From class to wavelength, there are a number of important factors to consider when choosing a Cool Laser Therapy device that will help your patients and improve your bottom line.
These days, more pet parents are seeking veterinarians who offer safe, effective and pain-free technologies to help heal their dogs and cats without pharmaceutical intervention. Veterinarians, in turn, are looking to add technologies to their practice that enable them to meet this growing demand. As a result, Cool Laser Therapy (CLT) has become one of the most commonly used tools in veterinary medicine for pain management, tissue healing and reducing inflammation.
However, it can be difficult to find the right CLT device for your practice. The internet provides an overabundance of technical information from various manufacturers making it nearly impossible to distinguish the most important characteristics. Below, you’ll find a basic overview of what to consider – and what to avoid – when shopping for a device.
Lasers are categorized according to international ANSI Z136 safety guidelines that determine how much laser energy is available to be delivered to eyes or tissue; hence, the Accessible Emission Limits (“AEL”) and Maximum Permissible Exposures (“MPE”) that are restricted for each laser class, based on the potential risk of causing injury/damage to skin and/or eyes.
The most common and safest class for administration of CLT to animals and humans alike is the class 3B laser for tissue treatment. No laser systems are recommended for treatment of the eyes, unless you are considering vision laser correction using excimer lasers.
Some manufacturers purport the benefits of using class 4 lasers for administration of CLT, but by ANSI Z136 safety guidelines, class 4 lasers cause thermal damage to tissue, if held in position on the body for any amount of time; therefore, an operator must continuously move this device to prevent burning the patient. Animals are restricted in their ability to communicate with the laser operator and since a class 4 laser system is capable of burning tissue within seconds, depending on its power level, a thermal burn may be delivered to the patient by the laser operator before the animal is able to alert them to their pain.
On the internet, you can find plenty of discussions on whether class 3 or class 4 lasers are better suited for therapeutic purposes; however, while class 4 lasers are able to deliver more power to tissue, this does not necessarily mean better clinical results. In fact, quite the opposite is true. As an example, two aspirins may be good medicine for a headache, but swallowing a whole bottle of aspirins will only land you at your local emergency department.
In order to maximize treatment safety and efficacy, the CLT device must deliver the optimal dose of laser light to the tissue of interest without exceeding the AEL and MPE of tissue (thermal limits of tissue), such as what a class 4 laser does. There are laws in physics, known as the Grotthus-Draper law and the Arndt-Schulz law, which respectively state, “Only that light which is absorbed by a system can bring about a photochemical change” and “High concentrations kill; medium concentrations suppress or inhibit; and low, or minute concentrations stimulate”.
In other words, CLT laser light must be powerful enough to penetrate tissue to the depth of the pain condition; however, it must not exceed certain power levels or it risks causing permanent thermal damage to the tissue surface and even worse, dermal layers below the tissue surface. Therefore, if insufficient laser light is delivered to tissue there will be little response. If the proper amount is delivered there will be an optimal response. If excessive there is a high risk of permanent thermal damage.
The so-called “therapeutic window” of tissue penetration has been scientifically determined to be between 600 to 950 nm; whereby, wavelengths less than this are almost totally absorbed by hemoglobin in the blood (on average 60 millilitres per kilogram of body weight) and wavelengths above this are almost totally absorbed by water (tissue is 50 to 60% water based on body weight). In the therapeutic window, depth of CLT penetration is governed by melanin, the natural skin coloration of tissue. The optimal therapeutic effect of a CLT device can best be achieved with a combination of the properly designed wavelengths, preferably 660 nm (for more superficial tissue structures to a few centimeters) and 905 nm (for deep tissue structures up to 10cm and greater) laser diodes.
Super pulsed versus continuous wave laser diodes
Continuous wave laser diodes are limited in the amount of optical power they can deliver to tissue without exceeding the AEL or MPE of the tissue surface. However, this issue is easily overcome by using super-pulsed laser diode technology, which provides laser pulses in the hundreds of watts, but only allows them to activate for billionths of a second (nanoseconds). The result is that for a number of nanoseconds, the CLT device operator is able to deliver significant laser power to the tissue surface to penetrate deeply into tissue, but the operation is automatically discontinued before any tissue thermal damage can result. Application of the laser light on one location, especially on high power (class 4), lasers can result in tissue overheating and significant tissue thermal damage. Super pulsed CLT lasers can penetrate far deeper than a class 4 laser into tissue without the risk of tissue thermal damage.
Lasers versus LEDs
Another important factor to consider is whether the CLT device is equipped with true laser diodes. Light Emitting Diodes (LEDs) are not in the same ballpark as lasers, as only a fraction of their energy is emitted in the forward direction and thus able to penetrate tissue. While some manufacturers use LEDs in their LED devices, only 5 to 6% of their rated light energy can move in the forward direction. True laser diodes, on the other hand, emit 100% of their laser energy to the tissue surface in the direction of the pain condition.
To summarize, CLT can be a one of the best investments to generate a new revenue stream for your practice. But like all technologies that you purchase for personal or commercial use, you need to do your research to ensure you purchase the best system for your practice. If you pay attention to the CLT characteristics discussed above, you will make the right purchasing decision in the choice of a CLT device that will improve your revenue, give you years of good service, and deliver exemplary clinical results safely and effectively for your patients.