Ultra Violet - Use of UV radiations in Skin Treatment

Ultra-violet lamps are useful in dermatology practice. These lamps are composed of quartz glass envelope filled up with mercury vapor and 2 electrodes. When in use electric current passes in between these two electrodes in the form of an arc between the intervening gaseous media and U.V. rays are generated. Mercury atoms have the property of emitting a spectrum of 185-400 nm in the ultraviolet range.

According to the radiation energy emitted, U.V. rays have been classified:

(1) U.V.A. 315-400 nm

(2) U.V.B. 280-315 nm

(3) U.V.C. 10-280 nm

U.V. rays have both surface and systemic actions. The former is confined to the area irradiated and consists of stimulation, killing of bacteria, peeling of the horny layer of the skin and pigmentation. Reaction to U.V.R. appears 2 to 12 hours after exposure. If a strong exposure is given, the skin may be irritated or a local burn may be produced.

The systemic effect of U.V.R. consists of stimulation of the metabolism, increasing the body's resistance and increasing also the production of vitamin D. In sunny tropical countries the cool morning sun does as much good as U.V.R. Photochemotherapy: U.V.A. 315 to 400 nm (fluorescent black light lamp) has lately been employed in the treatment of vitiligo and psoriasis along with oral 8-methoxy psoralen.

Often the beneficial effects of U.V.R. have been grossly exaggerated to the extent that it is considered a panacea by certain enthusiasts.

The contra-indications to the use of ultra violet rays are:

Acute eczema, acute vitiligo, spreading psoriasis; progressive alopecia, active pulmonary tuberculosis, lupus erythematosus and all light-sensitive dermatoses.

Dose schedule - After determining the minimal erythema dose, exposure can be given daily or alternate days depending on the discretion of physician and convenience of the patient. Once there is improvement in the disease process, the interval time can be lengthened.

The distance of the lamp from the patient, and the time of exposure, vary with each lamp. The manufacturers' instructions must be strictly adhered to, and a log book maintained every time the lamp is used. Proper records should be maintained of the doses administered to the patient. U.V.R. has a deleterious effect on the eyes; the patient, doctor and nurse should always wear well-fitting, colored glasses especially meant for the purpose every time they expose themselves to the lighted lamp. When giving U.V.R. to -"the eyelids, be sure that the patient's eyes are kept closed all the time. The lamp must be kept clean with methylated spirit. The practitioner should not carelessly expose his uncovered skin to U.V.R.