Strategies for the prevention of contact lens‐related Acanthamoeba keratitis: a review

Abstract

Purpose: Acanthamoeba keratitis is a severe, often sight threatening, corneal infection which in Western countries is predominantly seen in daily wear of contact lenses. This review aims to summarise the pathobiology and epidemiology of contact lens-related Acanthamoeba keratitis, and to present strategies for prevention, particularly with respect to modifiable risk factors in contact lens wear. Recent Findings: The virulence of Acanthamoeba and resistance to treatment in keratitis appears to be linked with the production of a low molecular weight pro-tease MIP133 by the organism, in response to binding to corneal epithelial cells through a mannose binding protein, and to the ability of the organism to convert from the trophozoite to the resistant cyst form. Recent epidemiological studies in contact lens relate disease have confirmed the link between solution topping up and Acanthamoeba keratitis and have reinforced the importance of avoidance of tap water, either as part of the care for the contact lens or storage case, handling lenses with wet hands or showering while wearing lenses. In the most recent analysis from the USA, there were no strong effects for solution type, water source or water disinfection process. Wearer age, lens wear time and history to appear to be linked with Acanthamoeba keratitis. Daily disposable contact lens use would be expected to reduce the prevalence of Acanthamoeba disease although this is unproven. Summary: While Acanthamoeba keratitis remains challenging to diagnose and manage, strategies to limit the disease severity in contact lens wearers should include attention to recently identified risk factors, particularly those related to water contact. Public health awareness measures, the use of daily disposable contact lenses, a better understanding of the contribution of the host immunity and the development of standardised methods for culture of amoeba and testing of contact lens care systems against Acanthamoeba in the licensing process may be of value. Alternative treatments for the future may include those which target the mannose binding protein or the genes which control conversion to the cyst form.

Contralateral eye comparison of the long‐term visual quality and stability between implantable collamer lens and laser refractive surgery for myopia

“…; Hedayati et al. ; Carnt & Stapleton ; Eissa ). Surgical options include implantable collamer lens (ICL; STAAR Surgical, Monrovia, CA, USA) and corneal laser refractive surgery (LRS).…”

The diagnosis and management of contact lens‐related microbial keratitis

“…While the immediate effect of the voluntary withdrawal of two CL disinfecting solutions was an apparent decrease in infections of both Acanthamoeba and Fusarium filamentary fungus, keratitis from both these organisms has been reported to be rising since. It was first highlighted that Acanthamoeba did not return to the base level before the outbreak in the mid‐2000s and indeed an increase in more recent years, beginning around 2012, has been reported from several centres not linked to a specific disinfecting solution . More recently, an increased level of filamentary fungal CL MK cases has been reported …”

“…In bacterial MK, 11–14 per cent of patients lose significant vision (two lines of vision or more) . For Acanthamoeba keratitis (AK), 30 per cent lose significant vision and keratoplasty occurs in at least 20 per cent of patients . For filamentary fungal keratitis, the need for keratoplasty is higher, with a British Ophthalmic Surveillance Study between 2003–2005 finding the proportion of keratoplasty at 40 per cent …”

The first Acanthamoeba keratitis case in the Midwest region of Brazil: diagnosis, genotyping of the parasite and disease outcome

“…The daily use of contact lenses may favor the appearance of microtraumas in the cornea that could represent a gateway for the development of Acanthamoeba keratitis. 1 It is an often sight-threatening and difficult-to-treat infection because trophozoites (the multiplicative stages) may differentiate into cysts (resistant, dormant stage) in response to drugs that act by different mechanisms of action 2 .…”