Introduction
This article aims to provide clarity on the use of lasers in veterinary treatments, specifically addressing the factors affecting light penetration and the efficacy of different wavelengths. This guide will cover key points about light absorption, the impact of various wavelengths, and practical tips for optimizing laser therapy.
Light Absorption and Wavelengths
Hemoglobin and Water: Hemoglobin absorbs light below 800 nm, while water absorbs infrared (IR) light above 900 nm. This limits the penetration of light into tissues at these wavelengths.
Ideal Wavelength for Penetration: IR light at 808 nm penetrates tissue most effectively because it is least absorbed by hemoglobin and water. In contrast, 904 nm light is more significantly absorbed by water, reducing its penetration depth.
Understanding the Graph
The absorption graph illustrates how different wavelengths interact with tissue components:
Logarithmic Scale: The y-axis of the graph is logarithmic, meaning each tick represents a tenfold increase. Hence, even small changes on the graph indicate significant differences in absorption.
Superpulsed Lasers
Power vs. Duration: Superpulsed lasers may have higher power (e.g., 50W) for very short durations (e.g., billionths of a second). While this can enhance penetration momentarily, prolonged treatment times are often required for therapeutic effect.
Melanin and Skin/Fur
Melanin Absorption: Melanin’s absorption is relatively consistent across the wavelengths used in veterinary lasers. Darker skin or fur absorbs more light, necessitating longer treatment times or higher power settings.
Adjusting for Dark Skin/Fur: Devices should be set to 25% more power for dark-skinned pets to ensure effective treatment.
Pressure Application
Improving Penetration: Applying pressure with the laser probe can move blood out of the way, reducing light absorption by hemoglobin and allowing deeper tissue penetration.
Ischemia Concerns: The goal is to move blood out of the path rather than causing ischemia (restricted blood flow). Removing spacers can help bring the light source closer to the skin for better penetration.
Practical Tips for Laser Therapy
Choosing the Right Wavelength: For deep tissue penetration, use lasers with wavelengths around 808 nm. Avoid using wavelengths heavily absorbed by water (e.g., 980 nm).
Adjusting Treatment for Dark Fur/Skin: Increase power settings by 25% for pets with dark fur or skin to compensate for higher light absorption.
Applying Pressure: Use the probe to apply gentle pressure, moving blood out of the way to enhance light penetration.
Understanding Treatment Time and Power: Treatment efficacy depends more on the wavelength than on power alone. Ensure you balance the wavelength and power settings appropriately for each case.
Frequently Asked Questions (FAQs)
Q: Can lasers penetrate thick fur or skin? A: Penetration can be challenging with thick fur or skin. Using appropriate wavelengths (e.g., 808 nm) and increasing power settings can help, but some light will still be absorbed or scattered.
Q: Does water absorption affect laser penetration? A: Yes, water significantly absorbs light above 900 nm, reducing penetration depth. Therefore, using wavelengths around 808 nm, which are less absorbed by water, is preferable.
Q: How does melanin affect laser treatment? A: Melanin absorbs light consistently across the relevant wavelengths, meaning darker skin or fur will absorb more light. Increasing power settings can help ensure effective treatment.
Q: Should I use a superpulsed laser for deeper penetration? A: While superpulsed lasers can momentarily enhance penetration, they require longer treatment times. The wavelength remains the primary factor for penetration depth.
Conclusion
Understanding the science behind laser wavelengths and their interaction with tissue components is crucial for effective veterinary treatments. By choosing the right wavelength, adjusting settings for dark fur/skin, and applying pressure correctly, practitioners can optimize laser therapy outcomes for their patients.