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Purpose: To define the histopathology of Salzmann nodular degeneration and suggest potential mechanisms involved in its pathogenesis., Methods: Archived corneal biopsy specimens from 5 patients with Salzmann nodular degeneration were evaluated by chemical and immunohistochemical staining to describe the structure of the Salzmann nodules and phenotypes of nodule epithelium and stromal cells., Results: Each Salzmann nodule appeared as a hypercellular mound of extracellular matrix located between a thinned corneal epithelium and a fragmented Bowman layer. Stromal cells within each nodule stained positively for vimentin, consistent with a fibroblast phenotype, whereas the epithelial cells overlying each nodule were positive for matrix metalloproteinase-2 and negative for matrix metalloproteinase-9., Conclusions: The observed epithelial expression of matrix metalloproteinase-2 overlying Salzmann nodules is consistent with chronic epithelial wounding in the disorder but does not identify a cause-effect relationship. Salzmann nodules might develop because of enzymatic disruption of the Bowman layer, anterior migration and proliferation of keratocytes, and secondary deposition of extracellular matrix. Alternatively, desiccation secondary to the elevation of the nodule might induce increased epithelial metalloproteinase expression.

This study describes the involvement of anterior chamber (AC) angle structures in patients with disseminated histoplasmosis. The postmortem eyes from three patients (aged 33, 41, and 42 years, respectively) with disseminated histoplasmosis, two of whom had acquired immunodeficiency syndrome, were examined by light microscopy using hematoxylin-eosin, periodic acid-Schiff (PAS), and Gomori's methenamide silver (GMS) stains. Electron microscopy studies of the choroid were performed in one eye. Significant numbers of budding yeast forms of Histoplasma capsulatum measuring 2-5 microns in diameter were observed within the trabecular meshwork, Schlemm's canal and in the deep intrascleral plexuses. All eyes showed massive involvement of the choroidal vasculature, including the choriocapillaris. The organisms were observed freely as well as in small clusters within the cytoplasm of circulating monocytes. The vessels of the limbal conjunctiva (two eyes) and ciliary body (three eyes) contained many Histoplasma organisms. In one eye, several budding yeast were noted in an iris vessel and in occasional histiocytes within the ciliary muscle. Blood smears containing Histoplasma organisms were observed in two cases. None of the patients had an ophthalmologic examination prior to death. Involvement of the intravascular structures of the eye as well as the AC angle was observed in three patients with disseminated histoplasmosis. The fungus most likely reached the AC angle structures by direct hematogenous dissemination or via the aqueous humor by migration from vessels in the ciliary body and iris. An abnormal retrograde blood flow into the AC angle structures may have also played an important role. We suggested that the intraocular pressure be monitored in cases of suspected disseminated histoplasmosis to detect functional alterations indicative of a blockage in the outflow channels.

A glaucoma filtering procedure was performed with the YAG laser in an eye to be enucleated for malignant melanoma. Scanning electron microscopic examination shows the extent and position of the incision and the effects of the procedure on the cornea. To our knowledge, this article represents the first report of complete perforation of the sclera in a living human eye with the use of a laser alone.

YAG sclerostomy is a filtering procedure performed entirely with the neodymium:YAG laser through a goniolens as an alternative to trabeculectomy in the treatment of glaucoma. Extremely large pulse powers have been required in the past to complete the procedure. We found that an injection of silver-stabilized protein intrasclerally prior to the procedure makes it possible to perform the procedure with low total power.

YAG sclerostomy was performed in 15 eyes of nine cynomolgus monkeys. Individual pulse energies ranged between 10 and 135 millijoules. Total pulse energy ranged between 2,000 and 36,000 millijoules in order to test the extreme range of energy that might be required. Both acute effects and chronic effects were studied in the corneal endothelium, the lens capsule, the iris, the ciliary body, the retina, and the sclera. Techniques included flat preparations of the corneal endothelium, paraffin sections for light microscopy, and scanning and transmission electron microscopy. Our conclusion is that individual pulse energies of up to 135 millijoules with a total of up to 36 joules of energy are safe in monkey eyes when performing YAG sclerostomy.

Two patients who had highly elevated pigmented masses associated with a chorioretinal scar were observed clinically for several years. The scar was due to presumed histoplasmosis in one patient and toxoplasmosis in the other. Histopathological examination disclosed choroidal and subretinal masses consisting of hyperplastic retinal pigment epithelium. The difficulty in making the diagnosis of RPE hyperplasia in such instances is discussed.