Can Compact Lasers Have An Impact For Onychomycosis?

Author(s): 
David Zuckerman, DPM, FACFAS

   The Nexus family of lasers comes in powers of 7 W, 10 W, 15 W, 20 W, 30 W and 60 W with wavelengths within the therapeutic window. Furthermore, Nexus lasers are all designed with a single diode to ensure the highest power density.

   Another laser of note is the compact Q-Clear laser (Light Age Technology), a Q-switched laser that works on cavitation rather than direct heating of the dermis. Accordingly, the laser does not cause the heat and pain that were characteristic of previous lasers. It is fast and affordable for the patient.

   The Q-Clear laser system is safer and more effective in treating dystrophic nails, particularly those due to onychomycosis, in comparison to previously available methods. In clinical studies, it has demonstrated a 97 percent success rate in providing significant clearance of affected toenails without any significant side effects and without causing pain.6 In addition, the average clearance of the toenail was 57 percent across the board. In these studies, most toenails achieved substantial or complete improvement after only a single treatment. These results occurred using a simple treatment protocol, which generally consisted of laser treatment without the application of adjunctive topical therapies or use of any anesthetic agents, and took less than five minutes per foot. Due to the efficacy, speed and lack of disposables, there are significantly reduced treatment costs that have helping to expand the availability of the treatment.

   The Q-Clear is a Nd:YAG laser system with certain unique properties that differentiate it from lasers that have been used previously in podiatry. Nd:YAG lasers themselves are relatively new in podiatry and the FDA has cleared the laser only within the last year for “the temporary increase of clear nail in patients with onychomycosis,” making Q-Clear only the third such laser system to be FDA cleared for this application.

   The Q-Clear laser system delivers sufficiently high pulse energies in spatial and temporal pulse formats. These formats were designed to provide the heating and photomechanical disruption needed to penetrate and kill the fungal colonies without causing pain or adversely affecting the surrounding tissue. In addition, the cost of treatment (for everything related to the laser system) is under $10 per fully treated foot.

Pertinent Insights On Q-Switching And Nd:YAG Technology

Nd:YAG laser systems provide fundamental light output in the near infrared region of the spectrum. Most commonly, the output is at a wavelength of 1,064 nm, slightly outside of the range of visible light (nominally 400 to 800 nm, violet to deep red). The output of these laser systems can occur in either a continuous wave or in a pulsed format. It is sometimes “frequency doubled” by the nonlinear process called second harmonic generation to the green laser wavelength of 532 nm.

   Of the pulsed format lasers, there are several types that are distinguished by the duration of the laser pulses. The most common are long-pulsed lasers and Q-switched lasers. Long-pulsed lasers have typical pulse durations in the millisecond (10-3 s) to microsecond (10-6 s) range and Q-switched lasers have pulse durations in the nanosecond (10-9) range. For a given pulse energy, generally expressed in units of millijoules or joules, the shorter the pulse duration, the higher the laser’s peak power. Continuous wave and long-pulse lasers interact with biological materials (“biomatter”) dominantly through photothermal means. In other words, the energy in the light absorbed rapidly converts into heat, causing a temperature rise in the material illuminated. Q-switched laser pulses additionally can interact more disruptively, causing photoacoustic, photoablative and other photomechanical effects.

Comments

There are two major factors that need to be taken into account when discussing lasers and podiatric therapeutic indications that are missing here for this discussion of onychomycosis.

First, the perimeter of a human nail is made up of three right angles (a three sided square) with a rounded edge at the proximal tip.

For an area like this to be correctly and adequately irradiated with laser energy, there needs to be a Uniform Beam Dosimetry across the entire diameter of the treatment spot. Only this will deliver a uniform therapeutic dose across the entire area of a nail being treated. The only device that accomplishes this task is the Noveon Podiatric Laser.

A uniform beam dosimetry is also known as a “flat-top projection” of laser energy. This is in contrast to a “Gaussian projection," which contains a hot spot and is non-uniform in its energy delivery, which is the delivery mechanism of most commercial near-IR devices.

Also, the Noveon treatment spot geometry is a larger flat-top circle. Hence with this difference in beam geometry, there is always a small area of paronychial tissue surrounding the nail that is included within the treatment area spot size. With distal lateral onychomycosis, this is necessary to help prevent re-infection.

Second, one should carefully review the peer-reviewed literature describing IRB approved human clinical trials before making any treatment decisions with lasers for their patients. In this way, good evidence based medicine can be practiced for potential patients. The largest body of this literature can be found below.

When a laser company tells you the data "is on file" and not published, one should ask the question why? If they do not have data, one should ask "Then how do I know what amount of energy to use?" and "Who has evaluated the use of this energy?"

Dr. Eric Bornstein
Chief Science Officer
Nomir Medical Technologies

Landsman, A. et al. (2010) Treatment of Mild, Moderate and Severe Onychomycosis Using 870nm and 930nm Light Exposure J. of the Am. Pod. Med. Assoc. 2010 100:166-177

Bornstein E., S. Gridley, and P. Wegender (2010) Photodamage to Multidrug-resistant Gram-positive and Gram-negative Bacteria by 870 nm/930 nm Light Potentiates Erythromycin, Tetracycline and Ciprofloxacin. Photochem. and Photobiol Volume 86 Issue 3, Pages 617 - 627

Bornstein E.S. (2009) A Review of current research in light-based technologies for treatment of podiatric infectious disease states. J. of the Am. Pod. Med. Assoc. 99 (4), 348-352.

Bornstein E., W. Hermans, S. Gridley, and J. Manni (2009) Near infrared Photo-inactivation of bacteria and fungi at physiologic temperatures. Photochem. and Photobiol. 85, 1364–1374

Bornstein E.S. (2009) Treatment of onychomycosis using the noveon® dual-wavelength laser. FDA Pivotal Study data presented at Council for Nail Disorders 13th Annual Meeting, San Francisco, CA, March 5, 2009.

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