Phototherapy, or light therapy, is the exposure to specific wavelengths of light using lasers, LEDs, or lamps for therapeutic purposes.

The "right" phototherapy device can accelerate tissue repair^1,2 and eliminate or reduce pain,^3-5 inflammation,⁶ and loss of range of motion.⁵ New research also has shown the beneficial effect of light on nerve regeneration.^7,8 But what is the "right" device? With a slew of manufacturers, it is not easy to sort through information and find the best product for your money.

Here the five most important factors to help you find the "right" light device:

1. Power: The power for a low-level light system is expressed in milliwatts, or mW. One thousand milliwatts equals 1 watt. Higher wattage corresponds to a faster treatment; however, this is dependent on the size of the probe. Most medical research and literature advocate a light dose between 3 and 8 J/cm².^9,10 Basically, the dosage depends on the size of the device, power, and treatment time. A dose between 3 and 8 J/cm² is considered a relatively low dosage and follows the Arndt-Schultz Law that low stimuli activate physiological processes where high stimuli inhibit physiological responses.

   Whether it takes 1 minute or 20 minutes, as long as you provide an adequate dose, your patients will benefit. When comparing the power of different manufacturers' devices, it is important to ask how long it takes to produce 1 joule per cm². Unless you are treating acupuncture points, it is not practical to buy a very low-powered device (<50 mW).

2. Wavelength: Look for a device that emits infrared light (>750 nm). It has been established that the penetration of light is deeper with higher wavelengths.^11,12 A strictly red light device will not penetrate deep enough and will be ineffective at treating deep musculoskeletal conditions.¹¹ Many devices have a combination of red and infrared light. Red light is beneficial at superficial levels and is used as a visual indicator that lets the user know when the device is operating, since infrared light cannot be seen with the human eye.

3. Cluster size: Today's phototherapy devices are made of LEDs/SLDs and lasers. SLD means super luminous diode. SLD is a fancy way of saying LED, and with today's technology, there is no difference between the two. Because of the makeup of lasers, they tend to be spaced farther apart, which reduces their ability to effectively treat larger areas.¹³ Lasers and LEDs produce the same therapeutic effect, and lately some researchers prefer LEDs over lasers.^13,14 LED systems tend to be more affordable, durable, and portable. The diodes can be packed closer together, and more wavelengths are available.^13,14

4. Ease of use: The light device should be lightweight, portable, and have a friendly user interface. Because light therapy treatment times are typically quick, you do not want a device that takes longer to set up than to treat.

5. Price: This is typically the biggest factor when deciding which new device to purchase. With the current competition available, you shouldn't have to pay more than a couple thousand dollars for a high-quality, high-powered light device.

The Horizon Infrared Device

The Horizon probe can be purchased as a plug-in to the new HF54 hands free ultrasound or separately as a portable stand-alone unit.

Hill Laboratories, a medical-table manufacturer, has expanded its therapy line by developing the Horizon infrared light device. The Horizon infrared and red light therapy unit delivers 800 mW of infrared (880 nm) and red (660 nm) light with 36 infrared LEDs and seven visible red LEDs. The treatment surface plate is roughly 2 inches in diameter. A dose of 4 J/cm² takes a little more than 90 seconds. The Horizon probe can be purchased as a plug-in to the new HF54 hands free ultrasound or separately as a portable stand-alone unit. The stand-alone Horizon was designed to be lightweight, durable, and portable. The entire unit weighs 2 pounds, 8 ounces, with the probe handle weighing only 81/2 ounces. This lightweight design eliminates operator fatigue and makes it easy to transport. The stand-alone power supply has two keyhole mounts on the backside of the enclosure, enabling it to be mounted to a wall like a telephone. Hill Laboratories also manufactures a rolling cart for $85, or the unit can simply sit on a shelf. The Horizon infrared device can be plugged into the HF54 hands free ultrasound for $1,499 or purchased with its own power supply (stand-alone) for $1,795.

When the Horizon is plugged into the HF54, ultrasound, muscle-stimulation, and light functions can operate at the same time. The HF54 uses a large 35/8-inch-diameter soundhead with three crystals. When treating a very large area (both sides of the spine), a second soundhead can be added to the system. The large soundhead produces pulsed ultrasound so the head can safely be left in a stationary position.

Dual-channel interferential and premod current come standard and can also be used in combination directly through the soundhead with ultrasound. The HF54 uses a special coupling agent called a gel pad. The gel pad contours to the patient's body and eliminates the mess and residue of liquid gel. Depending on patient volume, the gel pad can last between 2 and 5 weeks. Alcohol can be used to clean the gel pad, or a wet paper towel can be used to prevent direct contact with the patient.

The standard package of a single soundhead and interferential/premod current is $3,195. A total package including dual hands free ultrasound soundheads, interferential/premod current, and the Horizon light therapy is $5,289, which is lower than some phototherapy systems by themselves.

Operating the Horizon

The Horizon has only two buttons—one to select the time, and one to start and stop. To further simplify this unit, there are only three time selections: 30, 60, and 90 seconds. When the button is pressed a fourth time, all three time selections light up and the unit runs continuously. The buttons to operate the Horizon light probe are on the probe itself and not on the HF54 generator or the stand-alone power supply. All of the timing circuitry and on/off control for the output are within the handle of the light probe.

Patient Setup

When you are treating an acute or chronic non-wound condition:

1. Use alcohol or an alcohol wipe to prepare the treatment site.
2. Treat with firm and direct skin contact. Do not use through the clothes. Light transmission is almost completely blocked when used through the clothes.
3. Use the Select button to select a 30- , 60- , or 90-second treatment.
4. Press the Start/Stop button to begin the treatment.
5. Press Start/Stop a second time if you want to stop the treatment.
6. Keep the probe in one location at a time. Do not move or "bathe" the treatment area. If the treatment area is larger than the probe (2 inches), treat one area at a time until the entire area is covered.

Brady Aller is therapeutic product manager at Hill Laboratories. Contact him at .

References

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2. Loevschall H, Arenholt-Bindslev D. Effect of low level diode laser irradiation of human oral mucosa fibroblasts in vitro. Lasers Surg Med. 1994;14:347–351.
3. Thomasson TL. Effects of Skin-Contact Monochromatic Infrared Irradiation on Tendonitis, Capsulitis, and Myofascial Pain. J Neurol Orthop Med Surg. 1996;16:242–245
4. Gur A, Karakoc M, Cevik R, Nas K, Sarac AJ, Karakoe M. Efficacy of low power laser therapy and exercise on pain and function in chronic low back pain. Lasers Surg Med. 2003;32:233–238
5. Ozdemir F, Birtane M, Kokino S. The clinical efficacy of low-power laser therapy on pain and function in cervical osteoarthritis. Clin Rheumatol. 2001;20(3):181–1844.
6. Kana JS, Hutschenreiter G, Haina D, Waidelich W. Effect of low-power density laser radiation on healing of open skin wounds in rats. Arch Surg. 1981;116:293–296.
7. Mohammed IF, Al-Mustawfi N, Kaka LN. Promotion of regenerative processes in injured peripheral nerve induced by low-level laser therapy. Photomed Laser Surg. 2007;25(2):107–111.
8. Rochkind S, Nissan M, Alan M, Shamir M, Salame K. Effects of Laser: irradiation on the spinal cord for the regeneration of crushed peripheral nerve in rats. Lasers Surg Med. 2001;28:216–219.
9. Enwemeka CS. Attenuation and penetration of visible 632.8 nm and invisible infra-red 904 nm light in soft tissue. Laser Ther. 2001;13:95–101.
10. Reddy GK, Stehno-Bittel L, Enwemeka CS. Laser photostimulation of collagen production in healing rabbit Achilles tendons. Lasers Surg Med. 1998;22:281–287.
11. Ryan T, Smith RKW. An investigation into the depth of penetration of low-level laser therapy through the equine tendon in vivo. Ir Vet J, Volume 60 Number 5.
12. Tunér J, Hode L. Depth of Penetration of Laser Light in Tissue. Laser Therapy in Dentistry and Medicine. Prima Books AB, Grängesberg, Sweden, 1996
13. Whelan HT, Buchmann, EV, Whelan, NT et al. NASA Light-Emitting Diode Medical Applications From Deep Space to Deep Sea, Space Technology and Applications International Forum-2001, edited by M. S. El-Genk, American Institute of Physics CP552, l-56396-980, 35–45.
14. Enwemeka, CS. Therapeutic Light. Rehab Management, January/February 2004; 17(1):20–25, 56–7.