Challenges in Acanthamoeba Keratitis: A Review

Abstract

To review challenges in the diagnosis and management of Acanthamoeba keratitis (AK), along with prognostic factors, in order to help ophthalmologists avoid misdiagnosis, protracted treatment periods, and long-term negative sequelae, with an overarching goal of improving patient outcomes and quality of life, we examined AK studies published between January 1998 and December 2019. All manuscripts describing clinical manifestations, diagnosis, treatment, prognosis, and challenges in short- and long-term management were included. The diagnosis of AK is often challenging. An increased time between symptom onset and the initiation of appropriate therapy is associated with poorer visual outcomes. The timely initiation of standardized antiamoebic therapies improves visual outcomes, decreases the duration of treatment, and reduces the chances of needing surgical intervention. In clinical practice, AK diagnosis is often missed or delayed, leading to poorer final visual outcomes and a negative impact on patient morbidity and quality of life.

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

“…Medical management is generally attempted prior to surgery unless there is immediate threat to central nervous system penetration. Procedures such as penetrating keratoplasty (PKP) and deep anterior lamellar keratoplasty (DALK), which were originally performed with the intention of debriding diseased tissue and debulking disease, are now generally reserved for either cases refractory to medical management or for restoration of vision due to structural damage [6,19,20].…”

“…Diagnosis is complicated by various limitations of diagnostic testing. Although culture remains the gold standard (with 50%-75% sensitivity and 100% specificity), multiple recent studies have demonstrated its significantly inferior sensitivity compared to that of in vivo confocal microscopy (>90% sensitivity and specificity) [ 6 , 7 ]. An added benefit of confocal microscopy is that it offers an immediate diagnosis, allowing for rapid initiation of treatment.…”

“…Because of well-documented coinfections and known synergism between the protozoa and certain bacteria, some therapeutic regimens include an antibacterial agent, such as topical moxifloxacin, ciprofloxacin, trimethoprim-sulfamethoxazole, or erythromycin [ 6 ]. These are of unproven efficacy but may be useful empirically or perioperatively and are generally well tolerated.…”

Therapeutic Corneal Transplantation in Acanthamoeba Keratitis: Penetrating Versus Lamellar Keratoplasty

“…[5][6][7] Nevertheless, all patients are not responsive to the alternative antiamoebic drugs; therefore, a surgical approach is mandatory in such rare cases. Once medical treatment is not effective, usually if AK recurs despite 2 repeated medical cycles of topical drugs, 8 a TDALK procedure gives the best outcome in early stages of the disease. 9 TPK instead is the best choice in very advanced stages.…”

Novel Plant-Based Metabolites as Disinfectants against Acanthamoeba castellanii

“…With an increase in global warming, coupled with global water shortages and public reliance on household water tanks, especially in developing countries, it is likely that infections caused by free-living amoebae will rise; thus, the development of novel disinfectants which can target amoebae effectively is needed [ 5 ]. Furthermore, in the case of AK infection, because of the presence of amoebae cysts, recurrent amoebic infections are observed, as the cysts may withstand available therapies and revert to the active trophozoite stage following the treatment [ 4 , 6 , 7 , 8 ]. Antimicrobial topical treatments are available for AK infection and usually comprise a combination of propamidine isethionate and neomycin or chlorhexidine, while contact lens disinfectants often include chlorhexidine [ 2 ].…”