Editing Conjunctivitis (section)

== Diagnosis ==
[[File:Procedure of conjunctival swabs.jpg|thumb|The procedure of conjunctival swabs]]

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.<ref>{{cite book | vauthors = Sheikh A, Hurwitz B | chapter = BACTERIAL CONJUNCTIVITIS 372.05 (Infective Conjunctivitis, Mucopurulent Conjunctivitis, Purulent Conjunctivitis) |date=2008 | title = Roy and Fraunfelder's Current Ocular Therapy |pages=332–334 |publisher=Elsevier |doi=10.1016/b978-1-4160-2447-7.50182-1 |isbn=978-1-4160-2447-7 }}</ref>

A [[patch test]] is used to identify the causative allergen in allergic conjunctivitis.<ref name="google2">{{Cite book | vauthors = Mannis MJ, Macsai MS, Huntley AC |url=https://books.google.com/books?id=FtlsAAAAMAAJ&q=Conjunctivitis+%22patch+test%22 |title=Eye and skin disease |date=1996 |publisher=Lippincott-Raven |isbn=978-0-7817-0269-0 |access-date=23 April 2014 |archive-url=https://web.archive.org/web/20140705035958/http://books.google.com/books?id=FtlsAAAAMAAJ&q=Conjunctivitis+%22patch+test%22&dq=Conjunctivitis+%22patch+test%22&hl=en&sa=X&ei=oY9UU932MMPjsAT5j4KYCg&ved=0CF8Q6AEwBg |archive-date=5 July 2014 |url-status=live |df=dmy-all}}</ref>

Although conjunctival scrapes for [[Cytopathology|cytology]] can be useful in detecting chlamydial and [[Fungus#Mycology|fungal]] infections, allergies, 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]])<ref>{{cite journal | vauthors = Korkmaz Ekren P, Mogulkoc N, Toreyin ZN, Egrilmez S, Veral A, Akalın T, Bacakoglu F | title = Conjunctival Biopsy as a First Choice to Confirm a Diagnosis of Sarcoidosis | journal = Sarcoidosis, Vasculitis, and Diffuse Lung Diseases | volume = 33 | issue = 3 | pages = 196–200 | date = October 2016 | pmid = 27758983 | url = https://pubmed.ncbi.nlm.nih.gov/27758983/ }}</ref> or dysplasia are suspected.<ref>{{cite book | vauthors = Roberts F, Thum CK | chapter = The Conjunctival Biopsy |date=2021 | title = Lee's Ophthalmic Histopathology |pages=343–388 | veditors = Roberts F |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-030-76525-5_11 |isbn=978-3-030-76525-5 }}</ref>

=== Classification ===
Conjunctivitis may be classified either by cause or by extent of the inflamed area.{{citation needed|date=February 2023}}

==== Causes ====
* 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.{{citation needed|date=February 2023}}<!-- Source? -->

==== By extent of involvement ====
Blepharoconjunctivitis is the dual combination of conjunctivitis with [[blepharitis]] (inflammation of the eyelids).{{citation needed|date=February 2023}}

[[Keratoconjunctivitis]] is the combination of conjunctivitis and [[keratitis]] ([[cornea]]l inflammation).{{citation needed|date=February 2023}}<!-- Two good bullet points, but try to find a source for them. -->

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.<ref name="OGallagher">{{cite journal | vauthors = O'Gallagher M, Banteka M, Bunce C, Larkin F, Tuft S, Dahlmann-Noor A | title = Systemic treatment for blepharokeratoconjunctivitis in children | journal = The Cochrane Database of Systematic Reviews | volume = 2016 | issue = 5 | pages = CD011750 | date = May 2016 | pmid = 27236587 | pmc = 9257284 | doi = 10.1002/14651858.CD011750.pub2 }}</ref>

=== Differential diagnosis ===

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.<ref name="McGra-Hill">{{Cite book |title=Harrison's Principles of Internal Medicine |vauthors=Longo DL |date=2012 |publisher=McGra-Hill |chapter=Disorders of the Eye(Horton JC)}}</ref> 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 [[caroticocavernous fistula|carotico-cavernous fistula]] is important.{{citation needed|date=September 2022}}

A more comprehensive differential diagnosis for the red or painful eye includes:<ref name="McGra-Hill" />
* [[Corneal abrasion]]
* [[Subconjunctival hemorrhage]]
* [[Pinguecula]]
* [[Blepharitis]]
* [[Dacryocystitis]]
* [[Keratoconjunctivitis sicca]] (dry eye)
* [[Keratitis]]
* [[Herpes simplex]]
* [[Herpes zoster]]
* [[Episcleritis]] – an [[Inflammation|inflammatory]] condition that produces a similar appearance to conjunctivitis, but without discharge or tearing
* [[Uveitis]]
* [[Acute angle-closure glaucoma]]
* [[Endophthalmitis]]
* [[Orbital cellulitis]]