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Lindsay C. Romero, Jessica H. Mathew, John D. Goosey, Jan P. Bergmanson; Peeling and Melting of Anterior Limiting Lamina in Keratoconus. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5176.
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To detail ultrastucturally the destruction and removal of anterior limiting lamina (ALL) in keratoconous and seek structural implications from the loss of a corneal layer.
Fourteen keratoconic corneal buttons surgically removed with a keratoplasty procedure and 4 normal corneas from eye bank sources were examined. A fixative containg 2% glutaraldehyde in 80 mM sodium cacodylate at pH 7.4 and 320 mOsm/kg was used for minimal tissue shrinkage and distortion. Samples from central cone and periphery of button were processed for light microscopy (LM) and transmission electron microscopy (TEM). An Olympus BX51 digital LM and a Tecnai G 12 twin TEM were used to view specimens.
All Kc corneas had, in places, melting or complete loss of ALL but 2 had a hitherto not previously reported peeling of normal thickness ALL away from the epithelium. The peeling ALL measured 10.7 and 11.8um, while the control ALL were on average 8.9um. Scar tissue displaced ALL by as much as 114.6um from an epithelium that appeared more affected by the disease than the underlying stroma at this location.
The separation of ALL occurred where it was of normal thickness and not in places where it was thin and presumably less healthy. This raised the question of whether the signal for scar tissue formation originates from the epithelium, which has a poorly defined role in the Kc disease process. ALL peeling together with corneal thinning and lamellar fragmentation, may be an important risk factor in provoking corneal ectasia.
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