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Synonyms and keywords: Bloodshot eye

Overview

Red eye is one of the most common complaints managed by primary care physicians though in some cases it heralds a serious and life-threatening condition needing urgent referral to ophthalmologist. The etiology of red eye can be infectious, traumatic, inflammatory, allergic, autoimmune and rarely secondary to tumors. Red eye stems from pathologies of eye lid, conjunctiva, cornea, sclera and uvea. Signs and/or symptoms such as photophobia, pain, visual acuity, itchiness, foreign body sensation and if the condition is unilateral or bilateral, must be documented. Whenever a red flag is identified in a patient presenting with red eye, the clinician must refer the patient for a same-day ophthalmologist consult.

Classification

There is no established system for the classification of red eye.

Causes

The cause of red eye is diagnosed through a comprehensive eye examination and patient’s history. The most common cause of red eye is conjunctivitis and the most common etiology is viral. There are other causes though, and differential diagnosis must include other diseases such as corneal abrasion, blepharitis, subconjunctival hemorrhage, foreign body, iritis, keratitis, chemical burn, glaucoma, and scleritis that may confound the physician.^[1]^[2]
Conjunctivitis, episcleritis and subconjunctival haemorrhage make up about 70% of the primary care red eye consultations.

Sight-threatening causes

The most common causes of sight-threatening causes of red eye include^[3]

Keratitis
Scleritis
Acute glaucoma
Orbital cellulitis
Foreign body trauma
Chemical burns

Differentiating Red eye from other Diseases

While evaluating patients presenting with red eye, a crucial step is to identify the patients that have sight-threatening causes. This can be evaluated by asking historical questions about associated symptoms and performing a complete ocular examination. Associated symptoms include:^[4]^[5]

Pain
Photophobia
Visual acuity
History of trauma or exposure
History of secretion
History of systemic symptoms

Differential diagnosis of red eye^[6]^[1]
Condition	Signs	Symptoms	Causes	Treatment
Viral conjunctivitis	Normal vision Normal pupil size Diffuse conjunctival injections Preauricular lymphadenopathy	Mild to no pain Diffuse hyperemia Mild itching Watery to serous discharge Photophobia Subepithelial corneal opacities	Adenovirus VZV HSV	Supportive care and preservative-free artificial tears
Bacterial conjunctivitis	Eyelid edema Normal pupil size Normal visual acuity	Mild to moderate pain Foreign body sensation Mucopurulent secretions with bilateral glued eyes	Staphylococcus aureus Streptococcus pneumoniae Haemophilus influenzae	Topical antibiotics
Allergic conjunctivitis	Normal visual acuity and pupil reaction Red eye	Painless tearing Watery discharge Intense itching	Environmental antigens	Supportive care and topical antihistamines
Blepharitis	Swollen eyelids Dandruff-like scaling on eyelashes	Irritated eyes Itching	Chronic inflammation of eyelids (staphyloccocal infections)	Supportive cares Topical antibiotics Steroids eyedrops
Subconjunctival hemorrhage	Bright red patch on sclera	Mild pain No discharge No visual disturbance	Hypertension Atherosclerotic vessels Traumatic causes	Refer for further investigation
Episcleritis	Dilated episcleral blood Edema of episclera	Mild pain Watery discharge	Idiopathic inflammation	Topical lubricants Oral NSAIDs
Keratitis	Decreased visual acuity Corneal opacity Eyelid edema	Severe pain Photophobia Mucopurulent discharge Foreign body sensation	Bacterial Staphylococcus Streptococcus Viral VZV HSV	Bacterial Topical antibiotics Viral Topical or/and oral anti-virals Topical steroids
Iritis	Constricted and irregular pupil reaction Decreased visual acuity	Moderate to severe pain Photophobia Watery discharge	Idiopathic inflamation	Topical steroids
Acute angle closure glaucoma	Reduced visual acuity Non-reactive pupils Dilated pupils	Severe and throbbing pain Photophobia Halos when looking at light	Elevated intraocular pressure Optic nerve damage	Topical parasympathomimetics Topical beta-blockers Carbonic anhydrase inhibitors Alpha agnoists
Scleritis	Decreased visual acuity Sclera edema	Severe pain radiating to periorbital area Increased pain with eye movement Photophobia Watery discharge	Systemic diseases Rheumatoid arthritis Wegener granulomatosis Sarcoidosis Inflammatory bowel disease	Refer urgently

Treatment

In patients presenting with red eye, it is important to take a full detailed history and physical examination. In assessment of patient’s red eye, the diagnosis can be narrowed by distinguishing other associated symptoms.

DDx	Epidemiology	Manifestation	Cause	Treatment
Viral conjunctivitis^[7]	More than 80% of all acute conjunctivitis	Watery discharge Red eye Chemosis Bilateral conjunctivitis Ipsilateral lymphadenopathy (in severe cases)	Adenovirus is most common cause	Artificial tears Topical antihistamines Cold compresses
Bacterial conjunctivitis^[7]	Up to 50% of all acute conjunctivitis	Purulant discharge Red eye Adherence of eyelids Chemosis Eyelids swelling (in severe cases)	Staphylococcus aureus Streptococcus pneumoniae Haemophilus influenzae Chlamydia Neisseria gonorrhoeae	Most cases are self-limiting but Topical antibiotics reduce the duration In chlamydial conjunctivitis Oral azithromycin and doxycycline In gonococcal conjunctivitis Both topical and oral antibiotics
Allergic conjunctivitis^[7]	More than 40% of population	Red eye Itching	Environmental antigens	Artificial tears Saline solutions Topical decongestants and antihistamines
Blepharitis^[8]	More than 40% of patients presenting with red eye	Superficial discomfort Mild photophobia Redness	Staphylococcus epidermidis Staphylococcus aureus Proprionibacterium	Topical antibiotics or corticosteroids Hyperthermic lid compress
Subconjunctival hemorrhage^[9]	About 3% of patients with red eye	Mild to moderate pain Red eye	Trauma Eye surgery Inflammation of conjunctiva Conjunctivochalasis Systemic disorders Systemic vascular diseases	Refer to investigate for underlying cause
Glaucoma^[10]	More than 70 million cases worldwide	Reduced visual acuity Dilated pupils Red eye	Risk factors Old age Black race Use of systemic or topical corticosteroids	Lowering intraocular pressure Prostaglandin analogues Latanoprost Beta-blockers Timolol Alpha-agonists Brimonidine
Scleritis^[11]	Between 0.2% to 0.6% of patients with red eye	Severe and constant pain Pain typically worsens with eye movement Tearing Photophobia Decreased vision	It can be associated with some systemic disorders Rheumatoid arthritis Wegener’s granulomatosis	Topical steroids NSAIDs

For more information on treatment click here.

Related Chapters

List of eye diseases and disorders

↑ ^1.0 ^1.1 Tarff, Andreina; Behrens, Ashley (2017). “Ocular Emergencies”. Medical Clinics of North America. 101 (3): 615–639. doi:10.1016/j.mcna.2016.12.013. ISSN 0025-7125.
↑ Cronau H, Kankanala RR, Mauger T (January 2010). “Diagnosis and management of red eye in primary care” (2): 137–44.
↑ Kilduff C, Lois C (2016). “Red eyes and red-flags: improving ophthalmic assessment and referral in primary care”. BMJ Qual Improv Rep. 5 (1). doi:10.1136/bmjquality.u211608.w4680. PMC 4964165. PMID 27493748.
↑ Narayana, Sirisha; McGee, Steven (2015). “Bedside Diagnosis of the ‘Red Eye’: A Systematic Review”. The American Journal of Medicine. 128 (11): 1220–1224.e1. doi:10.1016/j.amjmed.2015.06.026. ISSN 0002-9343.
↑ Sethuraman U, Kamat D (2009). “The red eye: evaluation and management”. Clin Pediatr (Phila). 48 (6): 588–600. doi:10.1177/0009922809333094. PMID 19357422.
↑ Gilani CJ, Yang A, Yonkers M, Boysen-Osborn M (2017). “Differentiating Urgent and Emergent Causes of Acute Red Eye for the Emergency Physician”. West J Emerg Med. 18 (3): 509–517. doi:10.5811/westjem.2016.12.31798. PMC 5391903. PMID 28435504.
↑ ^7.0 ^7.1 ^7.2 Azari AA, Barney NP (2013). “Conjunctivitis: a systematic review of diagnosis and treatment”. JAMA. 310 (16): 1721–9. doi:10.1001/jama.2013.280318. PMC 4049531. PMID 24150468.
↑ Putnam CM (2016). “Diagnosis and management of blepharitis: an optometrist’s perspective”. Clin Optom (Auckl). 8: 71–78. doi:10.2147/OPTO.S84795. PMC 6095371. PMID 30214351.
↑ Tarlan B, Kiratli H (2013). “Subconjunctival hemorrhage: risk factors and potential indicators”. Clin Ophthalmol. 7: 1163–70. doi:10.2147/OPTH.S35062. PMC 3702240. PMID 23843690.
↑ Weinreb RN, Aung T, Medeiros FA (2014). “The pathophysiology and treatment of glaucoma: a review”. JAMA. 311 (18): 1901–11. doi:10.1001/jama.2014.3192. PMC 4523637. PMID 24825645.
↑ Galor A, Thorne JE (2007). “Scleritis and peripheral ulcerative keratitis”. Rheum Dis Clin North Am. 33 (4): 835–54, vii. doi:10.1016/j.rdc.2007.08.002. PMC 2212596. PMID 18037120.

[TarffBehrens2017-1] 1.0 ^1.1 Tarff, Andreina; Behrens, Ashley (2017). “Ocular Emergencies”. Medical Clinics of North America. 101 (3): 615–639. doi:10.1016/j.mcna.2016.12.013. ISSN 0025-7125.

[2] Cronau H, Kankanala RR, Mauger T (January 2010). “Diagnosis and management of red eye in primary care” (2): 137–44.

[pmid27493748-3] Kilduff C, Lois C (2016). “Red eyes and red-flags: improving ophthalmic assessment and referral in primary care”. BMJ Qual Improv Rep. 5 (1). doi:10.1136/bmjquality.u211608.w4680. PMC 4964165. PMID 27493748.

[NarayanaMcGee2015-4] Narayana, Sirisha; McGee, Steven (2015). “Bedside Diagnosis of the ‘Red Eye’: A Systematic Review”. The American Journal of Medicine. 128 (11): 1220–1224.e1. doi:10.1016/j.amjmed.2015.06.026. ISSN 0002-9343.

[pmid19357422-5] Sethuraman U, Kamat D (2009). “The red eye: evaluation and management”. Clin Pediatr (Phila). 48 (6): 588–600. doi:10.1177/0009922809333094. PMID 19357422.

[pmid28435504-6] Gilani CJ, Yang A, Yonkers M, Boysen-Osborn M (2017). “Differentiating Urgent and Emergent Causes of Acute Red Eye for the Emergency Physician”. West J Emerg Med. 18 (3): 509–517. doi:10.5811/westjem.2016.12.31798. PMC 5391903. PMID 28435504.

[pmid24150468-7] 7.0 ^7.1 ^7.2 Azari AA, Barney NP (2013). “Conjunctivitis: a systematic review of diagnosis and treatment”. JAMA. 310 (16): 1721–9. doi:10.1001/jama.2013.280318. PMC 4049531. PMID 24150468.

[pmid30214351-8] Putnam CM (2016). “Diagnosis and management of blepharitis: an optometrist’s perspective”. Clin Optom (Auckl). 8: 71–78. doi:10.2147/OPTO.S84795. PMC 6095371. PMID 30214351.

[pmid23843690-9] Tarlan B, Kiratli H (2013). “Subconjunctival hemorrhage: risk factors and potential indicators”. Clin Ophthalmol. 7: 1163–70. doi:10.2147/OPTH.S35062. PMC 3702240. PMID 23843690.

[pmid24825645-10] Weinreb RN, Aung T, Medeiros FA (2014). “The pathophysiology and treatment of glaucoma: a review”. JAMA. 311 (18): 1901–11. doi:10.1001/jama.2014.3192. PMC 4523637. PMID 24825645.

[pmid18037120-11] Galor A, Thorne JE (2007). “Scleritis and peripheral ulcerative keratitis”. Rheum Dis Clin North Am. 33 (4): 835–54, vii. doi:10.1016/j.rdc.2007.08.002. PMC 2212596. PMID 18037120.

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Health Dictionary

Red eye

Introduction