PURPOSE: 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.
METHODS: 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.
RESULTS: 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.
CONCLUSIONS: 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.