|| The following article is a valuable
editorial contribution. It deals with the most important parameters and
describes their interrelation and the limits within which we can get reproducible
biostimulative effects. As Andrei Sommer also points out, this article
describes the very important outer parameters of technical and physical
nature, being fairly easy to determine, while the detailed situation that
occurs inside a living, laser illuminated tissue is far more complex and
much more difficult to control.
Biostimulatory Windows in Low Intensity Laser Activation:
Lasers, Scanners and NASA's Light Emitting Diode Array System
By Dr. Andrei P. Sommer.
[Short version of the article published in the Journal of Clinical Laser
Medicine & Surgery, Vol. 19, Number 1, 2001, Mary Ann Liebert, Inc.
It took 33 years
The purpose of the international study published in the February 2001
issue of JCLMS was to assess and to formulate physically an irreducible
set of irradiation parameters, which could be of relevance in the achievement
of reproducible light induced effects in biological systems - in vitro
and in vivo. There is ample evidence that the action of light in biological
systems depends at least on two threshold parameters: the energy density
and the intensity. Depending on the particular light delivery system
coupled to an irradiation source, the mean energy density and the local
intensity have to be determined separately, by help of adequate experimental
methods. The biological independence between the two threshold parameters
is of practical importance for the medical application of photobiological
effects achieved at low energy density levels, accounting for the success
and the failure in most of the cold laser uses since Mester's pioneering
Ameliorated wound closures were achieved at energy densities between
1 and 4 · 104 Jm-2 in the therapy of ulcera cruris with 50mW
He/Ne-Lasers [ 3] . This and further evidence has led to the establishment
of one basic Arndt-Schultz-curve showing different modes of cell reaction
at different energy density levels [ 1,2,3,4,5,6,7,8] . When the levels
were too small, there were no observable effects. Higher levels resulted
in the inhibition of cellular functions. Energy densities of therapeutically
relevant photobiological effects [ 8,9,10,11,12,13,14,15,16,17,18,19,20,21]
, were in accordance with the energy density range described in the
The influence of the power density (light intensity) on irradiated cells
was demonstrated in fibroblast cultures [ 22] ; and possibly as well
in animal experiments: The mast cells of irradiated mouse tongues showed
a progressing degranulation with increasing laser power (4mW, 50mW)
where the locally administered energy density was kept at the same level
[ 23] .
Observations in patients revealed also that thresholds of light intensity
(presumably wavelength dependent) have to be surpassed in order to achieve
reproducible biostimulatory effects. A documentation of the precise
threshold values was prior to our study lacking. What had been repeatedly
found, was that the clinical use of lasers with a power smaller than
4mW in the field of application, induced no reproducible biological
effects, independent of the length of the total irradiation time [ 24,25]
Applications of the LILAB-equation
In practice it is of great importance to apply the laser light to a
much greater area than the laser beam cross section itself. Due to the
cooperative behaviour of photostimulated cells [ 28,29] , it seems to
be important to simultaneously irradiate the application field in order
to avoid adverse effects with respect to the intended aims [ 30] . Consequently
the application field would have to be irradiated in the shortest possible
period, creating a homogenously distributed mean energy density with
the necessary local light intensity - as required for activation.
For these practically important cases scanners have been developed.
Scanners were used in vivo with satisfactory results. The suitability
of conventional scanners for medical applications depends, besides the
values of the local light intensity, on the uniformity of the mean energy
density in the application field.
In agreement with equation (1), the biologically effective light intensities
can also be applied on greater areas by use of high power lasers in
combination with optical lenses (beam diverging systems). Beam diverging
systems could be adequate with suitable semiconductor lasers, as reported
on the successful photobiostimulation of General Motors workers and
other patients with carpal tunnel syndrome . Promising for photobiostimulation
of extended wound areas with homogenous mean field intensities and energy
densities within the activating range , appear to us, as potential
light sources, light emitting diodes (LED) and NASA's lightweight light
emitting diode array systems in particular [17,18].
In contrast to the threshold intensity necessary for activation Istim
- a quantity directly calculable from the technical data of the laser
- the mean field intensity Ifield in any
application field A greater than the cross section of the laser beam,
can only be determined accurately by measuring the mean energy density
(E/A). The determination of this quantity, is relatively simple in case
of the spot surfaces generated by beam diverging systems, and more complicated
in case of the light patterns generated by scanners as described in
literature [ 8,32,33] . The question whether (E/A) is an activating
energy density or not, depends not explicitly on the particular magnitude
of the associated Ifield-value, but primarily
on the value of the local light intensity Istim
and the total duration of the local light stimulus per activated field.
The LILAB-System , being an exemplary model to demonstrate the interplay
between biologically relevant irradiation parameters - and a relatively
simple irradiation system, is based on a fast beam distributor, designed
for homogenous irradiation of arbitrarily large application fields [
8] . Using a prototype LILAB-System based on a 25mW He/Ne-Laser (632.8nm),
we could generate various, nearly homogenously spread energy density
fields. Representatively for mean field intensities of biological relevance
(72Wm-2) , we could apply intensities within the range administered
via NASA's irradiation system (24Wm-2 to 743Wm-2), found to be effective
in fibroblasts, osteoblasts and skeletal muscle cells [16,17,18]. Recent
laboratory results observed in murine osteoblasts irradiated with the
NASA-LEDs, and the associated exemplary experimental protocol accounting
for the irreducible set of the three biologically independent parameters
(wavelength, energy density, intensity) necessary for complete characterization
of the irradiation, have been recently published [16, 38].
The existence of an upper limit for the applicable light intensity -
as found in cell culture experiments by Lubart [ 22] - could not be
observed in clinical practice, presumably because of the change of the
intensity with the depth of penetration due to absorption.
Realizing the importance of intensity and energy density, there is no
way to circumvent in future laser experiments the specification of the
laser beam diameter - and in using scanners - the measurement of the
mean energy density. The method for the measurement of the mean energy
density generated by scanners and its validation has been published
. Besides the light intensity thresholds and the activating mean
energy densities - determined in case of the scanners by the cumulation
of the duration of local light stimuli -, certain beam repetition frequencies
with extended influence on activation seem to exist. There is also evidence
from literature for their existence. The biological effect of the pulse
frequency received support from the experimental side - from the observation
of an additional Ca2+ uptake in macrophages [ 34] and an enhanced chemiluminescence
in murine splenocites [ 35] , after irradiation with pulsed semiconductor
lasers of suitable pulse duration and repetition frequency - and also
from the clinical side . Thus, the periodical stimulation of extended
tissue areas with maximum local photon density, uniform energy density
and minimum thermal effects - as realized e.g. with the LILAB-System
- is regarded to be a powerful method for the achievement of photobiological
results with lasers [ 37] .
The suggestion of the present study, holding for most of the medically
used laser and related irradiation systems operating at low energy density
levels, hence of general interest, is that the irradiation of areas
exceeding the cross section of laser beams with homogenous energy densities
must be paralleled in practice by the precise measurement of at least
two independent threshold parameters: the local intensity of the laser
beam, respectively diode field, and the mean energy density in the application
1. Mester, E., Szende, B., and Gartner, P. (1968). The Effect
of Laser Beams on the Growth of Hair in Mice. Radiobiol. Radiother.
9 (5), 621-6.
2. Mester, E., Spiry, T., Szende, B., and Tota, J.G. (1971). Effect
of Laser Rays on Wound Healing. Am.-J.-Surg. 122 (4), 532-5.
3. Mester, E. (1981). Über die stimulierende Wirkung der Laserstrahlung
auf die Wundheilung, in: Der Laser: Grundlagen und Klinische Anwendungen.
K. Dienstl, and P.L. Fischer (eds.). Berlin, Heidelberg, New York: Springer,
4. Mester, E., Mester, A., and Toth, J. (1983). Biostimulative Effect
of Laser Beams, in: New Frontiers in Laser Medicine and Surgery. K.
Atsumi (ed.). Excerpta Medica, pp. 481-489.
5. Mester, A.R., Nagylucskay, S., Mako, E., et al. (1998). Experimental
Immunological Study with Radiological Application of Low Power Lasers,
in: Laser in Medicine. W. Waidelich (ed.). Berlin, Heidelberg, New York:
Springer, pp. 502-512.
6. Ohshiro, T. (1988). Low Level Laser Therapy: A Practical Introduction.
New York: John Willey and Sons, pp. 30.
7. Mester, E., Mester, A.F., and Mester, A. (1985). The Biomedical Effect
of Laser Application. Lasers Surg. Med. 5, 31-39.
8. Sommer, A., and Franke, R.P. (1993). LILAB - a new System for Low
Intensity Laser Activated Biostimulation. Biomed. Tech. 38, 168-171.
9. Yamada, K. (1991). Biological Effects of Low Power Laser Irradiation
on Clonal Osteoblastic Cells (MC3T3-E1). J. Jpn. Orthop. Assoc. 65,
10. Trelles, M.A., and Mayayo, E. (1987). Bone Fracture Consolidates
Faster With Low Power Laser. Lasers Surg. Med., 7, 36-45.
11. Wu, W., Naim, J.O., and Lanzafame, R. J. (1994). The effect of laser
irradiation on the release of bGFG from 3T3 fibroblasts. Photochem.-Photobiol.
59 (2), 167-170.
12. Rosner, M., Caplan, M., Cohen, S., Duvdevani, R., Solomon, A., Assia,
E., Belkin, M., and Schwartz, M. (1993). Dose and temporal parameters
in delaying injured optic nerve degeneration by low energy laser irradiation.
Lasers Surg. Med. 13 (6), 611-617.
13. Pinheiro, A.L., Cavalcanti, E.T., Pinheiro, T.I., Alves, M.J., and
Manzi, C.T. (1997). Low level laser therapy in the management of disorders
of the maxillofacial region. J. Clin.-Laser-Med.-Surg. 15 (4), 181-3.
14. Bihari, I. (1994). CO2 Laser in Low Power Applications in Wound
Healing. Laser Therapy, 6 (1), 43.
15. Sroka, R., Schaffer, M., Fuchs, C., Pongratz, T., Schrader-Reichard,
U., Busch, M., Schaffer, P.M., Duhmke, E., and Baumgartner, R. (1999).
Effects on the mitosis of normal and tumor cells induced by light treatment
of different wavelengths. Lasers Surg. Med. 25 (3), 263-71.
16. Whelan H.T., personal communication: NASA-LEDs presented in [17,18]
were used to irradiate the Osteoblasts.
17. Whelan, H.T., Houle, J.M., Whelan N.T., Donohoe, D.L., Cwilinski,
J., Schmidt, M.H., Gould, L., Larson, D.L., Meyer, G.A., Cevenini, V.,
and Stinson, H. (2000). The NASA light-emitting diode medical program
- progress in space flight and terrestrial applications. Space Tech.
& App. Int'l. Forum - 2000, 504, 37-43.
18. Whelan, H.T., Houle, J.M., Donohoe, D.L., Bajic, D.M., Schmidt,
M.H., Reichert, K.W., Weyenberg, G.T., Larson, D.L., Meyer, G.A., and
Caviness, J.A. (1999). Medical applications of space light-emitting
diodes technology - space station and beyond. Space Tech. & App.
Int'l. Forum - 1999, 458, 3-15.
19. Pinheiro, A.L.B. personal communication: Irradiation of mouth ulcers
in 57 HIV-positive patients - in average three ulcers per patient (23
patients with lesions strongly related to the HIV infection) - using
5mW lasers (635 and 670nm, beam cross sections ~ 1mm2) and local light
doses between 0.9 and 3.4·104 Jm-2, revealed generally a ca.
50% reduction of the total healing period of the ulcers, when compared
to non irradiated cases. In the HIV related cases, the healing times
depended upon the actual status of infection of the patients: ARC patients
reacted in general better to the laser therapy than patients having
developed full AIDS.
20. Pinheiro, A.L.B. personal communication: Laser irradiation of tissues
contacting implants improved osteointegration (animal experiment): Laser
power 40mW, wavelength 830nm, beam cross section ~ 1mm2, dose per spot
1.2·104 Jm-2 and total dose per session 4.8·104 Jm-2.
Abstract in: Martins, P.P.M., Pinheiro, A.L.B., Oliveira, M.A.M., and
Gerbi, M.E.M. (2000). P.P.M.M. Implant System Have Osteointegration
Improved by LLLT. World Association for Laser Therapy, Third World Congress.
Athens, 11-13 May.
21. Tunér, J., and Hode, L. (1999). Low Level Laser Therapy -
Clinical Practise and Scientific Background. Sweden: Prima Books, pp.
22. Lubart, R., Friedmann, H., Peled, I., and Grossman, N. (1993). Light
Intensity Effect on Cell Proliferation. Fifth Congress of the European
Society for Photobiology. Marburg/Lahn, September 19-26.
23. Trelles, M.A., and Mayayo, E. (1992). Mast Cells are Implicated
in Low Power Laser Effect on Tissue. A Preliminary Study. Lasers in
Medical Science, 7, 73-77.
24. Mester, A.R. (1992). Modalities of low power laser applications.
Laser Applications in Medicine and Surgery. Laser Bologna 92. Third
World Congress - International Society for Low Power Laser Applications
in Medicine. Bologna, September 9-12.
25. Mester, A.R. (1994). Low power laser in the complex wound management.
Laser Therapy, 6 (1), 39.
26. Sommer, A. (1993). Fast Surface Covering Beam Distributor for Lasers.
German Patent Office, Munich, Patent Nr. 4308474/2000.
27. Lubart, R., Friedmann, H., Peled, I., and Grossman, N. (1993). Fibroblasts
proliferation and light - a non linear interaction. Lasers Surg. Med.
9 (2), 143.
28. Costato, M. (1992). Laser light and biological response: cooperative
phenomena vs. order and disorder. Laser Bologna 92. Third World Congress
- International Society of Low Power Laser Application in Medicine.
Bologna, September 9-12.
29. Dahle, J., Kaalhus, O., Moan, J., and Steen, H.B. (1997). Cooperative
effects of photodynamic treatment of cells in microcolonies. Proc. Natl.
Acad. Sci. USA, 94 (5), 1773-8.
30. Longo, L., and Corcos, L. (1992). Defocused CO2 Laser therapy in
pathologic wound healing, in: Laser in Medicine. W. Waidelich (ed).
Berlin, Heidelberg, New York: Springer, pp. 409-412.
31. Gwynne, P. (1994). Cold Laser Uses Move Beyond Carpal Tunnel. Biophotonics,
32. Sommer, A., and Franke, R.P. (1993). Evaluation of the Energy Density
Distribution in Laser Light Fields generated with the LILAB System.
Biomed. Tech. 38, 240-242.
33. Sommer, A., and Franke, R.P. (1995). Determination of the Energy
Density of a Periodical Homogenous Laser Light Pattern Used in Medical
Applications. Biomed. Tech. 40, 133-136.
34. Young, S.R., Dyson, M., and Bolton, P. (1991). Effect of Light on
Calcium Uptake by Macrophages. Laser Therapy, 3, 1-5.
35. Karu, T., Andreichuk, T., and Ryabykh, T. (1993). Changes in Oxidative
Metabolism of Murine Spleen Following Laser and Superluminous Diode
(660-950nm) Irradiation: Effects of Cellular Composition and Radiation
Parameters. Lasers Surg. Med. 13, 453-462.
36. Goldman, J.A., Chiapella, J., Cassey, H., et al. (1980). Laser therapy
of rheumatoid arthritis. Lasers Surg. Med. 1 (1), 93-101.
37. Sommer, A., and Franke, R.P., (1994). The Low Intensity Laser Activation
Biostimulation (LILAB) System. Laser Therapy, 6 (1), 23.
38. Sommer, A.P., Pinheiro, A.L.B., Mester, A.R., Franke, R.P., Whelan,
H.T. (2001). Biostimulatory Windows in Low-Intensity Laser Activation:
Lasers, Scanners, and NASA's Light-Emitting Diode Array System. J. Clin.-Laser.-Med.-Surg.
19 (1), 29-33.
We are grateful to the American Chemical Society (ACS) for supporting
the advance in the investigation of the molecular mechanism of accelerated
wound healing processes induced by light, by cosponsoring the 1st International
Workshop on Nearfield Optical Analysis.
The Cochrane analyses - can they be improved?
Jan Tunér DDS,
The aim of the international Cochrane collaboration
is to continuously evaluate new and old medical therapies. The basis
for their systematic reviews is the recognition of Randomised Controlled
Trials as the "gold standard" for scientific evaluation of
small and moderate effects from treatment (1). A thorough search is
made for the available literature and the most qualified studies are
analysed. The purpose of the analysis is to find out whether or not
there is any solid support for a specific medical treatment modality.
Such analyses are published in medical journals and extended versions
are quarterly updated in the Cochrane Library.
Three systematic reviews of the effectiveness of Laser Therapy have
been published in the Cochrane Library. These reviews have evaluated
the effect of Laser Therapy for Venous ulcers (1), Osteoarthritis (2)
and Rheumatoid arthritis (3). However, the Cochrane style of reviewing
has been criticised (9) for not taking into account the variability
of diagnoses, treatment procedures and dosage of the included trials.
Critical comments are, according to the rules of the Cochrane system,
supposed to be included into the ongoing updating of the reviews, but
the comments on the venous ulcer analysis by the author of this article
have not been published, nor commented.
The impact of the Cochrane Library is profound in medicine. It is therefore
essential to "evaluate the evaluation", to find out whether
or not these analyses can live up to the prestige of the Cochrane Library.
The following text is a critical "analysis of the analyses".
Four trials are analysed; two comparing laser with placebo, one comparing
laser with non-coherent light and one comparing laser with ultraviolet
light. The two studies comparing laser with placebo are (4) and (5).
In (4) a 6 mW HeNe laser was used. 4 J/cm2 was said to be given to the
ulcers. Ulcer size ranged from 3-32 cm2. Treatment technique is not
stated. Regardless of technique, it would take between 36 minutes and
6 hours to achieve the stated dose, per wound and session. Using a sweep
technique with a focused beam, the power density would be around 0.15
W/cm2. If a defocused beam was used to cover the entire largest wound
(32 cm2), energy density would be around 0.00019 W/cm2, which is lower
than the energy density of the normal illumination in an operatory,
which is extremely low. A dose miscalculation is probable but the authors
of the study have been reluctant to reveal the parameters used. In the
absence of such parameters, this study cannot be properly evaluated,
but very low power density is a probable reason for negative results.
In the second study on venous ulcer (5), GaAs was employed. 4 mW was
used for 10 minutes on ulcers ranging from 4 to 52 cm2, regardless of
ulcer size. The 4-cm2 wound would thus receive 0.6 J/cm2 and the largest
wound 0.046 J/cm2, not the 1.96 J/cm2 stated by the authors. Energy
density as well as dose for larger wounds are thus low. Treatment technique
is not indicated. "The laser was held perpendicular to the surface
of the wound". This is not a sufficient description of the treatment
method. There is a great difference between following the outer border
of the wound (active healing area) and spreading the beam over the open
wound area. The distance between diode and wound is not indicated.
In summary, the energy said to be applied in these studies must be questioned.
The Cochrane evaluators have not observed the essential contradiction
between the actual dose and the dose indicated by the authors. In one
of the four studies (Crorus and Malherbe, 1988) the laser wavelength
and dose is not stated in the original paper. This makes an evaluation
Five trials were included out of 142 potentially relevant articles.
Six abstracts are awaiting assessment, after having contacted the authors
for further details. These are our comments on the evaluation:
- a. Bülow (1994) (negative outcome) is a good study with a reasonable
energy (22.5 J/session) for painful knee osteoarthritis. However,
see discussion on this study in the text on RA.
- b. Basford (1987) (negative outcome) used 0.007 J per point for
thumb arthritis. Meaningless dosage.
- c. Jensen (1987) (negative outcome) used 0.2 J in total for painful
knee arthrosis. Clearly a meaningless dosage.
- d. Stelian (1992) (positive outcome) used around 11 J per session,
twice daily, so 22 J per knee and day, 10 consecutive days. This study
has a dose that is acceptable even in the light of to-days experiences,
although it was published already in 1992. The outcome of this study
is in sharp contrast to the rather similar study by Bülow. Dose
is the same, number of sessions is almost the same (10/9). However,
Bülow treated 2-4 times a week, Stelian daily.
- e. Walker (1983) (positive outcome) is a classical positive study,
but the use of a less-than 1 mW HeNe laser clearly puts this study
in doubt. In our opinion it should not be used as anything but a purely
The crucial criticism of the evaluation of the studies above is that
there is no discussion about dosage! On the Jadad quality scale (1-5),
Basford is given 3 and Bülow 2. However, Basford has used a non-significant
dosage for a finger joint, while Bülow has a reasonable dose for
knee osteoarthritis. Johansen (see RA below) has been over the generally
accepted dosage window. In retrospect, the Bülow trial has been
criticised for overlooking a significant short-term effect of active
laser treatment by only testing the statistical significance at follow-up
(Marks & de Palma 2000). Stelian used 55 times higher energy than
Jensen, for knee osteoarthritis! The Jadad quality scale is applied
correctly to the studies. But without inclusion of the laser parameters
in the scale, the evaluation rather becomes a "study design beauty
contest" instead of an evaluation of therapeutical significance.
3. Rheumatiod arthritis
8 out of 191 articles met the inclusion criteria, five were RCT:s. Five
studies are waiting assessment, pending answers from the authors. Comments:
- a. Johansen (1994) (negative outcome) used 11.9 J per finger joint,
which is a high dose, maybe too high.
- b. Heussler (1993) (negative outcome) used 1.5 J per finger, which
is on the low side.
- c. Walker (1987) (positive outcome), see above for relevance. Although
Johansen has used 1700 times higher a dose, both studies are "put
in the same basket", although a low/high dose evaluation is performed.
The wide gap in dosages does not justify a subgroup analysis of merely
- d. Hall (1994) and Goats (1996) used combined coherent and non-coherent
light. Combined single wavelength coherent light and multi-wavelengths
non-coherent light is a poorly studied area and there is no ground
for postulating that they produce the same biological effects when
used in combination or alone.
- e. The authors quote Seichert (1991): "The laser light loses
its coherency completely after only a few tenths of mm in depth".
This is not in accordance with laser physics, but a tall tale. Fact
is that the length of coherence is considerably reduced but remains
within the laser speckles, which can penetrate considerable depth
in the infra-red.
- f. The meta analysis by Gam (one of the Cochrane co-authors) (8)
is referred to. This analysis did not find any effect of Laser Therapy
for musculoskeletal pain. The re-evaluation of the same studies made
by Bjordal (9) found a clear effect, since an analysis of the dosage
and therapeutic techniques was included. This later meta- analysis
is not mentioned. As stated above, critical comments on the Cochrane
reviews are supposed to be included.
The evaluators of the Cochrane groups have been successful in finding
many of the relevant studies in the literature. Several interesting
observations have been made and a skilful analysis of the design parameters
has been performed.
Evaluation of effects is a universal problem for all empirically developed
therapies, where consensus of a clearly defined optimal dose range and
adequate treatment procedure is lacking. For clinicians practising laser
therapy it is hard to understand that the reviewers have disregarded
which locations for laser exposure and which laser doses that are being
used. The methodology used seems to be that of drug studies. But drugs
and LLLT are quite different. While the oral intake of the drug is the
only procedure, LLLT has several, such as local irradiation, trigger
point irradiation, acupuncture irradiation and irradiation over peripheral
nerves. All these methods must be evaluated separately.
The biggest problem has been the fact that most of the reviews have
included a variety of diagnoses, doses and treatment procedures and
then been "put into the same basket". New treatment methods
are often subject to trials where clinicians include all their non-responder
patients, and the early laser literature is no exception. The laser
literature involves around 100 double blind trials (12). They include
a heterogeneous sample of around 20 different diagnoses, which vary
widely in pathology, tissue involved and prognosis. Adding to this are
all the inadequate treatment procedures and doses that have been employed
in clinical LLLT trials, so we should be very careful about putting
all the trial results together, to see if they add up to an effect that
is significantly better than placebo. Under such circumstances the majority
of these trials will find no effect of active treatment. Future reviews
are suggested to analyse the positive studies in order to find out what
kind of parameters seem to work. Subgroup analyses are of particular
importance. Dosage analysis cannot be limited to the groups "high"
and "low" because of the great variations in dosage.
So what have these new Cochrane reviews brought us? Three distinct steps
of progress can be identified. The first is the new review limitation
to specific diagnosis (2) (3). The second is that in the RA review,
attempts have been made to evaluate effects separately for high and
low dose. And thirdly, but not least they even give a (conditioned)
recommendation: "Low level laser therapy could be considered for
treatment of rheumatoid arthritis for its short term effect and lack
of side effects".
In my opinion both laser researchers and reviewers have common responsibilities
in enhancing our understanding of LLLT. The three existing Cochrane
reviews on Laser Therapy have drawn a conclusion to which I can subscribe:
The literature on the evaluated indications is ambiguous, the average
quality of the studies is not high and the number of relevant studies
is low. It can therefore be postulated that there is still insufficient
scientific support for the general use of Laser Therapy for these indications
and that only moderate and short-term effects can be confirmed. However,
I would appreciate if reviewing methodology included validity criteria
for doses and targets for laser irradiation (synovia, triggerpoints,
acupuncture points, peripheral nerve, etc.).
I would also appreciate if the effect calculations were performed for
subgroups of different doses, treatment frequencies and laser types.
And there is still room for improvement of the literature search. Further,
reviewers must make their own dosage calculations, not taking the doses
quoted in the studies for granted. Too many of the negative LLLT studies
contain serious flaw (11) and such flaw must be firmly investigated
in the evaluation of studies. My main impression is that reviewing methodology
slowly is improving, but there is still a long way to go before the
Cochrane Collaboration can claim propriety over the term "evidence-based
medicine" in this field of medicine.
- Flemming K, Cullum N. Laser Therapy for venous leg ulcers (Cochrane
review). In: The Cochrane Library, 4, 2000.
- Brosseau L, Welch V, Wells G et al. Low level laser therapy (Classes
I, II and III) for treating Osteoarthritis. The Cochrane Library.
Issue 4, 2000.
- Brosseau L, Welch V, Wells G et al. Low level laser therapy (Classes
I, II and III) for treating rheumatoid arthritis. The Cochrane Library.
Issue 4, 2000.
- Lundeberg T, Malm M. Low power HeNe laser treatment of venous leg
ulcers. Ann Plast Surg. 1991; 27: 537.
- Malm M, Lundeberg T. Effect of low power gallium arsenide laser
on healing of venous ulcers. Scand J Plast Reconstr Hand Surg. 1991;
- Siebert W, Seichert N et al. What is the efficacy of "soft"
and "mid" lasers in therapy of tendinopathies? A double
blind study. Archives of Orthopaedic & Traumatic Surgery 1987;106
- Seichert N et al: Wirkung einer Infrarot-Laser-Therapie bei weichteilrheumatischen
Beschwerden in Doppel-blindversuch. Terapiwoche. 1987; 37: 1375.
- Gam A et al: The effect of low-level laser therapy on musculo-skeletal
pain: a meta-analysis. Pain. 1993; 52: 63-66
- Bjordal JM, Greve G: "What may alter the conclusions of reviews?".
Physical Therapy Reviews. 1998; 3: 121-132
- Beckerman H et al: The efficacy of laser therapy for muscoskeletal
and skin disorders: a criteria-based meta-analysis of randomized clinical
trials. Physical Therapy. 1992; 7 (72): 483
- Tunér J, Hode L. It´s all in the parameters - a critical
analysis of some well-known negative studies on low-level laser therapy.
J Clin Lasers Med Surg. 1998; 16 (5): 245-248.
- Tunér J. What is in the LLLT literature? In: Lasers in Medicine
and Dentistry, Ed. Simunovic Z. European Medical Laser Ass. 2000,