Keratitis
Encyclopedia
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.
.
Deep keratitis involves deeper layers of the cornea, and the natural course leaves a scar
upon healing that impairs vision
if on or near the visual axis. This can be reduced or avoided with the use of topical corticosteroid
eyedrops.
secondary to an upper respiratory infection, involving cold sores.
.
Antibacterial solutions include Quixinex (levofloxacin
), Zymar (gatifloxacin
), Vigamox (moxifloxacin
), Ocuflox (ofloxacin
— available generically). Steroid containing medications should not be used for bacterial infections, as they may exacerbate the disease and lead to severe corneal ulceration and corneal perforation. These include Maxitrol (neomycin
+polymyxin
+dexamethasone
— available generically), as well as other steroid medications.. One should consult an ophthalmologist or optometrist for treatment of an eye condition.
Some infections may scar the cornea to limit vision. Others may result in perforation of the cornea, (an infection inside the eye), or even loss of the eye. With proper medical attention, infections can usually be successfully treated without long-term visual loss.
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
's 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...
, the front part of the eye, becomes inflamed
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...
. The condition is often marked by moderate to intense pain and usually involves impaired eyesight.
Types
Superficial keratitis involves the superficial layers of the cornea. After healing, this form of keratitis does not generally leave a scarScar
Scars are areas of fibrous tissue that replace normal skin after injury. A scar results from the biological process of wound repair in the skin and other tissues of the body. Thus, scarring is a natural part of the healing process. With the exception of very minor lesions, every wound results in...
.
Deep keratitis involves deeper layers of the cornea, and the natural course leaves a scar
Scar
Scars are areas of fibrous tissue that replace normal skin after injury. A scar results from the biological process of wound repair in the skin and other tissues of the body. Thus, scarring is a natural part of the healing process. With the exception of very minor lesions, every wound results in...
upon healing that impairs vision
Visual perception
Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...
if on or near the visual axis. This can be reduced or avoided with the use of topical corticosteroid
Corticosteroid
Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...
eyedrops.
Causes
Keratitis has multiple causes, one of which is an infection of a present or previous herpes simplex virusHerpes simplex virus
Herpes simplex virus 1 and 2 , also known as Human herpes virus 1 and 2 , are two members of the herpes virus family, Herpesviridae, that infect humans. Both HSV-1 and HSV-2 are ubiquitous and contagious...
secondary to an upper respiratory infection, involving cold sores.
Pathogens
- Amoebic keratitis. Amoebic infection of the cornea is the most serious corneal infection, usually affecting contact lensContact lensA contact lens, or simply contact, is a lens placed on the eye. They are considered medical devices and can be worn to correct vision, for cosmetic or therapeutic reasons. In 2004, it was estimated that 125 million people use contact lenses worldwide, including 28 to 38 million in the United...
wearers. It is usually caused by AcanthamoebaAcanthamoebaAcanthamoeba is a genus of amoebae, one of the most common protozoa in soil, and also frequently found in fresh water and other habitats. The cells are small, usually 15 to 35 μm in length and oval to triangular in shape when moving. The pseudopods form a clear hemispherical lobe at the anterior,...
. On May 25, 2007, the CDC issued a health advisory due to increased risk of Acanthamoeba keratitis (AK) associated with use of Advanced Medical OpticsAdvanced Medical OpticsAbbott Medical Optics Inc. earlier known as Advanced Medical Optics, Inc. is a global medical supply company. Products in the ophthalmic surgical line include intraocular lenses, laser vision correction systems, phacoemulsification systems, viscoelastics, microkeratomes and related products used...
(AMO) Complete Moisture Plus Multi-Purpose eye solution. - Bacterial keratitis. Bacterial infection of the cornea can follow from an injury or from wearing contact lenses. The bacteria involved are Staphylococcus aureusStaphylococcus aureusStaphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...
and for contact lens wearers, Pseudomonas aeruginosaPseudomonas aeruginosaPseudomonas aeruginosa is a common bacterium that can cause disease in animals, including humans. It is found in soil, water, skin flora, and most man-made environments throughout the world. It thrives not only in normal atmospheres, but also in hypoxic atmospheres, and has, thus, colonized many...
. Pseudomonas aeruginosa contains enzymes that can digest the cornea. - Fungal keratitisFungal keratitisA fungal keratitis is an 'inflammation of the eye's cornea' that results from infection by a fungal organism. Keratomycosis is the Greek terminology equivalent of fungal keratitis - it is the fungal infection of the cornea, the anterior part of the eye which covers the pupil...
(cf. FusariumFusariumFusarium is a large genus of filamentous fungi widely distributed in soil and in association with plants. Most species are harmless saprobes, and are relatively abundant members of the soil microbial community. Some species produce mycotoxins in cereal crops that can affect human and animal health...
, causing recent incidences of keratitis through the possible vector of Bausch & LombBausch & LombBausch & Lomb, an American company based in Rochester, New York, is one of the world's leading suppliers of eye health products, such as contact lenses and lens care products today. In addition to this main activity, in recent years the area of medical technology has been developed...
ReNuReNuReNu is a brand of soft contact lens care products produced by Bausch & Lomb. It was by far the most popular brand of lens solutions until 2006. The original products are still availabe as renu fresh and renu sensitive...
with MoistureLoc contact lensContact lensA contact lens, or simply contact, is a lens placed on the eye. They are considered medical devices and can be worn to correct vision, for cosmetic or therapeutic reasons. In 2004, it was estimated that 125 million people use contact lenses worldwide, including 28 to 38 million in the United...
solution) - ViralVirusA virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
keratitis - Herpes simplexHerpes simplexHerpes simplex is a viral disease caused by both Herpes simplex virus type 1 and type 2 . Infection with the herpes virus is categorized into one of several distinct disorders based on the site of infection. Oral herpes, the visible symptoms of which are colloquially called cold sores or fever...
keratitis. Viral infection of the cornea is often caused by the herpes simplex virusHerpes simplex virusHerpes simplex virus 1 and 2 , also known as Human herpes virus 1 and 2 , are two members of the herpes virus family, Herpesviridae, that infect humans. Both HSV-1 and HSV-2 are ubiquitous and contagious...
which frequently leaves what is called a 'dendritic ulcer'. - Herpes zosterHerpes zosterHerpes zoster , commonly known as shingles and also known as zona, is a viral disease characterized by a painful skin rash with blisters in a limited area on one side of the body, often in a stripe...
keratitis - OnchocercalOnchocerciasisOnchocerciasis , also known as river blindness and Robles' disease, is a parasitic disease caused by infection by Onchocerca volvulus, a nematode . Onchocerciasis is the world's second-leading infectious cause of blindness. It is not the nematode, but its endosymbiont, Wolbachia pipientis, that...
keratitis, which follows O. volvulusOnchocerca volvulusOnchocerca volvulus is a nematode that causes onchocerciasis or "river blindness" mostly in Africa. Long-term corneal inflammation, or keratitis, leads to thickening of the corneal stroma which ultimately leads to blindness. Humans are the only definitive host for O. volvulus. The intermediate host...
infection by infected blackfly bite. These blackflySimuliumSimulium is a genus of black flies, which may transmit diseases such as onchocerciasis . It is a large genus with several hundred species, and 41 sub-genera....
usually dwell near fast-flowing African streams, so the disease is also called "river blindness".
Other
- Exposure keratitis — due to dryness of the cornea caused by incomplete or inadequate eye-lid closure.
- PhotokeratitisPhotokeratitisPhotokeratitis 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...
— keratitis due to intense ultraviolet radiation exposure (e.g. snow blindness or welderWelderA welder is a tradesman who specializes in welding materials together. The materials to be joined can be metals or varieties of plastic or polymer...
's arc eye.) - Ulcerative keratitisCorneal ulcerA corneal ulcer, or ulcerative keratitis, is an inflammatory condition of the cornea involving loss of its outer layer. It is very common in dogs and is sometimes seen in cats...
- Contact lens acute red eye (CLARE) — a non-ulcerative sterile keratitis associated with colonization of Gram-negativeGram-negativeGram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...
bacteria on contact lenses. - Severe allergic response may lead to corneal inflammation and ulcerationCorneal ulcerA corneal ulcer, or ulcerative keratitis, is an inflammatory condition of the cornea involving loss of its outer layer. It is very common in dogs and is sometimes seen in cats...
(i.e. vernal keratoconjunctivitisVernal keratoconjunctivitisVernal keratoconjunctivitis or Spring catarrh is a recurrent, bilateral, and self limiting inflammation of conjunctiva, having a periodic seasonal incidence.-Etiology:...
). - Feline eosinophilic keratitis — affecting cats and horses; possibly initiated by feline herpesvirus 1 or other viral infection.
Diagnosis
Effective diagnosis is important in detecting this condition and subsequent treatment as keratitis is sometimes mistaken for an allergic conjunctivitisConjunctivitis
Conjunctivitis refers to inflammation of the conjunctiva...
.
Treatment
Treatment depends on the cause of the keratitis. Infectious keratitis generally requires antibacterial, antifungal, or antiviral therapy to treat the infection. This treatment can involve prescription eye drops, pills, or even intravenous therapy. Over-the-counter eye drops are typically not helpful in treating infections. In addition, contact lens wearers are typically advised to discontinue contact lens wear and discard contaminated contact lenses and contact lens cases.Antibacterial solutions include Quixinex (levofloxacin
Levofloxacin
Levofloxacin is a synthetic chemotherapeutic antibiotic of the fluoroquinolone drug class and is used to treat severe or life-threatening bacterial infections or bacterial infections that have failed to respond to other antibiotic classes. It is sold under various brand names, such as Levaquin and...
), Zymar (gatifloxacin
Gatifloxacin
Gatifloxacin sold under the brand names Gatiflo, Tequin and Zymar, is an antibiotic of the fourth-generation fluoroquinolone family, that like other members of that family, inhibits the bacterial enzymes DNA gyrase and topoisomerase IV...
), Vigamox (moxifloxacin
Moxifloxacin
Moxifloxacin is a fourth-generation synthetic fluoroquinolone antibacterial agent developed by Bayer AG . It is marketed worldwide under the brand names Avelox, Avalox, and Avelon for oral treatment. In most countries, the drug is also available in parenteral form for intravenous infusion...
), Ocuflox (ofloxacin
Ofloxacin
Ofloxacin is a synthetic chemotherapeutic antibiotic of the fluoroquinolone drug class considered to be a second-generation fluoroquinolone. The original brand, Floxin, has been discontinued by the manufacturer in the United States on 18 June 2009, though generic equivalents continue to be...
— available generically). Steroid containing medications should not be used for bacterial infections, as they may exacerbate the disease and lead to severe corneal ulceration and corneal perforation. These include Maxitrol (neomycin
Neomycin
Neomycin is an aminoglycoside antibiotic that is found in many topical medications such as creams, ointments, and eyedrops. The discovery of Neomycin dates back to 1949. It was discovered in the lab of Selman Waksman, who was later awarded the Nobel Prize in Physiology and medicine in 1951...
+polymyxin
Polymyxin
Polymyxins are antibiotics, with a general structure consisting of a cyclicpeptide with a long hydrophobic tail. They disrupt the structure of thebacterial cell membrane by interacting with its phospholipids...
+dexamethasone
Dexamethasone
Dexamethasone is a potent synthetic member of the glucocorticoid class of steroid drugs. It acts as an anti-inflammatory and immunosuppressant...
— available generically), as well as other steroid medications.. One should consult an ophthalmologist or optometrist for treatment of an eye condition.
Some infections may scar the cornea to limit vision. Others may result in perforation of the cornea, (an infection inside the eye), or even loss of the eye. With proper medical attention, infections can usually be successfully treated without long-term visual loss.
See also
- Chronic superficial keratitisChronic superficial keratitisChronic superficial keratitis , also known as pannus or Uberreiter’s disease, is an inflammatory condition of the cornea in dogs, particularly seen in the German Shepherd Dog.-Affected breeds:...
, or pannus, for the disease in dogs - List of eye diseases and disorders
- List of systemic diseases with ocular manifestations
- Thygeson's superficial punctate keratopathyThygeson's superficial punctate keratopathyThygeson's superficial punctate keratopathy is a disease of the eyes. The causes of TSPK are not currently known, but details of the disease were first published in the Journal of the American Medical Association in 1950 by Phillips Thygeson - after whom it is named.- Symptoms :A patient with TSPK...
External links
- Facts About the Cornea and Corneal Disease The National Eye Institute (NEI)
- Filimentary keratitis