I would like to respond to Drs. Katzen and
Sullivan regarding their impressions on laser
therapy for onychomycosis. I was disturbed by
Dr. Sullivan's description of his tests of the
laser for the treatment of onychomycosis. In my
opinion, this type of anecdotal observation is
really misleading for a variety of reasons.
Among my strongest concerns are the following:
-There is no doubt that fungus and bacteria are
heat labile. Apply enough heat and they die.
This is very strongly supported in the
literature. The question is how much heat did
you apply? Several factors have to be
considered. Some devices raise the tissue
temperature to 42C, while other devices can
reach 80C. This is strongly dependent on the
waveform used to deliver the energy.
Each machine uses a different, proprietary
waveform, and this has a direct impact on the
temperature achieved. Similarly, the inexpensive
diode lasers lack the energy necessary to
generate enough heat. All 1064 lasers are not
created equally. Only one 1064 device has
actually gone through the process of submitting
clinical data to the FDA. All the rest have a
510K clearance, and we really don't know how or
if they work.
-Spot size is also critical. Larger spot sizes
are usually detrimental to the antifungal
process due to a degradation in temperature from
the center of the laser beam to the perimeter.
Larger spot size means greater loss of
temperature. This is why the FDA clearly
specified a 1.5mm spot size.
-Number of pulses must also be monitored. We
recently participated in a study in which 4
sites were utilized. One of the 4 sites used 50%
fewer pulses, and their outcomes were dismal,
while the other sites did extremely well.
-Remember that the gold standard is the oral
medication, and the success rate for "total
cure" (i.e. negative mycology, and at least 5 mm
of clear nail) ranges from 39-59%. When I first
began to prescribe oral anti-fungals, they were
also not covered by insurance, and we saw about
50% success. Our patients new up front what
their chances were and made an informed
decision.
In conclusion, these "simple" studies are just
that. They give very little information of
value, and tend to attract harsh critics who
have not had the results they hoped for, for a
variety of reasons. Like with everything in
medicine, proper technique always matters.
Disclosure: I am an advisor to PinPointe and
conducted clinical studies on behalf of both
Pinpointe and Nomir.
Adam Landsman, DPM, PhD, Cambridge,
MA,alandsman@challiance.org
