In vivo efficacy of silver-impregnated barrel contact lens storage cases

Purpose: This study examined the rate and level of microbial contamination of silver and non-silver (control) barrel contact lens storage cases in vivo.

Methods: A prospective, single-centre, randomized, double blinded, crossover study was conducted to evaluate the efficacy of silver and control barrel cases used with an Oxipol™-based disinfecting solution over a two-month period. Lens cases were collected, and the frequency, type and level of microbial contamination evaluated using viable culture and standard identification methods. Questionnaires were used to assess the contact lens-related hygiene compliance of the participants.

Results: Forty eight daily contact lens wearers completed the study. Overall, 27 % of silver and 35 % control lens cases (P > 0.05) were contaminated, predominantly with Gram-positive bacteria. Only, 12 % of participants had good compliance, with 46 % having average compliance and 43 % poor compliance. Compliance score was not associated with level of microbial contamination. However, the use of hydrogel lenses in combination with silver cases compared to non-silver barrel cases resulted significantly greater numbers of bacteria colonising cases.

Conclusion: The present investigation demonstrated that the use of silver barrel cases does not reduce the overall rate and level of bacterial contamination, but that using hydrogel lenses in combination with silver cases resulted in higher numbers of bacteria isolated from cases.