Combined morphologic effects of cryolathing and lyophilization on epikeratoplasty lenticules

A correlative microscopic analysis of factory-prepared epikeratoplasty lenticules, corneas stored in McCarey-Kaufman medium for two to four days, and fresh human corneas disclosed ultrastructural abnormalities in Bowman's membrane and in the corneal stroma of the lyophilized lenticules that were not present in the control corneas. These features included mottling of Bowman's membrane, with large interfibrillar spaces; a roughness to its surface; and wide interlamellar lacunae within the corneal stroma, with significant changes in interfibrillar collagen distance and fibril diameter. The morphologic features of a clinical specimen excised three months following myopic epikeratoplasty were similar to those found with the factory-prepared lenticules. Our patient's corneal curvature steepened almost 3 diopters following lenticule removal. Our results suggest that additional studies of lyophilized epikeratoplasty lenticules should be performed.