Longitudinal study of contact lens care in Hong Kong and the effect of interventions on compliance

Abstract

Background Increasing usage of contact lenses for vision correction has been reported in Hong Kong and South China. It has been estimated that there are currently over six hundred thousand contact lens wearers in Hong Kong. In order to get a clearer picture of the use of contact lenses, there is a need to determine current trends in contact lens usage, the level of microbiological contamination of contact lenses, the level of compliance of contact lens wearers, and lens care accessories. Purpose The objectives of this study were (1) to report practitioners' preferences and prescribing habits of contact lenses, their management of contact lens patients, and to evaluate the use of speciality contact lenses and the development of the contact lens market in Hong Kong; (2) to study the level of microbial contamination and identify contaminants associated with contact lenses, lens cases, and opened lens care solutions used by contact lens wearers; (3) to determine the level of compliance of contact lens wearers, and to identify common non-compliant procedures during contact lens handling; (4) to study the effect of a compliance enhancement strategy (regular self-review exercise) on the level of compliance. Method The usage of contact lenses was studied by means of a large scale survey. A total of 1306 questionnaires were sent to all registered contact lens practitioners in Hong Kong, asking for information about their choices of types of contact lenses prescribed and lens care products recommended; their usage of speciality contact lenses, and their opinions on future trends of contact lens development in Hong Kong. The levels of microbial contamination of contact lenses and lens care accessories were studied by bacterial culture of the collected contact lenses, lens cases, and lens care solutions of a group of young and asymptomatic contact lens wearers. The contaminants associated with these items were identified using standard microbiological techniques. Contamination rates of these samples were recorded and compared with those reported in previous studies. To study the level of compliance, a group of contact lens wearers were interviewed to collect information on how they used and handled their contact lenses. The level of compliance for each subject was evaluated with a self-administered questionnaire together with microbiological examination of their contact lenses, lens case and lens care solutions. The effect of the intervention on the level of compliance was studied by separating subjects into test and control groups, with a regular self-review exercise on proper lens handling being given to the test group once every 3 months for 12 months. The level of compliance between test and control groups was compared at the end of the 12 month period to evaluate the effect of the intervention. Result Vision correction with contact lenses in Hong Kong Our survey results showed that, soft, planned replacement, contact lenses together with multipurpose solutions dominated the contact lens market in Hong Kong. Usage of rigid lenses had not increased over the past few years, and the usage of speciality contact lenses, especially overnight orthokeratology and silicone hydrogel lenses was limited. Dryness was the major problem reported by contact lens wearers. Practitioners look forward to further development of custom-made toric, multifocal and silicone hydrogel lenses; and continuous education courses that could fit their needs. Contamination of contact lenses Contact lenses, lens cases, and lens care solutions of the 101 asymptomatic contact lens wearers were tested for microbial contamination. At least one of the collected samples of around half of our subjects were found to be contaminated. Of the samples tested, 9% of lens extracts, 34% of case extracts and 11% of solutions were contaminated with potential pathogenic bacteria. Serratia, Staphylococcus aureus, coagulase-negative staphylococci, Acinetobacter, and Pseudomonas were the most common micro-organisms isolated from the cultured samples. Lens cases were the most frequently contaminated item, and they also supported the growth of the widest variety of bacterial species. Contact lenses and lens cases used on an occasional-wear basis, and lens care solution used by contact lens wearers with longer contact lens experience were associated with higher contamination rates. Rinsing contact lenses with either saline or multipurpose solution after cleaning was found to be an effective way to prevent contact lens contamination. Level of compliance of contact lens wearers and the effect of interventions Information of 65 contact lens wearers on how they handled their contact lenses and lens care accessories was collected by questionnaire. Our study illustrated that all of the contact lens wearers showed some degree of non-compliance in the care of their contact lenses and lens accessories. Of 15 lens care procedures, most subjects were non-compliant with up to seven procedures. Common non-compliant behaviours among contact lens wearers included: not disinfecting the lens case weekly, not re-disinfecting contact lenses after they have been left in lens case for longer than indicated, not cleaning the lens case with contact lens solution, not changing lens cases every 3 months, not checking the expiry dates of contact lens solutions, and not discarding solution and air drying the lens case. Our compliance enhancement strategy (regular self-review exercise) did not significantly improve the level of compliance, mainly because compliance improved in both test and control groups. The contamination of contact lenses and lens care accessories was lowered with the improvement in the level of compliance. Conclusion There is increased demand for convenient contact lens wear. The use of overnight wear contact lenses such as those used for orthokeratology and silicone hydrogel lenses were limited due to the practitioners' concerns about safety. Our findings demonstrate that contact lenses, lens case and lens care accessories are not well maintained by contact lens wearers. Nearly half of the contact lens wearers are using either contaminated contact lenses or lens care accessories. This is probably due to the low level of compliance among contact lens wearers. All of our subjects showed some degree of non-compliance and the spectrum of non-compliance is wide. Our compliance enhancement strategy (regular self-review exercise) did not show a significant effect on the level of compliance. Further investigations are required to study new methods to prevent contamination of contact lenses and lens care accessories, and to improve the level of compliance among contact lens wearers.