Light therapy: Ultraviolet

1. What is the wavelength of UV light? What are its physiological effects?
2. What are indications for using UV light?
3. What are contraindications to using UV light?
4. What is the MED? What dosage of MED is usually given and what is the maximum?
5. How often can treatments be given?

Answers:
1. Wavelength is 2000-4000A. It is bactericidal on motile bacteria, provides increased vascularization of wound margins, produces hyperplasia and exfoliation, increased Vit D production, excites Ca metabolism, and results in tanning.
2. Indications include treatment of wounds, psoriasis, acne, and folliculitis.
3. Contraindications include pellagra, porphyria, sarcoidosis, acute psoriasis, lupus, eczema, herpes simplex, xeroderma pigmentosum. Use with precaution on fair skin, scars, atrophic skin, acute renal and hepatic failure, severe DM, hyperthyroidism, generalized dermatitis, advanced arteriosclerosis, active TB. Eyes should be protected with goggles.
4. MED is the Minimal Erythema Dosage, which is the minimal exposure time required to cause erythema on the volar surface of the forearm. It subsides in 24 hours. MED dosage is usually 1-2 MEDS and is kept to less than 5.
5. 2-3 times per week.