Study maps thermal dynamics of glaucoma laser treatments

Data from a new study examining the thermal dynamics of transscleral laser treatments for glaucoma have been released and spotlighted by Iridex.¹

The study evaluated thermal dynamics associated with continuous wave transscleral cyclophotocoagulation (CW-TSCPC) and transscleral laser therapy (TLT) using MicroPulse technology (MicroPulse TLT), such as temperature peak, exposure duration, and thermal spread in a simulated ciliary body using computer modeling. The study was led by Tomas M. Grippo, MD, of the Grippo Glaucoma & Cataract Center and provides the first quantitative computer models comparing the laser therapies mentioned, according to the company.

Using Monte Carlo computer simulations, authors modeled how each therapy heats the ciliary body and calculated temperature peaks, duration, and thermal spread. According to the study, the Monte Carlo algorithm used has been “well-established and accepted for tissue modeling for over 30 years.”²

Results² showed that with classic CW-TSCPC modeling at 2000 milliwatts for 2 seconds, the temperature peak exceeded 100°C (212°F) for approximately 1.8 seconds and remained above 60°C (140°F) for approximately 3.9 seconds. Results for a 1250-milliwatt slow coagulation CW treatment over 4 seconds saw temperature peak rises well above 100°C (212°F) for 2.2 seconds and remain above 60°C (140°F) for approximately 5.5 seconds. Both methods showed a thermally affected zone in the ciliary body measuring approximately 2 mm in diameter.

MicroPulse TLT was evaluated at 3000 and 2500 milliwatts at 31.3% duty cycle with 20-second and 40-second sweeps per hemisphere. Results showed that for 3000 milliwatts with 20-second sweeps, the thermally affected zone was 1 mm in width, while the ciliary body peak temperature was 67°C (152.6°F) and remained at or above 60°C for approximately 0.40 seconds. Results for 2500 milliwatts with 40-second sweeps showed the same thermally affected zone of 1 mm and the same peak temperature of 67°C (152.6°F) for approximately 0.9 seconds.

However, for MicroPulse TLT at 3000 milliwatts with 40-second sweeps, the thermally affected zone was 1.2 mm in width while the ciliary body peak temperature was 76°C (168.8°F) and remained at or above 60°C for approximately 1.1 seconds.

“Our study uses a computational model to analyze heat behavior in the ciliary body during CW-TSCPC and MicroPulse TLT treatments. By linking these findings to the safety, effectiveness, and mechanisms of action described in the literature for both treatments, we can reinterpret existing clinical evidence from a fresh perspective. This approach strengthens our understanding and conceptual framework for these techniques and provides insights that may help refine both laser procedures for improved patient outcomes,” said Grippo.

Authors concluded that MicroPulse TLT achieves lower, shorter-duration peak temperatures and shows less thermal spread with more uniform heat distribution than CW-TSCPC. In comparison, CW-TSCPC causes more significant damage to the entire structure, including the ciliary epithelium, muscle, stroma, and vascular supply, predominantly affecting the anterior portion of the ciliary body. However, MicroPulse TLT has lower temperatures, reduced spatial extent, and shorter duration, which induces moderate thermal injury primarily to the bulk muscle of the central and posterior portions.

Authors also noted that MicroPulse TLT’s lower temperatures minimize the risk of permanent coagulative tissue necrosis, which aligns with clinical literature supporting its enhanced safety profile over CW-TSCPC.

Lastly, authors noted that although the same laser wavelength is used, there are clear differences in the heat intensity, duration, and spread achieved, which may translate into different biological effects on the target tissues.

References:

1. Iridex Announces New Thermal Dynamics Study That Strengthens Clinical Foundation and Market Potential of MicroPulse® Technology and Continuous-Wave Laser for Glaucoma Treatment. Published December 8, 2025. Accessed December 8, 2025. https://iridex.gcs-web.com/news-releases/news-release-details/iridex-announces-new-thermal-dynamics-study-strengthens-clinical

2. Translational Vision Science & Technology November 2025, Vol.14, 32. doi:https://doi.org/10.1167/tvst.14.11.32