light therapy Flashcards
what is light therapy
exposure to specific wavelengths of light, which is administered for a specific amount of time.
wave length of infared light
760nm-10,000nm
wavelength of visible light
380nm-760nm
uv light wavelength
180-380nm
group a uv light wavelength and effect
315-380nm (causes pigmentation)
group b uv light wavelength and effect
280-315-nm (causes erythema)
group c uv light wavelength and effect
180-280nm (bactericidal effect)
what do the biological and physical effects of radiated light energy depend on:
⦁ Intensity and duration of exposure
⦁ The energy absorbed rather than the energy that is reflected/passes through.
what does the penetration depth of each light ray depends on
its wavelength:
penetration depth of ⦁ Infrared:
1-2cm penetration into the body
penetration depth of ⦁ Visible light
1-2mm penetration into the body
penetration depth of ⦁ UV light
0.5mm penetration into the body (only affects upper layers of the skin)
percentages of light energy from te sun that reaches the earth
⦁ Infrared – 51%
⦁ Visible light – 46%
⦁ UV – 3%
Artificial sources of light energy
⦁ Infrared – Solux lamp and Infrarouge
⦁ Visible light – blue and red filters (to achieve specific wavelengths)
⦁ UV – Quartz lamp
which light rays have the physiological effects of heat
Infrared and visible light rays produce heat after being transformed into kinetic energy.
Effects of infrared rays (5)
⦁ Hyperaemia and increased blood flow
⦁ Trophic effect (stimulation of biochemical processes and metabolism)
⦁ Anti-inflammatory (in chronic inflammatory conditions)
⦁ Muscle relaxation
⦁ Stimulation of endocrine system
Effects of Visible rays
local effect is the same as infared but weaker
general effect has effect on
1. CNS 2,ENDOCRINE 3, BILIRUBIN
Effects of Visible rays on CNS
moderate doses increases psychological tone, improve mood and performance (photostimulation of bioelectrical activity of the brain). The effect is specific to the colour of light:
red light effects on CNS
exciting (more aggressive than the other two, produce exogenous heat)
green light effects on CNS
relaxing
blue light effects on CNS
suppression of psychotic reactions.
Effects of Visible rays on endocrine
regulation through the hypothalamus centres
reg circ rythm
Effects of Visible rays on ilirubin
⦁ Photochemical degradation of bilirubin (visible blue spectrum only) – in treatment of jaundice of the newborn
characteristics of Ultraviolet
ionizing rays.
more energy than the other two
have both quantum photoelectric effect and specific photochemical effects
effects of UV on Metabolism
⦁ Ca-P metabolism – vit D3 is synthesized in the skin by UV irradiation of 7-dehydrocholesterol
⦁ Carbohydrate metabolism – normalisation of blood sugar level in mild diabetes
⦁ Protein metabolism – enhances purine metabolism and uric acid excretion
⦁ Lipid metabolism – regulation of cholesterol levels
effects UV on Haematological system
stimulates erythropoiesis
effects UV on Nervous system
⦁ Weak (suberythemal) doses: stimulating effect, used to stimulate recovery of peripheral nerves and nerve regeneration
⦁ Strong (erythemal) doses: blocking dose, has a suppressive effect. Pain relieving effect (“blocking erythema”) – usually 1 biodose or 1/2 biodose.
effects UV on Respiratory system
improves external respiration
effects UV on Endocrine system
stimulates thyroid, gonads and adrenocortical system (cortisol synthesis)
effects UV on ⦁ Stimulation of immunobiological reactivity
increases of levels of complement, gamma-globulin fraction, phagocytic activity, interferon and stimulation of the reticuloendothelial system.
indications for UV light include
psoriasis, rachitis (rickets) and disorders of the immune system.
Skin Reactions to Infrared and visible light
erythema caloricum
⦁ Vasomotor character (due to vasodilation)
⦁ Appears almost immediately (3-6 minutes after exposition)
⦁ Disappears 30 minutes–1 hour after onset
⦁ Non-homogenous
⦁ Doesn’t have clear margins
Skin Reactions to UV light
photoelectric erythema
⦁ Humoral character (reaction occurs in the epidermis)
⦁ More aggressive- denaturation of proteins and cell destruction
⦁ Biologically active substances formed as a result of cellular destruction
⦁ Appears after a latent period if 2-6h (sometimes takes up to 24h)
⦁ Disappears 24-48h after onset
⦁ 3-5 days after exposure, the skin darkens (due to the conversion of promelanin to melanin in the basal layer of the epidermis under the action of dopa-oxidase), the stratum corneum thickens and the old skin peels off
⦁ Homogenous character with clear, sharp margins
how is UV light dosed
using biodose
biodose definition
minimum duration (of exposure) in minutes necessary to cause the slightest hyperaemia with clearly defined margins, after exposure at a distance of 50cm. It is a method to check for individual sensitivity to UV light. It is measured in units of time, and is different for each person.
Most sensitive
Abdomen and lower back (lumbar region)
Chest and upper back
Flexor surfaces
Extensor surfaces
Least sensitive
Palm of hands and feet
skin folds
factors determining sensitivity to UV light
⦁ Sex ⦁ Age ⦁ Race ⦁ Endocrine disorders (e.g. thyrotoxicosis, lupus) ⦁ Hypertension ⦁ Jaundice
2 different types of doses
⦁ Erythemal dose
⦁ Suberythemal dose
Erythemal dose
exposure to one whole biodose.
It is only used locally and segmentally.
Suberythemal dose
exposure to part of a biodose.
It can be used locally or generally.
distance from lamp in local and general uv
local UV, the patient is 50cm away from the lamp.
general UV, the patient is 1m away from the lamp.
Indications
Infrared and Visible rays
(4)
⦁ Nervous system – neuritis, radiculitis, neuralgia, spastic hemiparesis
⦁ Musculoskeletal – inflammatory and degenerative joint disease and overuse syndromes
⦁ ENT – inflammation of upper respiratory tract (sinusitis and rhinitis)
⦁ Surgery – treatment of wounds
local UV indications
4
⦁ Rhinitis (on the nasopharyngeal mucosa)
⦁ Pharyngitis
⦁ Tonsillitis
⦁ Wounds
general UV indications
6
⦁ Prevention and treatment of influenza and other viral infections- stim phag, complement
⦁ Rachitis (rickets)
⦁ Secondary anaemia- stilm erythropoiesis
⦁ Diabetes and obesity
⦁ Neurosis
⦁ Allergic and autoimmune disorders
Contraindications for
Infrared and Visible rays
(4)
⦁ Acute inflammation
⦁ Purulent inflammation
⦁ Malignant tumours
⦁ Bleeding and haematomas
