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D.G. Dawson, G.P. Holley, I. Schmack, H.E. Grossniklaus, H.F. Edelhauser; Hydropic Degenerative Keratocytes Contribute to Corneal Haze in Edematous Human Corneas . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2993.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate normal human corneas using ex vivo confocal microscopy before and after inducing corneal edema. Histology and ultrastructural studies were correlated to the confocal images.
Twenty–four normal human corneosceral specimens (12 donors) were obtained from the Georgia Eye Bank. Paired corneas (right and left eye) were initially mounted in an artificial anterior chamber for specular perfusion endotheial studies. Both corneas of each pair were perfused for 1 hour with BSS Plus to allow the endothelial cells to regain function. The right eye of each pair was used as a control and was perfused with BSS Plus at a pressure of 15 mm Hg for 4 hours. The left eye of each pair was perfused with 1 of 4 different groups: 0.9% NaCl saline solution, sterile water, BSS Plus after endothelial scraping, and BSS Plus at a high pressure (55 mm Hg). Confocal microscopy was performed on the corneas before and after completion of the perfusion periods and specular microscopy was performed every 30 minutes during the perfusion to measure corneal thickness. Specimens were subsequently submitted for light and electron microscopy analysis.
Pre–perfusion confocal microscopy of the control and treated corneas showed a normal distribution of keratocytes in the stroma with an average haze value of 36 U. At the conclusion of the perfusion time period, the control corneas slightly thickened on average 40 um, but remained transparent with an average haze value of 45 U. In contrast, the treated corneas increased in thickness on average 200 um and became edematous and hazy with an average haze value of 108 U. The ex vivo confocal microscopy sections of the edematous corneas showed that most of the haze appeared to come from extremely swollen and brightly reflective keratocytes. Histologic and ultrastructural studies demonstrated loss of artifactural clefting, wide and irregular collagen fibril spacing, and severely hydropic degenerative keratocytes.
Our human laboratory model that produced corneal edema shows that a significant amount of stromal haze was from osmotic keratocyte degeneration, which corresponds to the hydropic degenerative changes seen in the stromal keratocytes histopathologically. Extracellular lakes of fluid and irregular collagen fibril spacing only mildly accounted for the increased haze seen on ex vivo confocal microscopy images.
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