Ultraviolet Phototherapy Flashcards
Applying any form of light to the skin is analogous to applying _____ to the skin
energy
UV light is part of the electromagnetic spectrum; it is _____
invisible
There is an _______ relationship between wavelength and energy
inverse
Does UV have a low or high photon energy? Low or high wavelength?
high photon energy; low wavelength
UVB wavelength ?
290-320 nm
UVA wavelength?
320-400 nm
Visible light wavelength?
400-750 nm
UVB is _____ times more potent than UVA in terms of biological effect. Why (2 reasons)?
100;
- UVB more efficiently absorbed by the skin
- UVB has more photon energy than UVA
UVC light does not reach the earth surface because of the _______
atmosphere
What are the 5 acute effects of UV light on the skin?
- vitamin D synthesis
- epidermal hyperproliferation
- hyperpigmentation
- sunburn
- immunosuppression
What are 3 chronic effects of UV light on the skin?
- photoaging
- immunosuppression
- skin cancer
How does UV light cause skin cancer?
via
- DNA damage
- chronic immunosuppression
Technically, what is the only beneficial thing that UV light does for your body?
synthesize Vit D
________ is a defense mechanism and a response to injury
hyperpigmentation
The mechanisms of action for the therapeutic use of UV light in skin disease are directly related to the known_____ effects of UV light on the skin
acute
UV__ is generally known for burning, and UV__ predominantly causes photoaging
B;A
UVB, not UVA, contributes to skin cancer (T/F).
FALSE - both contribute
_______ = with repeated exposures to UV, the actor response of the skin changes
photoadaptation
What two mechanisms are photo adaptation due to?
- increased melanization of the skin
2. epidermal hyper proliferation
In general, for significant improvement, UV therapy is usually give __-__ times per week, and __-__ session in total
2-3; 25-50
The therapeutic dose of UV light is normally (lower/higher) than the does that will cause an acute sunburn
higher
________ allows the therapist to start with a low dose that will not cause a sunburn, and then gradually increase the UV over successive exposures in order to achieve the therapeutic dose
photoadaptation
How do you measure UVB light?
time x intensity = fluence
What are the 3 ways to determine the starting dose?
- MED testing
- skin typing
- empiric
_____ = actual light energy dose delivered to the skin
fluence
_____ = lowest dose of light hat will cause redness of the skin
minimal erythema dose (MED)
With MED testing the pt is exposed to small doses of UV and then the skin is checked ___ hours later for erythema
24
What is skin typing ? What is it based on?
tan/burn history; Fitzpatrick skin typing
What are the 6 fitzpatrick skin typing ?
- burns easily, rarely tans
- burns easily, sometimes tans
- sometimes burns, easily tans
- rarely burns, tans easily
- darker skin
- very dark skin
______ way = every starts with the same dose
empiric way (BAD)
UV light dose = start at ___ % MED if using this method, and then increase by __-__% over the previous dose treatment as tolerated
70; 5-10
____ = most commonly used form of phototherapy in clinics
UVB
Broad band is more effective than narrow band UVB, but he exposure times are longer (T/F)
FALSE; other way around
What are 6 conditions amendable to UV therapy ?
- Psoriasis
- Eczema
- Vitiligo
- Pruritus secondary to renal or liver disease
- photodermatoses
- cutaneous lymphoma
What is the most common indication for phototherapy ?
psoriasis
Why is phototherapy effective in treatment of psoriasis?
immunosuppressive effects on overactive T cells in the skin that drive the inflammation and epidermal hyperproliferaion
How is phototherapy an effective treatment for eczema?
like proriasis; immunosuppressive to activated T cells that cause pruritis and inflammation
What are 2 ways that phototherapy is effective when treating vitiligo?
- stimulate melanocytes
2. suppress autoimmune reactions
_____ band UVB or _____ required to treat vitiligo
narrow; PUVA
Is broad band UVB effective in treating vitiligo?
no
How many treatment sessions are required to treat vitiligo?
100-200
UVB is effective in decreasing the _______ in pts with advanced kidney or liver failure
pruritus
Some pt’s with photodermatoses who are immunologically sensitive to light can be “_______” by using repeated low doses of UV light
desensitized
CI’s to UV phototherapy ?
- skin cancer
- connective tissue disease
- photosensitivity
