Cyclophotocoagulation: experimental investigations of dosage problems

Area of Science:

• Ophthalmology
• Medical Laser Technology
• Diagnostic Imaging

Background:

• Cyclophotocoagulation uses transscleral laser light to reduce aqueous humor production in the eye.
• Accurate patient-specific laser energy dosage remains a challenge in this therapy.
• Understanding tissue destruction intensity and distribution is crucial for treatment optimization.

Purpose of the Study:

• To investigate methods for visualizing tissue destruction during cyclophotocoagulation.
• To evaluate the potential of ultrasound and infrared thermography for real-time treatment monitoring.
• To establish a basis for ultrasound-controlled engineering of diode lasers in cyclophotocoagulation.

Main Methods:

• Developed a multifunctional measurement setup for visualizing cyclophotocoagulation effects.
• Utilized light microscopy, high-resolution ultrasound (B-mode, M-mode, RF signal analyses), and infrared thermography.
• Assessed temperature distribution on the scleral surface and structural changes in the coagulation area.

Main Results:

• High-resolution B-mode and M-mode ultrasound were insufficient for visualizing structural changes within the therapeutic width.
• RF ultrasound data analysis successfully detected structural changes within the therapeutic width.
• Infrared thermography showed surface temperature correlations with visible structural changes under specific laser parameters (long exposure, low power).

Conclusions:

• Visualization of coagulation effects in cyclophotocoagulation is feasible using high-resolution ultrasound or infrared thermography in specific cases.
• Spectrum analysis of RF ultrasound signals presents a promising method for effective control of cyclophotocoagulation.
• These imaging techniques may pave the way for advanced, on-line control systems in laser eye surgery.