Acanthamoeba Keratitis, Pathology, Diagnosis and Treatment

Abstract

Acanthamoeba keratitis is an unusual corneal infection that is recently increasing in frequency and is often contracted by contact lens wearers, someone who experienced recent eye trauma, or someone exposed to contaminated waters. Acanthamoeba survive in air, soil, dust, and water. Therefore, eye trauma and poor contact lens hygiene practices lead to the entrapment of debris and thus infection. Acanthamoeba keratitis results in severe eye pain, inflammation, and defects of the epithelium and stroma that can potentially result in vision loss if not diagnosed early and treated promptly. The disease can be diagnosed using corneal scrape/biopsy, polymerase chain reactions, impression cytology, or in vivo confocal microscopy. Once diagnosed, it is usually treated with an antimicrobial combination therapy of biguanide and aromatic diadine eye drops for several months. Advanced stages of the disease result in vision loss and the need for corneal transplants. Avoiding the risk factors and diagnosing the disease early are the most effective ways to combat Acanthamoeba keratitis.

Detection of Acanthamoeba spp. using carboxylesterase antibody and its usage for diagnosing Acanthamoeba-keratitis

“…Although several new diagnostic methods for AK have been proposed, corneal scraping culture is still considered to be the gold standard [ 10 , 14 , 16 ]. One advantage of using the CE antibody-based diagnosis is its non-invasive nature.…”

“…However, non-contact lens wearers can also be susceptible to acquiring AK upon corneal damage or exposure to Acanthamoeba -contaminated water [ 3 , 10 , 13 ]. Initial signs of AK were reported to be generally unilateral, which begins at the epithelial layer and gradually progressing towards the corneal stroma [ 13 , 14 ]. Unfortunately, clinical manifestations of AK are strikingly similar to corneal infections incurred by other pathogens, and differentiating bacterial or fungal keratitis from that of amoebic origin is difficult [ 2 , 14 – 16 ].…”

“…Initial signs of AK were reported to be generally unilateral, which begins at the epithelial layer and gradually progressing towards the corneal stroma [ 13 , 14 ]. Unfortunately, clinical manifestations of AK are strikingly similar to corneal infections incurred by other pathogens, and differentiating bacterial or fungal keratitis from that of amoebic origin is difficult [ 2 , 14 – 16 ]. Since delayed or misdiagnosis of AK can lead to serious eye damage that can result in permanent vision loss a diagnostic test enabling rapid and accurate detection of AK is urgently needed [ 2 , 3 , 16 ].…”

“…Currently available techniques for diagnosing AK are confocal microscopy, polymerase chain reaction (PCR), histopathological examination, and microbiological culture [ 2 , 14 , 16 – 18 ]. While these have been useful, there are several limitations associated with each of the aforementioned diagnostic methods.…”

Acanthamoeba Keratitis: A Single-Institution Series of Four Cases With Literature Review

“…Without treatment of coinfections, a symbiotic relationship between the two organisms persists, causing continued damage to the cornea despite treatment of the Acanthamoeba . Untreated and suboptimally treated infections have been observed to spread contiguously into the deeper structures of the eye and central nervous system manifesting as granulomatous amoebic encephalitis [ 5 ]. While AK infections are relatively uncommon, they are associated with significant morbidity and vision loss due to the diagnostic and therapeutic challenges they pose.…”