- Ophthalmic Surgery, Lasers and Imaging
- July/August 2012 - Volume 43 · Issue 4: 341-347
BACKGROUND AND OBJECTIVE:
The 577-nm (yellow) laser provides an alternative to the 532-nm (green) laser in retinal photocoagulation, with potential benefits in macular treatment and through ocular opacities. To assess relative risk of thermomechanical rupture of Bruch’s membrane with yellow laser in photocoagulation, the therapeutic window, the ratio of threshold powers for mild coagulation and rupture, was measured.
MATERIALS AND METHODS:
Retinal coagulation and rupture thresholds, visualized ophthalmoscopically, were measured with 577- and 532-nm lasers using 10- to 100-ms pulses in 34 rabbit eyes. Lesions at 1 and 7 days were assessed histologically.
Coagulation threshold with yellow laser was 26% lower than with green laser. The therapeutic window increased linearly with log-duration for both wavelengths with a difference in parallel-slope intercept of 0.36 ± 0.20, corresponding to 8% to 15% wider therapeutic window for yellow wavelength.
The therapeutic window of retinal photocoagulation in rabbits at 577 nm is slightly wider than at 532 nm, whereas histologically the lesions are similar.
From Topcon Medical Laser Systems, Inc. (CKS), Santa Clara, California; the Department of Ophthalmology (L-SBL, YMP, DVP), Stanford University, Stanford, California; and Hansen Experimental Physics Laboratory (DVP), Stanford University, Stanford, California.
Presented at the Association for Research in Vision and Ophthalmology annual meeting, May 1–5, 2011, Fort Lauderdale, Florida.
Supported by the Air Force Office of Scientific Research, grant FA9550-04, and by Stanford Photonics Research Center. PASCAL laser systems were provided by Topcon Medical Laser Systems, Inc.
Dr. Sramek is an employee of and Dr. Palanker is a consultant for Topcon Medical Laser Systems, Inc. Dr. Palanker holds a patent on patterned scanning laser photocoagulation licensed to Topcon Medical Laser Systems, Inc. Drs. Leung and Paulus have no financial or proprietary interest in the materials presented herein.
Address correspondence to Christopher K. Sramek, PhD, Topcon Medical Laser Systems, Inc., 3130 Coronado Dr., Santa Clara, CA 94054. E-mail: email@example.com
Received: July 12, 2011
Accepted: February 21, 2012
Posted Online: May 05, 2012