Recently Dr. Charles Faron, D.O, spoke to the Chicago Area Local Group. He treats post-surgical patients at Chicago Cornea Consultants offices and at Rush Medical Center. Since most of the group are Fuchs’ patients, he chiefly addressed Fuchs’ questions and problems.
Cornea and Fuchs’ Diagnosis and Facts
The cornea, he noted, is responsible for 75% of our ”refractory power, or what we call “ vision,” and serves as a barrier to infections. Made up of four layers (some researchers say five layers), most of the refractive power resides in Bowman’s Layer. He repeatedly stressed that refraction (focus and acuity) demands that all layers of the cornea must be in perfect condition for best vision. For many patients, the difference between ophthalmology and optometry is unclear. Dr. Faron told the group that simply put, the optometrist is our eyes’ primary care doctor. They can diagnose and prescribe, but only medical doctors, ophthalmologists, can do surgeries. For most people after forty years old, Fuchs’ is the most common corneal dystrophy and the disease responsible for the greatest number of corneal transplants, he told the group.
Dr. Faron emphasized that a slit lamp exam is the bare minimum at an exam, and a corneal surface mapping should be done at every exam. Failure to perform the slit lamp exam, he believes, is a serious omission rising to the level of malpractice. The slit lamp brings the back of the cornea into view. There the doctor may see guttatae (guttae). Some number of these small bumps are normal as we mature and age. A larger number than typical for the patient age is an indicator of Fuchs’. Corneal mapping, or “pachymetry,” is also essential both to help diagnose Fuchs’ and to track cornea health. It lets the doctor know if there are uneven patches that cause astigmatism and may reflect the swelling or “edema” of Fuchs’. This is the second test Dr. Faron said is essential with any regular eye examination.
A measurement of corneal thickness is to a diagnosis of Fuchs’. As more pumping cells die or become ineffective, the cornea swells with retained fluid. Once corneal thickness reaches 620, a transplant is needed. Fuchs’ affects both eyes, but not always with the same symptoms or at the same severity at the same time. It is always bilateral. Though Fuchs’ is primarily hereditary with each child of a Fuchs’ patient having a 50/50 chance of developing the symptoms, it can sometimes occur without a heredity factor. Glare, he stated, is another major diagnostic indication of the need for a corneal transplant for Fuchs’. He emphasized that even patients with 20/20 vision can be blinded by the effects of their Fuchs’ in glare conditions. When glare is blinding, it tells the doctor that a transplant is needed as soon as possible. He gave the example of meeting someone who is seated in front of a sunny window, but being unable to recognize the features of that person’s face due to glare.
Waiting For Surgery
Blisters, often painful, on the surface of the eye are evidence that Fuchs’ has progressed significantly. They recur and cause scarring on the front of the cornea, eventually blocking incoming light and causing near blindness. When Fuchs’ affects daily activities it is time for transplants. Patients who wait too long for transplants risk scarring on the epithelium so disabling that only a full thickness transplant (PK) is possible to restore sight. There are several other treatments in the experimental stages, but not everyone is a candidate for some, and others are in the pipeline not yet in human trials.
Fuchs’ with Other Problems
Cataracts commonly occur at the same life stage as do Fuchs’ symptoms. He stated strongly that the surgeon needs to know about the Fuchs’ before surgery in order to take proper precautions to protect the Fuchs’ endothelial layer during cataract surgery. This employs a visco-elastic gel during surgery and can require an incision that is out of the line of central vision. Even when done properly, cataract removal can accelerate and worsen Fuchs’ symptoms making a transplant urgent. When choosing the artificial lens to implant after cataract surgery, Dr. Faron strongly stated that a multifocal lens is never a good choice.
Glaucoma, he said, and Fuchs’ go hand in hand. The same patient seems to have a high likelihood of having both. Further, some patients will develop high intra ocular pressure as a response to the anti-rejection steroid drops used for the first year after the transplant. These patients are termed “steroid responders.” They must add a drop to control pressure to their prescriptions after transplant.
Keratoconus and Fuchs’ can also occur, he told the group. Corneal dystrophy is not necessarily limited to one per patient. Epithelial Basement Membrane Dystrophy is another dystrophy that can and fairly often does accompany Fuchs’.
DSAEK and DMEK Transplants
Both Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) and Descemet’s Endothelial Keratoplasty (DMEK) are “refractively neutral.” Neither changes the ability of the eye to produce useful vision or changes the mechanics of vision. DSAEK uses a donor Descemet’s Membrane and the cells that cling to it. It also uses a small bit of stroma (layer adjacent to Descemet) to stabilize the graft. This extra tissue makes the graft thicker and thus less likely to result in perfect 20/20 vision. However, it can get very close. DMEK uses only the Descemet’s Membrane and the cells on it. Thus it is thinner and less likely to alert the immune system that foreign tissue has entered the body so reducing the already small likelihood of rejection. The graft is so thin that it does not thicken the cornea, and thus it is more likely to achieve 20/20 vision.