LASERS & Lights By Beverly Nelson

Outline of Presentation Defining LASER Production of laser Classification of Laser Method of application Biological effects Clinical indications Precautions & contraindications

What is LASER ? Acronym for Light Amplification of Stimulated Emissions of Radiation Relatively new modality which is still undergoing research

Physics of LASER production Please read handout provided Laser light contains electromagnetic energy

Properties of LASER Coherence- Monochromaticity Collimination

Classification of Lasers According to the nature of material placed between the two reflecting surfaces Many types of lasers, each with specific wavelength and characteristics

Classification cont’d Crystal Gas Glass Semiconductor or diode chemical

Classification cont’d Classification according to high or low power Depends on the intensity of energy they deliver

Classification cont’d High power lasers or Hot Lasers generate thermal response Used in the Medical Realms- surgical cutting

Low level power laser Used as a rehabilitation intervention for pain management and wound healing. Is relatively new area in medicine (20 – 25 yrs) Maximal output of power < 1 milliWatt

Low lever Laser Work by producing photochemical rather than thermal effect

Laser light used in Rehab There are two types of Laser lights used in rehabilitation Helium Neon –HeNe Gallium Arsenide -- GaAs

Helium Neon Gas laser Uses a mixture of Helium and Neon in a pressurised tube Creates Laser in the Red portion of the electromagnetic spectrum Has a wavelength of 632.8nm

Depth of penetration Absorbed in the superficial tissues mm of soft tissue Indirect effect at 8 – 10 mm depth of soft tissue

Laser output is affected by Care of the equipment The number of operating hours Quality of fibreoptics used

Gallium Arsenide Laser Utilise a diode to produce an infrared ( invisible) Laser Wavelength of 904nm 3 – longer wavelength than HeNe Absorbed at depths of 1 – 2 cm Indirect effect of up to 5cm

GaAs Laser Has a peak power of 2watts which is delivered in a pulsed mode to decrease the thermal effect Greater potential for treatment of deeper soft tissue

Method of application There are three methods of application: Gridding Scanning Wanding

Biological effects Promotes ATP production Promotes collagen production Modulates inflammation Inhibits bacterial growth Promotes vasodilatation- microcirculation Alters nerve conduction velocity

Effects of Laser Facilitate wound healing Reduction of pain Increase tensile strength of star Decrease in inflammation Bone response

Clinical indication Tissue healing :chronic and acute wounds( can promote tissue repair but more high quality studies needed) accelerated healing Arthritis Postmasectomy Lymphedema (more evidence needed)

Clinical indication cont’d May reduce pain in patients with neuromusculoskeletal conditions. Eg back pain, neck pain, trigger points Pain management

Contraindications Direct irradiation of the eyes Malignancy Ares recently exposed to radiotherapy Haemorrhaging Regions

Precautions Low back or abdomen during pregnancy Epiphyseal plates in children Impaired sensation or mentation

Parameters for the use of lasers Type of diode Wavelength Power Energy density

Type of Diode LED – light emitting diode- semiconductor diode that produces low power light in a range of frequencies SLD- supraluminous diode- semiconductor that produces high power light in a narrow frequency range Laser diode – semiconductor diode and optics that produce laser light

Wavelength Laser light applicators produce/output light in the visible or near visible wavelength range of the electromagnetic spectrum IR (700 – 1100nm)- longer wavelength and penetrates deeper tissue up to 30 to 40 mm Red light( nm)- short wavelength and suitable for treating superficial tissue at a depth of 5- 10mm

Power Light applicator is measured in milliwatts Laser for therapy are power more than 5mW and less than 500mW Low power light applicators require more time to deliver the same amount of energy as high power light applicators

Energy Density Lower energy density recommended for acute and superficial conditions High energy density recommended for chronic and deeper conditions

Documentation Type of Diode- LD, LED,LED ? Wavelength (nm) Power (mV) Area of body to be treated Energy Density

Suggested readings Physical Agents in Rehabilitation by Michelle Cameron Therapeutic Modalities in Rehabilitation by William E.Prentice