27 Optical Coherence Tomography–Assisted Anterior-Segment Surgery
Femtosecond laser–assisted cataract surgery has been used to create the main corneal incision, side-port incision, capsulorhexis, and precutting of the nucleus. 1 The aim of this technology is to increase precision. Incision size and shape become more predictable. Capsulorhexis size, shape, and centration reach previously unknown accuracy. 2 Initially, femtosecond laser technology was used without additional control with intraoperative optical coherence tomography (OCT). Today, all available femtosecond-assisted cataract machines take advantage of increased control using intraoperative OCT monitoring (Fig. 27.1).
27.1 Intraoperative OCT in Cataract Surgery
Future perspectives on the intraoperative use of OCT technology in cataract surgery (Fig. 27.2) could include continuous monitoring of the anterior-chamber depth or volume to prevent surge phenomenon. An automated posterior-capsule recognition modes could be used to prevent phaco-tip contact to the posterior capsule and capsular breaks, which would increase dramatically the safety of cataract surgery, as capsular breaks with vitreous loss are still the most common complication of phacoemulsification. 3 OCT-assisted grading of hardness of the crystalline lens with automated selection of machine settings could optimize applied energy and fluidics and increase the effectiveness and safety of cataract surgery. Intraoperative control of intraocular lens (IOL) position could help to prevent refractive surprises. Once capsular bag refilling becomes available, intraoperative OCT control could be an option.
Besides cataract surgery, OCT technology seems quite useful in other anterior-segment surgeries. 4 Mounting an OCT to a microscope makes it possible to create intraoperative images or videos. With future developments, high-speed OCT (swept-source technology) and three-dimensional (3-D) calculations could be used. If the images are mirrored into a head-up display into the surgeon’s microscope view, the surgeon is enabled to continue surgery while moving his or her attention from the surgical area. Furthermore, both hands remain free and able to continue bimanual surgery. As technology improves, OCT might be added to view areas (like the anterior-chamber angle) that were previously difficult to observe. Microscope-mounted OCTs (Zeiss Meditec, Oberkochen, Germany) have intraoperative settings that monitor images using 3-D anterior-segment OCT reconstruction of the anterior-chamber angle region (Tomey Corporation, Tokyo, Japan) (Fig. 27.3).