title: Preliminary tear film measurements of tolerant and non-tolerant contact lens wearers.
abstract: BACKGROUND: The relationship between contact lens intolerance and tear stability, tear quantity, distribution and consistency has yet to be clearly established. In this study, we have examined the tear film of several tolerant and non-tolerant soft contact lens wearers. We aimed to develop a number of clinical and biochemical techniques to establish a correlation between one or more factors leading to contact lens intolerance. METHODS: Subjects were separated by their self-described tolerance to contact lens wear. Five tolerant and five non-tolerant subjects were chosen. A McMonnies symptomatology questionnaire was used to ascertain subject history, while non-invasive tear break-up time (TBUT) examined tear stability. Basal tear collection was performed using glass capillary tubes, the tear flow rate was measured and one dimensional gel electrophoresis used to analyse protein differences. RESULTS: Non-tolerant subjects experienced primary symptoms, such as dryness and grittiness, more often than tolerant subjects (p = 0.007). The TBUT of non-tolerant lens wearers was also reduced (average of seven seconds) compared to tolerant lens wearers (p < 0.002). Tolerant lens wearers had a longer more stable tear film with an average TBUT of 20 seconds and this correlated with a fast tear flow rate (p < 0.04). Protein gel electrophoresis showed that some subjects who were non-tolerant to lens wear had variations in their tear protein profiles compared to tolerant subjects. CONCLUSION: These preliminary results demonstrate that clinical and biochemical tear profiles can be used to differentiate subjects with good lens wear tolerance from those who may be non-tolerant to lens wear.
authors.affiliation: Cooperative Research Centre for Eye and Research Technology, University of New South Wales Building R2, 22-32 King Street, Randwick, New South Wales, 2031, Australia. M.Glasson@cclru.unsw.edu.au
authors.forename: M J
authors.initials: MJ
authors.lastname: Glasson
authors.forename: S
authors.initials: S
authors.lastname: Hseuh
authors.forename: M DP
authors.initials: MD
authors.lastname: Willcox