What condition is primarily treated using a Wood's lamp?

A Wood's lamp is primarily used in dermatology to examine the skin and identify certain conditions based on their fluorescence under ultraviolet light. When certain fungal infections, like tinea pedis (commonly known as athlete's foot), are present, they can fluoresce a specific color under the Wood's lamp, making it easier for clinicians to diagnose the infection. This diagnostic tool is particularly effective for tinea because fungi such as Microsporum species will emit a characteristic bright green or yellow-green light, helping to distinguish it from other skin conditions.

In contrast, conditions like psoriasis, dermatitis, and eczema typically do not show fluorescence under a Wood's lamp. While they can be diagnosed through clinical evaluation and other methods, they do not exhibit the specific visual cues under the ultraviolet light that a Wood's lamp utilizes to assist in diagnosing fungal infections such as tinea pedis. Thus, the connection of the Wood's lamp to the treatment and diagnosis of athlete's foot solidifies its role as the primary choice for that condition.