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3. Class IV Laser


A number of commonly available class IV cold laser treatment units are taking the marketplace by storm (Table 1). Patients will no longer need convincing that there “really is something going on,” as was often the case when using the 632-nm light wavelength or less-powerful class IIIb devices (usually <1 W total power emission capability). The class IV units, on the other hand, can be “felt” because they generate significant heat in the irradiated region.

With more energy emission comes shorter treatment times and a different dynamic in photo-biological approaches. The higher energy capabilities measured in total energy per area per session (power density x time) and power densities (power x time/area) will demand a new set of data. Those who like to make assumptions via extrapolation—beware. There are no dose response curves available in photobiology as there are for toxic exposures and for pharmaceuticals. The speed with which a treatment is delivered and the total energy exposures will change from class III to class IV devices, hence, the need for good in vivo and in vitro studies followed by clinical trials.

Strength of Treatment

Unlike some of the more passive treatments, the class IV laser produces heat that can be felt, eliminating any patient doubts whether the device is “turned on” or not. Although not a necessary requirement for a photo-biological effect, the secondary heating aspect of these devices will add another element to be considered, and, ultimately, the intensity of the beam may be the rate-limiting factor for patient tolerance. As expected, with additional power levels (2 to 3 times the order of magnitude of prior generation units), it behooves the practitioner to have sufficient understanding of laser biophysiology plus some hands on training prior to treating patients.

Ease of Treatment

The class IV laser systems all have a very useful feature, especially appreciated by the novice user—pre-programmed dosages already built into the selection circuitry. The clinician simply selects the condition (Achilles tendonitis-acute) and the system calculates the time and settings. Where we used to have to calculate power densities and total energy applied, the device can now recommend those parameters. Manufacturers got it right when they began performing and inputting the calculated values in the machines, requiring the provider to only select a condition.

Patient Adherence

Patient adherence to class IV laser treatment tends to be very strong as long as the sessions are uncomplicated (no adverse events) and out of pocket fees are not a barrier. In centers that charge an extra fee for the treatment, patients experiencing a marginal benefit usually will drop out after just a few sessions. The perceived value of the session, as well as with total patient experience, are determining factors.


Class IV lasers are not inexpensive ($4,000-$20,000). This creates a situation whereby a device with seemingly promising properties and some good healing potential is put in front of physical medicine and rehabilitation practitioners at a high price point. The challenge with the class IV predecessors has been that providers have unknowingly been advised by market representatives to bill insurance companies using the CPT infra-red code (78552). If one reads the descriptor for proper use of this code, however, it defines infrared irradiation as not only consisting of an infrared wavelength but also producing heat (heat lamp). Cold lasers do not generate heat since they are non-thermal. Insurance audit assessments have routinely requested pay back of all cold laser treatments that were billed based on erroneous use of this code. The new generation of class IV devices should more appropriately fit the CPT definition espoused in the CPT manual.

I have alluded to the potential effectiveness of this modality, especially now that the higher power ranges are available. Not that extra power always equates to better treatment outcome. The Arndt-Schulz law is a reminder that sometimes less is better. In this case, it is our subjective opinion that more power was needed to irradiate larger areas and that adequate energy saturation at greater intensities required increased wattage. The cost for professional grade clinical class IV laser systems continues to be prohibitive for too many practitioners. Greater market penetration would be expected with significant cost reductions—not unlike for many of the products making this top 10 list.

Research Base

I have alluded to the great number of available reports and publications in the field of laser therapy. However, the reason laser therapy continues to have many detractors and skeptics is simply because of the quality of the available research. More and better (more convincing) research is needed to take class IV laser therapy to the next level.

Continue Reading: 4. H-Wave Electrotherapy

Last updated on: October 16, 2014
First published on: October 1, 2014