Measurement of Depth of Intacs Implanted Via Femtosecond Laser Using Pentacam

Abstract

To measure the depth of intracorneal ring segments (Intacs, Addition Technology Inc) implanted via femtosecond laser by Pentacam rotating Scheimpflug camera (Oculus Optikgeräte GmbH) and to determine the change in depth at 1-year follow-up. Thirty-two eyes of 23 keratoconic patients receiving Intacs intrastromal corneal ring segments implanted by femtosecond laser were included in the study. The depth of intracorneal channel and Intacs segments were measured for 7 predetermined points at 1 week and 1 year postoperatively using Scheimpflug images. Mean achieved intrastromal channel depth exceeded the intended parameter by 6.5 microm to 69.0 microm. The standard deviation varied between +/- 13.5 microm and +/- 44.2 microm. The segment depth decreased at the end of the first postoperative year in all measured points, and the change was statistically significant at the superior, inferior, and temporal sides of the Intacs. The degree of change was not correlated with size of the Intacs, preoperative central corneal thickness, and mean keratometric values. Pentacam provided imaging of the Intacs segments and measurement of their depth, enabling evaluation of the changes in depth at 1-year follow-up. The Intacs segments tended to shallow over time, which may be a factor for depth-related complications.