that the collagen fibrils are quite close together. This makes the cornea transparent. When the cornea becomes water-logged, the collagen fibrils move apart and the cornea becomes less transparent. When you are born, the corneal endothelial cell density is between 3500 and 4000 cells per square millimetre. By the time Fuch’s is noted, corneal endothelial cell density may be as low as 1200 cells per square millimetre and by the time the count is 800 cells per square millimetre, a corneal transplant is required. Unfortunately, these cells cannot divide and progressively die with age. The corneal cell density is reduced by intraocular surgery, which means that cataract surgery can precipitate worsening of vision (corneal decompensation) in patients with Fuch’s.
The condition is often picked up by an optician before any symptoms develop. The first symptoms are blurring of vision in the morning (the cornea tends to swell overnight and dry out during the day). When advanced, vision is blurred all the time and the eye may become painful because of swelling and erosions of the corneal epithelium which lines the front of the eye.
No treatment can prevent progression of this condition. Initially, the vision may improve with hyperosmolar drops and ointment (sodium chloride 5%), which dry out the cornea. Some patients derive benefit from using a hair dryer at arms length to dry out the cornea. Often patients can be observed for many years without surgical intervention. Eventually, however, many patients require either full thickness corneal transplantation or transplantation of the back layer of the cornea only (endothelial transplantation).