Authors: C Maya Tong, Rénuka S. Birbal, Philip W. Dockery, Jack S. Parker, Gerrit R. J. Melles
Author Disclosure Block: C. Tong: None. R.S. Birbal: None. P.W. Dockery: None. J.S. Parker: DORC International, Ziemer Ophthalmic Systems – Consultant. G.R.J. Melles: DORC International, SurgiCube International – Consultant.

Abstract Body:

Purpose: To describe the use of intraoperative anterior segment optical coherence tomography (iAS-OCT) as a useful tool to help surgeons better visualize midstromal dissection for Bowman layer (BL) transplantation, and ultimately alter surgical decision making for patients with Keratoconus.
Study Design: Retrospective cohort study
Methods: Twenty one consecutive eyes of twenty patients with Keratoconus underwent Bowman layer transplantation. Midstromal dissection was facilitated using an operating microscope (Lumera 700; Carl Zeiss Meditec, Inc) fitted with iAS-OCT (Callisto; Carl Zeiss Meditec, Inc). Intra- and postoperative complications (up to 6 month follow-up) were recorded.
Results: In nineteen eyes, BL transplantation aided with iAS-OCT enabled visualization of the dissection plane, even in cases for which blood, edema, or scarring otherwise would have obscured the surgeon’s view of the air-endothelial reflex. This allowed dissections proceeding too anteriorly or posteriorly to be course-corrected before inadvertent perforation occurred and proper placement and total unfolding of the donor graft could be confirmed. In two eyes, intraoperative perforation during stromal dissection resulted in the operation being aborted. 89% of patients (16/18) demonstrated a reduction in Kmax 1 day postoperatively, which was maintained in 86% of patients (12/14) at 6 months postoperatively. No immediate postoperative complications occurred.
Conclusions: Particularly during the surgical learning curve, or for surgeons not experienced with manual dissection DALK, iAS-OCT may enable corneal surgeons to be more confident and comfortable with their stromal dissections and to achieve better results with BL transplantation.