Contact lens wearer susceptibility to corneal infiltrative events due to risk taking behaviour and genetics

Abstract

This thesis was designed to determine if risk taking propensity of contact lens (CL) wearers and practitioners impacted non-compliance thereby increasing the susceptibility to corneal infiltrative events (CIE) and furthermore to determine if genetic profiles contribute to the risk of keratitis. Following pilot testing, an Australian community based study of CL practitioners and wearers took place.CL practitioners and wearers were surveyed for risk taking propensity with a 20 item validated insrument. CL wearers were also surveyed for compliance and practitioners asked to subjectively rate compliance for each of the wearers. Furthermore, practitioners were surveyed on prescribing habits including the volume of their CL practice. A retrospective case control study of microbial and sterile keratitis participants recruited from studies that took place in Australia and London during 2003-5. DNA was collected via buccal swabs sent by post. After method optimisation, single nucleotide polymorphisms (SNPs) of Interleukins (IL) 1β, 6, 12B, beta defensin 1 (DEFB1) and toll like receptor 4 (TLR4) were analysed with pyrosequencing. The results showed that high risk taking CL wearers were less compliant and risk taking propensity was a better indicator of compliance compared to gender, youth and practitioner perception. Practitioners with higher risk taking propensity had higher volume CL practices but had similar prescribing habits compared to other colleagues. SNPs and haplotypes of IL-6 were associated with increased severity and susceptibility to keratitis. A SNP of IL-12 increased susceptibility to SK. Certain mutations of DEFB1 tended to be associated with increased susceptibility and severity of keratitis. This information leads to better identification of non-compliant wearers and provides practitioners with more information to better manage wearers. High risk taking practitioners are unlikely to impact the compliance of wearers but have higher volume CL practices, which may be important information for understanding determinants of growth in the CL industry. The identification of additional genetic markers for susceptibility and severity of CIEs will increase confidence in this area and may direct the further investigation of other inflammatory markers that are in various stages of in vitro assessment. This may assist in prevention, management and reducing morbidity associated with CIEs.