Diagnosis of fungal keratitis: current options

Fungal keratitis is prevalent in tropical regions of the world and is being increasingly recognized as an important cause of ocular morbidity. Early diagnosis and appropriate treatment are essential to avoid blindness. Clinical impression is often suggestive but clinical features may vary considerably and no one clinical feature may be pathognomonic of fungal infection.

This review describes a combination of methods for the diagnosis of fungal keratitis. Both in vivo and in vitro techniques are described along with their advantages and limitations. In vivo confocal microscopy has made it easier for ophthalmologists to back up their clinical suspicion. In vitro methods include microscopy and culture for fungi. A wide range of conventional and molecular techniques are currently available that provide rapid diagnosis of fungal keratitis.

Owing to the sensitivity and specificity of over 80%, when available, confocal microscopy could be useful for the diagnosis of fungal keratitis in the clinic. Among the laboratory techniques, a 10% potassium hydroxide wet mount or Gram stain are simple and sensitive enough to be adopted as office methods by ophthalmologists to rule out fungal etiology in patients with microbial keratitis. Empiric antifungal therapy is discouraged and confirmation of the diagnosis prior to institution of treatment is recommended.