Keratoplasty in aphakic eyes with corneal edema. Results in 100 cases with 10-year followup

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Corneal dystrophies. II. Endothelial dystrophies

In general, endothelial dystrophies present three types of clinical manifestations: 1) production of collagenous tissue posterior to Descemet's membrane which appears as cornea guttata, polymorphic excrescences or gray sheets; 2) a disrupted endothelial mosaic in specular reflection; and 3) corneal edema as a reflection of decreased endothelial barrier and pump functions. In this review, the authors discuss three endothelial dystrophies -- Fuchs', posterior polymorphous and congenital hereditary. They describe the clinical, histopathologic and biochemical features, and illustrate each dystrophy with a composite drawing. Dystrophies of the epithelium, Bowman's layer, and stroma were reviewed separately in the September-October 1978 issue of this journal.

Optometric management of Fuchs's endothelial dystrophy

Fuchs's endothelial dystrophy interferes with removal of fluid from the cornea by the endothelium. It progresses through stages of corneal guttata, corneal edema, bullous keratopathy, vascularization, and scarring, and complications such as glaucoma or infection. The optometrist can detect this disorder and manage its early stages as well as provide counseling and proper referral. This paper includes a case study and a discussion of the course and treatment of this disease.

Corneal dystrophies. I. Dystrophies of the epithelium, Bowman's layer and stroma

Most corneal dystrophies are autosomal dominant, bilateral disorders that primarily affect one layer of an otherwise normal cornea, progress slowly after their appearance in the first or second decade, and are not associated with a systemic disease. Epithelial basement membrane dystrophy and Fuchs' endothelial dystrophy are seen commonly by the general ophthalmologist; fleck, posterior polymorphous, granular or lattice dystrophies are seen more rarely, and others may never be seen in general office practice. While the distinctive clinical appearance of most corneal dystrophies allows accurate diagnosis, the integration of slitlamp findings with histopathologic and biochemical findings aids in the understanding of the clinical observations and provides a more rational basis for therapy. Transmission electtron microscopy is the most accurate method of histopathologic diagnosis. Epithelial dystrophies usually manifest intraepithelial cysts and abnormal basement membrane. In stromal dystrophies, an abnormal substance accumulates within the keratocytes or among the collagen fibrils; it may be an excess normal metabolite (like glycosaminoglycans in macular dystrophy), a material not usually present (like amyloid in lattice dystrophy), or a substance of unknown composition (like hyaline in granular dystrophy). Each dystrophy is illustrated with a composite drawing. Endothelial dystrophies will be reviewed separately in a second article.

Effects of ultrasound on the corneal endothelium: I. The acute lesion

The ultrasonic radiation utilised in phacoemulsification procedures for the removal of cataractous lenses results in the widespread production of discrete lesions in the corneal endothelium. The morphology of this induced damage has been examined in rabbit and man using both scanning and transmission electron microscopy. The illustrated results are related to both the duration of the ultrasonic exposure and to the mechanisms of damage.

[Fuchs' endothelial dystrophy--the appearance of the corneal endothelium under the electron microscope (author's transl)]

Studying the various stages of Fuchs' endothelial dystrophy with transmission and surface electronmicroscopy makes the dystrophic and degenerative changes in the endothelial and Descemet's membrane visible: dystrophic changes by the formation of tuberosities, whose structure is very similar to that Descemet's membrane, and degenerative changes by reduction in the number of endothelial cells through destruction of the intercellular connections and through cell necrosis. The second stage is the reformation of the structure by fibroblastic cells. The dystrophic cells lead to the formation of a fibrillary tissue between the cells and the tuberosity-laden Descemet's membrane, which is different from the primary structure of this tissue. The origin of these cells is unknown.

Contributions of electron microscopy to the study of corneal pathology

Most of the electron microscopic studies of pathological corneas have been done only recently. Keratoplasty has been the most important source of specimens for ultramicroscopic investigation. With the introduction of electron microscopic techniques, we have been able to confirm many light microscopic studies in pathological corneas. This contribution has been most valuable in the identification of the sites and types of pathological changes in corneal dystrophies and degenerations. This review of electron microscopic studies describes the present concepts on the nature of the histological changes in dystrophies and degenerations of the anterior and posterior corneal layers and corneal stroma. It also includes a review of some corneal inflammatory conditions as well as metabolic disorders affecting its transparency.