This review describes the impact of contact lens wear on the tear film lipid layer and how changes in the lipid layer might modulate contact lens-related discomfort. Relevant clinical, functional, and biochemical aspects of the tear film lipid layer are reviewed. Contact lens wear modulates these aspects of the lipid layer, specifically the prelens lipid layer thickness is reduced; tear evaporation rate is increased; tear breakup time is reduced; and the concentration of lipid components such as cholesterol esters, wax esters, and phospholipids varies. The full implications of these changes are unclear; however, there is some evidence that contact lens-related discomfort is associated with a thinner prelens lipid layer, increased lipid degradation, and greater secretory phospholipase A2 activity. Certain fatty acids appear to be associated with maintaining the structural stability of the tear film but their role in retarding tear evaporation and modulating contact lens-related discomfort remains to be elucidated.
Brien Holden Vision Institute (A.R., F.S.), University of New South Wales, Sydney, New South Wales 2052, Australia; and
School of Optometry and Vision Science (M.W.), University of New South Wales, Sydney, New South Wales, Australia.
Address correspondence and reprint requests to Athira Rohit, B.S., Brien Holden Vision Institute, University of New South Wales, New South Wales 2052, Australia; e-mail: email@example.com
There are no proprietary interests for any of the authors. Following Australian Government policy related to CRC Grants, the Vision CRC and partners including the Brien Holden Vision Institute receive royalties on the sales of certain silicone hydrogel contact lenses.
Supported in part by the Brien Holden Vision Institute, the Vision Cooperative Research Centre (CRC), and University of New South Wales; and by the Tuition Fee Remission Scholarship (TFRS) by UNSW and an additional top-up postgraduate grant by Vision Cooperative Research Center, Australia (A.R.).
Accepted January 31, 2013