Conjunctivitis is a very common reason for experiencing an uncomfortable, red eye. There are a number of causes for conjunctivitis, including bacteria, viruses and, importantly, allergies. Allergic conjunctivitis affects the conjunctiva of the eye. The conjunctiva refers to the thin, translucent lining of the eyeball and the undersurface of the eyelids.
Atopic keratoconjunctivitis (AKC) refers to a particular type of allergic conjunctivitis. Commonly, both eyes are affected in AKC. It is strongly linked to atopic dermatitis (eczema).
The majority of people who are affected by allergic conjunctivitis experience simple allergic conjunctivitis. The other forms of conjunctivitis such as AKC make up a small proportion of cases, estimated to be less than 1% of all eye allergies. AKC is rare, occurring in approximately 1 in 10,000 people.
The rate of AKC varies with the season and the country. For example, more people are affected in Italy, Japan and other warmer climates. It is also reported that AKC is more commonly experienced by males.
AKC is strongly associated with atopic dermatitis, which affects about 3% of the population. Of these people, it is estimated that 15–67% have some form of eye involvement, which is usually AKC.