Temperature Increase and Damage Extent at Retinal Pigment Epithelium Compared between Continuous Wave and Micropulse...

Area of Science:

• Ophthalmology
• Biomedical Optics
• Laser-Tissue Interaction

Background:

• Retinal pigment epithelium (RPE) is crucial for retinal health.
• Understanding laser effects on RPE is vital for ophthalmic procedures.
• Continuous wave (CW) and microsecond pulse (MP) lasers have different thermal profiles.

Purpose of the Study:

• Compare cell damage and temperature rise in RPE from CW vs. MP laser irradiation.
• Investigate the impact of duty cycle (DC) on laser-induced RPE effects.
• Assess the role of microbubble formation in laser-induced RPE damage.

Main Methods:

• Irradiation of porcine RPE-choroid-sclera explants with a 577 nm laser (CW or MP, 5%/15% DC).
• Evaluation of cell viability using calcein-AM staining to determine dead cell area (DCA).
• Optoacoustic (OA) technique for real-time temperature measurement during irradiation.

Main Results:

• No significant difference in DCA increase between CW and MP modes up to 40 mW for 200 ms irradiation.
• MP laser at 5% DC showed a significantly reduced DCA increase from 50 mW, linked to microbubble formation.
• OA measurements revealed similar average temperature increases for CW and MP modes at equivalent power levels.

Conclusions:

• CW and MP laser modes exhibit comparable average temperature rises in RPE at the same average power.
• Lower duty cycles in MP laser irradiation necessitate caution due to potential mechanical damage from microbubble formation.
• Laser parameters, including pulse mode and duty cycle, must be carefully considered to minimize RPE damage.