Acanthamoeba keratitis beyond "wear" and "tear:" There is more than what meets the eye!

Background: Acanthamoeba keratitis (AK) is a diagnostic challenge. Establishing a microbiological diagnosis using culture, polymerase chain reaction (PCR), and ascertaining genotype is the current global norm. Although ocular trauma and extended contact lens (CL) wearing are classical risk factors, evidence is accumulating that AK can result even in their absence. Aims & objectives: The study aimed to identify the risk factors, genotypes, and clinical outcomes associated with AK at our institution. Materials and Methods: In a prospective analysis, corneal scrapings, CL, and lens solution specimens processed in the department of parasitology between January 2019 and December 2021 were subjected to microscopy, axenic culture on nonnutrient agar, and 18SrRNA PCR. The amplified products were subjected to gene sequencing, and a phylogenetic tree was constructed using available sequences in the database. Results: Ten cases of AK were identified by culture and PCR during the study period. Sequence analysis and phylogenetic tree revealed that nine were genotype T4 and one was T5. The mean age of the patients was 29.5 years (range: 16-39 years), and male: female was 9:1. History of CL wearing was present only in four patients and extended wear in only one. Another patient had a history of ocular trauma, while five others had no risk factor. All were treated with polymyxin, polyhexamethylene biguanide, and voriconazole, and two underwent therapeutic keratoplasty. Conclusion: A high index of suspicion should be kept in patients even without classical AK risk factors. Microbiological diagnosis along with genotyping would add to the increasing database of global AK cases.