Corneal Biomechanical Properties and their Correlates with Healing Process after Descemetic versus Pre-Descemetic Lamellar Keratoplasty

Abstract

Purpose: To evaluate the influence of the wound-healing process on corneal biomechanics in patients after 2 types of deep anterior lamellar keratoplasty: Descemetic with total stromal resection vs pre-Descemetic with deep stromal dissection.

Methods: This prospective comparative study consisted of 32 eyes of 32 patients. Patients were divided into 2 groups: Descemetic (17 eyes) and pre-Descemetic (15 eyes). Reichert ocular response analyzer was used to measure corneal hysteresis (CH) and corneal resistance factor (CRF) at 1 and 3 months postoperatively. Central corneal thickness (CCT) was measured using ultrasonic pachymetry. In vivo confocal microscopy was also used to study the corneal wound-healing process and to correlate these events with the corneal biomechanics postoperatively in both groups.

Results: Both mean CH and mean CRF were significantly lower in the Descemetic than the pre-Descemetic group at 1 and 3 months postoperatively (p≤0.0001). The reflectivity of activated keratocytes at both the interface and wound edge was less in the Descemetic than the pre-Descemetic group at all times as revealed by the confocal microscopy. No statistically significant difference in mean CCT was found between both groups at 1 and 3 months. Subsequent and progressive decrease in interface reflectivity of activated keratocytes was presented in both groups.

Conclusions: Healing process at the interface is key to optimal corneal integrity. In the pre-Descemetic group, stroma-to-stroma healing stimulated more activated keratocytes and hence stronger healing response, providing superior corneal biomechanics. Significant positive correlation between the intensity of the keratocyte activation and corneal integrity was found.

Keywords: Corneal hysteresis; Deep lamellar keratoplasty; Descemet membrane; Ocular response analyzer.