Laser Care For Onychomycosis: Can It Be Effective?
- Volume 23 - Issue 5 - May 2010
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Although laser energy can eliminate dermatophytes in vitro, the direct laser elimination of onychomycosis is not successful due to difficulties in selectively delivering laser energy to the deeper levels of the nail plate without collateral damage.
One study utilized a femtosecond (fsec) infrared titanium sapphire laser to circumvent this problem by the nonlinear interactions of these lasers with biological media.19 This quality, combined with the deeply penetrating nature of the near-infrared radiation, allows elimination of deeply seeded nail dermatophytes without associated collateral damage.
Researchers used nail cuttings obtained from patients with onychomycosis caused by T. rubrum and subjected the samples to fsec laser irradiation, using increasing laser intensities with the focus scan throughout the whole thickness of the nail specimen. Researchers evaluated the efficacy of the laser treatment via subculture and used scanning electron microscopy to determine if there was fsec laser-induced collateral damage.19
The study found that the fsec laser successfully inhibited the growth of the fungus in all samples examined.19 This suggests that T. rubrum-mediated onychomycosis may be treated by fsec laser technology.
Assessing The Preliminary Claims And Evidence On Emerging Lasers
Currently two lasers exist in the marketplace with the PinPointe™ FootLaser™ (PathoLase) and the Noveon laser (Nomir Medical).
The PinPointe FootLaser, introduced in 2008, uses a patented laser technology to target the pathogens that cause onychomycosis. The manufacturer claims that PinPointe treats patients safely and quickly with no drugs, no anesthesia or pain. PinPointe’s laser light reportedly passes through the toenail without causing damage to the nail or surrounding skin. Following the procedure, the new nail will reportedly grow in healthy and clear, according to the manufacturer. The laser lacks a specific indication for onychomycosis at the present time.
A study of a small group of patients with onychomycosis indicated a potential efficacy rate with the PinPointe FootLaser as high as 87 percent.20 Currently, there is an ongoing multicenter trial evaluating the PinPointe Foot Laser for onychomycosis.
The Noveon laser is a device which employs two distinct, near infrared wavelengths (870 nm and 930 nm) that are known to cause cellular photodamage via an endogenous reactive oxygen species mechanism of action in the absence of exogenous dyes or chemicals. Researchers have demonstrated photoinactivation of the fungi that causes onychomycosis when they have used the Noveon laser at safe energy densities in vitro and in vivo at physiologic temperatures.21
Human studies with the Noveon laser have met the published criteria for calculating the individual maximum safe radiant exposure (IMSRE) for human phototherapy as researchers reported no negative interactions in either the onychomycosis or MRSA IRB-approved studies.22,23
Until such time that researchers perform a randomized double-blinded trial comparing a laser to a placebo in the treatment of onychomycosis, its use should be guarded and patients should consider the treatment experimental. In the age of advancing medical technology, we as physicians must resist the claims of companies promoting the advantages of their products and only subject our patients to treatment that has withstood the scrutiny of a large independent clinical study. Like all practitioners who treat patients with onychomycosis, I hope such claims do eventually come to fruition.
Dr. Haverstock is an Assistant Clinical Professor of Surgery and the Chief of the Division of Podiatric Surgery in the Department of Surgery at the University of Calgary. He is the Director of the Diabetic Foot and Limb Preservation Centre in Calgary. Dr. Haverstock is also a Fellow of the American Society of Podiatric Dermatology.