A granulomatous reaction was identified in six corneal buttons obtained from patients with herpetic stromal keratitis. The inflammation, characterized by lymphocytes, plasma cells, macrophages andSevere herpetic stromal keratitis is an important cause of ocular morbidity (Figure 1). A granulomatous reaction at Descemet's membrane is a well-documented response to chronic herpetic stromal keratitis.' It has been suggested that this inflammatory response at Descemet's membrane is non-specific as it is seen in various conditions.2We studied six corneal buttons with light microscopy, scanning electron microscopy and immunohistochemical stains in an attempt to ascertain the pathogenesis of this unusual reaction.
MATERIALS AND METHODSThree hundred and fourteen corneas received over the past three years were reviewed. A granulomatous reaction was identified in six corneas, and these formed the basis of this study. The corneas were fixed in 10% buffered formalin for 12 hours. In three cases the gross specimen was stained with the Perls' stain for haemosiderin to demonstrate any iron lines or scarring. These corneas were bisected across the densest positively stained area in order to maximize the yield of scarring in the sections. The other three cases were bisected at random.
Summary
The dilator pupillæ of postmortem human eyes was examined by light microscopy and scanning electron microscopy. The results are reviewed in association with reports in the literature. The dilator pupilæ forms a dense layer with both muscular and epithelial functions (myoepithelium). During muscular activity the myoepithelial cells undergo marked intracellular rearrangement from long and fusiform in miosis, to columnar in wide mydriasis. During contraction of the dilator the myoepithelial cells change in a manner vastly different from mesodermal, visceral, smooth muscle cells.
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