Abstract
Members of the filamentous fungal genus Aspergillus are among the agents frequently causing keratomycosis in humans. Aspergillus keratitis is most common among agricultural workers in geographical regions with hot, humid, tropical or semi-tropical climates. Trauma by vegetable matter during agricultural activities is the main predisposing factor of the infection. A persistent infiltrate at the site of superficial injury is often present, which gradually increases in size and density. If untreated, a full thickness corneal ulcer may develop, which leads to perforation and may progress to endophthalmitis. Early and accurate diagnosis coupled with appropriate antifungal therapy is crucial for improving the chances of complete recovery. The main causative agents of Aspergillus keratitis are A. flavus, A. fumigatus, A. terreus and A. niger, while A. glaucus, A. ochraceus, A. fischerianus, A. nidulans and A. tamarii are rarely occurring. Morphology-based diagnosis of Aspergillus keratitis can be made by means of smear, staining, fungal culture and confocal microscopy. Molecular methods based on simplified PCR kits could have the potential to provide highly sensitive and specific diagnostic capabilities for detecting Aspergillus species in corneal samples. Rabbits are frequently used in model systems of experimental keratitis for studying the possible virulence factors and testing potential antifungal agents. Potential virulence factors of Aspergillus species causing corneal infections include extracellular proteinases, mycotoxins and fungal adhesins. The treatment of Aspergillus keratitis involves both medical and surgical management. The disease is usually treated with a topical antifungal agent, but surgical interventions may be needed for patients whose corneal infections do not resolve. Possible surgical interventions include regular debridement at the base of the ulcer, superficial lamellar keratectomy, excimer laser photo ablation of superficial stromal corneal infiltrates, temporary or permanent amniotic membrane transplantation and penetrating keratoplasty.