Fuchs' Corneal Dystrophy and Cataract Surgery
Fuchs' Corneal Dystrophy is disease of the corneal endothelium; the inner lining of the cornea. It causes blurred vision. In this post, you will learn about what causes Fuchs, how it is diagnosed, how it might affect your cataract surgery, and how it is treated and potentially cured.
Anatomy
Below is a cross section of the cornea showing three major substructures; the epithelium, endothelium, and stroma. The epithelium is on the surface of the cornea, the endothelium is on the inside, and the stroma, or body of the cornea, is in between.
Figure 1. Fuchs' corneal dystrophy is a disease of the corneal endothelium.
This next picture is an actual cross section of the cornea created by a high technology imaging system.
Figure 2: OCT image of the anterior segment of the eye
The stroma tends to absorb fluid, and when it does so it swells. It becomes thicker and less clear. This is where the epithelium and endothelium become important. Both cell layers act as water pumps. They pump water out of the stroma.
A well functioning corneal endothelial cell layer is essential to maintaining corneal clarity. The endothelial cell layer is only one cell layer thick and does not regenerate. So if there are not enough of these cells, or if the cells don’t work right, the endothelium can’t perform its pumping function adequately. The cornea retains water, gets thick and loses its clarity.
Fuchs' Corneal Dystrophy is a disorder in which there are not enough endothelial cells or they don’t work right. Most people who have it don’t experience any symptoms until they are at least 50 years old, and some never have any symptoms. Women are at slightly more risk than men, and the disease is bilateral, meaning it occurs in both eyes.
Symptoms
The first symptom of Fuchs' Corneal Dystrophy is painless blurred vision in one or both eyes in the morning. It takes awhile- perhaps hours- to get better. (Note- blurred vision for a few minutes after getting up in the morning is not a symptom of Fuchs.)
Morning blurring occurs because, for reasons that are beyond this discussion, the endothelial pumps have to work harder at night when your eyes are closed. By morning, those pumps are tired. They can’t remove fluid fast enough and have gotten behind. The stroma is full of backed-up fluid and the cornea is not clear. Once your eyes are open, the endothelial cells’ job becomes easier. Over an hour or two the pumps catch back up, and the cornea slowly clears.
Fuchs is a progressive disease. Morning blurring might initially last 30-60 minutes, then last all morning, and then perhaps persist all day.
Fuchs' and cataract surgery
Even in the most expert hands with the state of the art in equipment, cataract surgery is a stress for the corneal endothelium. Fuchs which was not symptomatic before surgery can become symptomatic after surgery. The cornea might remain blurry for weeks to a month or more, rather than just a few days.
Very mild Fuchs is not uncommon. The chances that your postoperative recovery might be affected at least a little bit by Fuchs is very roughly 1-5%.
Your cataract surgeon will look for Fuchs before your cataract surgery. He or she will look for microscopic bumps called guttatae at the slit lamp. Guttatae may be visible to your ophthalmologist well before you have any symptoms. Many surgeons also measure baseline corneal thickness (pachymetry) and some even have the equipment to assess the density of the corneal endothelial cells. This last measurement is the most precise.
What happens if your surgeon identifies Fuchs before your surgery? Your surgeon may be able to perform your surgery without any particular precautions. It may not affect your post op course at all. Or your vision may remain blurry a little longer after your surgery than in most patients.
Treatment of Fuch's with DSAEK
Mild Fuchs can be treated with eyedrops. If your corneal thickness and endothelial density readings indicate more advanced Fuchs, your surgeon may recommend a corneal endothelial cell transplant either during or after your cataract surgery. This procedure is called DSAEK.
DSAEK replaces your corneal endothelium with a sheet of healthy human donor endothelial cells. Your own endothelium is gently scraped away, and the donor endothelial cell sheet is placed carefully on the inside of the cornea. The donor endothelium sticks quite well and can stay there for the rest of your life.
Sometimes, Fuchs is subtle enough that it is not identified until the endothelium is stressed by cataract surgery. When this happens, you might unexpectedly experience blurred vision for longer than other patients in the waiting room, and may even need DSAEK after cataract surgery to get the ideal vision from your surgery. This is unlikely, but can occur.
If you have Fuchs, there is some possibility that you will have a longer postoperative recovery after your cataract surgery. Thankfully, though, Fuchs' Corneal Dystrophy is a treatable disease.
Christopher Kuntz, MD has 20 years of experience performing cataract surgery and counseling patients regarding their choices. He is the author of the patient education website https://www.cataractsurgerydesign.com.
