Conjunctivitis (Pink Eye/Eye Flu)
Conjunctivitis, commonly known as pink eye, is an inflammation of the conjunctiva, which is the outermost layer of the white part of the eye and the inner surface of the eyelid. This condition causes the eye to appear pink or reddish and may result in various symptoms, including pain, burning, scratchiness, or itchiness. The affected eye may also produce increased tears or become “stuck shut” in the morning due to discharge. Swelling of the white part of the eye and itchiness, particularly in allergic cases, are also common symptoms. Conjunctivitis, which can affect one or both eyes, is a prevalent condition worldwide.
Causes
- Infectious Causes:
- Viral: Viral conjunctivitis is the most common form of infectious conjunctivitis in adults, accounting for approximately 80% of cases. It is often associated with upper respiratory infections such as the common cold or a sore throat. Adenoviruses are the primary cause, responsible for 65% to 90% of viral conjunctivitis cases. Herpetic keratoconjunctivitis, caused by herpes simplex viruses, and acute hemorrhagic conjunctivitis, caused by enteroviruses, are other notable viral causes.
- Bacterial: Bacterial conjunctivitis is more common in children and accounts for about 70% of cases. The most common bacteria include Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Less frequently, Chlamydia trachomatis and Neisseria gonorrhoeae can cause bacterial conjunctivitis. This type of conjunctivitis typically presents with a rapid onset of conjunctival redness, swelling of the eyelid, and a sticky discharge.
- Non-Infectious Causes:
- Allergic: Allergic conjunctivitis results from an allergic reaction to substances like pollen, animal hair, dust mites, perfumes, or cosmetics. This type of conjunctivitis is characterized by redness, swelling, itching, and increased tear production. It is the most common type of conjunctivitis, affecting 15% to 40% of the population.
- Chemical: Chemical conjunctivitis is caused by exposure to acidic or alkaline substances, leading to conjunctival burns and inflammation. Alkali burns are particularly severe and can result in significant eye damage. Immediate irrigation with saline or Ringer’s lactate solution is crucial for treatment.
Signs and Symptoms
- General: Conjunctivitis typically presents with bloodshot eyes, redness, swelling of the conjunctiva, and watering of the eyes. The pupils should be normally reactive, and visual acuity should remain normal. Other common symptoms include:
- Viral: Excessive watering, itching, watery discharge, and symptoms of upper respiratory infections such as a common cold or sore throat. The infection usually starts in one eye but can easily spread to the other.
- Allergic: Redness, swelling, itching, and increased tear production due to histamine release from mast cells.
- Bacterial: Rapid onset of redness, swelling, sticky discharge, grittiness, and severe crusting around the infected eye, particularly in the morning.
Diagnosis
The diagnosis of conjunctivitis is often based on clinical signs and symptoms. In certain cases, a sample of the discharge may be taken for culture to determine the specific cause. Diagnostic methods include the following:
- Clinical Examination: A thorough eye examination, often using a slit lamp, to observe the conjunctiva and other eye structures.
- Culture Tests: Swabs for bacterial or viral cultures in persistent or severe cases.
- Patch tests are used to identify specific allergens in allergic conjunctivitis.
- Biopsy: Occasionally performed when granulomatous diseases or dysplasia are suspected.
Treatment
Treatment for conjunctivitis varies depending on the underlying cause.
- Viral Conjunctivitis: Most cases of viral conjunctivitis resolve on their own without specific treatment. Antihistamines or mast cell stabilizers may be used to alleviate symptoms. In cases of herpetic keratoconjunctivitis, antiviral medications like acyclovir are necessary.
- Bacterial Conjunctivitis: While bacterial conjunctivitis often resolves without treatment, antibiotics can shorten the duration of the illness. Antibiotics are recommended for contact lens wearers, immunocompromised individuals, and those with severe symptoms or infections caused by gonorrhea or chlamydia.
- Allergic Conjunctivitis: Mild cases can be managed with cool water rinses and artificial tears. More severe cases may require nonsteroidal anti-inflammatory medications, antihistamines, or topical steroid drops.
- Chemical Conjunctivitis: Immediate irrigation with saline or Ringer’s lactate solution is essential. Chemical burns, particularly alkali burns, require urgent medical attention to prevent severe eye damage.
Prevention
Preventative measures for conjunctivitis include:
- Hygiene: proper handwashing and avoiding touching the eyes with unwashed hands.
- Vaccination: Vaccination against pathogens such as Haemophilus influenzae, pneumococcus, and Neisseria meningitidis can help prevent certain types of conjunctivitis.
- Avoiding Allergens: Minimizing exposure to known allergens like pollen, dust mites, and animal dander.
Epidemiology
It is the most common eye disease, affecting millions of people annually. In the United States, acute conjunctivitis affects an estimated 3 to 6 million people each year. The condition imposes significant economic and social burdens, with costs related to treatment and loss of productivity. Seasonal trends have been observed, with bacterial conjunctivitis peaking from December to April, viral conjunctivitis in the summer months, and allergic conjunctivitis in the spring and summer.
Historical Outbreaks
Conjunctivitis can lead to significant outbreaks, as seen in September 2023 in Pakistan. The outbreak, which started in Karachi, quickly spread to Lahore, Rawalpindi, and Islamabad, resulting in over 86,133 reported cases in Punjab alone. The rapid spread of the disease led to the temporary closure of schools and highlighted the importance of effective public health measures in controlling infectious diseases.
Society and Culture
It imposes economic and social burdens. In the United States, the cost of treating bacterial conjunctivitis is estimated to be between $377 million and $857 million per year. Approximately 1% of all primary care office visits are related to conjunctivitis, with 70% of acute conjunctivitis cases presenting to primary care and urgent care facilities.
Summary
Conjunctivitis, or pink eye, is a common and often self-limiting condition that can be caused by viral, bacterial, allergic, or chemical factors. Proper diagnosis and treatment are essential for managing the condition and preventing its spread. Good hygiene practices, such as handwashing and avoiding contact with infected individuals, can help prevent conjunctivitis. Vaccination against specific pathogens also plays a crucial role in prevention. While most cases resolve without complications, severe or persistent symptoms may require further medical evaluation and treatment.
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