The effect of silver-infused silicone hydrogel contact lenses on the ocular biota during daily wear

Abstract

Purpose: Silver-infused contact lenses (CLs) may provide benefits to CL wearers by reducing adherence of potential pathogens to CL surfaces; however, they have the potential to modify the normal ocular biota during wear. This study investigated the effect of silverinfused silicone hydrogel CLs on conjunctival flora over six months of daily wear (DW). Method: A prospective, randomised, doublemasked, contralateral study was conducted. Sixty subjects were randomly assigned to wear silverinfused (galyfilcon A with incorporated silver ions, test) and standard (galyfilcon A, control) silicone hydrogel CLs on a contralateral basis for six months of DW. Prior to assignment of the test and control CLs, all subjects were fitted with etafilcon A daily disposable CLs for a one week wearin period. Conjunctival flora were cultured at screening/pre-baseline (with subjects’ habitual CLs), baseline (after daily disposable wear) and four weeks, three and six months following commencement of test and control CL wear, using sterile calcium alginate swabs moistened with sterile unpreserved 0.9% saline. Results: There were no statistically significant differences between the conjunctivae of test and control eyes in incidence of positive cultures (p>0.05), culture classification grades (p>0.05), microorganism levels (p>0.05) or numbers of different types of microorganisms isolated (p>0.05). Wear of the test CLs did not promote fungal or yeast colonisation of the conjunctivae. The most frequently isolated microorganisms were Gram-positive bacteria considered to be part of the normal ocular flora. Conclusions: Wear of the silver-infused CLs did not result in any statistically or clinically significant alterations to the ocular biota over six months of DW.