Silver Nanoparticles Conjugated with Contact Lens Solutions May Reduce the Risk of Acanthamoeba Keratitis

Abstract

Acanthamoeba keratitis (AK), a severe sight-threatening corneal infection, has become a significant medical problem, especially among contact lens wearers. The disease manifests as eye pain, congestion, blurred vision, lachrymation, and ring-shaped infiltrates of the cornea, and can lead to permanent blindness. Inappropriate habits of contact lens users may result in an increased risk of AK infection. The anti-amoebic efficiency of popular multipurpose contact lens solutions is insufficient to reduce this risk. An effective and non-toxic therapy against AK has not yet been developed. The prevention of AK is crucial to reduce the number of AK infections. Nanoparticles are known to be active agents against bacteria, viruses, and fungi and were also recently tested against protozoa, including Acanthamoeba spp. In our previous studies, we proved the anti-amoebic and anti-adhesive activity of silver nanoparticles against Acanthamoeba castellanii. The aim of this study is to evaluate the activity, cytotoxicity, and anti-adhesive properties of silver nanoparticles conjugated with five commonly used multipurpose contact lens solutions against the Acanthamoeba castellanii NEFF strain. The obtained results show a significant increase in anti-amoebic activity, without increasing the overall cytotoxicity, of Solo Care Aqua and Opti Free conjugated with nanoparticles. The adhesion of Acanthamoeba trophozoites to the contact lens surface is also significantly reduced. We conclude that low concentrations of silver nanoparticles can be used as an ingredient in contact lens solutions to decrease the risk of Acanthamoeba keratitis infection.

Tannic Acid-Modified Silver Nanoparticles in Conjunction with Contact Lens Solutions Are Useful for Progress against the Adhesion of Acanthamoeba spp. to Contact Lenses

“…None of the tested contact lens solutions reduced amoebae adhesion in all four types of contact lenses. We obtained similar results in our previous study in 2021 [27].…”

“…In the FDA 1 and FDA 3 groups of contact lenses, the most beneficial dose-dependent effect on adhesion reduction was shown with SCA + AgTANPs. As confirmed in our previous studies [27] and based on the current morphological assessment of the trophozoites (Figure 2), it seems that contact lens solutions in conjunction with AgTANPs influence the cell shape by reducing the number of acanthopodia, thus affecting the adhesion process. In the FDA 2 and FDA 4 groups of contact lenses, the most beneficial dose-dependent effect on adhesion reduction (AR) was shown with O-F + AgTANPs.…”

“…In addition, the Acanthamoeba Neff strain used in our adhesion assays showed more stable population dynamics, which allowed us to perform all tests in the logarithmic growth phase of the trophozoites population. We also showed that pure AgNPs significantly increased the anti-adhesion properties of the selected contact lens solutions [27]. In the present study, we showed that silver nanoparticles in conjunction with tannic acid (AgTANPs) increased the anti-adhesion properties of the tested contact lens solutions even more than pure AgNPs.…”

“…The adhesion of Acanthamoeba trophozoites to contact lenses and their transmission from the contact lens surface to the corneal epithelium is the first step to AK development [11]. Here, we showed that adhesion to lenses composed of ionized material (FDA groups 3 and 4) was much higher and stronger compared to non-ionized lenses (FDA groups 1 and 2) [27]. The obtained results, which are also supported by those from other authors, suggest that the ionization of contact lens materials may be a significant factor favoring Acanthamoeba adhesion [7].…”

“…However, most of contact lens solutions are not effective against Acanthamoeba trophozoites and cysts. Therefore, there is still an urgent need to enhance their anti-amoebic and anti-adhesive properties [20][21][22][23][24][25][26][27].…”