History

Fact Explanation
Ocular itch. Due to the acute inflammation of the conjunctiva [1].
Tearing. Tears are produced by stimulating the terminations of the 5th cranial nerve, such as those branches ending in an inflamed conjunctiva [2].
Red eye. Due to dilatation of the conjunctival blood vessels as a result of the inflammatory response [3].
Purulent discharge. It occurs in herpes zoster ophthalmicus as a result of vesicular eruptions of purulent material from the conjuncitvae [4].
History of recent exposure to individuals who have conjunctivitis or upper respiratory tract infection. Viral conjunctivitis is highly contagious [5].
References
  1. MAHMOOD AHMED R., NARANG ANEESH T.. Diagnosis and Management of the Acute Red Eye. Emergency Medicine Clinics of North America [online] 2008 February, 26(1):35-55 [viewed 31 July 2014] Available from: doi:10.1016/j.emc.2007.10.002
  2. MUTCH JR. THE LACRIMATION REFLEX Br J Ophthalmol [online] 1944 Jul, 28(7):317-336 [viewed 31 July 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC510379
  3. GREENBERG MARC F, POLLARD ZANE F. The red eye in childhood. Pediatric Clinics of North America [online] 2003 February, 50(1):105-124 [viewed 31 July 2014] Available from: doi:10.1016/S0031-3955(02)00114-1
  4. EDGERTON AE. Herpes Zoster Ophthalmicus: Report of Cases and a Review of the Literature Trans Am Ophthalmol Soc [online] 1942:390-439 [viewed 01 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1315060
  5. GALOR A., JENG B. H.. Red eye for the internist: When to treat, when to refer. Cleveland Clinic Journal of Medicine [online] 2008 February, 75(2):137-144 [viewed 31 July 2014] Available from: doi:10.3949/ccjm.75.2.137

Examination

Fact Explanation
Unilateral or bilateral conjunctival hyperemia. Due to dilatation of the conjunctival blood vessels as a result of the inflammatory response [1].
Preauricular lymphadenopathy. The conjunctivae drain to the preauricular lymph nodes [2].
Corneal dendrites on slit lamp examination. Occasionally, the cornea may show a immune reaction [1]. This occurs commonly in conjunctivitis caused by herpes simplex virus.
Purulent discharge. It occurs in herpes zoster ophthalmicus as a result of vesicular eruptions of purulent material from the conjuncitvae [3].
References
  1. GREENBERG MARC F, POLLARD ZANE F. The red eye in childhood. Pediatric Clinics of North America [online] 2003 February, 50(1):105-124 [viewed 31 July 2014] Available from: doi:10.1016/S0031-3955(02)00114-1
  2. FRIEDMANN A. M.. Evaluation and Management of Lymphadenopathy in Children. Pediatrics in Review [online] 2008 February, 29(2):53-60 [viewed 31 July 2014] Available from: doi:10.1542/pir.29-2-53
  3. EDGERTON AE. Herpes Zoster Ophthalmicus: Report of Cases and a Review of the Literature Trans Am Ophthalmol Soc [online] 1942:390-439 [viewed 01 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1315060

Differential Diagnoses

Fact Explanation
Blepharoconjunctivitis. It also presents with an itchy red eye, but the eyelid is also edematous as a result of its inflammation [1].
Bacterial conjunctivitis. It also presents with red eye, but a profuse, thick, yellow-green purulent secretion characteristically occurs [2].
Keratoconjunctivitis sicca. It also presents with eye discomfort, but dry eyes and dry mouth are also prominent features [3].
Allergic conjunctivitis. It presents with itchy red eyes, but there is a history of exposure to known allergens and symptoms are seasonal [4].
Anterior uveitis. It presents with a painful red eye, but photophobia and blurred vision also commonly occur [5].
Episcleritis. It also presents with a watery red eye, but focal areas of redness are usually observed rather than a diffuse process. Nodular episcleritis also presents with a tender scleral nodule on examination [5].
References
  1. GREENBERG MARC F, POLLARD ZANE F. The red eye in childhood. Pediatric Clinics of North America [online] 2003 February, 50(1):105-124 [viewed 31 July 2014] Available from: doi:10.1016/S0031-3955(02)00114-1
  2. HøVDING GUNNAR. Acute bacterial conjunctivitis. [online] 2008 June, 86(1):5-17 [viewed 31 July 2014] Available from: doi:10.1111/j.1600-0420.2007.01006.x
  3. BJERRUM KIRSTEN B.. Keratoconjunctivitis sicca and primary Sjögren's syndrome in a Danish population aged 30-60 years. [online] 2009 May, 75(3):281-286 [viewed 31 July 2014] Available from: doi:10.1111/j.1600-0420.1997.tb00774.x
  4. BIELORY LEONARD, FRIEDLAENDER MITCHELL H.. Allergic Conjunctivitis. Immunology and Allergy Clinics of North America [online] 2008 February, 28(1):43-58 [viewed 31 July 2014] Available from: doi:10.1016/j.iac.2007.12.005
  5. MAHMOOD AHMED R., NARANG ANEESH T.. Diagnosis and Management of the Acute Red Eye. Emergency Medicine Clinics of North America [online] 2008 February, 26(1):35-55 [viewed 31 July 2014] Available from: doi:10.1016/j.emc.2007.10.002

Investigations - for Diagnosis

Fact Explanation
It is mainly a clinical diagnosis. Acute infectious conjunctivitis is mostly a self-limiting disease, and symptomatic management is usually adequate whatever the cause may be [1].
Slit lamp examination to identify corneal dendrites. This occurs in conjunctivitis caused by herpes simplex virus and should be differentiated from other causes of conjunctivitis since the management differs [2].
References
  1. RIETVELD R. P. Diagnostic impact of signs and symptoms in acute infectious conjunctivitis: systematic literature search. BMJ [online] 2003 October, 327(7418):789-789 [viewed 31 July 2014] Available from: doi:10.1136/bmj.327.7418.789
  2. KOWALSKI RP, THOMPSON PP, CRONIN TH. Cell culture isolation can miss the laboratory diagnosis of HSV ocular infection Int J Ophthalmol [online] , 3(2):164-167 [viewed 31 July 2014] Available from: doi:10.3980/j.issn.2222-3959.2010.02.17

Management - General Measures

Fact Explanation
Maintenance of good hygiene by the patient: Hand washing; avoiding the sharing personal items; taking leave from work (when it involves close contact with other individuals) until eye discharge ceases; avoidance of using public swimming pools. Viral conjunctivitis is highly contagious [1].
Use of cold compresses. It improves patient comfort by causing vasoconstriction [2].
Artificial tears. It improves patient comfort by acting as a lubricant [2].
References
  1. GALOR A., JENG B. H.. Red eye for the internist: When to treat, when to refer. Cleveland Clinic Journal of Medicine [online] 2008 February, 75(2):137-144 [viewed 31 July 2014] Available from: doi:10.3949/ccjm.75.2.137
  2. SCHMID KATRINA L, SCHMID LEISA M. Ocular allergy: causes and therapeutic options. [online] December, 83(5):257-270 [viewed 01 August 2014] Available from: doi:10.1111/j.1444-0938.2000.tb05014.x

Management - Specific Treatments

Fact Explanation
Topical steroids (Prednisolone ophthalmic solution). 1-2 drops of 1% solution twice a day. Its anti-inflammatory properties reduce occular edema [1]. This should be used with caution because steroid eye drops may worsen ocular herpetic disease.
Topical antibiotics. At times the diagnosis is difficult to discern from bacterial conjunctivitis [1].
Topical antivirals. Trifluridine 1% drops, five times per day, or vidarabine 3% ointment, five times per day for 10-14 days. It is used when there is a diagnosis of herpes simplex ocular infection since corneal involvement is common and it is a major cause of corneal blindness [2].
References
  1. MAHMOOD AHMED R., NARANG ANEESH T.. Diagnosis and Management of the Acute Red Eye. Emergency Medicine Clinics of North America [online] 2008 February, 26(1):35-55 [viewed 31 July 2014] Available from: doi:10.1016/j.emc.2007.10.002
  2. DAROUGAR S, WISHART M S, VISWALINGAM N D. Epidemiological and clinical features of primary herpes simplex virus ocular infection.. British Journal of Ophthalmology [online] 1985 January, 69(1):2-6 [viewed 01 August 2014] Available from: doi:10.1136/bjo.69.1.2