Wood’s light

Lawrence NL, Cox SE, Brady HJ (1977) Treatment of melasma with Jessner s solution versus glycolic acid a comparison of clinical efficacy and evaluation of the predictive ability of Wood s light examination. J Am Acad Dermatol 36 589-593... 

Wood s light this technique is useful to determine depth of pigmentation in order to predict a patient s treatment response. 

Mixed melasma increased melanin in the epidermis and dermis.Clinically, melasma is dark brown and its appearance is not enhanced by Wood s light. 

Assess phototype, degree of sebaceous activity, skin thickness, and pigmentary abnormalities (Wood s light). 

The near UV spectral range is divided in three bands the short wave band or UV-C emission runs from 180 to 280 nm with a peak at 254 nm. The medium wave band or UV-B runs from 280 to 320 nm with a peak at 312 nm, while the UV-A long wave band runs from 320 to 380 nm with a peak at 365 nm. The long wave emission is commonly called "Black light" or "Wood s light". Only the UV-A portion of the lamp spectrum is useful for UV reflectivity measurements, since wavelengths under 400 nm are cut off by the glass optics of the objective. However, the full power of the lamp is used for UV fluorescence measurements. 

M. audouinii cosmopolitan used to be tiie most common cause of epidemics of tinea capitis in Europe and N. America, Ectothrix Wood s light positive downy white surface to grayish-white mouse-fur , reverse salmon to peach-pink, sometimes rusty slow growth pectinate ( comb-like ) and racquet (rackett) hyphae, thick-walled chlamydospores rare micro- and (bizarre) macroconidia... 

M. ferrugineum E. Europe, Asia, C. Afr., S. America epidemics of tinea capitis in children, ectothrix invasion of hair Wood s light positive waxy, convoluted, slowly growing diallus, color cream to yellow to red no macro- or microconidia, but hyphae of irregular shape with prominent septae ( bamboo hyphae )... 

T. mentagrophytes var. quinckeanum cosmopolitan mouse favus in man rarely scutulae seldom endo- or ectothrix invasion Wood s light negative... 

M. equinum Europe, N. Am., Austr. horses rare ectothrix Wood s light positive... 

Wood s light This lamp emitting UV light at a wavelength of above 365 nm is helpful in the diagnosis of tinea capitis (bright greenish yellow), erythrasma. 

Additives Effect on the Catalyzed Monomer Solution. Soluble dyes can be added to the catalyzed monomer solution to color the final wood-polymer composite. Any color of the visible spectrum can be added, browns to simulate black walnut, red and blues for national colors. The color emphasizes the grain structure of the particular species and combines with the polymer to add a three-dimensional depth not present in surface-finished wood. A dense black wood-polymer, so desirable for musical instruments, is difficult to obtain because of wood s light color and the tendency of the microstructure to chromatographically separate a dye of several components into its separate colors. Dyes have an inhibiting effect on the polymerization of wood-monomer composites, some more so than others. Additional catalyst can be added to overcome this inhibition, but in the radiation process of a given geometry additional time must be allowed for complete curing. 

Purely epidermal there is a lot of melanin in the basal and suprabasal layers of the epidermis. It is occasionally found throughout the epidermis. A Wood s light increases the contrast between the melasma and normal skin. This is the most common type of melasma. 

Dermal the melanin accumulates in the macrophages of the papillary and/or reticular dermis. A Wood s light does not increase the contrast. 

Mixed epidermal-dermal a Wood s light accentuates the contrast in some areas and not in others, but an epidermal area can hide an underlying dermal area. 

It is not possible to do a Wood s light examination on very dark skin types. 

It is useful to evaluate the depth of pigmentation a Wood s lamp can be used to do this, as shown in Figure 30.10. The worse the pigmentation appears when exposed to the Wood s light (i.e. the more patchy the skin appears), the more superficial the melanin is and the treatment will soon take effect. Superficial pigmentation does not need to be treated with phenol, and can be treated effectively with less aggressive peels. 

Apart from the therapeutic application of porphyrins, tumor tissues can be made visible on the basis of porphyrins typical brick-red fluorescence under Wood s light. This prineiple has been termed fluorescence diagnosis with ALA-induced porphyrins (FDAP) or photodynamic diagnosis (PDD). 

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