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Proceedings Paper

Scanning mid-IR laser apparatus with eye tracking for refractive surgery
Author(s): William B. Telfair; Paul R. Yoder; Carsten Bekker; Hanna J. Hoffman; Eric F. Jensen
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Paper Abstract

A robust, real-time, dynamic eye tracker has been integrated with the short pulse mid-infrared laser scanning delivery system previously described. This system employs a Q- switched Nd:YAG laser pumped optical parametric oscillator operating at 2.94 micrometers. Previous ablation studies on human cadaver eyes and in-vivo cat eyes demonstrated very smooth ablations with extremely low damage levels similar to results with an excimer. A 4-month healing study with cats indicated no adverse healing effects. In order to treat human eyes, the tracker is required because the eyes move during the procedure due to both voluntary and involuntary motions such as breathing, heartbeat, drift, loss of fixation, saccades and microsaccades. Eye tracking techniques from the literature were compared. A limbus tracking system was best for this application. Temporal and spectral filtering techniques were implemented to reduce tracking errors, reject stray light, and increase signal to noise ratio. The expanded-capability system (IRVision AccuScan 2000 Laser System) has been tested in the lab on simulated eye targets, glass eyes, cadaver eyes, and live human subjects. Circular targets ranging from 10-mm to 14-mm diameter were successfully tracked. The tracker performed beyond expectations while the system performed myopic photorefractive keratectomy procedures on several legally blind human subjects.

Paper Details

Date Published: 18 June 1999
PDF: 9 pages
Proc. SPIE 3591, Ophthalmic Technologies IX, (18 June 1999); doi: 10.1117/12.350567
Show Author Affiliations
William B. Telfair, IRVision, Inc. (United States)
Paul R. Yoder, IRVision, Inc. (United States)
Carsten Bekker, IRVision, Inc. (United States)
Hanna J. Hoffman, IRVision, Inc. (United States)
Eric F. Jensen, IRVision, Inc. (United States)


Published in SPIE Proceedings Vol. 3591:
Ophthalmic Technologies IX
Bruce E. Stuck; Pascal O. Rol; Michael Belkin; Karen Margaret Joos; Fabrice Manns; Bruce E. Stuck; Michael Belkin, Editor(s)

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