Wood's lamp: A modified method of examination

S Veeranna

 Rohith Skin Clinic, Vidyaranyapuram 2nd Main, Mysore, India

Correspondence Address:
S Veeranna
Rohith Skin Clinic, Vidyaranyapuram, 2nd Main, Mysore Karnataka- 570 008
India

Sir,

Wood′s lamp is an important diagnostic tool in dermatology. It was invented in 1903 by a Baltimore physicist, Robert W Wood.[1] The first reported use of this lamp was in 1925 for the detection of tinea capitis. It is mainly used in the diagnosis of bacterial infection, fungal infection and pigmentary disorders.

Successful use of Wood′s lamp depends on three essentials: a totally dark room, a totally dark-adapted retina and a lamp operating at full power.[2] Although the instrument is simple to use, dermatologists do not routinely use it, mainly because a dark windowless room is required for its use.

To overcome this, a simple modification can be made so that even in illuminated rooms this instrument can be used with the same accuracy. A rectangular black cotton cloth measuring 25 X 18 inches is taken. Its size can be altered according to the outer circumference of the Wood′s lamp. One free edge of the cloth is attached to the outer circumference of the Wood′s lamp with foam tape, and the other end, which is kept open, rests on the part to be examined. The lamp is held 2-3 inches from the surface of the skin. [Figure - 1] The lamp is switched on and held in position for 3-4 minutes to visualize the fluorescence. It is better to sit opposite and as far away as possible from the source of illumination in the room so as to minimize the light entering the view hole. When the lamp is used on the face, the patient should use UV protection goggles or close the eyes.

This simple modification makes the Wood′s lamp more user friendly. Used in this manner, the lamp will be invaluable in school surveys for tinea capitis because it makes the invisible visible.[2]

1.	Asawanonda P, Tylor CR. Wood's light in dermatology. Int J Dermatol 1999;38:801-7. [Google Scholar]
2.	Shelley WB, Shelley ED. Advanced dermatologic diagnosis. Philadelphia: WB Saunders; 1992. [Google Scholar]