Spotting Fuchs' Dystrophy
BY WILLIAM L. MILLER, OD, PHD, FAAO
Upon examining a 38-year-old patient who presented with bacterial conjunctivitis, I came across a finding that hadn't appeared in her records through nearly 10 years of consistent routine eye care. Looking beyond the conjunctivitis, I noted a high level of central and paracentral guttata. The patient had no symptoms, and I made a tentative diagnosis of Fuchs' Dystrophy.
The Fuchs' diagnosis tipping point for many clinicians is the presence of obvious and numerous guttata accompanied by symptoms related to corneal edema. However, other practitioners may make their diagnosis based on the guttata (magnitude and number) without obvious symptoms. For most, treatment intervention occurs when the symptoms manifest, requiring the clinician to address the outcomes of the disease process.
Figure 1. Appearance of Fuchs'
Dystrophy guttata with confocal microscopy.
Occurring typically in the fifth decade of life and more commonly in women, Fuchs' Dystrophy is an autosomal dominant corneal dystrophy with a wide range of presentations and symptoms (or lack thereof). Early in the course of the disease, many patients are asymptomatic and practitioners observe little except a few guttata, which are excrescences of basement membrane that squeeze between the endothelial cells, disrupting the normal barrier function of that layer. Additionally, the posterior limiting lamina increases in thickness during the course of the disease.
Biomicroscopy shows the guttata as bright, beaten entities in the endothelial layer. A specular or confocal microscope shows a more precise picture in which they are black in contrast to endothelial cells (Figure 1). Base your differential diagnosis on the pattern and extent of the guttata and distinguish it from pseudoguttata (usually related to injury, trauma, infection or inflammation) and posterior polymorphous dystrophy (same level but appearing as sinewy strands or vacuolated spots).
Chandler's syndrome (a type of iridocorneal-endothelial syndrome) can have a similar beaten appearance with biomicroscopy, but its other ocular signs (iridocorneal adhesions, iris atrophy) and laterality (unilateral) distinguish it from Fuchs' Dystrophy.
Treatment when the patient is symptomatic aims at reducing corneal edema and consists of topical hypertonic solutions. In cases of increased edema and bullae formation, bandage contact lenses may help reduce pain. Topical nonsteroidal anti-inflammatory agents may also relieve pain, but they may adversely affect epithelial wound healing, thus negating the pain relief.
A progressive or intractable edematous response warrants a penetrating keratoplasty (PKP). Fuchs' Dystrophy accounts for nearly 15 percent of all PKP operations in the United States and almost nine percent in the United Kingdom. An alternative surgery, deep lamellar keratoplasty or endokeratoplasty, involves replacing only the endothelium and is reserved for patients who have an aberrant endothelium and posterior stromal edema.
Managing the Patient
In this case, I appropriately counseled the patient about Fuchs' Dystrophy. Although I didn't initiate any treatment, I did educate her about possible interventions, should the need arise. I also gave her a topical antibiotic for the bacterial conjunctivitis.
Dr. Miller is on the faculty at the University of Houston College of Optometry. He is a member of the American Optometric Association and serves on its Journal Review Board. You can reach him at firstname.lastname@example.org.