UV Flashcards
___ relationship between wavelength ad UV energy
inverse
wave length is measured in
nanometers
increase wavelength
UVC, UVB, UVA , colours, Infared
increasing photon energy
inferred, colour, UVA, B, C
most harmful
UVC
can you feel infrared
yes but you can’t see
UVB is ___ more potent than UVA in terms of biological effect
1000
why is UVB more potent than UVA
b/c its more efficiently absorbed by skin
has more photon energy
why does UVC reach earth surface
because ozone layer
acute effects of UV light on skin
vitamin D synthesis epidermal hyperproflieration (thickness) hyper pigmentation (tanning) sunburn (erythema, edema) immunosuppression
chronic effect of UV light on skin
photoaging
immunosuppression
skin cancer
hows skin cancer come about
DNA damage and chronic immunosuppression
T/F tan is a response to injury
YES
which one is for burning and which for aging
UVB - burning
UVA - aging
___ is the only known beneficial effect of UV light
vitamin d metabolism
T/F both UVB and UVA contribute to skin cancer
T
photoadaptation
with repeated exposure to UV, acute response to skin ages is this
photo adaptation is due to
inc melanization of skin (tanning)
epidermal hyperprolifferation
how often is UV light given for therapy benefits
2-3 x week
25-50 sessions per course
T/F the therapeutic dose of UV light is higher than the dose that will cause an acute sunburn
yes
why does UV therapy burn if its higher than sunburn
because photoadpation allows us to start low dose and inc
measuring UVB light equation
seconds x intensity = fluence (j/cm)
3 ways to determine starting dose of UV therapy
MED testing
skin typing
Empiric
MED testing
minimal dose that will cause redness, examine it 24 hrs later
Skin typing
1-6, from burn easily and I rarely tan, to very dark skin
T/F e1-4 system is used alot
not
Empiric
everyone starts at same dose no matter what
UV light dosimetry
start at 70% of MED if using this method
increase 5-10% each session
do we give UVB or UVA
B because more effective
natural sunlight is what type
heliotherapy
tanning booths are predomintayl what
UVA
how can photosensitizes be adminsitered
orally, bathtub to soak in, cream`
whats wrong with PUVA
its carcinogenic
___ most commonly used form of phototherapy in clinics
UVB
is UVB broad or narrow band more effective
narrow but exposure time is longer
dermatoses amenable to UV therapy
psoriasis
eczema
vitilgo
in psoriasis/ exczema phototherapy is ___ to overactive T cells in the skin
immunosuppressive
the itch that rashes is
eczema
T//F UVB may be combined with UVA to treat eczema
T
Vitilligo requires
narrow UVB or PUVA
BROAD IS NOT EFFECTIVE
__ if effective in decreasing pruritus
UVB
photodermatoses
ppl are sensitive to outdoor light exposure
they can get desensitived
cutaneous lymphoma treated with
UVB
contraindications for UV
skin cancer
connective tissue disease (lupus)
photosensitive (some drugs cause this)
