Non-compliance and microbial contamination in orthokeratology

To determine the rates of microbial contamination of solutions and lens accessories of existing ortho-k lens wearers and the effect on contamination rates of monthly replacement and warnings. To investigate self-reported levels of compliance with care of the lenses and lens accessories and correlation of these levels with the rates of microbial contamination.

Asymptomatic ortho-k lens wearers with at least 6-month successful use were requested to bring their lenses, solutions, and accessories to their next aftercare visit. All items, except the lenses, were replaced at each data collection visit. Samples collected from the lens surface, solution, and accessories were cultured for pathogens. These procedures were repeated twice at 1-month intervals. At the first visit, each subject and/or parent was interviewed about the care/use of the lens and accessories.

Thirty-eight subjects completed the study. Initial contamination rates of the lenses, lens cases, and tweezers were 29, 34, and 46%, respectively. Rates of contamination dropped for lenses, suction holders, and tweezers during the three-visit intervention. Contact lens solutions, except lens cleaner were contaminated on all occasions with the most contaminated product being artificial tears [33% (n = 18)]. There was no improvement in the contamination rate of the lens cases. The most common pathogens isolated were Staphylococcus aureus and Serratia marcescens. Compliance was lowest for care of lens cases and highest for care of lenses. However, correlation between reported compliance and presence of pathogens failed to reach significance.

Subjects' awareness of the importance of lens cleanliness is high and can be improved by regular reinforcements. However, attitudes toward cleaning of accessories was far less satisfactory and while replacement and warnings resulted in significant improvements of contamination rates of tweezers and suction holders, more emphasis should be placed on educating patients on correct care of lens accessories.