Fungal smear test is clinically known as KOH test. The test is a fungal culture to detect and treat the fungal infection of the lungs and the immunosuppressive condition. Fungal infection of the lung is caused by fungi or microorganisms like yeast or mold. If the fungal infection is superficial, then a simple clinical/microscopic examination is enough to identify the infection. In order to identify the infection causing organism, and to dig deeper into the root cause of the fungal infection, the KOH test is ordered. The test reveals the presence of any fungal antigens and antibodies. The test may vary depending on whether the infection is superficial or systemic.