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Turning the tide for gas permeable contact lenses

Gill, Felicity Rosemary 2010. Turning the tide for gas permeable contact lenses. PhD Thesis, Cardiff University.

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Gas permeable (GP) lens materials and design technology have advanced in recent years and GP lenses are recognised as providing the wearer with a reduced risk of serious sight-threatening complications, better vision and better long-term comfort. Yet despite these advantages, GP lens prescribing in the UK remains in decline. This thesis investigates how the decline might be addressed by studying the influence of prescribing habits, fitting strategies and lens surface treatments. Initially a questionnaire was designed to investigate practitioner attitudes and behaviour toward GP lenses, and to ascertain whether eye care practitioner (ECP) reservations were responsible for prescribing decline. This survey found that, despite ECP awareness of the advantages of GP lenses, the challenges of reduced initial comfort and increased time required in fitting, results in significant negative practitioner attitudes. In an effort to address the reservations discovered, an investigation of topical anaesthetic (TA) instillation prior to GP fitting was performed in a large case-control study. The results demonstrated that this practice has no negative clinical impact on the ocular surface, marginally improves patient comfort at fitting, and significantly reduces patient anxiety prior to successive GP lens insertion. The remainder of this thesis presents the results from a longitudinal study where groups of neophyte and soft lens wearers were fitted with GP lenses for three months with and without plasma surface treatment (PST). Subjects were monitored and lenses harvested for surface analysis using atomic force microscopy. Examination of GP lenses demonstrated that PST produces smoother surface topographies, prior to and following wear, but this difference reduces after three months wear. Subjects previously wearing soft lenses report lower levels of comfort than neophytes, and PST does not seem to enhance the experience for either group in this cohort. In summary, this thesis presents important findings about the influence of initial comfort on patient anxiety and practitioner attitudes towards GP lens fitting, and gives important insights into the impact of plasma treatment on comfort and performance over the first three months of lens wear.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Optometry and Vision Sciences
Subjects: R Medicine > RE Ophthalmology
ISBN: 9781303218194
Funders: No. 7 Contact Lens Laboratories, EPSRC
Date of First Compliant Deposit: 30 March 2016
Last Modified: 19 Mar 2016 23:31

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