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What are the acute physiological effects of UV radiation on the skin and erythema (redness of skin)?
- -differs from depending on the application- has a sharp distinct edge at the junction with the unexposed areas
- - believed that thecapillaries in the dermis dilate, not the arterioles
- - reaction is due to the release of chemical mediators
- - effectiveness in producing erythema increase with decreasing wavelengths
- - erythema will appear 2-4hr affter application (latent period)
- - UV induce erythema reaches max intensity 8-24 hrs after exposure. Take several days to resolve
- - 20mJ/ cm2 of 300nm UVB are required for minial erytheme in a fair skinned person
- - an erythema from UVA is immediate and merges into a much later erythema- lasts several days
What are the acute physiological effects of UV radiation on the skin and pigmentation?
- -occurs gue to the formation of melanin in the deep parts of epidermis and migrate into superficial layers
- - takes around 2 days to occur after exposure
- - strongly stimulated by erythema producing UVB at around 300nm, andto a lesser degree by longer wavelengths UVA
What are the acute physiological effects of UV radiation on skin growth
- - epidermal thickening or hyperplasia
- - increase rate of division of basal epidermal cells
- - pigmentation and hyperplasia will fade over 4-6 weeks if there is no further application of UVR
What are the acute physiological effects of UV radiation and vitamin D production?
- UVB is able to convert steroids in the skin to vit D in the form of calciferol and cholecalciferol
What are the acute physiological effects of UV radiation snf immunosuppressive effects?
- - UVB destroys langerhans cells and stimulates the production of suppressor t cells
- - suppressor t cells are regulatory and suppress the action of other T cells, including specific killer t cell
- - amy contribute to the development of cancer
What are the acute physiological effects of UV radiation on the eyes?
- UVB and UVC radiation to the eyes can lead to conjunctivitis and photokeratits
What are the therapeutic uses of UVR?
- - psoriasis
- - Acne vulgaris
- - Eczema
- - chronic infection
- - vertiligo
- - vit D deficiency
- - mild hypertension
- - pruritis
What is psoriasis?
- -autoimmune disease affecting the skin
- most commonly presenting form is chronic discoid psoriasis
- other types include guttate pustular, generalised pustular, erythrodermic and flexura
How does UVR help psoriasis?
- - epidermal transit time reduced to 5 days- limits keratinocytes developing in the usual way. As a result, theykepp thier nuclei and tend to stick together forming aque
- - UV effects is unclear. In part centrally mediated, immunosupressive effect
What are therapeutic regimes?
- - goeckerman regime
- - ingram or leeds regime
- Photochemotherapy (PUVA)
- -radiations of UVS and a sensitiser
- - psoralen type drug given to the pt around 2hr before treatment
- - pead of the UVA erythema occurs 24-48 hrs post irradation
- - maintenance therapy of PUVA is rarely used
UVR effects on acne vulgaris?
- - UVR given in doses to cause significant desquamation- E2 dose
- Effects of this treatmet:
- - acceleration of skin growth
- - non- specific anti- inflam reaction
- - temporary sterilisation of skin surface
- - pigmentation
- - imporvement is dramatic but only temporary
UVR effects on chronic infection
- dose high enough to kill surface bacteria
What are the dangers of UVR and how can you control them?
- - eyes- therapist and pt need to wear goggles- to protect from scattered reflected radiation
- - overdose- too long an exposure, pt too close to lamp, previously protected skin is irradiated in subsequent treatments, sensiters, change in lamp
- - ozone- adequately ventilation
What are the contraindication of UVR?
- - acute skin conditions, eg eczema, dermatitis and existing ultraviolet erythema
- - skin damage due to ionising radiations (deep x-ray treatment)
- - systemic lupus erythematosus (autoimmune disease where body attacks healthy cells) may be triggered or accelerated by UVR
- - photoallergy ie allergic reaction to UVR
- - acute bebrile illness (skin disease). In this thw whole body shouldnt be treated.
- - recent skin grafts
What are the dosages of UVR?
- 1. quantity of ultraviolet energy applied per unit of the skin
- - bunsen- roscoe reciprocicty law
- the amount of energy, or radiation response depends on;
- - output of the lamp and the skin
- - angle at which the radiations fall on the skin
- - time for which the radiation is applied- used as the primary way of regulating dosages
- 2. Biological responsiveness (sensitivity) of the skin to which is applied
- - can only be adequately judges by trial applications of UVR
- - depends on the nature of the skin
- - woolf (1997)
- type 1- always burns, never tans
- type 2- always burns, tans slightly
- type 3- sometimes burns, always tans
- types 4- never burns, always tans
- type 5- pigmented skin- monogoloid
- type 6- heavily pigmented skin- negroid
- - recent exposures to UVR will alter the biolgical response
Degrees of erythema/ pts response
Sensitisation of the pt
- Ingested drugs
- - psoralens
- - sulphonamides- antibiotics
- - tetracyclines- antibiotics
- - griseofulvin- antifungal agent
- -phenothiasine- tranquillizer
- - hypnotic drugs eg veronal
- - barbiturates
- - gold therapy
- - various hormone
- - asprin and derivatives
- Substances applied to the surface
- - coal tar
- - dithranol
- - psoralens
- - eosin
- - Lowered E1 in the affected area
What is the warning for the initial treatment?
- During a UV treatment you may feel nothing or you may notice a little heat. If you do feel any discomfort or notice any other change you must call me immediately, otherwise you may risk skin damage.
- Please do not move or touch any of the equipment during treatment. If you become uncomfortable, call me.
- Do you understand what I have said? Do you have any questions? Are you happy for me to proceed?
Warning for subsequent treatments
If you have changed your medication or noticed any differences in response following the last treatment it is important that you tell me as this may mean today’s dosage should be changed. Do you understand what I have said? Do you have any questions? Are you happy for me to proceed?
Progression of UVR dosage
Proportion of the body surface irradiated
- - large doses over extensive can cause systemic illness
- - guidelines for the maximum proportion of the body surface to be irradiated with UVR are
- E1- whole
- E2- 20%
- E3- 4% (about 600cm2)