It is a regrettable fact that the reporting of laser parameters has not yet reached a satisfactory level in scientific journals. These parameters must always be reported, or should the paper be returned for improvement or discarded. These parameters must also be included in the abstract. Indeed, in several papers the proper reporting is found in the manuscript but not in the abstract. But the abstract goes in an unchanged version to PubMed – and most people confine themselves to reading the PubMed abstracts. The original papers are expensive to buy, if not available through a university library.

Below are the first ten PubMed papers on LLLT from a random day in July 2012. Reviews and Meta analyses were excluded. Let us see what is reported about the laser parameters!

They received transcutaneous LLLT irradiation at the lesion site. The LLLT parameters were: wavelengths - 660 or 780 nm; energy densities - 10, 60 or 120 J/cm²; power - 40 mW; spot - 4 mm².

  • Comment: Not bad at all, but the energy is not reported and since the time per point is not reported, it cannot be calculated.

This study evaluated the effect of LLLT (GaAlAs, 780 nm, 20 J/cm², 40 mW)

  • Comment: The lasing medium such as GaAlAs is of no interest, wavelength tells anyway. Applied energy, spot size and time per spot missing.

A 5×200-mW 810-nm cluster array was used to deliver 25 W/cm2 to the skin.

  • Comment: With cluster probes, the spot size and the geometrical configuration needs to be reported. A total of 1 W over one cm2? Reporting is inadequate.

Transcutaneous 808 nm, 450 mW, (13.5 or 54 J) continuous wave (cw) mode or 650 nm, 35 mW, (1.1 or 4.4 J), cw LI or sham LI, was applied for 30 or 120 sec to a single point overlying the midpoint of rat sciatic nerve.

  • Comment: Spot size and J/cm2 missing.

…was performed followed by 25 mW/cm2) LLLT at 650 nm for 10 min/day

  • Comment: Not very informative

….λ 820 nm; continuous wave; output power: 50 mW; focal spot: 0.0314 cm2; exposure duration: 5 sec; power density: 1.59 W/cm2; energy dose: 0.25 J; energy density: 7.96 J/cm2) for each shot)

  • Comment: Wow!

….investigated the effects of LLLT with a diode laser (808 nm) device on the healing

  • Comment: Everything missing except for the wavelength.

…before and after treatment with low-level laser therapy (LLLT)

  • Comment: The least informative of them all.

Group 1 was the control group, group 2 received 830 nm laser radiations, and group 3 was submitted to 670 nm laser radiation (power density=0.5 mW/cm2). The animals underwent laser therapy with 36 J/cm2 energy density (total energy=2.52 J and 72 sec per session) immediately after surgery and on the 4 subsequent day. Power density (mW/cm2) is reported; good!

  • Comment: Power of lasers missing. Were the parameters of the two wavelengths really identical? But one of the best abstracts, still.

…10 sessions of LLLT (830 nm, output power of 50 mW, and fluence of 707 J/cm2.

  • Comment: energy, time and spot size missing

So why are all these parameters necessary? One obvious reason is that it must be clear what was actually performed. The other one is that with all parameters given, a qualified reader will be able to make a control calculation of the reported parameters. Too often (in fact, always) the discussion part in LLLT papers refer to studies with a great variation of parameters and without stating these differences. So the discussion will compare apples and bananas.
So, here is the checking list for your next study. Report these parameters in the manuscript and in the abstract:

  1. Wavelength
  2.  Output power in mW (as independently measured)
  3. For GaAs laser: average output in mW
  4. Spot size
  5.  Energy per point (J)
  6.  Energy density (J/cm2)
  7.  Power density (mW/cm2)
  8. Time per point, in seconds

And before you start, check these guidelines too:

Complicated and difficult? Yes, it’s science!