Interferometric Assessment of Contact Lens Wettability

  • Raied Ahmed Fagehi

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)


The aim of these studies was to measure parameters with a thin-film interferometry (TFI) technique to evaluate the wettability of soft contact lens materials both in-vitro and in-vivo.

A Doane’s interferometer, connected to a camera, captured images of pre-lens liquid film. The images were analysed using a MATLAB application developed for this study. The contact lens wettability parameters measured were: time to first breakup (onset latency, OL), duration of lens surface drying (drying duration, DD), maximal speed of drying (maximal speed, MS) and time to reach this maximal speed (peak latency, PL).

The technique was applied to different contact lens materials in-vitro and the results were compared with the more traditional contact angle (CA) measurement, of the same lens materials, by the captive bubble technique. No correlation was found between the CA and the new wetting parameters (p > 0.05). An analysis of the results by ANOVA and post hoc tests showed that the new wetting measures differentiated effectively between the lenses better than CA did.

The TFI technique was also applied to evaluate the in-vivo wettability of the same lens materials in five contact lens wearers. The results showed good differential performance between the contact lens wettability.

The effects of different contact lens storage solutions on lens wettability in-vitro and in-vivo were evaluated. Contact lens wettability and tear film dynamics were also investigated in symptomatic and asymptomatic contact lens wearers. Finally, the effect of lubricant eye drops on in-vivo lens wetting was also investigated.

The new interferometry method for assessing contact lens wettability by measuring drying dynamics of the lens surface through duration and speed of drying, allowed good differentiation between lens materials. The TFI technique showed the ability to evaluate the combination of tear film and care solution or lubricating eye drops (in-vivo) in terms of their combined effects on contact-lens wettability. The new technique has the major advantage that it can be applied invitro as well as in-vivo.
Date of Award2014
Original languageEnglish
Awarding Institution
  • Glasgow Caledonian University
SupervisorAlan Tomlinson (Supervisor)

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