Conjunctivitis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]; Associate Editor(s)-in-Chief: Sara Mehrsefat, M.D. [3]

Conjunctivitis (con·junc·ti·vi·tis) is an inflammation of the conjunctiva (the outermost layer of the eye and the inner surface of the eyelids), most commonly due to an allergic reaction or an infection (usually bacterial or viral). Conjunctivitis may be classified based on the duration of symptoms into hyperacute, acute, or chronic. Additionally, based on the causality of the inflammation and age group, conjunctivitis may be classified into infective conjunctivitis (bacterial and viral), neonatal conjunctivitis (ophthalmia neonatorum), allergic conjunctivitis, keratoconjunctivitis sicca (dry eye syndrome), and superior limbic keratoconjunctivitis (SLK). Common causes of conjunctivitis include bacteria, viruses, and environmental factors. Viral conjunctivitis is the most common cause of infectious conjunctivitis both overall and in the adult population. Between 65% and 90% of cases of viral conjunctivitis are caused by adenoviruses. Bacterial conjunctivitis is the second most common cause. Allergic conjunctivitis is the most frequent cause, affecting 15% to 40% of the population. Noninfectious conjunctivitis includes keratoconjunctivitis sicca (dry eye syndrome) and superior limbic keratoconjunctivitis, which may caused by inflammation secondary to immune-mediated diseases. Prognosis for conjunctivitis usually good with treatment. Infective conjunctivitis resolves, in 65% of cases, within 2-5 days. Complete history will help determine the correct therapy. The symptoms of conjunctivitis differ based on the cause of the inflammation. Common symptoms to all forms of conjunctivitis include redness, excessive tearing, and irritation. Photophobia, itching, mucopurulent or non-purulent discharge, chemosis, burning eyes, blurred vision, and eyelid swelling are variable. Physical examination of patients with conjunctivitis is usually remarkable for conjunctival injections, epiphora, hyperemia, chemosis, and muco-purulent or watery discharge. However, ophthalmologic examination may be varies based on conjunctivitis subtypes. Laboratory tests are not often required in patients with mild conjunctivitis. Conjunctival cultures are generally reserved for conjunctivitis presenting with severe purulent discharge, and cases suspicious for gonococcal or chlamydial infection. Allergic conjunctivitis may be treated with artificial tears and topical antihistamines, vasoconstrictive agents, mast cell stabilizers, NSAIDs, and corticosteroids. Cool compresses are recommended to reduce eyelid and periorbital edema. Topical antimicrobial therapy is only recommended for patients with either bacterial or herpetic conjunctivitis, but not allergic or adenoviral conjunctivitis. Systemic antibiotic therapy is necessary to treat conjunctivitis due to Neisseria gonorrhoeae and Chlamydia trachomatis.

Conjunctivitis is an ancient disease. In 1750, neonatal conjunctivitis (ophthalmia neonatorum) was first described by S.T. Quellmaz. In 1883, Koch discovered the bacilli of two different forms of infectious conjunctivitis, or Egyptian ophthalmia.^[1][2]

Conjunctivitis may be classified based on the duration of symptoms into hyperacute, acute, and chronic.^[3][4] Additionally, conjunctivitis may be classified according to the causality of the inflammation or age groups into several subtypes: infective conjunctivitis (bacterial and viral), neonatal conjunctivitis (ophthalmia neonatorum), allergic conjunctivitis, keratoconjunctivitis sicca (dry eye syndrome), superior limbic keratoconjunctivitis, and chemical conjunctivitis.^[5][6]

Conjunctivitis is defined as inflammation of bulbar and/or palpebral conjunctiva. Conjunctivitis has many etiologies, but the majority of cases can be caused by allergies or infection. Infective conjunctivitis is an infection of the conjunctiva either caused by viruses or bacteria. Airborne antigens may be involved in the pathogenesis of allergic conjunctivitis. Common airborne antigens include pollen, grass, and weeds. Keratoconjunctivitis sicca (dry eye syndrome) is a multifactorial disease and associated with different medical conditions.^[7][8]

Common causes of conjunctivitis include bacteria, viruses, and environmental factors.^[3] Viral conjunctivitis is the most common cause of infectious conjunctivitis both overall and in the adult population. Bacterial conjunctivitis is the second most common cause and is responsible for the majority of cases in children(Haemophilus influenzae,Moraxella catarrhalis,Streptococcus pneumoniae). Most of the cases in adults are caused by Staphylococcus aureus. Allergic conjunctivitis is the most frequent cause, affecting 15% to 40% of the population. Noninfectious conjunctivitis includes keratoconjunctivitis sicca (dry eye syndrome) and superior limbic keratoconjunctivitis caused by inflammation secondary to immune-mediated diseases or mechanical irritation.^[7]

Conjunctivitis symptoms and signs are relatively non-specific. Even after biomicroscopy, laboratory tests are often necessary to determine the underlying pathophysiology with certainty. An eye examination can help to differentiate conjunctivitis from other medical conditions.^[9][10] Conjunctivitis must be differentiated from blepharitis, keratitis, and scleritis.

Conjunctivitis accounts for 1% of all primary care and emergency room visits. The incidence of viral conjunctivitis is approximately 80,000 per 100,000 cases with acute conjunctivitis. Viral conjunctivitis more commonly affects adults while bacterial conjunctivitis more commonly affects children. The prevalence of conjunctivitis varies according to the underlying cause, which may be influenced by the patient’s age, as well as the season of the year.^[11]

The most potent risk factor in the development of infective conjunctivitis is a direct or indirect contact with an infected person’s eye drainage. Common risk factors in the development of conjunctivitis are poor hygienic habits, contaminated personal articles, history of ocular diseases (dry eye, blepharitis, and anatomic abnormalities of the ocular surface), recent ocular surgery, medication use, and history of autoimmune disorders. Additionally, vaginal delivery is a risk factor for conjunctivitis in babies born to mothers infected with either Neisseria gonorrhoeae or Chlamydia trachomatis.^[12][13]

General screening for conjunctivitis is not recommended. However, according to the Centers for Disease Control and Prevention (CDC), screening for sexually transmitted diseases (STDs) is recommended among pregnant women to prevent conjunctivitis and other medical conditions in newborns.^[14]

If left untreated, viral conjunctivitis will generally clear without any complications. Bacterial conjunctivitis is often self-limited. If left untreated, bacterial conjunctivitis will clear within 1 or 2 weeks without any complications, and it is generally associated with a favorable long-term prognosis.^[9] Allergic conjunctivitis improves by eliminating or significantly reducing contact with the allergen. If left untreated, most cases of allergic conjunctivitis may resolve without any long-term consequences. Keratoconjunctivitis sicca associated with Sjögren’s syndrome is associated with a particularly poor prognosis and requiring a longer course of treatment.^[15][16][17] Prognosis for conjunctivitis is generally good with treatment.

The symptoms of conjunctivitis differ based on the cause of the inflammation. Redness, excessive tearing, and irritation are symptoms common to all forms of conjunctivitis. Photophobia, itching, mucopurulent or non-purulent discharge, chemosis, burning eyes, blurred vision and eyelid swelling are variable. Complete history will help to determine whether the condition is associated with any specific environmental or work-related exposure.^[15][9]

Physical examination of patients with conjunctivitis is usually remarkable for conjunctival injections, epiphora, hyperemia, chemosis, and muco-purulent or watery discharge. However, ophthalmologic examination may be varies based on conjunctivitis subtypes.^[18][7]

Laboratory tests are not often required in patients with mild conjunctivitis. Conjunctival cultures are generally reserved for recurrent conjunctivitis, conjunctivitis recalcitrant to therapy, conjunctivitis presenting with severe mucopurulent discharge, and cases suspicious for gonococcal or chlamydial infection.^[7][19]

There are no imaging findings associated with conjunctivitis. However, dynamic meibomian imaging (DMI) can be used to obtain a distinct picture of the entire everted inferior tarsal plate in a patient with keratoconjunctivitis sicca (dry eye syndrome).^[20]

Other diagnostic studies for viral conjunctivitis include rapid antigen testing.^[18] Other diagnostic studies for keratoconjunctivitis sicca (dry eye syndrome) conjunctivitis include corneal sensation, tear break up time, ocular surface staining, and Schirmer’s test.^[21][22]

Allergic conjunctivitis may be treated with artificial tears and topical antihistamines, vasoconstrictive agents, mast cell stabilizers, NSAIDs, and corticosteroids. Cool compresses are recommended to reduce eyelid and periorbital edema. Topical antimicrobial therapy is only recommended for patients with either bacterial or herpetic conjunctivitis, but not allergic or adenoviral conjunctivitis. Systemic antibiotic therapy is necessary to treat conjunctivitis due to Neisseria gonorrhoeae and Chlamydia trachomatis.

Surgical intervention is not recommended for the management of infective and neonatal conjunctivitis. Allergic conjunctivitis is a self-limited disease, and extensive surgery may not be acceptable. However, surgical techniques include superficial keratectomy and penetrating keratoplasty are usually reserved for severe cases of corneal involvement. Despite the availability of efficient tear substitutes, many patients with keratoconjunctivitis sicca (dry eye syndrome) experience severe corneal injuries and a subsequent loss of vision. Surgical techniques include lateral tarsorrhaphy, punctal plugs, lens therapy, amniotic membrane transplantation, and salivary gland duct transposition.^{[19][1][23][24][25][26][27]}

There are no formal established methods for primary prevention of allergic conjunctivitis, keratoconjunctivitis sicca (dry eye syndrome), and superior limbic keratoconjunctivitis. However, early determination of these conditions is very important in terms of morbidity.^[28]

Secondary prevention strategies following conjunctivitis include discontinued contact lens wear (infective conjunctivitis), ocular prophylaxis with 0.5% erythromycin ointment or 1% tetracycline hydrochloride (ophthalmia neonatorum), and avoiding the offending antigen (allergic conjunctivitis). Secondary prevention strategies following keratoconjunctivitis sicca (dry eye syndrome) include avoiding very dry environments, dusty areas, and prolonged visual tasks. There is no established method for secondary prevention of superior limbic keratoconjunctivitis (SLK). However, educating patients about disease process can improve compliance of patients with treatment, and help them to cope with the often prolonged symptoms.^{[15][28][29][30][27]}

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sara Mehrsefat, M.D. [2]

Conjunctivitis is an ancient disease, and was first described by S.T. Quellmaz.^[1] In 1881, Crédé introduced 2% silver nitrate for the first time as a prophylaxis treatment method for conjunctivitis in the newborns in Leipzig.^[2]

• In 1750, neonatal conjunctivitis (ophthalmia neonatorum) was first described by S.T. Quellmaz.^[1]
• In 1881, Crédé introduced 2% silver nitrate for the first time as a prophylaxis treatment method for conjunctivitis in the newborns in Leipzig.^[2]
• In 1883, Koch discovered the bacilli of two different forms of infectious conjunctivitis or Egyptian ophthalmia.
• In 1886, Weeks discovered the same organism to be the cause of pink eye.^[3]
• In 1953, Micheal Hogan first described the association between atopic dermatitis and conjunctival inflammation.^[4]
• In 1963, Thygeson and Kimura first described superior limbic keratoconjunctivitis as a chronic, localized, filamentary conjunctivitis, and later this condition was given its name, superior limbic keratoconjunctivitis, by Theodore.^[5]
• In 1968, Tenzel and Corwin were the first to discover the association between thyroid abnormalities and development of superior limbic keratoconjunctivitis.^[6]
• In 1969, acute hemorrhagic conjunctivitis was first described as occurring in Ghana.^[7]
• Between 1981-2003, four major epidemics of acute hemorrhagic conjunctivitis had occurred in the Western Hemisphere.^[8]
• In 2006, an epidemic acute hemorrhagic conjunctivitis (involving more than 200,000 people) was reported as occurring in Brazil.^[9]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [3]; Associate Editor(s)-in-Chief: Sara Mehrsefat, M.D. [4]

Conjunctivitis may be classified based on the duration of symptoms into hyperacute, acute, and chronic.^[1][2] Additionally, conjunctivitis may be classified according to the causality of the inflammation or age groups into several subtypes: infective conjunctivitis (bacterial and viral), neonatal conjunctivitis (ophthalmia neonatorum), allergic conjunctivitis, keratoconjunctivitis sicca (dry eye syndrome), superior limbic keratoconjunctivitis, and chemical conjunctivitis.^[3][4]

Based on the duration of symptoms, conjunctivitis may be classified into hyperacute, acute (less than 3 weeks), and chronic (greater than 3 weeks).

According to the etiology and age groups, conjunctivitis may be classified into:^{[5][6][5][7][8] [9]}

• Infective conjunctivitis
  • Viral, bacterial, fungal, rickettsial, protozoal, and parasitic
• Neonatal conjunctivitis (ophthalmia neonatorum)
  • Bacterial, viral, and chemical
• Allergic conjunctivitis
  • Seasonal allergic conjunctivitis
  • Perennial allergic conjunctivitis
  • Vernal keratoconjunctivitis
  • Atopic keratoconjunctivitis
  • Giant papillary conjunctivitis
• Keratoconjunctivitis sicca (dry eye syndrome)
• Superior limbic keratoconjunctivitis (SLK)
• Chemical or irritative conjunctivitis

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [3]; Associate Editor(s)-in-Chief: Sara Mehrsefat, M.D. [4]

Conjunctivitis is defined as inflammation of bulbar and/or palpebral conjunctiva. Conjunctivitis has many etiologies, but the majority of cases can be caused by allergies or infection. Infective conjunctivitis is an infection of the conjunctiva either caused by viruses or bacteria. Airborne antigens may be involved in the pathogenesis of allergic conjunctivitis. Common airborne antigens include pollen, grass, and weeds. Keratoconjunctivitis sicca (dry eye syndrome) is a multifactorial disease and associated with different medical conditions.^[1][2]

Infective conjunctivitis is an infection of the conjunctiva either caused by viruses or bacteria, such as adenovirus, Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae. Any change in the host defense, or in the species of normal flora of the eye, can lead to clinical infection and conjunctivitis.

Change in the normal flora may occur by:^[3]

• External contamination
• Contact lens wear
• Swimming

Infective conjunctivitis is usually spread by:^[1][2]

• Direct contact with the infected person’s eye drainage or drainage from the person’s cough, sneeze, or runny nose
• Contact with the infected person’s fingers, hands, or objects (eye makeup applicators, towels, shared eye medications)
• Adjacent infectious sites (rubbing of the eyes)

Neonatal conjunctivitis is occurring in a newborn during the first month of life, and often known as ophthalmia neonatorum. Neonatal conjunctivitis is mainly caused by sexually transmitted diseases agents such as Chlamydia trachomatis, Neisseria gonorrhoeae, and herpes simplex virus (HSV). Chlamydia trachomatis is the most common cause of ophthalmia neonatorum in the developed countries because of higher prevalence of chlamydia as a sexually transmitted disease.

The recognized routes of transmission of the organisms to the newborns include:^[4]

• Infected birth canal during vaginal birth
• Transmembrane transmission of the infection
• Transplacental transmission of the infection

Additionally, silver nitrate drops (ocular prophylaxis) can cause ocular irritation and result in chemical conjunctivitis in newborn.^[5]

Development of allergic conjunctivitis is the result of type 1 hypersensitivity reaction in the conjunctiva. Allergic conjunctivitis is caused by the immunoglobulin E (IgE) mediated reaction to environmental allergens. Following exposure to environmental allergens in sensitized individual, the cross-linking of IgE at the mast cell membrane level results in subsequent cell degranulation and secretion of histamine, leukotriene, and prostaglandin. The principal effects of these products are vasodilation and smooth-muscle contraction. Common airborne antigens involve in the pathogenesis of allergic conjunctivitis include pollen, grass, and weeds.^[6][7]

Combination of type 1 and type 4 hypersensitivity reactions may be responsible for giant papillary conjunctivitis. Also, prolonged mechanical irritation to the superior tarsal conjunctiva of the upper lid from foreign bodies may also be a contributing factor in giant papillary conjunctivitis.^[8][9]

Keratoconjunctivitis sicca (dry eye syndrome) is a multifactorial disease and associated with different medical conditions such as:^[10][11]

• Sjögren’s syndrome
• Ocular surface disease
• Ocular allergy
• Dysfunction of the lacrimal gland with reduced tear production and mucin deficiency
• Anxiety disorder
• Depression

The exact pathogenesis of the keratoconjunctivitis sicca associated Sjögren’s syndrome is not fully understood. It is thought that keratoconjunctivitis sicca associated Sjögren’s syndrome is the result of lymphocytic infiltration and malfunction of the lacrimal glands. This lymphasitic infiltration (CD4+ T cells and B cells) may result in lacrimal gland dysfunction and reduced tear production (mediated by apoptosis).

Superior limbic keratoconjunctivitis (SLK) is disease characterized by inflammation of the upper palpebral and superior bulbar conjunctiva. The exact pathogenesis of superior limbic keratoconjunctivitis is not fully understood, a mechanical hypothesis seems most attractive. It is thought that mechanical trauma from tight upper lids or loose redundant conjunctiva can lead to the disruption of normal epithelium. Also, the association between thyroid abnormalities (graves ophthalmopathy) and superior limbic keratoconjunctivitis has been reported.^[12][13][14]

On gross pathology, the following are characteristic findings of conjunctivitis:^[15]

• Conjunctival injection
• Mucopurulent discharge or non-purulent discharge
• Pseudomembrane formation
• Chemosis
• Eyelid edema
• Conjunctival hemorrhage (specific for acute hemorrhagic conjunctivitis)

On microscopic histopathological analysis, the following are characteristic findings of conjunctivitis:^[16]

• Mild spongiotic reaction pattern (low power view of the histology)
• Stromal infiltration by polymorphonuclear cells, leukocytes, plasma cells, mastocytes, and lymphocyte
• Eosinophils (allergic conjunctivitis)
• Numerous neutrophils (bacterial conjunctivitis)
• Hyperplastic with increase numbers of plasma cell (chronic conjunctivitis)
• Keratinization of the superior limbus (superior limbic keratoconjunctivitis (SLK))
• Dyskeratosis (superior limbic keratoconjunctivitis (SLK))

The following are gross and microscopic images associated with conjunctivitis:

• 
  Viral conjunctivitis – By Joyhill09 – I took this photo with a Nikon D40 of my eye infected with conjunctivitis, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=18954730
• 
  Acute hemorrhagic conjunctivitis – By James Heilman, MD – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=27401136
• 
  Neonatal conjunctivitis – Source: https://www.cdc.gov/

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [4]; Associate Editor(s)-in-Chief: Ogheneochuko Ajari, MB.BS, MS [5], Sara Mehrsefat, M.D. [6]

Common causes of conjunctivitis include bacteria, viruses, and environmental factors.^[1] Viral conjunctivitis is the most common cause of infectious conjunctivitis both overall and in the adult population. Bacterial conjunctivitis is the second most common cause and is responsible for the majority of cases in children. Allergic conjunctivitis is the most frequent cause, affecting 15% to 40% of the population. Noninfectious conjunctivitis includes keratoconjunctivitis sicca (dry eye syndrome) and superior limbic keratoconjunctivitis may cause by inflammation secondary to immune-mediated diseases or mechanical irritation.^[2]

Viral conjunctivitis^[3]

• Adenovirus (most common)
• Herpes simplex virus (HSV) type 1 and 2
• Varicella zoster virus
• Picornaviruses (Coxsackievirus A24 and Enterovirus 70)
• Molluscum contagiosum
• Rubella virus
• Epstein-Barr virus (EBV)

Bacterial conjunctivitis^[4]

• Gram-positive bacteria
  • Staphylococcus aureus
  • Methicillin-resistant Staphylococcus aureus (common in nursing homes)
  • Streptococcus pneumoniae
• Gram-negative bacteria
  • Pseudomonas aeruginosa
  • Serratia marcescens
  • Haemophilus influenzae (most common pathogen in children)
  • Moraxella catarrhalis
  • Chlamydia trachomatis (sexually transmitted bacteria)
  • Neisseria gonorrhoeae (sexually transmitted bacteria)

Neonatal conjunctivitis^[5][6]

• Septic
  • Chlamydia trachomatis
  • Neisseria gonorrhoeae
  • Herpes simplex virus
  • Pseudomonas aeruginosa (non–sexually transmitted bacteria)
  • Staphylococcus aureus (non–sexually transmitted bacteria)
• Aseptic
  • Chemical (silver nitrate solution)

Allergic conjunctivitis^[3]

• Allergens (pollen, animal dander, dust mites, or molds)

Keratoconjunctivitis^[7]

• Lacrimal gland dysfunction (Sjögren’s syndrome) with reduced tear production
• Reflex hyposecretion
• Mucin deficiency
• Low blink rate
• Mechanical trauma
• Vitamin A deficiency
• Autoimmune diseases
• Unknown etiology

Irritative Conjunctivitis

• Contact lenses
• Lens solutions
• Chlorine in a swimming pool
• Smog
• Cosmetics

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sara Mehrsefat, M.D. [2]

Conjunctivitis must be differentiated from blepharitis, keratitis, and scleritis.^[1][2] Conjunctivitis symptoms and signs are relatively non-specific. Even after eye examination, laboratory tests are often necessary to determine the underlying pathophysiology with certainty.

A mucopurulent discharge strongly suggests bacterial cause, unless there is known exposure to toxins. Infection with Neisseria gonorrhoeae and Chlamydia trachomatis should be suspected if the discharge is particularly thick and copious. Bacterial conjunctivitis must be differentiated from:^[1][2]

• Viral conjunctivitis
• Keratoconjunctivitis sicca (dry eye syndrome)
• Glaucoma
• Blepharitis
• Uveitis
• Iritis
• Keratitis
• Episcleritis
• Scleritis
• Neisseria meningitis (it can lead to fatal meningeal or systemic infection in the patient with hyperacute conjunctivitis due to Neisseria gonorrhoeae)

A diffuse, highly contagious, characterized by watery discharge, less injected conjunctivitis (looking pink rather than red) suggests a viral cause. Viral conjunctivitis must be differentiated from:^[3]

• Bacterial conjunctivitis
• Keratoconjunctivitis
• Nasolacrimal duct obstruction
• Foreign body
• Keratitis
• Uveitis
• Pharyngoconjunctival fever

Neonatal conjunctivitis must be differentiated from:^[4][5]

• Dacrocysitis
• Congenital glaucoma
• Nasolacrimal duct obstruction
• Preseptal/Orbital cellulitis
• Keratitis

Allergic conjunctivitis has a protracted course, with the severity of symptoms waxing and waning throughout the allergy season. It is characterized by itchy eyes, tearing, bilateral eye redness, and watery discharge. Allergic conjunctivitis must be differentiated from:^[6]

• Viral conjunctivitis
• Bacterial conjunctivitis

Keratoconjunctivitis sicca (dry eye syndrome) must be differentiated from:^[7][8]

• Allergic conjunctivitis (atopic and vernal keratoconjunctivitis)
• Blepharitis
• Bell’s palsy
• Keratoconjunctivitis sicca (dry eye syndrome)
• Thyroid ophthalmopathy

Superior limbic keratoconjunctivitis (SLK) is chronic condition with remission and exacerbations, and it must be differentiated from:^[9]

• Infective conjunctivitis
• Allergic conjunctivitis
• Keratoconjunctivitis sicca (dry eye syndrome)
• Floppy eyelid syndrome
• Thyroid ophthalmopathy
• Ocular surface squamous neoplasia
• Sebaceous gland carcinoma
• Episcleritis
• Trachoma

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sara Mehrsefat, M.D. [2]

Conjunctivitis accounts for 1% of all primary care and emergency room visits. The incidence of viral conjunctivitis is approximately 80,000 per 100,000 cases with acute conjunctivitis. Viral conjunctivitis more commonly affects adults while bacterial conjunctivitis more commonly affects children.

• The prevalence and incidence of conjunctivitis varies according to the underlying cause, which may be influenced by the patient’s age, as well as the season of the year.^[1]

• The incidence of viral conjunctivitis is approximately 80,000 per 100,000 cases with acute conjunctivitis.
• The incidence of viral conjunctivitis caused by adenoviruses approximately ranges from 65,000 to 90,000 cases per 100,000 cases with viral conjunctivitis .
• The incidence of viral conjunctivitis caused by herpes simplex virus (HSV) ranges from 1,300 to 4,800 cases per 100,000 cases with acute conjunctivitis.^[2]
• The incidence of bacterial conjunctivitis was estimated to be 1,350 cases per 100,000 cases with acute conjunctivitis.^[3]

• Worldwide, neonatal conjunctivitis or ophthalmia neonatorum still blinds approximately 10,000 babies annually.^[4]

• The prevalence of allergic conjunctivitis is estimated to range from 6,000 to 40,000 cases per 100,000 individuals annually.^[5][6]

• The prevalence of keratoconjunctivitis sicca (Dry eye syndrome) approximately ranges from 10,000 to 30,000 cases per 100,000 individuals annually.^[7]

• Viral conjunctivitis commonly affects adults, and bacterial conjunctivitis commonly affects children.
• The incidence of infective conjunctivitis is higher in children <1 year old (8,000 cases per 100,000 patient) than in children >4 years of age (1,200 cases per 100,000 patient).^[8]
• Vernal keratoconjunctivitis (VKC), an allergic conjunctivitis subtype, commonly affects young males.^[9]
• Keraroconjunctivitis sicca commonly affects patients older than 40 years.^[10]
• Superior limbic keratoconjunctivitis (SLK) commonly affects middle-aged people (around the sixth decade of life).^[11]

• Infective Conjunctivitis occurs equally in males and females.^[12]
• The incidence of neonatal conjunctivitis does not vary by gender.^[13]
• Women are more commonly affected with keratoconjunctivitis sicca associated with Sjögren’s syndrome than men. The female to male ratio is approximately 9 to 1.^[14]
• Women are more commonly affected with Superior limbic keratoconjunctivitis (SLK) than men. The female to male ratio is approximately 3 to 1.^[15]

• The prevalence of Infective conjunctivitis does not vary by race.^[16]
• Vernal keraroconjunctivitis commonly affects dark-skinned individuals from Africa and India.^[17]
• Keraroconjunctivitis sicca usually affects individuals of the Hispanic and Asian populations.^[18]

Prevalence of neonatal conjunctivitis has decreased significantly in developed countries since the abandonment of silver nitrate as topical prophylaxis. Current prevalence of neonatal conjunctivitis in developed countries are 5 per 1,000 live births.^[19]

• In Belgium and the Netherlands, the prevalence of neonatal conjunctivitis due to gonococcal infection was estimated 0.04 per 1,000 live births.^[20]
• In the United States, the prevalence of neonatal conjunctivitis due to gonococcal infection was estiamted 0.3 per 1,000 live births.
• In the United States, the prevalence of neonatal conjunctivitis caused by chlamydial infection was estimated 5 to 60 cases per 1,000 live births.
• In the United Kingdom, the prevalence of neonatal conjunctivitis caused by chlamydial infection was estimated 4 cases per 1,000 live births.^[21]
• In the United States, the incidence of bacterial conjunctivitis is 23,000 per 100,000 cases (in the 0-2 year age range), 28,000 per 100,000 cases (in the 3-9 year range), 13,000 per 100,000 cases (in the 10-19 year range) with the remaining 36,000 per 100,000 cases (in adults).^[22]

• In developing countries, the incidence of bacterial conjunctivitis is continuing to decrease.

• In the Africa, the incidence of neonatal conjunctivitis is still high.^[21]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sara Mehrsefat, M.D. [2]

The most potent risk factor in the development of infective conjunctivitis is a direct or indirect contact with an infected person’s eye drainage. Common risk factors in the development of conjunctivitis are poor hygienic habits, contaminated personal articles, history of ocular diseases (dry eye, blepharitis, and anatomic abnormalities of the ocular surface), recent ocular surgery, medication use, and history of autoimmune disorders. Additionally, vaginal delivery is a risk factor for conjunctivitis in babies born to mothers infected with either Neisseria gonorrhoeae or Chlamydia trachomatis.^[1][2]

Common risk factors in the development of infective conjunctivitis include:^[2][3][4]

• Poor hygiene
• Contact lens misuse
• Contaminated personal articles
• Crowded living or social conditions (elementary schools, military barracks)
• History of ocular diseases including dry eye, blepharitis, and anatomic abnormalities of the ocular surface and lids
• Recent ocular surgery, exposed sutures, or ocular foreign bodies
• Chronic use of topical medications
• Immune compromise
• Winter/Summer months (bacterial conjunctivitis peaks in the winter and viral conjunctivitis peaks in the summer)

Common risk factors in the development of neonatal conjunctivitis include:^[5][6][7]

• Maternal infections harbored in the mother’s birth canal
• HIV infected mothers
• Exposure of the infant to infectious organisms
• Premature rupture of membranes (PROM)
• Inadequacy of ocular prophylaxis after birth
• Silver nitrate exposure
• Ocular trauma during delivery
• Mechanical ventilation
• Prematurity
• Poor prenatal care
• Poor hygienic delivery conditions

Common risk factors in the development of allergic conjunctivitis include:^[8][9]

• Pollen from trees and grass
• Animal skin and secretions, such as saliva
• Perfumes
• Cosmetics
• Air pollution
• Smoke
• Spring/Summer months

Common risk factors in the development of keratoconjunctivitis sicca (dry eye syndrome) include:^[10][11][12]

• Allergies
• Decreased hormones (aging and pregnancy)
• Thyroid eye conditions
• Blepharitis
• Medication use (antihistamines, beta-blockers, pain relievers, sleep aid, diuretics, hormone replacement, and oral contraceptives)
• Autoimmune disorders (Sjogren’s syndrome, lupus, and rheumatoid arthritis)
• Eye surgery
• Infrequent blinking (e.g., frequent staring at computer and Parkinson’s)
• Environmental (dusty or windy)
• Contact lens use
• Neurologic conditions (stroke, Bell’s palsy, Parkinson’s, trigeminal nerve dysfunction)
• Uveitis
• Iritis
• Diabetes
• Vitamin A deficiency

Common risk factors in the development of superior limbic keratoconjunctivitis (SLK) include:^[13][14]

• Mechanical soft-tissue microtrauma (conjunctiva laxity)
• Morphologic changes in superior conjunctival
• Prolonged eyelid closure
• Thyroid abnormalities

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Sara Mehrsefat, M.D. [2]

General screening for conjunctivitis is not recommended. However, according to the Centers for Disease Control and Prevention (CDC), screening for sexually transmitted diseases (STDs) is recommended among pregnant women to prevent conjunctivitis and other medical conditions in newborns.^[1]

General screening for conjunctivitis is not recommended. However, if a baby is born to a mother who has an sexually transmitted disease (STD), during delivery the bacteria (Chlamydia trachomatis, Neisseria gonorrhoeae) or virus (Herpes simplex virus) can pass from the birth canal into the baby’s eyes, and cause septic conjunctivitis. Antibiotic ointment or eye drops is given to all babies immediately after birth to prevent conjunctivitis and other medical conditions in newborns. Occasionally, this treatment causes a mild chemical conjunctivitis, which is usually self-limiting. Screening has been recommended by CDC in pregnant women for sexually transmitted diseases (STDs) to prevent spreading the infection to the baby.^[1][2]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]; Associate Editor(s)-in-Chief: Sara Mehrsefat, M.D. [3]

If left untreated, viral conjunctivitis will generally clear without any complications. Bacterial conjunctivitis is often self-limited. If left untreated, bacterial conjunctivitis will clear within 1 or 2 weeks without any complications, and it is generally associated with a favorable long-term prognosis.^[1] Allergic conjunctivitis improves by eliminating or significantly reducing contact with the allergen. If left untreated, most cases of allergic conjunctivitis may resolve without any long-term consequences. Keratoconjunctivitis sicca associated with Sjögren’s syndrome is associated with a particularly poor prognosis and requiring a longer course of treatment.^[2][3][4] Prognosis for conjunctivitis is generally good with treatment.

Viral conjunctivitis is often caused by adenovirus. It presents with watery discharge, hyperemia, chemosis, and lymphadenopathy. If left untreated, most cases of viral conjunctivitis are mild and will clear in 7 to 14 days without any long-term consequences. if complications arise, viral conjunctivitis can take two or more weeks to resolve. Some cases of viral conjunctivitis may develop stromal or subepithelial abnormalities. In such cases, if subepithelial infiltrates are in the pupillary axis, they may lead to decreased vision. Usually stromal abnormalities may persist for months to years, long after the epithelial changes have resolved.^[1][2][5]

Acute hemorrhagic conjunctivitis is often caused by picornavirus. It presents with a severe red, swollen eyes as well as subconjuntival hemorrhaging, and will clear up in 5 to 7 days. If left untreated, acute hemorrhagic conjunctivitis almost always resolves without sequelae.^[6]

Bacterial conjunctivitis presents with red eye, mucopurulent discharge, and chemosis. The incubation period for bacterial conjunctivitis is estimated to be 1 to 7 days. If left untreated, most cases of bacterial conjunctivitis will clear in 7 to 10 days without any long-term consequences. If left untreated, In patients who have purulent or mucopurulent discharge (suspected chlamydial and gonococcal conjunctivitis), who wear contact lenses, and who are immunocompromised, conjunctivitis may cause corneal damage (such as corneal ulcer, scar, and perforation), sepsis, and meningitis. This may lead to permanent blindness and death.^[1][2][7]

Hyperacute bacterial conjunctivitis (HBC) is often caused by Neisseria gonorrhoeae in sexually active adults. It presents with a severe copious purulent discharge, eyelid swelling, eye pain on palpation, preauricular adenopathy, and decreased vision. If left untreated, hyperacute bacterial conjunctivitis may cause corneal involvement, and ultimately corneal perforation.^[8]

Neonatal conjunctivitis is one of the most common infections occurring in the first month of life. Chemical conjunctivitis secondary to silver nitrate solution application usually occurs in the first day of life, and disappears spontaneously within 2- 4 days. In the absence of adequate prophylaxis, 30% to 42% of infants born by vaginal delivery to infected mothers will develop gonococcal conjunctivitis. Gonococcal conjunctivitis tends to occur 2-7 days after birth, and tends to be more severe than other causes of ophthalmia neonatorum. It presents with severe bilateral purulent conjunctivitis, tearing, and eyelids swelling. If left untreated, gonococcal conjunctivitis may cause corneal involvement such as corneal ulceration, diffuse opacification, and corneal perforation. This may lead to blindness, sepsis, or death. The onset of chlamydial conjunctivitis is usually later than gonococcal conjunctivitis. In the absence of adequate prophylaxis, 30%-50% of infants born by vaginal delivery to infected mothers will develop chlamydial conjunctivitis. The incubation period is 5-14 days. Chlamydial conjunctivitis presents with mild hyperemia, watery discharge, eyelid swelling, papillary reaction, and pseudomembrane formation. If left untreated, chlamydial conjunctivitis can progress to copious and purulent discharge. This may lead to central corneal opacification and blindness. Herpetic conjunctivitis is a rare cause of neonatal conjunctivitis. Herpetic conjunctivitis usually occurs within the first 2 weeks after birth and has an incubation period of approximately 6-14 days. If left untreated, HSV conjunctivitis can cause corneal scarring and ulceration. Additionally, disseminated HSV infection can cause central nervous system (CNS) involvement. Ophthalmia neonatorum caused by pseudomonas is rare but can present with eyelid edema, erythema, and purulent discharge. If left untreated, ophthalmia neonatorum can progress to corneal perforation, endophthalmitis, blindness, and possibly death.^[9][10][11]

Allergic conjunctivitis usually presents with itching of the eyes and eyelid swelling. Seasonal allergic conjunctivitis is the most common form of the condition, and symptoms are related to season-specific aeroallergens. If left untreated, most cases of allergic conjunctivitis improve by eliminating or significantly reducing contact with the allergen (pollen or animal dander) without any long-term consequences.^[12][13][14]

Keratoconjunctivitis sicca (dry eye syndrome) presents with a foreign body sensation, mucoid discharge, ocular dryness, excessive tearing (reflex secretion), photophobia, itching, and blurry vision. Symptoms tend to be worse toward the end of the day with prolonged use of the eyes. If left untreated, it can progress to corneal ulceration, corneal perforation, and ultimately permanent blindness.^[3][15][16]

Superior limbic keratoconjunctivitis (SLK) symptoms develop around the sixth decade of life, and include a foreign body sensation, burning sensation, pruritus, and dry eye sensation. Superior limbic keratoconjunctivitis is typically associated with remission as the natural history and eventual total resolution, although symptoms may last for years.^[4][17]

Complications to viral conjunctivitis include:^[5][18]

• Bacterial superinfection
• Keratitis
• Subepithelial infiltrates
• Corneal ulceration with keratoconjunctivitis
• Chronic infection

Complications to bacterial conjunctivitis include:^[19][20]

• Corneal perforation
• Keratitis
• Corneal epithelial defects

Complications to neonatal conjunctivitis include:^[11][21]

• Ocular complications
  • Pseudomembrane formation
  • Corneal edema
  • Thickened palpebral conjunctiva
  • Peripheral pannus formation
  • Corneal opacification
  • Staphyloma
  • Corneal perforation
  • Endophthalmitis
  • Loss of eye and blindness
• Systemic complications of chlamydia conjunctivitis
  • Pneumonia
  • Otitis
  • Pharyngeal and rectal colonization
• Systemic complications of gonococcal conjunctivitis
  • Arthritis
  • Meningitis
  • Anorectal infection
  • Septicemia

Complications to allergic conjunctivitis include:^[13][14]

• Conjunctivochalasis (chronic recurrences)
• Corneal ulceration
• Corneal opacification
• Visual loss
• Steroid induced intraocular pressure elevations
• Cataract

Complications to Keratoconjunctivitis sicca (dry eye syndrome) include:^[15][16]

• Corneal ulceration
• Corneal erosions
• Corneal neovascularization
• Corneal scarring
• Corneal thinning
• Corneal perforation

• Viral conjunctivitis is often associated with a favorable long-term prognosis. However, viral conjunctivitis associated with subepithelial infiltrates may last for several months and cause decreased vision.^[5][18]
• Acute hemorrhagic conjunctivitis almost always resolves without sequelae, and has a good visual prognosis.^[6]
• Bacterial conjunctivitis is often associated with a favorable long-term prognosis.

Early detection and early treatment of extremely pathogenic bacteria, such as Chlamydia trachomatis or Neisseria gonorrhoeae, is associated with a good prognosis.^[19][20]

• Early detection and early treatment of hyperacute bacterial conjunctivitis (HBC) is associated with a good prognosis.^[22]
• Early detection and early treatment of neonatal conjunctivitis is associated with a good prognosis.^[11][21]
• Allergic conjunctivitis is associated with a favorable long-term prognosis. However, atopic keratovonjunctivitis and vernal keratoconjunctivitis (allergic conjunctivitis subtypes) are associated with poor outcomes.^[23]
• The prognosis of Keratoconjunctivitis sicca (dry eye syndrome) associated with Sjögren’s syndrome is poor. These patients require a longer course of treatment.^[16]
• Superior limbic keratoconjunctivitis (SLK) is associated with excellent prognosis.^[4][17]

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