Peripheral intrastromal hydration facilitates safe, deep trephination in corneas of irregular thickness

Purpose: To evaluate the feasibility of regularizing the peripheral corneal thickness before deep trephination in highly irregular corneas undergoing deep anterior lamellar keratoplasty (DALK) by means of intrastromal hydration with saline. Methods: This is an interventional case series including all eyes with irregular peripheral corneal thickness undergoing DALK for any indication between January 1, 2016, and January 1, 2017, at a single tertiary center in Forli, Italy. Before trephination, 1 mL of normal saline was injected intrastromally into each clock hour of peripheral thinning (determined using preoperative pachymetry) using a 30-gauge needle. A deep trephination of 400 to 450 mm was then performed, and DALK was completed as per our previously described technique. Primary outcome measures were perforation during trephination and intraoperative complications, with secondary outcomes of best corrected visual acuity and refraction. Results: Peripheral intrastromal hydration was performed in 61 eyes of 61 patients. Intrastromal hydration ensured a safe trephination without perforation into the anterior chamber (AC) in 59 of 61 eyes. In the 2 cases in which perforation occurred, the perforation site was sutured with a full-thickness suture and the surgery was completed successfully. No cases required conversion to penetrating keratoplasty. Intrastromal injection of 1 mL of normal saline resulted in an increase in corneal thickness of 31%. After surgery, double AC was observed in 3 cases (4.9%), with all cases being managed successfully by air injection into the AC. Conclusions: Zonal peripheral intrastromal hydration is a feasible technique to enable safe, deep trephination even in corneas of highly irregular thickness.