|Fuchs Endothelial Dystrophy
Signs and Symptoms
The clinical and histopathological progression of Fuchs is complex, but can best be divided into three stages, which usually span 10 to 20 years. In the first stage the patient is initially asymptomatic, but manifests central irregularly distributed guttata warts and geographically arranged pigment dusting. Occasionally, a diffuse brown pigmentation of the central posterior surface is also seen. Histologically, the endothelial cells show degeneration and deposition of abnormal Descemets membrane material.
In the second stage the patient develops stromal and epithelial edema, with symptoms of glare and hazy vision. Visual acuity is usually 20/30 or better. As edema increases, the stroma thickens centrally, the opacity spreads peripherally and the epithelium develops bullae, which correspond to intraepithelial lakes of fluid. As stromal edema increases, Descemets membrane develops folds and vision falls. Eventually, the benefit of better vision late in the day is lost, the epithelium becomes more bullous, and pain and photophobia develops.
In the third phase, subepithelial connective tissues appears centrally. This is an avascular tissue that does not migrate in from the periphery like pannus, but arises in the central cornea. Clinically, it appears as an irregular, dense, gray, swirling sheet of scar tissue. Histologically, it consists of active fibroblasts and of large and small collagen fibrils between Bowmans layer and the epithelium. In advanced cases, the stromal edema and epithelial bullae disappear as the stroma scars, and the patient becomes more comfortable even though the visual acuity is severely reduced.
A therapeutic soft lens (bandage lens) is beneficial in alleviating patient discomfort. A loosely fitting, flat, high-water content soft contact lens will decrease the irregular astigmatism and the pain from ruptured epithelial bullae. This mode of treatment has made life more pleasant for patients who could not afford corneal transplants or who are awaiting a triple procedure with advancing cataract. Take note that any elevation of IOP forces more fluid into the stroma across the compromised endothelium. Appropriate pressure reduction with topical and or oral ocular antihypertensive medications may decrease the progression and symptoms secondary to corneal edema. Corneal grafts for Fuchs dystrophy account for approximately 10 percent of all corneal grafts performed. Generally, if the graft is performed before there is involvement of the peripheral cornea, there is an 80 percent likelihood that the graft will remain clear for two years. Keratoplasty in eyes with narrow angles should include lens removal to avoid angle closure with formation of peripheral anterior synechiae. Patients with both Fuchs endothelial dystrophy and cataracts will do well with a combined penetrating keratoplasty and cataract extraction.
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Eyelids & Eyelashes | Conjunctiva & Sclera | Cornea
Uvea | Vitreous & Retina | Optic Nerve & Brain | Oculosystemic Disease
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