Keratoconjunctivitis
Encyclopedia
Keratoconjunctivitis is inflammation
("-itis") of the cornea
and conjunctiva
.
When only the cornea
is inflamed, it is called keratitis
; when only the conjunctiva
is inflamed, it is called conjunctivitis
.
There are several potential causes of the inflammation:
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
("-itis") of the cornea
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...
and conjunctiva
Conjunctiva
The conjunctiva covers the sclera and lines the inside of the eyelids. It is composed of rare stratified columnar epithelium.-Function:...
.
When only the cornea
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...
is inflamed, it is called keratitis
Keratitis
Keratitis is a condition in which the eye's cornea, the front part of the eye, becomes inflamed. The condition is often marked by moderate to intense pain and usually involves impaired eyesight.-Types:...
; when only the conjunctiva
Conjunctiva
The conjunctiva covers the sclera and lines the inside of the eyelids. It is composed of rare stratified columnar epithelium.-Function:...
is inflamed, it is called conjunctivitis
Conjunctivitis
Conjunctivitis refers to inflammation of the conjunctiva...
.
There are several potential causes of the inflammation:
- Keratoconjunctivitis siccaKeratoconjunctivitis siccaKeratoconjunctivitis sicca , also called keratitis sicca, xerophthalmia or dry eye syndrome is an eye disease caused by eye dryness, which, in turn, is caused by either decreased tear production or increased tear film evaporation. It is found in humans and some animals...
is used when the inflammation is due to dryness. ("Sicca" means "dryness" in medical contexts.) It occurs with 20% of RA patients. - The term "Vernal keratoconjunctivitisVernal keratoconjunctivitisVernal keratoconjunctivitis or Spring catarrh is a recurrent, bilateral, and self limiting inflammation of conjunctiva, having a periodic seasonal incidence.-Etiology:...
" (VKC) is used to refer to keratoconjunctivitis occurring in springSpring (season)Spring is one of the four temperate seasons, the transition period between winter and summer. Spring and "springtime" refer to the season, and broadly to ideas of rebirth, renewal and regrowth. The specific definition of the exact timing of "spring" varies according to local climate, cultures and...
, and is usually considered to be due to allergenAllergenAn allergen is any substance that can cause an allergy. In technical terms, an allergen is a non-parasitic antigen capable of stimulating a type-I hypersensitivity reaction in atopic individuals....
s. - "Atopic keratoconjunctivitis" is one manifestation of atopyAtopyAtopy or atopic syndrome is a predisposition toward developing certain allergic hypersensitivity reactions.Atopy may have a hereditary component, although contact with the allergen must occur before the hypersensitivity reaction can develop ....
. - "Epidemic keratoconjunctivitis" is caused by an adenovirus infection.
- "Infectious bovine keratoconjunctivitisInfectious bovine keratoconjunctivitisInfectious bovine keratoconjunctivitis, or IBK, is a veterinary infection of cattle caused by Moraxella bovis, a gram negative, β-haemolytic, aerobic, rod shaped bacterium. It is spread by direct contact or by the common fly serving as a vector. It is the most common ocular disease of cattle...
" (IBK) is a disease affecting cattle caused by the bacteria Moraxella bovisMoraxella bovisMoraxella bovis is a Gram-negative, aerobic, oxidase-positive diplococcus that is implicated in infectious keratoconjunctivitis in cattle, also colloquially known as Pink Eye.-Weblinks:* - Department of Primary Industries...
. - "Superior limbic keratoconjuctivitis" is thought to be caused by mechanical trauma.
- "Keratoconjunctivitis photoelectrica" (arc eye) means inflammation caused by photoelectric UV light. It is a type of ultraviolet keratitis. Such UV exposure can be caused by arc weldingWeldingWelding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes...
without wearing protective eye glass, or by high altitude exposure from sunlight reflected from snow ("snow blindnessSnow blindnessPhotokeratitis or ultraviolet keratitis is a painful eye condition caused by exposure of insufficiently protected eyes to the ultraviolet rays from either natural or artificial sources. Photokeratitis is akin to a sunburn of the cornea and conjunctiva, and is not usually noticed until several...
"). The inflammation will only appear after about 6 to 12 hours. It can be treated by rest, as the inflammation usually heals after 24–48 hours. Proper eye protection should be worn to prevent keratoconjunctivitis photoelectrica.