Abstract

The ability of excimer lasers to remove corneal tissue in submicron increments has led to interest in the use of these lasers for keratorefractive surgery, in particular, linear incision keratotomy and large area ablation. To exploit the potential for micron resolution ablation control, a precise method for monitoring the incision depth is needed. Linear incision keratotomy produces narrow high aspect ratio cuts that are difficult to range with ultrasonic pachymetry and most optical pachymetry methods due to the requirements for high transverse resolution and nocontact measurement. Time domain reflectometry (OTDR) using femtosecond pulses¹ satisfies these requirements. However, femtosecond time domain reflectometry requires complicated laser systems which are bulky and costly. We report here the measurement of corneal thickness and incision depth by optical coherence domain reflectometry (OCDR) using a compact diode laser source. The OCDR system has comparable spatial resolutions and better sensitivity than previously demonstrated with femtosecond OTDR ranging of corneal incisions.¹ The experimental setup (Fig. 1) is similar to those used in OCDR² and OTDR³ systems developed for measurement and localization of reflections in integrated optical devices.

© 1990 Optical Society of America