keratitis

Definition

Keratitis is an inflammation of the cornea, the transparent membrane that covers the colored part of the eye (iris) and pupil of the eye.

Description

There are many types and causes of keratitis. Keratitis occurs in both children and adults. Organisms cannot generally invade an intact, healthy cornea. However, certain conditions can allow an infection to occur. For example, a scratch can leave the cornea open to infection. A very dry eye can also decrease the cornea's protective mechanisms.

Risk factors that increase the likelihood of developing this condition include:

• poor contact lens care; overuse of contact lenses
• illnesses or other factors that reduces the body's ability to overcome infection
• cold sores, genital herpes, and other viral infections
• crowded, dirty living conditions; poor hygiene
• poor nutrition (especially a deficiency of Vitamin A, which is essential for normal vision)

Some common types of keratitis are listed below, however there are many other forms.

A major cause of adult eye disease, herpes simplex keratitis may lead to:

• chronic inflammation of the cornea
• development of tiny blood vessels in the eye
• scarring
• loss of vision
• glaucoma

This infection generally begins with inflammation of the membrane lining the eyelid (conjunctiva) and the portion of the eyeball that comes into contact with it. It usually occurs in one eye. Subsequent infections are characterized by a pattern of lesions that resemble the veins of a leaf. These infections are called dendritic keratitis and aid in the diagnosis.

Recurrences may be brought on by stress, fatigue, or ultraviolet light (UV) exposure (e.g., skiing or boating increase the exposure of the eye to sunlight; the sunlight reflects off of the surfaces). Repeated episodes of dendritic keratitis can cause sores, permanent scarring, and numbness of the cornea.

Recurrent dendritic keratitis is often followed by disciform keratitis. This condition is characterized by clouding and deep, disc-shaped swelling of the cornea and by inflammation of the iris.

It is very important not to use topical corticosteroids with herpes simplex keratitis as it can make it much worse, possibly leading to blindness.

People who have bacterial keratitis wake up with their eyelids stuck together. There can be pain, sensitivity to light, redness, tearing, and a decrease in vision. This condition, which is usually aggressive, can be caused by wearing soft contact lenses overnight. One study found that overnight wear can increase risk by 10-15 times more than if wearing daily wear contact lenses. Improper lens care is also a factor. Contaminated makeup can also contain bacteria.

Bacterial keratitis makes the cornea cloudy. It may also cause abscesses to develop in the stroma, which is located beneath the outer layer of the cornea.

Usually a consequence of injuring the cornea in a farm-like setting or in a place where plant material is present, fungal keratitis often develops slowly. This condition:

• usually affects people with weakened immune systems
• often results in infection within the eyeball
• may cause stromal abscesses

Peripheral ulcerative keratitis is also called marginal keratolysis or peripheral rheumatoid ulceration. This condition is often associated with active or chronic:

• rheumatoid arthritis
• relapsing polychondritis (connective-tissue inflammation)
• wegener's granulomatosis, a rare condition characterized by kidney disease and development of nodules in the respiratory tract

Often associated with the type of viruses that cause upper respiratory infection (adenoviruses), superficial punctate keratitis is characterized by destruction of pinpoint areas in the outer layer of the cornea (epithelium). One or both eyes may be affected.

This pus-producing condition is very painful. It is a common source of infection in people who wear soft or rigid contact lenses. It can be found in tap water, soil, and swimming pools.

Photokeratitis or snowblindness is caused by excess exposure to UV light. This can occur with sunlight, suntanning lamps, or a welding arc. It is called snowblindness because the sunlight is reflected off of the snow. It therefore can occur in water sports as well, because of the reflection of light off of the water. It is very painful and may occur several hours after exposure. It may last one to two days.

Also called parenchymatous keratitis, interstitial keratitis is a chronic inflammation of tissue deep within the cornea. Interstitial keratitis is rare in the United States. Interstitial keratitis affects both eyes and usually occurs as a complication of congenital or acquired syphilis. In congenital syphilis it can occur between age two and puberty. It may also occur in people with tuberculosis, leprosy, or other diseases.

— Maureen Haggerty

For more information on keratitis, visit Britannica.com.

Any inflammation of the cornea.

Inflammation of the cornea of the eye. It may be caused by trauma, exposure to dust or ultraviolet light, or extreme cold. Participants of winter sports such as skiing are particularly at risk. Keratitis can be avoided by wearing appropriate protective glasses. See also snow-blindness.

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Keratitis
Classification and external resources
An eye with non-ulcerative sterile keratitis.
ICD-10	H16.
ICD-9	370
DiseasesDB	7150
MeSH	[1]

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. ^[1]

Contents 1 Types 2 Causes 2.1 Pathogens 2.2 Other 3 Diagnosis 4 Treatment 5 See also 6 References 6.1 Footnotes 6.2 Notations 7 External links

Types

Superficial keratitis involves the superficial layers of the cornea. After healing, this form of keratitis does not generally leave a scar.

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 steroid eyedrops.

Causes

Keratitis has multiple causes, one of which is an infection of a present or previous herpes simplex virus 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 lens wearers.^[2] It is usually caused by Acanthamoeba. On May 25, 2007, the CDC issued a health advisory due to increased risk of Acanthamoeba keratitis (AK)infection associated with use of Advanced Medical Optics (AMO) Complete Moisture Plus Multi-Purpose eye solution. See CDC Advisory
• Bacterial keratitis. Bacterial infection of the cornea can follow from an injury or from wearing contact lenses. The bacteriums usually involved are Staphylococcus aureus and for contact lens wearers Pseudomonas aeruginosa.
• Fungal keratitis (cf. Fusarium, causing recent incidences of keratitis through the possible vector of Bausch & Lomb ReNu with MoistureLoc contact lens solution)
• Viral keratitis

• Herpes simplex keratitis. Viral infection of the cornea is often caused by the herpes simplex virus which frequently leaves what is called a 'dendritic ulcer'.
• Herpes zoster keratitis

• Onchocercal keratitis—for which reason onchocerciasis is also named "river blindness"

Other

• Exposure keratitis
• Photokeratitis - keratitis due to intense ultraviolet radiation exposure (e.g. snow blindness or welder's arc eye.)
• Ulcerative keratitis
• Contact lens acute red eye (CLARE) - a non-ulcerative sterile keratitis associated with colonization of Gram-negative bacteria on contact lenses
• Severe allergic response may lead to corneal inflammation and ulceration (i.e. vernal keratoconjunctivitis).[2]
• Feline Eosinophilic Keratitis - affecting cats and horses; possibly initiated by feline HSV-1 or other viral infection.^[3]

Diagnosis

Effective diagnosis is important in detecting this condition and subsequent treatment as keratitis is sometimes mistaken for an allergic conjunctivitis.

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 discarding contaminated contact lenses and contact lens cases. Antibacterial solutions include Quixin (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 Optometrist or qualified Ophthalmologist 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

• List of eye diseases and disorders
• List of systemic diseases with ocular manifestations
• Thygeson's superficial punctate keratopathy
• Chronic superficial keratitis, or pannus, for the disease in dogs

References

Footnotes

1. ^ Keratitis
2. ^ Martín-Navarro, M.; Lorenzo-Morales, J.; Cabrera-Serra, G.; Rancel, F.; Coronado-Alvarez, M.; Piñero, E.; Valladares, B. (Nov 2008). "The potential pathogenicity of chlorhexidine-sensitive Acanthamoeba strains isolated from contact lens cases from asymptomatic individuals in Tenerife, Canary Islands, Spain". Journal of medical microbiology 57 (Pt 11): 1399–1404. doi:10.1099/jmm.0.2008/003459-0. ISSN 0022-2615. PMID 18927419.  edit
3. ^ http://www.vet.uga.edu/VPP/clerk/mackey/index.php

Notations

• UIC Eye Center

External links

• Facts About the Cornea and Corneal Disease The National Eye Institute (NEI)
• Filimentary keratitis

v • d • e Eye disease · pathology of the eye (H00-H59, 360-379) Adnexa eyelid: inflammation (Stye, Chalazion, Blepharitis) · Entropion · Ectropion · Lagophthalmos · Blepharochalasis · Ptosis · Blepharophimosis · Xanthelasma · Trichiasis · Madarosis lacrimal system: Dacryoadenitis · Epiphora · Dacryocystitis orbit: Exophthalmos · Enophthalmos Eyeball Conjunctiva Conjunctivitis (Allergic conjunctivitis) · Pterygium · Pinguecula · Subconjunctival hemorrhage Fibrous tunic sclera: Scleritis cornea: Keratitis (Herpetic keratitis, Acanthamoeba keratitis, Fungal keratitis) · Corneal ulcer · Snow blindness · Thygeson's superficial punctate keratopathy · Corneal dystrophy (Fuchs', Meesmann) · Keratoconus · Keratoconjunctivitis sicca · Arc eye · Keratoconjunctivitis · Corneal neovascularization  · Kayser-Fleischer ring · Arcus senilis · Band keratopathy Iris and ciliary body Iritis · Uveitis (Intermediate uveitis) · Iridocyclitis · Hyphema · Rubeosis iridis · Persistent pupillary membrane · Iridodialysis · Synechia Lens Cataract · Aphakia · Ectopia lentis Choroid Choroideremia · Choroiditis (Chorioretinitis) Retina Retinitis (Chorioretinitis, Cytomegalovirus retinitis) · Retinal detachment · Retinoschisis · Ocular ischemic syndrome/Central retinal vein occlusion · Retinopathy (Bietti's crystalline dystrophy, Coats disease, Diabetic retinopathy, Hypertensive retinopathy, Retinopathy of prematurity) · Macular degeneration · Retinitis pigmentosa · Retinal haemorrhage · Central serous retinopathy · Macular edema · Epiretinal membrane · Macular pucker · Vitelliform macular dystrophy · Leber's congenital amaurosis · Birdshot chorioretinopathy Optic nerve and visual pathways Optic neuritis · Papilledema · Optic atrophy · Leber's hereditary optic neuropathy · Dominant optic atrophy · Optic disc drusen · Glaucoma · Toxic and nutritional optic neuropathy · Anterior ischemic optic neuropathy Ocular muscles, binocular movement, accommodation and refraction Paralytic strabismus: Ophthalmoparesis · Progressive external ophthalmoplegia · Palsy (III, IV, VI) · Kearns-Sayre syndrome Other strabismus: Esotropia/Exotropia · Hypertropia · Heterophoria (Esophoria, Exophoria) · Brown's syndrome · Duane syndrome Other binocular: Conjugate gaze palsy · Convergence insufficiency · Internuclear ophthalmoplegia · One and a half syndrome Refractive error: Hyperopia/Myopia · Astigmatism · Anisometropia/Aniseikonia · Presbyopia Visual disturbances and blindness Amblyopia · Leber's congenital amaurosis  · Subjective (Asthenopia, Hemeralopia, Photophobia, Scintillating scotoma) · Diplopia · Scotoma · Anopsia (Binasal hemianopsia, Bitemporal hemianopsia, Homonymous hemianopsia, Quadrantanopia) · Color blindness (Achromatopsia, Dichromacy, Monochromacy) · Nyctalopia (Oguchi disease) · Blindness/Low vision Pupil Anisocoria · Argyll Robertson pupil · Marcus Gunn pupil · Adie syndrome · Miosis · Mydriasis · Cycloplegia Eye infections Trachoma · Onchocerciasis Other Nystagmus · Glaucoma/Ocular hypertension · Floater · Leber's hereditary optic neuropathy · Red eye · Keratomycosis · Xerophthalmia · Phthisis bulbi eye navs: anat/physio, noncongen/congen/neoplasia, eponymous signs, proc

v • d • e Inflammation Acute Plasma derived mediators Bradykinin · complement (C3, C5a, MAC) · coagulation (Factor XII, Plasmin, Thrombin) Cell derived mediators preformed: Lysosome granules · vasoactive amines (Histamine, Serotonin) synthesized on demand: cytokines (IFN-γ, IL-8, TNF-α, IL-1) · eicosanoids (Leukotriene B4, Prostaglandins) · Nitric oxide · Kinins Chronic Macrophage · Epithelioid cell · Giant cell · Granuloma Processes Traditional: Rubor · Calor · Tumor · Dolor (pain) · Functio laesa Modern: Acute-phase reaction/Fever · Vasodilation · Increased vascular permeability · Exudate · Leukocyte extravasation · Chemotaxis Specific types Nervous CNS (Encephalitis, Myelitis) · Meningitis (Arachnoiditis) · PNS (Neuritis) · eye (Dacryoadenitis, Scleritis, Keratitis, Choroiditis, Retinitis, Chorioretinitis, Blepharitis, Conjunctivitis, Iritis, Uveitis) · ear (Otitis, Labyrinthitis, Mastoiditis) Cardiovascular Carditis (Endocarditis, Myocarditis, Pericarditis) · Vasculitis (Arteritis, Phlebitis, Capillaritis) Respiratory upper (Sinusitis, Rhinitis, Pharyngitis, Laryngitis) · lower (Tracheitis, Bronchitis, Bronchiolitis, Pneumonitis, Pleuritis) · Mediastinitis Digestive mouth (Stomatitis, Gingivitis, Gingivostomatitis, Glossitis, Tonsillitis, Sialadenitis/Parotitis, Cheilitis, Pulpitis, Gnathitis) · tract (Esophagitis, Gastritis, Gastroenteritis, Enteritis, Colitis, Enterocolitis, Duodenitis, Ileitis, Caecitis, Appendicitis, Proctitis) · accessory (Hepatitis, Cholangitis, Cholecystitis, Pancreatitis) · Peritonitis Integumentary Dermatitis (Folliculitis) · Cellulitis · Hidradenitis Musculoskeletal Arthritis · Dermatomyositis · soft tissue (Myositis, Synovitis/Tenosynovitis, Bursitis, Enthesitis, Fasciitis, Capsulitis, Epicondylitis, Tendinitis, Panniculitis) Osteochondritis: Osteitis (Spondylitis, Periostitis) · Chondritis Urinary Nephritis (Glomerulonephritis, Pyelonephritis) · Ureteritis · Cystitis · Urethritis Reproductive female: Oophoritis · Salpingitis · Endometritis · Parametritis · Cervicitis · Vaginitis · Vulvitis · Mastitis male: Orchitis · Epididymitis · Prostatitis · Balanitis · Balanoposthitis pregnancy/newborn: Chorioamnionitis · Omphalitis Endocrine Insulitis · Hypophysitis · Thyroiditis · Parathyroiditis · Adrenalitis Lymphatic Lymphangitis · Lymphadenitis

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