The effect of surface treatment of silicone hydrogel contact lenses on the attachment of Acanthamoeba castellanii trophozoites.
OBJECTIVE
To determine if plasma surface treatment of Focus Night & Day silicone hydrogel contact lenses affects the attachment of Acanthamoeba.


METHODS
Unworn lotrafilcon A contact lenses with (Focus Night & Day) and without surface treatment and Acuvue, conventional hydrogel lenses, were quartered before 90-min incubation with Acanthamoeba castellanii trophozoites. After incubation and rinsing, the trophozoites attached to one surface of each quarter were counted by direct light microscopy. Sixteen replicates were observed for each lens type. Logarithmic transformation of data allowed the use of parametric analysis of variance.


RESULTS
No significant difference in attachment was established between the untreated lotrafilcon A and the conventional hydrogel lenses (P<0.001); however, surface treatment of the native Focus Night & Day material produced a significant increase in attachment (P<0.001).


CONCLUSIONS
Commercially available Focus Night & Day lenses are subjected to a plasma surface treatment to reduce lens hydrophobicity; however, this procedure results in an enhanced acanthamoebal attachment. It is possible that the silicone hydrogel lens could be at a greater risk of promoting Acanthamoeba infection if exposed to the organism because of the enhanced attachment characteristic of this material. Eye care professionals should be aware of the enhanced affinity that Acanthamoeba show for this lens and accordingly emphasise to patients the significance of appropriate lens hygiene. This is particularly important where lenses are worn in a regime that could increase the chance of exposure to the organism, i.e., 6 nights/7 days extended wear or daily wear, where lenses will be stored in a lens case, or where lenses are worn when in contact with potentially contaminated water sources, i.e., swimming or showering.
Beattie
Tara K
TK
Department of Civil Engineering, University of Strathclyde, Glasgow, Scotland. t.k.beattie@strath.ac.uk
Tomlinson
Alan
A
D048248:Acanthamoeba castellanii / Q000502:physiology*; D002448:Cell Adhesion; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects*; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D020100:Hydrogels; D012828:Silicones; D013499:Surface Properties; D053058:Trophozoites / Q000502:physiology*; D005466:Fluorocarbons
D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D020100:Hydrogels; D012828:Silicones; C481129:lotrafilcon A; D005466:Fluorocarbons