Assessment of tear breakup time when wearing lipid-laden daily disposable contact lenses

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Contact lens discomfort and its associated dryness are the primary reason to discontinue using contact lenses. In addition, users with decreased tear volume are more prone to be intolerant to soft contact lenses. The lipids of the tear film are produced in the meibomian gland in the eyelids and this lipid is delivered from the meibomian gland to the eye to form part of the tear film lipid layer. This layer promotes tear film stability and prevents drying of the ocular surface. Several of these lipids help stabilise and spread tears across the ocular surface and retard tear evaporation. The amount of lipids in tears is reduced in people with dry eye, and dry eye is related to contact lens comfort. Contact lens discomfort is worse when people’s meibomian glands are blocked. Therefore, we hypothesize that adding lipids back to the eye during contact lens wear will help form a stable tear film and reduce dry eye sensations. We and many others have shown that delivering components from contact lenses is preferable to delivering by eye drops as more of the component remains on the eye. We have produced lipids in the form of small particles that are stabilized using a surfactant compound, and shown that these can be imbedded into contact lenses. A small-scale study has shown that these lipid-containing contact lenses do not increase redness or other clinical measures associated with toxic responses. Now, we would like to test these lenses in a larger study and measure whether lens wearers can notice an improvement in symptoms during wear. In this study, participants will randomly wear lipid-imbibed lenses (O-L), control lenses that contain only the small particles of surfactant with no lipid (C-L), and normal commercially available contact lenses (M-L). The same lens will be worn in both eyes, all participants will wear all 3 lens types (in total 7 visits), and the lenses will be randomly assigned for wear. The primary endpoint is the changes in the tear break-up time, tear evaporation rate, and lipid layer thickness of contact lens wearer over the 8 h of lens wear. The secondary endpoint is the changes in the ocular surface and eyelids of the contact lens wearer over the 8 h of lens wear. The changes in the ocular surface will be investigated by corneal and conjunctival staining and Slit-Lamp Biomicroscopy. The objectives will be a) to measure the comfort response of people wearing lipid-imbibed contact lenses (O-L) vs control lenses (C-L) vs commercially available contact lenses (M-L). b) to measure tear break-up time (tear stability) during contact lens wear of the lenses. c) to measure and evaluate tear lipid layer thickness during contact lens wear. d) to measure corneal and conjunctival staining after contact lens wear.

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