Confocal Microscopy of Corneal Wound Healing After Deep Lamellar Keratoplasty in Rabbits

Objective: To compare wound healing and morphologic characteristics of the host-donor interface in rabbit corneas after maximum-depth and near-Descemet membrane anterior lamellar keratoplasty. Design: Descriptive analysis of confocal microscopy images after 2 types of deep lamellar keratoplasty (deep stromal dissection vs total stromal resection). Methods: Deep anterior lamellar keratoplasty (DALK) was performed in 16 rabbit eyes, with exposure of the Descemet membrane in 8 eyes (deep group) and deep stromal dissection to near the Descemet membrane in 8 eyes (near group). A full-thickness graft devoid of endothelium and Descemet membrane was sutured in place. Confocal examination of lamellar interface and wound edge was performed throughout 6 months. Results: Four days postoperatively, confocal microscopy revealed numerous highly reflective keratocytes at and adjacent to the interface in all eyes, fewer in the deep than the near group. Keratocyte density and reflectivity returned to normal at 4 to 6 weeks (deep) and 8 to 10 weeks (near) postoperatively. Conclusions: In the deep group, the smooth interface showed less scarring. In the near group, stroma-to-stroma healing stimulated more activated keratocytes and hence more haze. Successful DALK requires minimal central healing for clarity but significant suture-stimulated healing at the edge to prevent corneal bulge. Clinical Relevance: Deep anterior lamellar keratoplasty is rarely accompanied by rejection, avoids entrance into the anterior chamber, and can be performed with tissue that does not have living keratocytes. Interface healing is a determinant of the final visual acuity; depth of the lamellar bed is a major determinant of the healing response. Although dissection to bare the Descemet membrane is more difficult, there is less keratocyte activation and scarring.