Clinical Use of Low Level Laser Therapy
Philip A.M. Rogers MRCVS
(1992, updated 1993, 1995)
Postgraduate Course in Veterinary AP, Dublin, 1996
(1992, updated 1993, 1995)
Postgraduate Course in Veterinary AP, Dublin, 1996
ABSTRACT
1. An infra-red (IR, 904 nM) LASUWA diode laser, pulsed at 5000 Hz and with a mean output power of 30 mW when full on, was used in uncontrolled clinical tests in animal and human subjects for 2 years.
2. Low level laser therapy (LLLT) had analgesic, vasodilatory and anti-inflammatory properties. It greatly enhanced the healing of accidental /surgical wounds and of minor skin burns. It gave rapid and excellent results in lesions of the skin, superficial tissues (subcutaneous tissue and periosteum) and superficial Trigger Points (TPs).
3. When combined with a knowledge of the acupuncture (AP) system, LLLT was effective in treating myofascial syndromes in dogs and humans, but it was about 10% less successful than AP in treating myofascial problems in horses.
4. LLLT gave poor results in severe tendon strain in horses. It was useless in serious spinal pathology, some idiopathic lameness in dogs and people, carpal swelling in horses and arthritic swelling of human finger joints.
5. Although there were some complete and partial failures and although AP and other therapies were combined with LLLT occasionally, the clinical results confirm published claims that LLLT is valuable in veterinary and paramedical practice.
INTRODUCTION
Low level laser therapy (LLLT) is gaining increasing acceptance in conventional veterinary practice (as a therapy for tissue trauma, wounds, granuloma, myositis, tendinitis etc). Cold (soft) lasers are available as robust, portable instruments. They are operated by batteries or by mains electricity.
LLLT also is used instead of needles in veterinary acupuncture (AP) to stimulate the acupuncture points (APs) and Trigger Points (TPs) in animals but there are few published studies to date. Commercial interests claim excellent results in a wide variety of clinical conditions. Russian and German workers have used LLLT at the human APs for many years. Since 1984, there are many papers on the method in humans (Rogers 1991g).
The history, theoretical uses and physics of laser are discussed in detail in Pontinen's textbook (1995).
Though laser light is emitted in a continuous wave (cw) beam, it can be interrupted (modulated) at variable frequencies and intervals by mechanical or electronic means. Interruption of the light beam at fixed intervals is called pulsing. Pulsed lasers, especially those interrupted 2000-10000 times/second (Hz), penetrate deeper in tissue than unpulsed lasers.
LLLT has some advantages over needling or point injection in AP or TP therapy:
LLLT usually is given on 2-8 occasions, at intervals of 1-3 days in acute cases and 3-7 days in chronic cases. At each session, the laser is applied for 20-120 seconds/point over or around the rim of the lesion and to each of the APs or TPs selected for the case.
Total treatment time/session depends on mean output power (MOP) and the depth of point. High output lasers (MOP >30 mW) and superficial points need less irradiation time than low output lasers (MOP 1-10 mW) and deeper points. With 30-50 mW MOP lasers, dose time is 10-60 seconds/point, but with 3-5 mW MOP lasers, the required dose time/point is 10 times longer.
The LASUWA laser claims a MOP of 30 mW. It has a strong metallic probe, with the glass shield of the diodes set back about 0.5 cm from its tip. In horses, the probe can be applied with heavy pressure over muscular areas, thereby gaining 1-3 cm extra penetration into the tissues, their TPs and APs, as well as achieving a massage effect at the tender areas.
From September 1989 to September 1991, I used LASUWA LLLT experimentally in clinical conditions in horses, dogs and people. This article summarises my experiences during that time.
CONDITIONS TREATED AND METHODS USED
The main types of conditions treated were: (a) equine, human and canine muscle pain and lameness; (b) human and canine "disc disease"; (c) equine flexor tendon injuries; (d) equine and human periostitis; (e) skin lesions; (f) miscellaneous human conditions; (g) haematoma.
From September 1989 and April 1990, most cases were treated by LLLT alone. The laser was applied over or near the affected area, to TPs and key APs for the affected area. If systemic signs were present, the relevant APs were treated also (for example in a case of chicken-pox, LLLT was applied to points GV14, LI04,11; ST36 (for their effect on fever and the immune system), as well as to the pruritic lesions. In a few cases, AP needles were inserted in TPs also, especially if the TPs were deep, as in heavily muscled areas. In a small number of cases, other therapies (electro-AP, local medication, Dermisol or ointments) were combined with LLLT.
CLINICAL RESULTS
(a) Equine, human and canine muscle pain/lameness
Most cases involved para-vertebral pain (cervical, thoracic, lumbar or sacral). Some involved pain of limb muscles (scapula, arm, forearm, thigh, gluteals, gastrocnemius).
LLLT (10-30 seconds/point) was used on the TPs and APs for the affected area and over the painful muscle(s). As many points were treated at each session, the session time was usually 10-20 minutes. Treatment was given every 1-2 days in acute cases and every 5-9 days in chronic cases. Excellent results were got in 2-4 sessions over 4-9 days in acute cases and in 1-7 sessions over 16-35 days in chronic cases.
In dogs and people, results were similar to those using simple AP, electro-AP or point injection in similar cases over the previous few years. In horses, in which TPs can be 7-12 cm deep, the clinical results were about 10% points below those attained by earlier AP methods and clinical success took 1-3 sessions more to attain than with earlier AP methods.
(b) Human and canine "disc disease"
Four acute cases of human low lumbar disc disease were treated by LLLT, often with needles, at TPs plus BL23, GB34 bilateral, plus GV03. The cases were diagnosed clinically as Grade 1 by a positive "Straight Leg Raising Test" and a history of pain radiating along the sciatic path. All had excellent results in 3-5 sessions at intervals of 1 week.
Three cases of acute canine thoracolumbar disc disease (diagnosed as Grades 1 to 3 on clinical examination) were treated by LLLT, often with needles, at TPs plus BL23, GB34 bilateral, plus GV03. All had excellent results in 2-4 sessions at intervals of 5-9 days.
As the diagnosis was made on clinical grounds only (i.e. did not involve myelography or radiography), some of these cases may have been myofascial paravertebral pain (section (a), above), rather than "disc disease".
(c) Equine flexor tendon injuries
IR LLLT was used on 10 cases: 4 were acute (recent strain, hot and painful), 2 were acute local nodules/swellings (caused by suspected brushing) and 4 were chronic (bowed tendon).
LLLT was used 3-6 times in 1-4 weeks (10-20 seconds/point) on about 8 points along each surface of the tendon (lateral, posterior and medial), concentrating especially on the bowed or swollen area. LLLT was used also on LI04,11 and Thoresen's Ting points (PC09, LU11, HT09).
Of the 6 acute cases, two passed veterinary inspection for the Newmarket yearling November sales and were sold within 5-7 days of presentation for treatment; 1 case became cool after 2 weeks but some tendon thickening was still present. Three cases failed (swelling and heat persisted). That trainer refused to comply with my advice to rest the horses for the first few weeks. He changed to another vet, who gave other treatments, which also failed.
All 4 chronic cases improved markedly, with disappearance of the "bow" and lessening of the mediolateral thickening in 2-4 weeks. These cases were rested for 6 weeks (kept in the box and given only walking or paddock exercise daily) before gradual resumption of training.
Initially, IR LLLT gave very encouraging results in tendon injury, whereas AP methods used in previous years gave very poor success in such cases. However, all 4 of the chronic bowed tendons relapsed or the horses broke down on the opposite leg and were shot or retired and 3/6 of the acute cases failed to become sound.
Today, I would confine my use of LLLT in equine tendon problems mainly to recent superficial injury, especially that caused by brushing. Before starting to treat the case, I would extract an undertaking from the trainer that the horse would not be worked for 10 months, or until I was satisfied that the tendon was well healed.
I would attempt to treat chronic tendonitis only if trainer would undertake not to work the horse for 10 months.
(d) Equine and human periostitis
During the acute (hot, painful) stage, 8 equine cases of splint, spavin or bucked shins were treated 2-4 times every 1-2 days by local LLLT (20 seconds on a few positions on and around the lesion and on AP + Ting points for the area). All cases became painless in 2-9 days.
LLLT was used in 3 chronic but painful human cases (1 shin splint; 2 cases of lateral humeral epicondylitis, or "tennis elbow"). All became painless in 1-10 days. One patient (a human with a painful shin-splint) ran in a cross country race 3 days after the first (and only) session. He ran a good race, finishing in the top third of the field.
(e) Skin lesions
Many types of skin lesions were treated by IR LLLT (without AP needles). In all, about 19 cases were treated, mainly human lesions: (abrasions, knife cuts, minor burns, wounds, chronic head ulcer; pruritic lesions (chicken-pox), facial herpes, retro- and para-scrotal wet eczema; interdigital fungal infection (athlete's foot), acne). A few equine lesions were treated also (granulation wound; cracked heels).
In addition, 2 surgical suture lines were treated: one purulent area following rumen fistulation in a bullock and one swollen painful incision line following reposition of a dislocated shoulder and a compound fracture of the clavicle in a man).
Acute cases were treated every day and chronic cases every 3-7 days. LLLT was applied locally for 30-60 seconds, on and around the lesion. It was applied occasionally to AP points or Ting points for the region also.
Clinical results in acute cases in humans were dramatic, with relief of pain or pruritus and marked anti-inflammatory effect within 1-3 days and excellent healing within 7-14 days. In wet eczema of the retro- and para-scrotal eczema, 1 session of LLLT + application of 5% copper sulphate solution gave cure in 2 days.
In chronic cases, with granulation and purulent infection, healing was slower but was markedly enhanced: purulent discharge was gone within days and healing (by second intention) was complete within 3 weeks. LLLT was excellent in acne (2 cases): the lesions cleared within 2 weeks (6 sessions).
(f) Miscellaneous human conditions
LLLT only
IR LLLT was used at TPs, local AP points and AP points for the region. Conditions which were treated included joint sprain (shoulder, wrist, fingers, thumb, knee, ankle), headache, acute and chronic sinusitis, purulent gingivitis, earache, painful haemorrhoids, minor abdominal pain, hay-fever, bronchitis and gastroenteritis.
LLLT (1-2 sessions in 1-2 days) gave excellent results in joint sprain.
LLLT (1-5 sessions in 1-10 days) gave excellent results in headache, sinusitis, gingivitis, earache, haemorrhoids and minor abdominal pain.
Results in hay-fever, bronchitis and gastroenteritis were positive but less satisfactory.
LLLT + AP
A 32-year old woman presented with a history of chronic mid-cycle abdominal and back pain due to a medically-diagnosed cyst on the left ovary. She had been offered surgery but refused it. She had been attending another acupuncturist who had given her considerable relief with AP in 3 previous cycles. Her therapist was on holiday and the pain had recurred. Other symptoms were abdominal cramps, sensation of bloating, headaches, depression, paraesthesia of the left leg. She attributed some of the symptoms to hypoglycaemia and food allergy.
Manual AP was applied (10 minutes) to BL23 and SP06 bilaterally. LLLT was applied for 10 seconds each to BL22,23,24,25; SP06; ST25,36; LI04,11 bilaterally and to GV03,04,14; CV03,06,12 and Earpoints SP, KI, Uterus, Ovary, Internal Secretion. She was told to use thumbnail pressure on the earpoints and to massage SP06 daily.
Outcome: The woman did not return for session 2. Some months later, she reported that the effect of session 1 was "miraculous" and that she was well since then. Years later, she reported that the problem had not recurred.
(g) Haematoma
One case of penile haematoma in a stallion was treated with IR LLLT, applied locally and at AP points for the penis (GV03; BL30,31,32,33,34; SP06). The results were excellent and the stallion was back in service within 1 week.
CLINICAL FAILURES
No method is 100% successful in all cases. Failure using LLLT, with or without AP occurred in some cases, notably idiopathic lameness, cervical vertebral spondylosis and posterior paresis in old dogs. Other failures were due to misdiagnosis (carpal and sesamoideal chips not diagnosed in the early stages).
(a) Idiopathic hindquarter lameness in a setter
This show dog was lame at the walk but ran normally. He had been referred, after a conventional examination, by a colleague. No cause and no TPs were found. LLLT was applied for 8 seconds to BL11,23,25,28,67; GB30,34,44 (all bilateral) and to GV03. The dog had 3 sessions in 10 days, with AP needling added at the last session. There was no improvement.
(b) Human cervical vertebral spondylosis
A middle-aged lady with radiologically confirmed spondylosis requested AP-type therapy for chronic neck pain which had failed to respond to conventional therapy for more than 1 year. She had TPs in the supra-scapular, trapezius and cervical muscles. She received 3 sessions of LLLT on TPs plus neck points (GB20,21,34; SI03; ST38; Hand Point "Neck"), after which she self-administered transcutaneous electrical nerve stimulation (TENS) for 1 month. There was an initial improvement, followed by a relapse to her original state. Many months later, she had a few sessions of neck manipulation (by an osteopath), a course of homeopathy and 7 or 8 sessions of needle AP (from a naturopath) without success. She still wore her cervical collar. Some years later, this lady attended a different osteopath, claimed great improvement following spinal manipulation and discarded the collar.
(c) Posterior paresis in old dogs
Two old dogs were presented with chronic paresis of the hind limbs. They had loss of deep pain sensation on compression of the toes were treated with LLLT plus AP needling, as for thoracolumbar disc disease. Their condition did not improve and treatment was terminated after 4-6 sessions.
(d) Carpal swelling in horses
One foal with carpal cold oedema had marked success with 5 sessions in 12 days. LLLT was applied locally + AP points for carpus + Ting points. The condition recurred (probably due to trauma) on day 14.
One horse in training developed carpal pain and swelling, with heat in the joint. LLLT (3 sessions over 12 days) gave no success. Carpal chips were removed surgically but the horse had to be retired from racing.
(e) Septic tendinitis (sesamoideal chips missed)
A horse with a severely infected tendon showed a dramatic reduction in the swelling after a few sessions of LLLT. The swelling returned later and sesamoideal chips were found on X-ray. The horse was shot.
(f) Arthritis of the fingers
Two women were treated for arthritis of the finger joints. One (middle-aged), with joint enlargement and stiffness (no pain) got LLLT every 1-2 days for about 8 sessions (local points + AP points LI04,11) There was no improvement. The other woman (elderly) got LLLT + electro-AP every 5-8 days for 6 sessions at similar points, plus BL11. Joint pain and stiffness were relieved greatly, but the joints remained enlarged.
DISCUSSION AND CONCLUSIONS
Clinical uses of LLLT: Trelles et al 1987 reviewed the use of local irradiation with cold laser in therapy. The stimulus was applied mainly to local lesions to elicit the following types of effect:
biostimulatory (reparative effects in ulcers, granulomas, burns, septic wounds and trauma to superficial tissues (tendon, bursa, sheath, joint and muscle); it stimulates local cell metabolism in damaged tissues in vivo and in vitro (mitosis, local DNA and protein synthesis, local phagocytosis, antibody formation and activity of local tissue enzymes (succinyl- and lactate- dehydrogenase, acid phosphatase, non-specific esterase). It enhances scar formation and tissue regeneration (wounds, ulcers of skin and portio uteri), enhances mitogenic activity (cell proliferation), enhances osteogenic activity (in bone fractures, arthritis, osteomyelitis),
analgesic, antiexudative, antihaemorrhagic,
antiinflammatory (in herpes lesions, urethritis, haemorrhoids, sinusitis etc),
antineuralgic, antioedematous, antiseptic,
antispasmodic (in muscle injury),
vasodilatory (in local disorders, organic disorders and alopecia areata).
Trelles et al 1987 and Muxeneder 1987 also reviewed the effects of LLLT in vertebral pain, headaches and local immune responses. The main clinical uses include wound healing, pain control, soft tissue injury, arthropathy and osteopathy and treatment of existing scars.
(a) Wound healing: Most He-Ne and IR lasers, even those <5 mW/cm sq, are said to be effective in treating wounds (surgical, accidental or septic) and superficial disorders (cuts, bruises, granulomas, ulcers, fistulas). Local irradiation stimulates extremely rapid healing, even of extensive indolent superficial wounds. It is effective and safe. Wound area decreases after 2 sessions and strength of the peripheral area increases due to growth of collagen tissue. Scarring is minimal. The effects in wound healing (including wounds refractory to other treatment) are dramatic (Mester et al 1985; Dyson and Yang 1986; Muxeneder 1987). It increases peripheral vascularisation and local tissue nutrition; a "halo phenomenon" is evident around treated wounds after 1-2 sessions (Muxeneder 1987). Speed of granulation, tensile strength of the scar and speed of resolution are enhanced. Many irradiated septic wounds heal as if by first intention.
Clean wounds can be irradiated (edges, underneath the flaps, exposed tissue). Septic wounds, fistulas, ulcers and granulomas should be debrided before irradiation. LLLT is superb in the management of post-operative wounds.
Apart from the review of Trelles et al (1987), little has been published on LLLT of burns but it is probable that it would be effective. Sumano & Casaulon (1987) reported dramatic effects of electro-AP and TENS in treating infected wounds and burns in experimental animals.
b. Pain control: Acute and chronic pain, especially traumatic pain in superficial tissues (including joints) can be alleviated if the primary sites are irradiated. Results are even better if the associated superficial TPs and APs are also treated (Airaksinen et al 1988; Pontinen 1987).
c. Soft tissue injury: Pain, swelling and inflammation in superficial muscles, tendons, ligaments, bursae and sheaths can be alleviated by irradiation of the affected areas, TPs and associated APs. In a double blind crossover study in humans, IR LLLT (1.5 J/point) caused a highly significant elevation of pressure thresholds of TPs as compared with placebo LLLT (Airaksinen et al 1988).
d. Arthropathy and osteopathy: Pain, swelling and inflammation of accessible joints can be alleviated by mid lasers. Initially, the effect was thought to be anti-inflammatory but recent work has shown that LLLT enhances the inflammatory response, to reach the proliferative and healing stage much earlier. It is effective also in pain control and resolution of osteitis and periostitis in superficial areas (splints, ringbone, curb, sore shins etc). It is preferable to ultrasound in these conditions, as ultrasound can heat bone.
e. Treatment of existing scars: Old scars (surgical or traumatic) can act as TPs if there are tender areas, keloid formation and adhesions along the scar. Such scars can be associated with chronic, refractory functional (reflex) pain, lameness and autonomic effects. LLLT of such scars, especially if concentrated on the tender and keloid- areas and on those with obvious adhesions, can produce dramatic clinical improvement in these cases.
Dangers, contraindications and problems of LLLT: Mid lasers (Class 3A, 3B) may damage the retina and should not be shone directly into the eye. They are used to treat keratitis and corneal ulcers but should be aimed tangentially at the target for 30 seconds/session. Operators who use mid lasers every day are advised to wear appropriate goggles. This is especially important when IR lasers are used, as the beam is invisible.
Over-stimulation does not seem to cause problems but, because of the mitotic effects, it is wise not to irradiate cancerous tissue. Some authors advise against using laser over acutely infected closed swellings, as this may spread the local infection.
Faulty lasers may not emit at the stated MOP or may have a too wide divergence (angle of irradiation). For maximum effect the light beam should be parallel and the light-spot should be small (concentrated). The glass at the probe-tip should be cleaned regularly, as dirt may limit MOP. The better IR lasers have an in-built optical sensor to monitor MOP before use.
Some devices, sold as lasers, do not emit laser light. Some "lasers" are based on light emitting diodes and not on laser diodes. They emit non-parallel light of different wavelengths simultaneously or by selective control. Sunlight or a cheap flashlight would probably be just as effective.
Clinical results: From September 1989 and April 1990, my experimental use of IR LLLT gave very encouraging results in equine, human and canine muscle pain/ lameness; equine flexor tendon strain; equine and human periostitis; human and canine "disc disease" and miscellaneous human conditions. In particular it gave dramatic results in skin lesions, wounds and (minor) burn cases.
Cases which failed to respond to LLLT (and also failed to respond to AP) included human cervical vertebral spondylosis and idiopathic lameness, posterior paresis in old dogs, carpal swelling in horses and misdiagnosed cases.
From April 1990 and September 1991, I reduced my use of LLLT in horses. I have reverted to injection of the AP points as the routine method of treating horses. Most cases respond to AP point injection in 2-4 sessions, as compared with 2-6 sessions of LLLT.
In spite of initially encouraging results in equine tendon strain, most (70%) of the cases treated by LLLT relapsed, broke down on the other leg, failed to heal or were shot or retired. Therefore, unless the trainer undertakes not to work the horse for 10 months, I am reluctant to use LLLT in equine tendon strain (as distinct from trauma due to brushing or superficial traumatic swelling).
The present: Now, I use IR LLLT regularly with very good success in human and canine conditions but I often combine it with standard AP techniques to get a faster and more long-lasting response.
LLLT sessions in horses (because of their large size and the number of APs which may need to be treated) take too much time (20-30 minutes, including examination time), or too many sessions are needed. In the more common equine muscular problems, AP point injection is 10-20 minutes faster and the clinical results are 10% points better than LLLT. I confine LLLT use in horses mainly to superficial injuries and periostitis.
There are also reports from veterinary colleagues that low MOP lasers (especially those <10 mW/cm sq) are not as effective as AP (Rogers, Jagger & Janssens 1987). These agree with my experience that an IR mid-power laser (30 mW/cm sq) was not as effective as AP in horses.
The future ?: Further work is needed to document the uses and limitations of LLLT, the effects of power, wavelength, different pulse frequencies, different exposure dosage etc. With the rapid pace of research in physical therapies, I believe that we will see increased use of electromagnetic therapy, including LLLT, ultrasound and microwave stimulation in medical and vet therapy in the next few years.
ACKNOWLEDGEMENT
I thank Normedica, PO Box 392, 8201 Schaffhausen, Switzerland for presenting me with the laser for experimental purposes.
REFERENCES
1. An infra-red (IR, 904 nM) LASUWA diode laser, pulsed at 5000 Hz and with a mean output power of 30 mW when full on, was used in uncontrolled clinical tests in animal and human subjects for 2 years.
2. Low level laser therapy (LLLT) had analgesic, vasodilatory and anti-inflammatory properties. It greatly enhanced the healing of accidental /surgical wounds and of minor skin burns. It gave rapid and excellent results in lesions of the skin, superficial tissues (subcutaneous tissue and periosteum) and superficial Trigger Points (TPs).
3. When combined with a knowledge of the acupuncture (AP) system, LLLT was effective in treating myofascial syndromes in dogs and humans, but it was about 10% less successful than AP in treating myofascial problems in horses.
4. LLLT gave poor results in severe tendon strain in horses. It was useless in serious spinal pathology, some idiopathic lameness in dogs and people, carpal swelling in horses and arthritic swelling of human finger joints.
5. Although there were some complete and partial failures and although AP and other therapies were combined with LLLT occasionally, the clinical results confirm published claims that LLLT is valuable in veterinary and paramedical practice.
INTRODUCTION
Low level laser therapy (LLLT) is gaining increasing acceptance in conventional veterinary practice (as a therapy for tissue trauma, wounds, granuloma, myositis, tendinitis etc). Cold (soft) lasers are available as robust, portable instruments. They are operated by batteries or by mains electricity.
LLLT also is used instead of needles in veterinary acupuncture (AP) to stimulate the acupuncture points (APs) and Trigger Points (TPs) in animals but there are few published studies to date. Commercial interests claim excellent results in a wide variety of clinical conditions. Russian and German workers have used LLLT at the human APs for many years. Since 1984, there are many papers on the method in humans (Rogers 1991g).
The history, theoretical uses and physics of laser are discussed in detail in Pontinen's textbook (1995).
Though laser light is emitted in a continuous wave (cw) beam, it can be interrupted (modulated) at variable frequencies and intervals by mechanical or electronic means. Interruption of the light beam at fixed intervals is called pulsing. Pulsed lasers, especially those interrupted 2000-10000 times/second (Hz), penetrate deeper in tissue than unpulsed lasers.
LLLT has some advantages over needling or point injection in AP or TP therapy:
- It is aseptic, non-invasive, painless and, if used properly, has no reported side-effects. The probe is held within 0-5 cm from the skin and the light is aimed at the point.
- It is ideal for use on painful (AhShi) points or in nervous/difficult animals. Children and cats tolerate LLLT very well.
- It may be used safely on dangerous points in large animals (such as points below the carpus and tarsus of cattle and horses).
- It is ideal for treatment of superficial APs, such as those on the ear.
LLLT usually is given on 2-8 occasions, at intervals of 1-3 days in acute cases and 3-7 days in chronic cases. At each session, the laser is applied for 20-120 seconds/point over or around the rim of the lesion and to each of the APs or TPs selected for the case.
Total treatment time/session depends on mean output power (MOP) and the depth of point. High output lasers (MOP >30 mW) and superficial points need less irradiation time than low output lasers (MOP 1-10 mW) and deeper points. With 30-50 mW MOP lasers, dose time is 10-60 seconds/point, but with 3-5 mW MOP lasers, the required dose time/point is 10 times longer.
The LASUWA laser claims a MOP of 30 mW. It has a strong metallic probe, with the glass shield of the diodes set back about 0.5 cm from its tip. In horses, the probe can be applied with heavy pressure over muscular areas, thereby gaining 1-3 cm extra penetration into the tissues, their TPs and APs, as well as achieving a massage effect at the tender areas.
From September 1989 to September 1991, I used LASUWA LLLT experimentally in clinical conditions in horses, dogs and people. This article summarises my experiences during that time.
CONDITIONS TREATED AND METHODS USED
The main types of conditions treated were: (a) equine, human and canine muscle pain and lameness; (b) human and canine "disc disease"; (c) equine flexor tendon injuries; (d) equine and human periostitis; (e) skin lesions; (f) miscellaneous human conditions; (g) haematoma.
From September 1989 and April 1990, most cases were treated by LLLT alone. The laser was applied over or near the affected area, to TPs and key APs for the affected area. If systemic signs were present, the relevant APs were treated also (for example in a case of chicken-pox, LLLT was applied to points GV14, LI04,11; ST36 (for their effect on fever and the immune system), as well as to the pruritic lesions. In a few cases, AP needles were inserted in TPs also, especially if the TPs were deep, as in heavily muscled areas. In a small number of cases, other therapies (electro-AP, local medication, Dermisol or ointments) were combined with LLLT.
CLINICAL RESULTS
(a) Equine, human and canine muscle pain/lameness
Most cases involved para-vertebral pain (cervical, thoracic, lumbar or sacral). Some involved pain of limb muscles (scapula, arm, forearm, thigh, gluteals, gastrocnemius).
LLLT (10-30 seconds/point) was used on the TPs and APs for the affected area and over the painful muscle(s). As many points were treated at each session, the session time was usually 10-20 minutes. Treatment was given every 1-2 days in acute cases and every 5-9 days in chronic cases. Excellent results were got in 2-4 sessions over 4-9 days in acute cases and in 1-7 sessions over 16-35 days in chronic cases.
In dogs and people, results were similar to those using simple AP, electro-AP or point injection in similar cases over the previous few years. In horses, in which TPs can be 7-12 cm deep, the clinical results were about 10% points below those attained by earlier AP methods and clinical success took 1-3 sessions more to attain than with earlier AP methods.
(b) Human and canine "disc disease"
Four acute cases of human low lumbar disc disease were treated by LLLT, often with needles, at TPs plus BL23, GB34 bilateral, plus GV03. The cases were diagnosed clinically as Grade 1 by a positive "Straight Leg Raising Test" and a history of pain radiating along the sciatic path. All had excellent results in 3-5 sessions at intervals of 1 week.
Three cases of acute canine thoracolumbar disc disease (diagnosed as Grades 1 to 3 on clinical examination) were treated by LLLT, often with needles, at TPs plus BL23, GB34 bilateral, plus GV03. All had excellent results in 2-4 sessions at intervals of 5-9 days.
As the diagnosis was made on clinical grounds only (i.e. did not involve myelography or radiography), some of these cases may have been myofascial paravertebral pain (section (a), above), rather than "disc disease".
(c) Equine flexor tendon injuries
IR LLLT was used on 10 cases: 4 were acute (recent strain, hot and painful), 2 were acute local nodules/swellings (caused by suspected brushing) and 4 were chronic (bowed tendon).
LLLT was used 3-6 times in 1-4 weeks (10-20 seconds/point) on about 8 points along each surface of the tendon (lateral, posterior and medial), concentrating especially on the bowed or swollen area. LLLT was used also on LI04,11 and Thoresen's Ting points (PC09, LU11, HT09).
Of the 6 acute cases, two passed veterinary inspection for the Newmarket yearling November sales and were sold within 5-7 days of presentation for treatment; 1 case became cool after 2 weeks but some tendon thickening was still present. Three cases failed (swelling and heat persisted). That trainer refused to comply with my advice to rest the horses for the first few weeks. He changed to another vet, who gave other treatments, which also failed.
All 4 chronic cases improved markedly, with disappearance of the "bow" and lessening of the mediolateral thickening in 2-4 weeks. These cases were rested for 6 weeks (kept in the box and given only walking or paddock exercise daily) before gradual resumption of training.
Initially, IR LLLT gave very encouraging results in tendon injury, whereas AP methods used in previous years gave very poor success in such cases. However, all 4 of the chronic bowed tendons relapsed or the horses broke down on the opposite leg and were shot or retired and 3/6 of the acute cases failed to become sound.
Today, I would confine my use of LLLT in equine tendon problems mainly to recent superficial injury, especially that caused by brushing. Before starting to treat the case, I would extract an undertaking from the trainer that the horse would not be worked for 10 months, or until I was satisfied that the tendon was well healed.
I would attempt to treat chronic tendonitis only if trainer would undertake not to work the horse for 10 months.
(d) Equine and human periostitis
During the acute (hot, painful) stage, 8 equine cases of splint, spavin or bucked shins were treated 2-4 times every 1-2 days by local LLLT (20 seconds on a few positions on and around the lesion and on AP + Ting points for the area). All cases became painless in 2-9 days.
LLLT was used in 3 chronic but painful human cases (1 shin splint; 2 cases of lateral humeral epicondylitis, or "tennis elbow"). All became painless in 1-10 days. One patient (a human with a painful shin-splint) ran in a cross country race 3 days after the first (and only) session. He ran a good race, finishing in the top third of the field.
(e) Skin lesions
Many types of skin lesions were treated by IR LLLT (without AP needles). In all, about 19 cases were treated, mainly human lesions: (abrasions, knife cuts, minor burns, wounds, chronic head ulcer; pruritic lesions (chicken-pox), facial herpes, retro- and para-scrotal wet eczema; interdigital fungal infection (athlete's foot), acne). A few equine lesions were treated also (granulation wound; cracked heels).
In addition, 2 surgical suture lines were treated: one purulent area following rumen fistulation in a bullock and one swollen painful incision line following reposition of a dislocated shoulder and a compound fracture of the clavicle in a man).
Acute cases were treated every day and chronic cases every 3-7 days. LLLT was applied locally for 30-60 seconds, on and around the lesion. It was applied occasionally to AP points or Ting points for the region also.
Clinical results in acute cases in humans were dramatic, with relief of pain or pruritus and marked anti-inflammatory effect within 1-3 days and excellent healing within 7-14 days. In wet eczema of the retro- and para-scrotal eczema, 1 session of LLLT + application of 5% copper sulphate solution gave cure in 2 days.
In chronic cases, with granulation and purulent infection, healing was slower but was markedly enhanced: purulent discharge was gone within days and healing (by second intention) was complete within 3 weeks. LLLT was excellent in acne (2 cases): the lesions cleared within 2 weeks (6 sessions).
(f) Miscellaneous human conditions
LLLT only
IR LLLT was used at TPs, local AP points and AP points for the region. Conditions which were treated included joint sprain (shoulder, wrist, fingers, thumb, knee, ankle), headache, acute and chronic sinusitis, purulent gingivitis, earache, painful haemorrhoids, minor abdominal pain, hay-fever, bronchitis and gastroenteritis.
LLLT (1-2 sessions in 1-2 days) gave excellent results in joint sprain.
LLLT (1-5 sessions in 1-10 days) gave excellent results in headache, sinusitis, gingivitis, earache, haemorrhoids and minor abdominal pain.
Results in hay-fever, bronchitis and gastroenteritis were positive but less satisfactory.
LLLT + AP
A 32-year old woman presented with a history of chronic mid-cycle abdominal and back pain due to a medically-diagnosed cyst on the left ovary. She had been offered surgery but refused it. She had been attending another acupuncturist who had given her considerable relief with AP in 3 previous cycles. Her therapist was on holiday and the pain had recurred. Other symptoms were abdominal cramps, sensation of bloating, headaches, depression, paraesthesia of the left leg. She attributed some of the symptoms to hypoglycaemia and food allergy.
Manual AP was applied (10 minutes) to BL23 and SP06 bilaterally. LLLT was applied for 10 seconds each to BL22,23,24,25; SP06; ST25,36; LI04,11 bilaterally and to GV03,04,14; CV03,06,12 and Earpoints SP, KI, Uterus, Ovary, Internal Secretion. She was told to use thumbnail pressure on the earpoints and to massage SP06 daily.
Outcome: The woman did not return for session 2. Some months later, she reported that the effect of session 1 was "miraculous" and that she was well since then. Years later, she reported that the problem had not recurred.
(g) Haematoma
One case of penile haematoma in a stallion was treated with IR LLLT, applied locally and at AP points for the penis (GV03; BL30,31,32,33,34; SP06). The results were excellent and the stallion was back in service within 1 week.
CLINICAL FAILURES
No method is 100% successful in all cases. Failure using LLLT, with or without AP occurred in some cases, notably idiopathic lameness, cervical vertebral spondylosis and posterior paresis in old dogs. Other failures were due to misdiagnosis (carpal and sesamoideal chips not diagnosed in the early stages).
(a) Idiopathic hindquarter lameness in a setter
This show dog was lame at the walk but ran normally. He had been referred, after a conventional examination, by a colleague. No cause and no TPs were found. LLLT was applied for 8 seconds to BL11,23,25,28,67; GB30,34,44 (all bilateral) and to GV03. The dog had 3 sessions in 10 days, with AP needling added at the last session. There was no improvement.
(b) Human cervical vertebral spondylosis
A middle-aged lady with radiologically confirmed spondylosis requested AP-type therapy for chronic neck pain which had failed to respond to conventional therapy for more than 1 year. She had TPs in the supra-scapular, trapezius and cervical muscles. She received 3 sessions of LLLT on TPs plus neck points (GB20,21,34; SI03; ST38; Hand Point "Neck"), after which she self-administered transcutaneous electrical nerve stimulation (TENS) for 1 month. There was an initial improvement, followed by a relapse to her original state. Many months later, she had a few sessions of neck manipulation (by an osteopath), a course of homeopathy and 7 or 8 sessions of needle AP (from a naturopath) without success. She still wore her cervical collar. Some years later, this lady attended a different osteopath, claimed great improvement following spinal manipulation and discarded the collar.
(c) Posterior paresis in old dogs
Two old dogs were presented with chronic paresis of the hind limbs. They had loss of deep pain sensation on compression of the toes were treated with LLLT plus AP needling, as for thoracolumbar disc disease. Their condition did not improve and treatment was terminated after 4-6 sessions.
(d) Carpal swelling in horses
One foal with carpal cold oedema had marked success with 5 sessions in 12 days. LLLT was applied locally + AP points for carpus + Ting points. The condition recurred (probably due to trauma) on day 14.
One horse in training developed carpal pain and swelling, with heat in the joint. LLLT (3 sessions over 12 days) gave no success. Carpal chips were removed surgically but the horse had to be retired from racing.
(e) Septic tendinitis (sesamoideal chips missed)
A horse with a severely infected tendon showed a dramatic reduction in the swelling after a few sessions of LLLT. The swelling returned later and sesamoideal chips were found on X-ray. The horse was shot.
(f) Arthritis of the fingers
Two women were treated for arthritis of the finger joints. One (middle-aged), with joint enlargement and stiffness (no pain) got LLLT every 1-2 days for about 8 sessions (local points + AP points LI04,11) There was no improvement. The other woman (elderly) got LLLT + electro-AP every 5-8 days for 6 sessions at similar points, plus BL11. Joint pain and stiffness were relieved greatly, but the joints remained enlarged.
DISCUSSION AND CONCLUSIONS
Clinical uses of LLLT: Trelles et al 1987 reviewed the use of local irradiation with cold laser in therapy. The stimulus was applied mainly to local lesions to elicit the following types of effect:
biostimulatory (reparative effects in ulcers, granulomas, burns, septic wounds and trauma to superficial tissues (tendon, bursa, sheath, joint and muscle); it stimulates local cell metabolism in damaged tissues in vivo and in vitro (mitosis, local DNA and protein synthesis, local phagocytosis, antibody formation and activity of local tissue enzymes (succinyl- and lactate- dehydrogenase, acid phosphatase, non-specific esterase). It enhances scar formation and tissue regeneration (wounds, ulcers of skin and portio uteri), enhances mitogenic activity (cell proliferation), enhances osteogenic activity (in bone fractures, arthritis, osteomyelitis),
analgesic, antiexudative, antihaemorrhagic,
antiinflammatory (in herpes lesions, urethritis, haemorrhoids, sinusitis etc),
antineuralgic, antioedematous, antiseptic,
antispasmodic (in muscle injury),
vasodilatory (in local disorders, organic disorders and alopecia areata).
Trelles et al 1987 and Muxeneder 1987 also reviewed the effects of LLLT in vertebral pain, headaches and local immune responses. The main clinical uses include wound healing, pain control, soft tissue injury, arthropathy and osteopathy and treatment of existing scars.
(a) Wound healing: Most He-Ne and IR lasers, even those <5 mW/cm sq, are said to be effective in treating wounds (surgical, accidental or septic) and superficial disorders (cuts, bruises, granulomas, ulcers, fistulas). Local irradiation stimulates extremely rapid healing, even of extensive indolent superficial wounds. It is effective and safe. Wound area decreases after 2 sessions and strength of the peripheral area increases due to growth of collagen tissue. Scarring is minimal. The effects in wound healing (including wounds refractory to other treatment) are dramatic (Mester et al 1985; Dyson and Yang 1986; Muxeneder 1987). It increases peripheral vascularisation and local tissue nutrition; a "halo phenomenon" is evident around treated wounds after 1-2 sessions (Muxeneder 1987). Speed of granulation, tensile strength of the scar and speed of resolution are enhanced. Many irradiated septic wounds heal as if by first intention.
Clean wounds can be irradiated (edges, underneath the flaps, exposed tissue). Septic wounds, fistulas, ulcers and granulomas should be debrided before irradiation. LLLT is superb in the management of post-operative wounds.
Apart from the review of Trelles et al (1987), little has been published on LLLT of burns but it is probable that it would be effective. Sumano & Casaulon (1987) reported dramatic effects of electro-AP and TENS in treating infected wounds and burns in experimental animals.
b. Pain control: Acute and chronic pain, especially traumatic pain in superficial tissues (including joints) can be alleviated if the primary sites are irradiated. Results are even better if the associated superficial TPs and APs are also treated (Airaksinen et al 1988; Pontinen 1987).
c. Soft tissue injury: Pain, swelling and inflammation in superficial muscles, tendons, ligaments, bursae and sheaths can be alleviated by irradiation of the affected areas, TPs and associated APs. In a double blind crossover study in humans, IR LLLT (1.5 J/point) caused a highly significant elevation of pressure thresholds of TPs as compared with placebo LLLT (Airaksinen et al 1988).
d. Arthropathy and osteopathy: Pain, swelling and inflammation of accessible joints can be alleviated by mid lasers. Initially, the effect was thought to be anti-inflammatory but recent work has shown that LLLT enhances the inflammatory response, to reach the proliferative and healing stage much earlier. It is effective also in pain control and resolution of osteitis and periostitis in superficial areas (splints, ringbone, curb, sore shins etc). It is preferable to ultrasound in these conditions, as ultrasound can heat bone.
e. Treatment of existing scars: Old scars (surgical or traumatic) can act as TPs if there are tender areas, keloid formation and adhesions along the scar. Such scars can be associated with chronic, refractory functional (reflex) pain, lameness and autonomic effects. LLLT of such scars, especially if concentrated on the tender and keloid- areas and on those with obvious adhesions, can produce dramatic clinical improvement in these cases.
Dangers, contraindications and problems of LLLT: Mid lasers (Class 3A, 3B) may damage the retina and should not be shone directly into the eye. They are used to treat keratitis and corneal ulcers but should be aimed tangentially at the target for 30 seconds/session. Operators who use mid lasers every day are advised to wear appropriate goggles. This is especially important when IR lasers are used, as the beam is invisible.
Over-stimulation does not seem to cause problems but, because of the mitotic effects, it is wise not to irradiate cancerous tissue. Some authors advise against using laser over acutely infected closed swellings, as this may spread the local infection.
Faulty lasers may not emit at the stated MOP or may have a too wide divergence (angle of irradiation). For maximum effect the light beam should be parallel and the light-spot should be small (concentrated). The glass at the probe-tip should be cleaned regularly, as dirt may limit MOP. The better IR lasers have an in-built optical sensor to monitor MOP before use.
Some devices, sold as lasers, do not emit laser light. Some "lasers" are based on light emitting diodes and not on laser diodes. They emit non-parallel light of different wavelengths simultaneously or by selective control. Sunlight or a cheap flashlight would probably be just as effective.
Clinical results: From September 1989 and April 1990, my experimental use of IR LLLT gave very encouraging results in equine, human and canine muscle pain/ lameness; equine flexor tendon strain; equine and human periostitis; human and canine "disc disease" and miscellaneous human conditions. In particular it gave dramatic results in skin lesions, wounds and (minor) burn cases.
Cases which failed to respond to LLLT (and also failed to respond to AP) included human cervical vertebral spondylosis and idiopathic lameness, posterior paresis in old dogs, carpal swelling in horses and misdiagnosed cases.
From April 1990 and September 1991, I reduced my use of LLLT in horses. I have reverted to injection of the AP points as the routine method of treating horses. Most cases respond to AP point injection in 2-4 sessions, as compared with 2-6 sessions of LLLT.
In spite of initially encouraging results in equine tendon strain, most (70%) of the cases treated by LLLT relapsed, broke down on the other leg, failed to heal or were shot or retired. Therefore, unless the trainer undertakes not to work the horse for 10 months, I am reluctant to use LLLT in equine tendon strain (as distinct from trauma due to brushing or superficial traumatic swelling).
The present: Now, I use IR LLLT regularly with very good success in human and canine conditions but I often combine it with standard AP techniques to get a faster and more long-lasting response.
LLLT sessions in horses (because of their large size and the number of APs which may need to be treated) take too much time (20-30 minutes, including examination time), or too many sessions are needed. In the more common equine muscular problems, AP point injection is 10-20 minutes faster and the clinical results are 10% points better than LLLT. I confine LLLT use in horses mainly to superficial injuries and periostitis.
There are also reports from veterinary colleagues that low MOP lasers (especially those <10 mW/cm sq) are not as effective as AP (Rogers, Jagger & Janssens 1987). These agree with my experience that an IR mid-power laser (30 mW/cm sq) was not as effective as AP in horses.
The future ?: Further work is needed to document the uses and limitations of LLLT, the effects of power, wavelength, different pulse frequencies, different exposure dosage etc. With the rapid pace of research in physical therapies, I believe that we will see increased use of electromagnetic therapy, including LLLT, ultrasound and microwave stimulation in medical and vet therapy in the next few years.
ACKNOWLEDGEMENT
I thank Normedica, PO Box 392, 8201 Schaffhausen, Switzerland for presenting me with the laser for experimental purposes.
REFERENCES
- Airaksinen,O., Rantanen,P., Kolari,P.J. and Pontinen,P.J. (1988) Effects of IR (904 nm) and He-Ne (632.8 nm) laser irradiation on pressure algometry at TPs. Paper to Nordic AP Society Annual Congress, Laugarvatn, Iceland, August 26th. Scand. J. of Acupuncture and Electrotherapy, 3,56-61.
- Dyson,M. and Yang,S. (1986) Effect of laser therapy on wound contraction andcellularity in mice. Lasers in med. science 1/2,125-130.
- Kolari,P.J., Hietanen,M., v. Nandelstad,P., Airaksinen,O. and Pontinen,P.J. (1988) Lasers in physical therapy-measurement of optical output power. Scand. J. Acupuncture and Electrotherapy.
- Mester,E., Mester,A.E. and Mester,A. (1985) The biomedical effect of laserapplication. Lasers in surgery and medicine 5, 31-39.
- Muxeneder,R. (1987). Soft laser in the conservative treatment of chronic skin lesionsin the horse. Der Prakt. Tierarzt, 68, No. 1, 12-21.
- Pontinen,P.J. (1987) Mid-laser and TNS in back pain. Nordic AP Society Annual Meeting: Seminar on back pain. Oslo, September 26.
- Pontinen,P.J. (1995) Low Level Laser Therapy (LLLT) and laser acupuncture: a manual for physicians, dentists, physiotherapists and veterinary surgeons.
- Rogers,P.A.M. (1991) AP for immune-mediated disorders. In: Acupuncture in Animals (Proceedings 167 of the Postgraduate Committee in Veterinary Science, University of Sydney), pp 124-142.
- Rogers,P.A.M., Janssens,L.A.A. & Jagger,D. (1987) The efficacy of cold laser: A survey of members of the International Veterinary Acupuncture Society. Unpublished.
- Sumano,H.L., & Casaulon,T. (1987) Evaluation of electro-AP and TENS effects on wound- and burn- healing. Personal Communication, Veterinary School, Mexico City.
- Trelles,M.A., Mayayo,E., Mester,A. & Rigau,J. (1987) Low power laser-therapy: Experimental and clinical data with special reference to Spain. Scandinavian Journal of Acupuncture & Electrotherapy, 2, 80-100.
APPENDIX
(Summarised from Pontinen's 1995 textbook)
OPTIMUM LASER IRRADIATION DOSE
The irradiation dose is the most important parameter for LLLT. It is more important than the type of laser used (visible v invisible; pulsed v unpulsed). The dose is measured in joules (J) per treated point (J/point) or per square centimetre (J/cm²). Both types of dose calculation (J/point and J/cm²) are needed, as LLLT is sometimes applied to specific points (TPs, AhShi points, APs, local points etc) and sometimes to larger areas (wounds, ulcers sprained areas etc).
The following are essential for successful results with LLLT:
1. For optimal biostimulatory effect (to treat wounds, burns, bruises etc), the irradiation dose has a lower and upper limit, with an optimum in the middle. If the dose is too low, it may induce no measurable effect. If the dose is too high, it may induce no effect, or may have a negative effect.
2. The biostimulatory effect is cumulative: repeated doses, at suitable, relatively short intervals, give an added response. Repeated low doses, at intervals of 1-7 days, induce stronger effects than the same total dose given in one treatment. The optimal weekly irradiation dose for HeNe LLLT is about 1 J/cm². With a laser emitting a mean output power (MOP) of 3 or 60 mW, this would take 333 or 16.5 seconds/cm² respectively. The dose for a GaAs laser on fibroblasts is lower than that for HeNe laser.
3. For optimal effect on the AP points, doses recommended in the former Soviet literature are about 0.1 J/AP point. With a laser emitting a MOP of 3 or 60 mW, this would take 33 or 1.65 seconds/AP point respectively.
CALCULATION OF THE IRRADIATION DOSE
One joule (J, unit of energy) is equal to one wattsecond (Ws), i.e. the energy which is generated when 1 watt (W) of power flows for 1 second (J = Ws).
The irradiation dose is the amount of energy which is conducted into the tissue. It is of great importance whether this energy has to be conducted through a small point (say 1 mm²) or through areas of several cm2. Therefore, in treating surfaces such as wounds, ulcers etc, it is better to express the dose as an energy density, i.e. as J/cm².
Because 1 J = 1 Ws, the irradiation dose (D) can be calculated as follows:
P (W) x t (s)
D (J/cm²) = ------------- Equation 1,
A (cm²)
where
D = Laser dose (J/cm²),
P = Laser power conducted to the tissue (W, or MOP mW/1000),
t = time of irradiation (s)
A = Area of treated surface (cm²)
This can be transformed to calculate the time needed for treatment:
D (J/cm²) x A (cm²)
t (s) = ------------------- Equation 2.
P (W)
To calculate the exposure time needed at a target area (A), the MOP of the laser must be converted to W: for example a laser of MOP 15 mW emits 15/1000 = .015 W. As 1 J = 1 Ws, 1 W = 1 J/s. Therefore, if a laser has e.g. a MOP of 15 mW, it emits laser energy of 0.015 W = 0.015 J/s. In 10 s the emission is 10 x 0.015 = 0.15 J etc.
The following table shows the emission dose/second and /minute respectively from lasers with MOP in the range 3 to 60 mW and the emission time needed to give a total irradiation dose of 1 and 2 J respectively.
(Summarised from Pontinen's 1995 textbook)
OPTIMUM LASER IRRADIATION DOSE
The irradiation dose is the most important parameter for LLLT. It is more important than the type of laser used (visible v invisible; pulsed v unpulsed). The dose is measured in joules (J) per treated point (J/point) or per square centimetre (J/cm²). Both types of dose calculation (J/point and J/cm²) are needed, as LLLT is sometimes applied to specific points (TPs, AhShi points, APs, local points etc) and sometimes to larger areas (wounds, ulcers sprained areas etc).
The following are essential for successful results with LLLT:
1. For optimal biostimulatory effect (to treat wounds, burns, bruises etc), the irradiation dose has a lower and upper limit, with an optimum in the middle. If the dose is too low, it may induce no measurable effect. If the dose is too high, it may induce no effect, or may have a negative effect.
2. The biostimulatory effect is cumulative: repeated doses, at suitable, relatively short intervals, give an added response. Repeated low doses, at intervals of 1-7 days, induce stronger effects than the same total dose given in one treatment. The optimal weekly irradiation dose for HeNe LLLT is about 1 J/cm². With a laser emitting a mean output power (MOP) of 3 or 60 mW, this would take 333 or 16.5 seconds/cm² respectively. The dose for a GaAs laser on fibroblasts is lower than that for HeNe laser.
3. For optimal effect on the AP points, doses recommended in the former Soviet literature are about 0.1 J/AP point. With a laser emitting a MOP of 3 or 60 mW, this would take 33 or 1.65 seconds/AP point respectively.
CALCULATION OF THE IRRADIATION DOSE
One joule (J, unit of energy) is equal to one wattsecond (Ws), i.e. the energy which is generated when 1 watt (W) of power flows for 1 second (J = Ws).
The irradiation dose is the amount of energy which is conducted into the tissue. It is of great importance whether this energy has to be conducted through a small point (say 1 mm²) or through areas of several cm2. Therefore, in treating surfaces such as wounds, ulcers etc, it is better to express the dose as an energy density, i.e. as J/cm².
Because 1 J = 1 Ws, the irradiation dose (D) can be calculated as follows:
P (W) x t (s)
D (J/cm²) = ------------- Equation 1,
A (cm²)
where
D = Laser dose (J/cm²),
P = Laser power conducted to the tissue (W, or MOP mW/1000),
t = time of irradiation (s)
A = Area of treated surface (cm²)
This can be transformed to calculate the time needed for treatment:
D (J/cm²) x A (cm²)
t (s) = ------------------- Equation 2.
P (W)
To calculate the exposure time needed at a target area (A), the MOP of the laser must be converted to W: for example a laser of MOP 15 mW emits 15/1000 = .015 W. As 1 J = 1 Ws, 1 W = 1 J/s. Therefore, if a laser has e.g. a MOP of 15 mW, it emits laser energy of 0.015 W = 0.015 J/s. In 10 s the emission is 10 x 0.015 = 0.15 J etc.
The following table shows the emission dose/second and /minute respectively from lasers with MOP in the range 3 to 60 mW and the emission time needed to give a total irradiation dose of 1 and 2 J respectively.
The Table shows that a Class 3B laser, emitting a MOP of 60 mW, can deliver a target dose of 2 J in 33 seconds, whereas a Class A laser, emitting a MOP of 3 mW would need twenty times longer (11 minutes and 8 seconds) to deliver the same dose (2 J). There is a practical advantage in using lasers in the upper end of Class 3B. They cut down dramatically on treatment time/session.
If GaAs lasers are made to work in a single pulsed mode with low frequencies, their MOP is very low. In order to allow direct comparison of different models of pulsed lasers, their emitted energy output (ìJ)/pulse (Ep) and the pulse frequency/second (Hz) (F) should be certified. Typical measured values for energy/pulse range from 0.1-5.0 ìJ and typical pulse frequencies range from 10-10000 Hz.
The MOP of a single pulsed laser depends on its frequency (F) and on the emitted energy/pulse (Ep) as shown in the following Table.
MOP (in mW) is calculated as (Ep x F / 1000). For example, if a laser pulses at 10000 hz and emits 5 ìJ/pulse, its MOP is (10000 x 5 / 1000) mW = 50 mW.
Mean output power (MOP) for a single pulsed GaAs laser with different frequencies (F) and varying pulse energy (Ep).
If GaAs lasers are made to work in a single pulsed mode with low frequencies, their MOP is very low. In order to allow direct comparison of different models of pulsed lasers, their emitted energy output (ìJ)/pulse (Ep) and the pulse frequency/second (Hz) (F) should be certified. Typical measured values for energy/pulse range from 0.1-5.0 ìJ and typical pulse frequencies range from 10-10000 Hz.
The MOP of a single pulsed laser depends on its frequency (F) and on the emitted energy/pulse (Ep) as shown in the following Table.
MOP (in mW) is calculated as (Ep x F / 1000). For example, if a laser pulses at 10000 hz and emits 5 ìJ/pulse, its MOP is (10000 x 5 / 1000) mW = 50 mW.
Mean output power (MOP) for a single pulsed GaAs laser with different frequencies (F) and varying pulse energy (Ep).
The table shows that a single pulsed laser is unlikely to be effective if the pulse frequency is less than 1000 Hz. For example, a laser with a pulse energy (Ep) of 1 ìJ and a pulse frequency of 1 KHz (=1000 Hz) has a MOP of only 0.1 mW. If a (5 x 5) cm2 area needs a laser dose of 1 J/cm², the exposure time (for a 0.1 mW MOP laser) is calculated as follows (as in Equation 2):
Desired dose (D): 1 J/cm²
MOP (P): 0.1 mW = 0.0001
W Target area (A): 25 cm²
D x A 1 x 25
t = --------, i.e. t = ---------- = 250000 s
P 0.0001
thus, t = 4167 min = c. 70 hours. This says that a laser with a MOP of 0.1 mW is of no practical use for LLLT. It also shows that one needs to know the MOP (or the mean pulse frequency and power/pulse) of the laser and how to calculate roughly the irradiation dose needed for effective LLLT.
Thousands of LLLT sessions have been given with irradiation doses far below the clinically effective range, mainly due to ignorance of those critical parameters.
The MOP is not completely dependant on the pulse frequency; both pulse frequency (Hz) and pulse energy (ìJ/pulse) are important in deciding MOP. These calculations and the previous Table demonstrate the advantage of high frequency pulse-train modulated, high pulse energy GaAs lasers over a single pulse laser.
Desired dose (D): 1 J/cm²
MOP (P): 0.1 mW = 0.0001
W Target area (A): 25 cm²
D x A 1 x 25
t = --------, i.e. t = ---------- = 250000 s
P 0.0001
thus, t = 4167 min = c. 70 hours. This says that a laser with a MOP of 0.1 mW is of no practical use for LLLT. It also shows that one needs to know the MOP (or the mean pulse frequency and power/pulse) of the laser and how to calculate roughly the irradiation dose needed for effective LLLT.
Thousands of LLLT sessions have been given with irradiation doses far below the clinically effective range, mainly due to ignorance of those critical parameters.
The MOP is not completely dependant on the pulse frequency; both pulse frequency (Hz) and pulse energy (ìJ/pulse) are important in deciding MOP. These calculations and the previous Table demonstrate the advantage of high frequency pulse-train modulated, high pulse energy GaAs lasers over a single pulse laser.
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