The aim of this study was to examine the literature with respect to inflammation of the ocular surface and the presence of inflammatory mediators in the tear film during contact lens wear.
The literature on contact lens discomfort that relates to signs of inflammation was searched. Reference was paid to the cardinal signs of inflammation (pain, heat, redness, and swelling) as well as the appearance of inflammatory mediators in the tear film during contact lens wear.
Contact lens wear does induce discomfort, which is a mild form of pain, and wearing of lenses can induce increases in limbal and conjunctival redness. However, there is little evidence for a direct relationship between limbal or conjunctival redness and contact lens discomfort. Contact lenses may increase the temperature of the ocular surface by a small amount (≤2.1°C). Corneal or conjunctival swelling has not been associated with contact lens discomfort. Complement or kinin breakdown products or histamine in tears are not associated with contact lens discomfort. Cytokines are generally not related to discomfort, although nerve growth factor levels were increased in tears of symptomatics in one report. The presence of degraded lipids, leukotriene B4 and peroxidation products, and the enzyme secretory phospholipase A2 in tears has been associated with contact lens discomfort, and this area is worthy of further research.
There have been only a few studies that have investigated a role for inflammation in contact lens–induced discomfort, and the strongest associations have been found with lipid degradation processes.
School of Optometry and Vision Science, University of New South Wales, Sydney, NSW, Australia.
Address correspondence to Mark D. P. Willcox, Ph.D., School of Optometry and Vision Science, University of New South Wales, Sydney, NSW 2052, Australia; e-mail: firstname.lastname@example.org
The authors have no funding or conflicts of interest to disclose.
Accepted September 19, 2016