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| {{Infobox_Disease | | {{Infobox_Disease |
| | Name = Corneal ulcer | | | Name = Corneal ulcer |
| | Image = Eyes corneal ulcer.jpg | | | Image = Eyes corneal ulcer.jpg |
| | Caption = Corneal ulcer. Marked generalized inflammation related to bacterial infection in this immunocompromised host. The cornea itself has become opaque secondary to this process. <br> (Image courtesy of Charlie Goldberg, M.D.) | | | Caption = Corneal ulcer. Marked generalized inflammation related to bacterial infection in this immunocompromised host. The cornea itself has become opaque secondary to this process.<br>(Image courtesy of Charlie Goldberg, M.D.) |
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| | ICD10 = {{ICD10|H|16|0|h|15}}
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| | ICD9 = {{ICD9|370.00}}
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| | MedlinePlus = 001032
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| | MedlinePlus_mult=MedlinePlus2|001017
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| '''For patient information click [[{{PAGENAME}} (patient information)|here]]''' | | '''For patient information click [[{{PAGENAME}} (patient information)|here]]''' |
| | {{Corneal ulcer}} |
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| {{SI}}
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| {{CMG}} | | {{CMG}} |
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| ==Overview==
| | {{SK}} Ulcerative keratitis; eye sore |
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| A '''corneal ulcer''', or '''ulcerative keratitis''', is an inflammatory or more seriously, infective condition of the [[cornea]] involving disruption of its epithelial layer with involvement of the corneal stroma. It is a common condition in humans particularly in the tropics and the agrarian societies. In developing countries, as well as in Florida, corneal ulcer is frequently the cause of great morbidity as well as economic loss to the person and family. Children afflicted by Vitamin A deficiency are at high risk for corneal ulcer and may become blind in both eyes, which may persist lifelong, causing tremendous & avoidable loss to the person and the society.
| | ==[[Corneal ulcer overview|Overview]]== |
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| ==Corneal anatomy of the humans== | | ==[[Corneal ulcer classification|Classification]]== |
| The cornea is a transparent structure that is part of the outer layer of the [[eye]]. It [[refraction|refract]]s light and protects the contents of the eye. The corneal thickness ranges from 450 to 610 micrometres and on an average 550 µm. thick in caucasian eyes. In Indian eyes, the average thickness is slightly less at 510 µm. The [[trigeminal nerve]] supplies the cornea via the [[long ciliary nerve]]s. There are [[nociceptor|pain receptor]]s in the outer layers and [[mechanoreceptor|pressure receptor]]s are deeper.
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| Transparency is achieved through a lack of blood vessels, pigmentation, and [[keratin]], and through tight layered organization of the [[collagen]] fibers. The collagen fibers cross the full diameter of the cornea in a strictly parallel fashion and allow 99 percent of the light to pass through without scattering.
| | ==[[Corneal ulcer pathophysiology|Pathophysiology]]== |
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| There are five layers in the human cornea, from outer to inner:
| | ==[[Corneal ulcer causes|Causes]]== |
| * [[Epithelium]]
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| * [[Bowman's membrane]]
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| * [[Stroma]]
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| * [[Descemet's membrane]]
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| * [[Endothelium ]]
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| The outer layer is the [[epithelium]], which is 25 to 40 µm micrometers and five to seven [[cell (biology)|cell]] layers thick. The epithelium holds the tear film in place and also prevents water from invading the cornea and disrupting the collagen fibers. This prevents corneal [[edema]], which gives it a cloudy appearance. It is also a barrier to infectious agents. The epithelium sticks to the [[basal lamina|basement membrane]], which also separates the epithelium from the [[stroma]]. The corneal stroma comprises 90 percent of the thickness of the cornea. It contains the collagen fibers organized into [[lamella]]e. The lamellae are in sheets which separate easily. Posterior to the stroma is [[Descemet's membrane]], which is a basement membrane for the [[corneal endothelium]]. The endothelium is a single cell layer that separates the cornea from the [[aqueous humor]].
| | ==[[Corneal ulcer differential diagnosis|Differentiating Corneal Ulcer from other Diseases]]== |
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| ==Corneal healing== | | ==[[Corneal ulcer epidemiology and demographics|Epidemiology and Demographics]]== |
| An ulcer of the cornea heals by two methods: migration of surrounding epithelial cells followed by [[mitosis]] (dividing) of the cells, and introduction of blood vessels from the [[conjunctiva]]. Superficial small ulcers heal rapidly by the first method. However, larger or deeper ulcers often require the presence of blood vessels to supply inflammatory cells. [[White blood cell]]s and [[fibroblast]]s produce [[granulation tissue]] and then scar tissue, effectively healing the cornea.
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| ==Superficial and deep corneal ulcers== | | ==[[Corneal ulcer risk factors|Risk Factors]]== |
| Corneal ulcers are a common human eye disease. They are caused by trauma, particularly with vegetable matter, as also chemical injury, contact lenses and infections. Other eye conditions can cause corneal ulcers, such as [[entropion]], [[distichia]]e, [[corneal dystrophy]], and [[keratoconjunctivitis sicca]] (dry eye).
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| Many micro-organisms cause infective corneal ulcer. Among them are bacteria, fungi, viruses, protozoa, and chlamydia. Bacterial keratitis is caused by [[Staphylococcus aureus]], [[Streptococcus viridans]], [[Escherichia coli]], [[Enterococci]], [[Pseudomonas]], [[Nocardia]] and many other bacteria.
| | ==[[Corneal ulcer natural history|Natural History, Complications and Prognosis]]== |
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| Fungal keratitis causes deep and severe corneal ulcer. It is caused by [[Aspergillus]] sp., [[Fusarium]] sp., [[Candida]] sp., as also Rhizopus, [[Mucor]], and other fungi. The typical feature of fungal keratitis is slow onset and gradual progression, where signs are much more than the symptoms. Small satellite lesions around the ulcer are a common feature of fungal keratitis and [[hypopyon]] is usually seen.
| | ==Diagnosis== |
| | [[Corneal ulcer history and symptoms|History and Symptoms]] | [[Corneal ulcer physical examination|Physical Examination]] | [[Corneal ulcer laboratory findings|Laboratory Findings]] | [[Corneal ulcer other diagnostic studies|Other Diagnostic Studies]] |
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| Viral keratitis causes corneal ulceration. It is caused most commonly by [[Herpes simplex]], [[Herpes Zoster]] and [[Adenovirus]]es. Also it can be caused by [[coronavirus]]es & many other viruses. Herpes virus cause a dendritic ulcer, which can be recur and relapse over the lifetime of an individual. Protozoa infection like Acanthamoeba keratitis is characterized by severe pain and is associated with contact lens users swimming in pools. [[Chlamydia trachomatis]] can also contribute to development of corneal ulcer.
| | ==Treatment== |
| | [[Corneal ulcer medical therapy|Medical Therapy]] | [[Corneal ulcer surgery|Surgery]] | [[Corneal ulcer primary prevention|Primary Prevention]] | [[Corneal ulcer cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Corneal ulcer future or investigational therapies|Future or Investigational Therapies]] |
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| Superficial ulcers involve a loss of part of the epithelium. Deep ulcers extend into or through the stroma and can result in severe scarring and corneal perforation. '''Descemetoceles''' occur when the ulcer extends through the stroma. This type of ulcer is especially dangerous and can rapidly result in corneal perforation, if not treated in time.
| | ==Case Studies== |
| | [[Corneal ulcer case study one|Case #1]] |
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| The location of the ulcer depends somewhat on the cause. Central ulcers are typically caused by trauma, dry eye, or exposure from [[facial nerve paralysis]] or [[exophthalmos]]. Entropion, severe dry eye and distichiasis (inturning of eye lashes) may cause ulceration of the peripheral cornea. Immune-mediated eye disease can cause ulcers at the border of the cornea and [[sclera]]. These include Rheumatoid arthritis, rosacea, systemic sclerosis which lead to a special type of corneal ulcer called '''Mooren's ulcer'''. It has a circumferential crater like depression of the cornea, just inside the limbus, usually with an overhanging edge.
| | ==Related Chapters== |
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| ===Symptoms=== | |
| Corneal ulcers are painful due to nerve exposure, and can cause tearing, squinting, and vision loss of the eye. There may also be signs of anterior [[uveitis]], such as [[miosis]] (small pupil), aqueous flare (protein in the [[aqueous humour]]), and redness of the eye. An axon reflex may be responsible for uveitis formation — stimulation of pain receptors in the cornea results in release inflammatory mediators such as [[prostaglandin]]s, [[histamine]], and [[acetylcholine]].
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| ===Diagnosis===
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| Diagnosis is done by direct observation under magnified view of [[slit lamp]] revealing the ulcer on the cornea. The use of [[fluorescein]] stain, which is taken up by exposed corneal [[stroma]] and appears green, helps in defining the margins of the corneal ulcer, and can reveal additional details of the surrounding epithelium. Herpes simplex ulcers show a typical dendritic pattern of staining. Rose-Bengal dye is also used for supra-vital staining purposes, but it may be very irritating to the eyes. In descemetoceles, the Descemet's membrane will bulge forward and after staining will appear as a dark circle with a green boundary, because it does not absorb the stain. Doing a corneal scraping and examining under the microscope with stains like Gram's and KOH preparation may reveal the bacteria and fungi respectively. Microbiological culture tests may be necessary to isolate the causative organisms for some cases. Other tests that may be necessary include a [[Schirmer's test]] for keratoconjunctivitis sicca and an analysis of [[facial nerve]] function for facial nerve paralysis.
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| ===Treatment===
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| Proper diagnosis is essential for optimal treatment. Bacterial corneal ulcer require intensive fortified antibiotic therapy to treat the infection. Fungal corneal ulcers require intensive application of topical anti-fungal agents. Viral corneal ulceration caused by herpes virus may antivirals like topical acyclovir oint instilled at least five times a day. Alongside, supportive therapy like pain medications are given, including topical cycloplegics like [[atropine]] or [[homatropine]] to dilate the pupil and thereby stop spasms of the [[ciliary muscle]]. Superficial ulcers may heal in less than a week. Deep ulcers and descemetoceles may require conjunctival grafts or conjunctival flaps, soft [[contact lens]]es, or [[cornea transplant|corneal transplant]]. Proper nutrition, including protein intake and Vitamin C are usually advised. In cases of Keratomalacia, where the corneal ulceration is due to a deficiency of Vitamin A, supplementation of the Vitamin A by oral or intramuscular route is given. Drugs that are usually contraindicated in corneal ulcer are topical [[corticosteroid]]s and [[anesthetics]] - these should not be used on any type of corneal ulcer because they prevent healing, may lead to superinfection with fungi and other bacteria and will often make the condition much worse.
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| ==Refractory corneal ulcers==
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| {{main|Recurrent corneal erosion}}
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| Refractory corneal ulcers are superficial ulcers that heal poorly and tend to recur. They are also known as '''indolent ulcers''' or '''Boxer ulcers'''. They are believed to be caused by a defect in the basement membrane and a lack of [[hemidesmosome|hemidesmosomal]] attachments. They are recognized by undermined epithelium that surrounds the ulcer and easily peels back. Refractory corneal ulcers are most commonly seen in diabetics and often occur in the other eye later. They are similar to Cogan's cystic dystrophy.
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| ===Treatment===
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| Topical fortified antibiotics are used at hourly intervals to treat infectious corneal ulcers. Cycloplegic eye drops are applied to give rest to the eye.Pain medications are given as needed. Loose epithelium and ulcer base can be scraped off and sent for culture sensitiviy studies to find out the pathogenic organism. This helps in choosing appropriate antibiotics. Complete healing takes anywhere from about few weeks to few months.
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| Refractory corneal ulcers can take a long time to heal, sometimes months. In case of progressive or non-healing ulcers, surgical intervention by an Ophthalmologist with corneal transplantation may be required to save the eye. In all corneal ulcers it is important to rule out predisposing factors like [[Diabetes Mellitus]] and Immunodeficiency.
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| ==Melting ulcers==
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| Melting ulcers are a type of corneal ulcer involving progressive loss of stroma in a dissolving fashion. This is most commonly seen in ''[[Pseudomonas]]'' infection, but it can be caused by other types of [[bacteria]] or [[fungus|fungi]]. These infectious agents produce [[protease]]s and [[collagenase]]s which break down the corneal stroma. Complete loss of the stroma can occur within 24 hours. Treatment includes antibiotics and collagenase inhibitors such as [[acetylcysteine]]. Surgery in the form of corneal transplantation (penetrating keratoplasty) is usually necessary to save the eye.
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| ==See also==
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| *[[Corneal abrasion]] | | *[[Corneal abrasion]] |
| *[[Keratitis]] | | *[[Keratitis]] |
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| ==References==
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| {{reflist|2}}
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| {{Eye pathology}} | | {{Eye pathology}} |
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| [[Category:Ophthalmology]] | | [[Category:Ophthalmology]] |
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