Conjunctivitis, also known as pink eye,[4] is inflammation of the outermost layer of the white part of the eye and the inner surface of the eyelid.[5] It makes the eye appear pink or reddish.[1] Pain, burning, scratchiness, or itchiness may occur.[1] The affected eye may have increased tears or be "stuck shut" in the morning.[1] Swelling of the white part of the eye may also occur.[1] Itching is more common in cases due to allergies.[3] Conjunctivitis can affect one or both eyes.[1]
Causes[edit]
Infective conjunctivitis is most commonly caused by a virus.[3] Bacterial infections, allergies, other irritants, and dryness are also common causes. Both bacterial and viral infections are contagious, passing from person to person or spread through contaminated objects or water. Contact with contaminated fingers is a common cause of conjunctivitis. Bacteria may also reach the conjunctiva from the edges of the eyelids and the surrounding skin, from the nasopharynx, from infected eye drops or contact lenses, from the genitals or the bloodstream.[13]Infection by human adenovirus accounts for 65% to 90% of cases of viral conjunctivitis.[14]
Viral[edit]
Adenoviruses are the most common cause of viral conjunctivitis (adenoviral keratoconjunctivitis).[15] Herpetic keratoconjunctivitis, caused by herpes simplex viruses, can be serious and requires treatment with aciclovir. Acute hemorrhagic conjunctivitis is a highly contagious disease caused by one of two enteroviruses, enterovirus 70 and coxsackievirus A24. These were first identified in an outbreak in Ghana in 1969, and have spread worldwide since then, causing several epidemics.[16]
Bacterial[edit]
The most common causes of acute bacterial conjunctivitis are Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae.[15][17]Though very rare, hyperacute cases are usually caused by Neisseria gonorrhoeae or Neisseria meningitidis. Chronic cases of bacterial conjunctivitis are those lasting longer than 3 weeks, and are typically caused by S. aureus, Moraxella lacunata, or Gram-negative enteric flora.
Allergic[edit]
Conjunctivitis may also be caused by allergens such as pollen, perfumes, cosmetics, smoke,[18] dust mites, Balsam of Peru,[19] or eye drops.[20] The most frequent cause of conjunctivitis is allergic conjunctivitis and it affects 15% to 40% of the population.[21] Allergic conjunctivitis accounts for 15% of eye related primary care consultations - most including seasonal exposures in the spring and summer or perpetual conditions.[22]
Other[edit]
Conjunctivitis is part of the triad of reactive arthritis, which is thought to be caused by autoimmune cross-reactivity following certain bacterial infections. Reactive arthritis is highly associated with HLA-B27. Conjunctivitis is associated with the autoimmune disease relapsing polychondritis.[23][24]
Diagnosis[edit]
Cultures are not often taken or needed as most cases resolve either with time or typical antibiotics. If bacterial conjunctivitis is suspected, but no response to topical antibiotics is seen, swabs for bacterial culture should be taken and tested. Viral culture may be appropriate in epidemic case clusters.
A patch test is used to identify the causative allergen in allergic conjunctivitis.[25]
Although conjunctival scrapes for cytology can be useful in detecting chlamydial and fungal infections, allergy, and dysplasia, they are rarely done because of the cost and the general dearth of laboratory staff experienced in handling ocular specimens. Conjunctival incisional biopsy is occasionally done when granulomatous diseases (e.g., sarcoidosis) or dysplasia are suspected.
Classification[edit]
Conjunctivitis may be classified either by cause or by extent of the inflamed area.
Causes[edit]
- Allergy
- Bacteria
- Viruses
- Chemicals
- Autoimmune
Neonatal conjunctivitis is often grouped separately from bacterial conjunctivitis because it is caused by different bacteria than the more common cases of bacterial conjunctivitis.
By extent of involvement[edit]
Blepharoconjunctivitis is the dual combination of conjunctivitis with blepharitis (inflammation of the eyelids).
Keratoconjunctivitis is the combination of conjunctivitis and keratitis (corneal inflammation).
Blepharokeratoconjunctivitis is the combination of conjunctivitis with blepharitis and keratitis. It is clinically defined by changes of the lid margin, meibomian gland dysfunction, redness of the eye, conjunctival chemosis and inflammation of the cornea.[26]
Differential diagnosis[edit]
Some more serious conditions can present with a red eye, such as infectious keratitis, angle-closure glaucoma, or iritis. These conditions require the urgent attention of an ophthalmologist. Signs of such conditions include decreased vision, significantly increased sensitivity to light, inability to keep the eye open, a pupil that does not respond to light, or a severe headache with nausea.[27] Fluctuating blurring is common, due to tearing and mucoid discharge. Mild photophobia is common. However, if any of these symptoms is prominent, considering other diseases such as glaucoma, uveitis, keratitis, and even meningitis or carotico-cavernous fistula is important.
A more comprehensive differential diagnosis for the red or painful eye includes:[27]
- Corneal abrasion
- Subconjunctival hemorrhage
- Pinguecula
- Blepharitis
- Dacryocystitis
- Keratoconjunctivitis sicca (dry eye)
- Keratitis
- Herpes simplex
- Herpes zoster
- Episcleritis - an inflammatory condition that produces a similar appearance to conjunctivitis, but without discharge or tearing
- Uveitis
- Acute angle-closure glaucoma
- Endophthalmitis
Prevention[edit]
The most effective prevention is good hygiene, especially avoiding rubbing the eyes with infected hands. Vaccination against adenovirus, Haemophilus influenzae, pneumococcus, and Neisseria meningitidis is also effective.[28]
Povidone-iodine eye solution has been found to prevent neonatal conjunctivitis.[29] It is becoming more commonly used globally because of its low cost.[29]
Management[edit]
Conjunctivitis resolves in 65% of cases without treatment, within 2–5 days. The prescription of antibiotics is not necessary in most cases.[30]
Viral[edit]
Viral conjunctivitis usually resolves on its own and does not require any specific treatment.[3] Antihistamines (e.g., diphenhydramine) or mast cell stabilizers (e.g., cromolyn) may be used to help with the symptoms.[3] Povidone-iodine has been suggested as a treatment, but as of 2008, evidence to support it was poor.[31]
Allergic[edit]
For allergic conjunctivitis, cool water poured over the face with the head inclined downward constricts capillaries, and artificial tears sometimes relieve discomfort in mild cases. In more severe cases, nonsteroidal anti-inflammatory medications and antihistamines may be prescribed. Persistent allergic conjunctivitis may also require topical steroid drops.
Bacterial[edit]
Bacterial conjunctivitis usually resolves without treatment.[3] Topical antibiotics may be needed only if no improvement is observed after 3 days.[32] No serious effects were noted either with or without treatment.[33] Because antibiotics do speed healing in bacterial conjunctivitis, their use may be considered.[33] Antibiotics are also recommended for those who wear contact lenses, are immunocompromised, have disease which is thought to be due to chlamydia or gonorrhea, have a fair bit of pain, or have copious discharge.[3] Gonorrheal or chlamydial infections require both oral and topical antibiotics.[3]
The choice of antibiotic varies based on the strain or suspected strain of bacteria causing the infection. Fluoroquinolones, sodium sulfacetamide, or trimethoprim/polymyxin may be used, typically for 7–10 days.[15] Cases of meningococcal conjunctivitis can also be treated with systemic penicillin, as long as the strain is sensitive to penicillin.
When investigated as a treatment, povidone-iodine ophthalmic solution has also been observed to have some effectiveness against bacterial and chlamydial conjunctivitis, with a possible role suggested in locations where topical antibiotics are unavailable or costly.[34]
Chemical[edit]
Conjunctivitis due to chemicals is treated via irrigation with Ringer's lactate or saline solution. Chemical injuries, particularly alkali burns, are medical emergencies, as they can lead to severe scarring and intraocular damage. People with chemically induced conjunctivitis should not touch their eyes to avoid spreading the chemical.
https://en.wikipedia.org/wiki/Conjunctivitis#Viral
https://www.healthline.com/health/sure-signs-you-ve-already-had-covid#summary
No comments:
Post a Comment