Thermal Tissue Modeling of the Ciliary Body With Continuous Wave Transscleral Cyclophotocoagulation and Transscleral Laser Therapy Using MicroPulse Technology.

PURPOSE: This study aims to evaluate 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 (CB) using computer modeling.

METHODS

The simulation is a five-layer homogeneous slab model determined via the Monte Carlo methods. CW-TSCPC modeling was based on the G-Probe delivery device, incorporating parameters from classic and slow coagulation techniques. The MicroPulse TLT modeling was based on the revised MicroPulse P3 probe, aligned with International MicroPulse TLT Consensus Guidelines. For Micropulse TLT the modeling evaluates an arbitrary sample section along a sweep path during a sweep.

RESULTS

CW-TSCPC techniques elevated the CB peak temperature well above 100°C for 1.8 seconds with classic and 2.2 seconds with slow coagulation. The CB temperature was elevated above 60°C for 3.9 seconds with classic and 5.5 seconds with slow coagulation, both with a thermal affected zone of 2 mm. The MicroPulse TLT techniques elevated the CB temperature above 60°C for 0.15 to 1.1 seconds, affecting a CB zone of 0.6 mm to 1.2 mm depending on sweep speed and power. The MicroPulse TLT did not reach temperatures above 100°C.

CONCLUSIONS

Modeling results indicate that MicroPulse TLT achieves lower, shorter duration peak temperatures, remaining below 100°C, and shows less thermal spread with more uniform heat distribution than CW-TSCPC. Main user settings for controlling CB temperature are sweep speed and power for MicroPulse TLT, and exposure time and power for CW-TSCPC. MicroPulse TLT's lower temperatures minimize the risk of permanent coagulative tissue necrosis, aligning with clinical literature supporting its enhanced safety profile over CW-TSCPC.

TRANSLATIONAL RELEVANCE: Understanding thermal dynamics may aid in refining and optimizing both techniques to maximize outcomes.