Conjunctivitis: Approach to the Child with a Red Eye

General Presentation

Red eye is also known as conjunctivitis.  Red eye is very common in children and a specific diagnosis can often be difficult as signs and symptoms are similar for many different etiologies.  There is a rapid onset of symptoms that are often self-limited. Conjunctivitis is characterized by the dilatation of superficial conjunctival blood vessels resulting in erythema and edema. Common symptoms include conjunctival injection (redness), discharge, matted eyelids and chemosis (swelling of conjunctiva). Ocular pain and photophobia are not common in conjunctivitis and tend to indicate a more serious etiology such as keratitis, scleritis, or corneal abrasion.  A decrease in visual acuity is not commonly associated with conjunctivitis and indicates a more serious condition.

Common etiologies

Table 1: Diagnosis of Conjunctivitis by Age

Age Group Common Etiology
Neonates* < 24 hrs Chemical conjunctivitis
< 1 week Neisseria gonorrhea
1-2 wks Chlamydia trachomatis
Infants and Toddlers Without otitis Haemolphilus. influenzae, Streptococcus pneumoniae
With otitis H. influenzae
School Age Children 1-5 years Herpes simplex virusVaricella-zoster
School Age Children and Adolescents Viral conjunctivitisAllergic conjunctivtis

Adapted from Diagnosis and Management of Pediatric Conjunctivitis 2003.

Questions to Ask

When a child presents with red eye, you must be able to identify potentially serious ocular conditions that will require immediate referral to an ophthalmologist.

  • Onset of redness – was the development gradual or sudden?
  • What are associated symptoms?  Ask about itchiness, lymphadenopathy, crusting, and lash matting.
  • Is there any discharge?  What type and how much? The discharge may be important in distinguishing viral, bacterial and allergic conjunctivitis.
  • Does the child wear contact lens? If so, the suspicion for Pseudomanal infection needs to be higher. Pseudomonas can perforate the cornea and so treatment must be initiated early with a bactericidal antibiotic.
  • Is there any swelling?
  • Does the child have photophobia? Is the child’s vision blurred?
  • Is there any ocular pain? If so, what type of pain?  Scratchy, gritty, well-defined pain likely indicates a corneal problem.  A deep, dull pain tends to indicate a more serious condition (such as iritis, scleritis, acute angle closure glaucoma).
  • Is there a personal or family history or atopy?  Is it spring or summer? Yes, to any of these questions points in the direction of allergic conjunctivitis?
  • What is the age of the child?  Is he/she school age??  Refer to table 1 for etiologies which are more common in certain age categories.
  • Is there any recent history of trauma?
  • Does the child wear contact lenses?  If so, the suspicion for Pseudomonas infection needs to be higher. Pseudomonas can perforate the cornea so treatment must be initiated early with a bactericidal antibiotic.
  • Remember it is extremely important to rule out serious ocular presentations; ocular pain and change in vision are indications for referral to an ophthalmologist.

Differential Diagnosis

  • Bacterial conjunctivitis: Purulent unilateral or bilateral discharge with conjunctival injection and edema
  • Viral conjunctivitis : Sudden onset hyperemia, pre-auricular lymphadenopathy and watery discharge. Herpetic lesions appear as dendritic ulcers and vesicular lid lesions; in recurrent infection it presents as a deep keratitis (see table 2)
  • Allergic conjunctivitis : Itchiness, bilateral chemosis greater than erythema, mucoid/watery discharge; associated disorders include rhinitis, asthma, eczema.  There is often a personal and/or family history of atopy.
  • Chemical conjunctivitis :  Neonate within 24 hrs due to silver nitrate
  • Foreign body: Unilateral, red, gritty feeling; visible or microscopic size
  • Blepharitis : Inflammation of the eyelid margin causing bilateral irritation, itching, hyperemia, crusting and lash matting.
  • Hordeola : Acute suppurative nodular inflammatory lesions of the eyelids associated with pain and redness; boil-like lesion (styes and chalazions)
  • Keratitis : Severe pain, corneal swelling, clouding, decreased vision, contact lens history; examination shows a white lesion.
  • Endophthalmitis : Emergent, sight threatening infection that usually follows trauma, surgery or hematogenous spread; extreme photophobia.
  • Dacrocystitis : obstructed lacrimal sac; pain, tenderness, edema, erythema and exudates in areas of lacrimal sac
  • Anterior uveitis (iridocyclitis) :associated with juvenile RA, Behcet diease and IBS; sudden onset pain, photophobia, blurred vision, irregular pupil, poor vision
  • Posterior uveitis (choroiditis) : no signs of erythema, decreased vision.  Etiology includes toxoplasmosis and histoplasmosis
  • Scleritis/Episcleritis : severe localized pain, intense unilateral erythema. Exam may show bluish-red discolouration. Associated with autoimmune illnesses.

Physical Examination

  • General well-being of the child.  Does the child look unwell?
  • Visual acuity using a Snellen’s chart.
  • Inspection of the pupils and conjunctivae.
  • Fundoscopic exam.
  • Fluorescein to check for abrasions.
  • Slit lamp exam (if available) to more closely assess conjunctivae, lashes, sclera, cornea and deeper eye structures.
  • Cultures are not routinely obtained because conjunctivitis is usually self limited or responds quickly to antibiotic treatment.
  • If you suspect scleritis, corneal abrasions, iritis, uveitis or other potentially serious ocular presentations, immediate referral to the ophthalmologist is necessary.


Viral and bacterial conjunctivitis have excellent prognoses. The major complication is keratitis leading to ulcerations and perforation; however, this is uncommon except for infections with N. gonorrhea.  Careful hand washing is very important to prevent the spread of conjunctivitis and thus all children need to be taught about proper hand washing techniques.

Remember that most causes of conjunctivitis resolve in about 7 days. If the red eye is persistent past this period, be sure to think of mimicking conditions such as lid disease or iritis associated with connective tissue diseases.


Table 2: Comparison of Bacterial and Viral conjunctivitis

Bacterial Viral
Common organisms Haemophilus influenzaeStreptococcus pneumoniaeMoraxella catarrhalis

Neisseria gonorrhea

Chlamydia trachomatis

Adenoviruses type 8, 19 EnterovirusesHerpes simplex virus
Incubation 24-72 hrs 1-14 days
Prevalent Age Neonates to toddlers School-age to adults
Photophobia Mild Moderate to severe
Blurred vision Common with discharge If keratitis present
Foreign body sensation Unusual Yes
Discharge Purulent discharge Watery discharge
Palpebral reaction Papillary response Follicular response
Preauricular lymph node Unusual for acute (<10%) More common (20%)
Chemosis Moderate Mild
Hemorrhagic conjunctivae Occasionally with Streptococcus or Haemophilus Frequent with enteroviruses
Associated disorders Otitis media Pharyngitis, URTI
End of contagious period 24 hr after start of effective treatment 7 days after onset of symptoms

Adapted from Nelson’s Essentials of Pediatrics and Diagnosis and Management of Pediatric Conjunctivitis 2003.

Note on Neonatal conjunctivitis

Neonatal conjunctivitis (Ophthamia neonatorum) is an extremely common form of conjunctivitis in the first month of life and is the most common infection in the neonatal period. In order of occurrence, the common causes of neonatal conjunctivitis include: chemical, chlamydial, bacterial and viral.  The timing and presentation of neonatal conjunctivitis are very useful in identifying the cause. Conjunctivitis within the first 24 hours of life is most commonly caused by an irritant reaction to silver nitrate used for gonorrhea prophylaxis.  This chemical conjunctivitis is characterized by watery discharge. This ocular reaction is decreased when using erythromycin or tetracycline prophylaxis.  Without prophylaxis, an infection with gonorrhea may present typically 1-7 days after birth with sudden onset, severe, grossly purulent conjunctivitis. If it is not recognized within 24 hours, it can rapidly progress to ulceration and perforation. Chlamydial conjunctivitis usually presents at 2 weeks of age with varying degrees of discharge, moderate conjunctival erythema and edema. There is no prophylaxis for chlamydial conjunctivitis.  Other common organisms responsible for causing bacterial conjunctivitis include Staphylococcus, Streptococcus and Pseudomonas.  Finally, <1% of neonatal conjunctivitis is accounted for by neonatal infection with herpes, commonly due to HSV-2.  It presents with clear discharge, lid swelling, clouding of the cornea and dendrite formation.


Kleigman RM, Marcdante KJ, Jenson HB, Behrman RE.  Nelson Essentials of Pediatrics 5th Edition.  Elsevier Saunders, 2006.

Teoh DL, Reynolds S. CME Review Article: Diagnosis and management of pediatric conjunctivitis. Pediatric Emergency Care 2003; 19:1.

Bal SK, Hollingworth GR. Red Eye. British Medical Journal 2005; 331:438.

Wirbelauer C.  Management of the Red Eye for the Primary Care Physician. The American Journal of Medicine 2006; 119: 302-306.


Written by: Anne Marie Jekyll

Edited by: Jeff Bishop

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