Effect of different femtosecond laser-firing patterns on collagen disruption during refractive lenticule extraction

Abstract

Purpose: To evaluate the changes in corneal collagen architecture subjected to different laser-firing patterns during refractive lenticule extraction. Setting: Singapore Eye Research Institute, Singapore. Design: Experimental study. Methods: Refractive lenticule extraction was performed in rabbits without lenticule removal. Rabbits were divided into 4 groups that had incisions in the following firing patterns: (A) from periphery in (lenticule's posterior surface) and from center out (lenticule's anterior surface); (B) from center out and from center out; (C) from periphery in and from periphery in; and (D) from center out and from periphery in. The corneas were collected 18 hours postoperatively and were subjected to immunofluorescent staining of fibronectin, CD11b, and collagen type I. Ultrastructural analysis was performed using transmission electron microscopy (TEM). Results: Refractive lenticule extraction-treated corneas showed no significant difference in fibronectin and CD11b expression. Similar expression patterns of collagen type I were observed in corneas that had femtosecond firing patterns A, B, and C; however, a discontinuous and relatively more intense staining pattern along the anterior plane of the lenticule was detected in corneas treated with pattern D. The TEM also showed a more disrupted collagen arrangement along the anterior incision site in pattern D-treated corneas. Conclusions: Differential laser firing patterns during refractive lenticule extraction resulted in different levels of collagen derangement along the anterior plane of the lenticule, with pattern D showing the most disrupted surface. Such disruption in the collagen architecture might affect postoperative visual recovery and refractive outcomes. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. © 2012 ASCRS and ESCRS.