OVERVIEW

What is conjunctivitis?

The conjunctiva is the thin membrane covering the white part of the eye and the inner surface of the eyelids. Conjunctivitis refers to inflammation of the conjunctiva^[1].

Is conjunctivitis common?

Yes.

The exact incidence of conjunctivitis is unclear, but it can occur in all age groups, with a higher prevalence among adolescents. It is more common in spring and autumn^[1].

What are the types of conjunctivitis?

1. Based on etiology, conjunctivitis can be divided into two types^[1]:

   • Infectious: Caused by pathogenic microorganisms such as bacteria (e.g., Staphylococcus aureus, Streptococcus pneumoniae), viruses (e.g., varicella-zoster virus, herpes simplex virus), or chlamydia.
   • Non-infectious: Caused by physical irritants (e.g., wind, dust, UV radiation) or chemical damage (e.g., acids, alkalis, toxic gases). Some cases may also result from immune factors like allergies or systemic diseases such as tuberculosis or syphilis^[2].

2. Based on disease course, conjunctivitis can be classified into three types^[2]:

   • Acute conjunctivitis: Incubation period ranges from 10 hours to 2–3 days, with rapid progression and abundant purulent discharge.
   • Subacute conjunctivitis: Incubation period is 1–3 days, duration less than three weeks, and more common in spring and autumn.
   • Chronic conjunctivitis: Slow progression, prolonged duration, lasting more than three weeks^[2].

SYMPTOMS

What are the common manifestations of conjunctivitis?

Common symptoms of conjunctivitis include eye redness (visible blood vessels or redness on the eye surface), foreign body sensation, burning, itching, photophobia (sensitivity to light), excessive tearing, and increased discharge (which may make it difficult to open the eyes upon waking in the morning). Eye pain may also occur in some cases^[1].

What are the symptoms of allergic conjunctivitis?

Allergic conjunctivitis is an inflammatory reaction of the conjunctiva triggered by exposure to allergens. Symptoms may include eye itching, redness, eyelid swelling, and thick, stringy discharge. Systemic allergic reactions, such as allergic infections or hives, may also occur.

What are the symptoms of bacterial conjunctivitis?

Initially, bacterial conjunctivitis usually affects one eye but can spread to both eyes through hand contact. Depending on the causative bacteria, symptoms may include varying degrees of eye redness, purulent or mucopurulent discharge, photophobia, tearing, and eyelid swelling. If the cornea is affected, some degree of vision impairment may occur.

What are the symptoms of viral conjunctivitis?

Typical symptoms of viral conjunctivitis include eye redness, foreign body sensation, watery discharge, eye pain, photophobia, and eyelid swelling. It is highly contagious and commonly referred to as "pink eye."

Can conjunctivitis cause long-term effects after recovery?

Not necessarily.

Most types of conjunctivitis do not leave lasting complications, though some may cause vision impairment if the inflammation affects the cornea.

Severe or chronic conjunctivitis may lead to irreversible damage, such as conjunctival scarring, adhesions, eyelid deformities, or secondary dry eye syndrome^[1].

CAUSES

How is conjunctivitis caused?

Common causes of conjunctivitis include^[1]:

• Infection by pathogenic microorganisms such as bacteria, viruses, chlamydia, fungi, or parasites.
• Allergies, such as pollen allergies.
• Immune-related diseases, like dry eye syndrome.
• Chemical damage from windblown dust, smoke, UV exposure, or acidic/alkaline/toxic gases.
• Systemic diseases, such as syphilis, tuberculosis, or thyroid disorders.
• Diseases of adjacent tissues affecting the conjunctiva, including conditions of the cornea, eyelids, sclera, or nasal cavity.

What are the common viruses causing viral conjunctivitis?

Common viruses that may lead to conjunctivitis include: adenovirus (types 8, 19, and 37), enterovirus, varicella-zoster virus, herpes simplex virus, measles virus, and hantavirus.

Is conjunctivitis contagious? What are the transmission routes?

Some forms of conjunctivitis are contagious^[1].

Infectious conjunctivitis spreads through contact, commonly via unwashed hands rubbing the eyes, sharing towels or washbasins, or using shared eye cosmetics^[3].

DIAGNOSIS

How to diagnose conjunctivitis?

Diagnosis is generally based on the following points^[1]:

• Medical history: Doctors usually inquire about infectious disease history or allergy history.
• Physical examination: Using ophthalmic instruments to observe signs of conjunctivitis, such as papillary hyperplasia on the conjunctiva.
• Laboratory tests:
• Cytological examination: A swab is used to collect eye discharge for lab analysis to determine the type of conjunctivitis.
• Pathogen testing: Similar to cytological examination but involves culturing the discharge to identify the infectious pathogen.
• Blood tests: Helps determine if conjunctivitis is caused by systemic diseases like syphilis or tuberculosis.

What diseases should conjunctivitis be distinguished from?

Conjunctivitis needs to be differentiated from common eye conditions such as uveitis, corneal ulcers, and acute glaucoma, as treatment approaches differ.

If symptoms like foreign body sensation, eye redness, itching, burning, photophobia, eye pain, or tearing occur, prompt ophthalmologic consultation is necessary to identify the underlying cause and choose the appropriate treatment.

Is conjunctivitis the same as "pink eye"?

Not exactly.

"Pink eye" specifically refers to acute conjunctivitis, characterized by noticeable eye redness, high contagiousness, and frequent occurrence in spring and autumn.

TREATMENT

Which department should I visit for conjunctivitis?

Ophthalmology or Emergency Department.

Patients with symptoms such as redness, increased discharge, or photophobia should prioritize visiting ophthalmology. If the condition is caused by chemical exposure, they should seek immediate care in the emergency department.

How is conjunctivitis treated?

Treatment primarily involves eye drops or ointments. Oral antibiotics are only necessary for severe cases like gonococcal or chlamydial conjunctivitis^[1].

For excessive discharge, conjunctival sac irrigation may be performed to remove secretions. This involves using non-irritating solutions like saline or 3% boric acid, applied 1–2 times daily to flush out discharge^[1].

During irrigation, the unaffected eye should be positioned above the affected one to prevent cross-contamination^[1].

How is allergic conjunctivitis treated?

• Avoid allergens: Identify and avoid triggers, or undergo desensitization therapy to eliminate symptoms.
• Eye drops: Use topical steroid eye drops, NSAIDs, antihistamines, or mast cell stabilizers to alleviate symptoms^[1].
• Oral medication: Severe cases may require oral antihistamines as prescribed by a specialist.

How effective is allergic conjunctivitis treatment?

Most patients respond well without lasting vision impairment, provided allergens are avoided. Chronic cases may lead to pigmentation, eyelid scarring, or ectropion, potentially affecting vision.

How is viral conjunctivitis treated?

Viral conjunctivitis is often self-limiting in immunocompetent individuals.

Cold compresses and vasoconstrictors can relieve symptoms. Antiviral eye drops are used in acute phases. Severe corneal involvement requires prompt ophthalmologic care, possibly with steroid eye drops under close monitoring^[1].

How effective is viral conjunctivitis treatment?

Outcomes are generally favorable if the cornea remains unaffected. However, delayed or irregular treatment may lead to recurrence.

What are the consequences of untreated conjunctivitis?

While some acute cases resolve spontaneously in 2–3 weeks, targeted therapy reduces severity and duration. Chronic or severe untreated conjunctivitis may cause permanent damage, including scarring, eyelid deformities, dry eye, or vision loss^[1].

Is conjunctivitis prone to recurrence?

With timely and proper treatment, recurrence is rare. Incomplete treatment, re-exposure to allergens, or reinfection may trigger relapse.

DIET & LIFESTYLE

What should conjunctivitis patients pay attention to in daily life?

• Strictly follow the doctor's instructions for medication. Do not change the dosage or frequency of medication without authorization, and be aware of potential adverse drug reactions.
• Maintain eye hygiene and keep the eyes clean. Avoid rubbing the eyes with unclean hands, refrain from using eye drops of unknown effects, and do not wear contact lenses until the conjunctivitis is fully cured.
• Engage in moderate exercise to boost immunity, avoid overexertion, and ensure adequate rest.
• Some patients may experience negative emotions such as depression or sadness due to the appearance or discomfort caused by conjunctivitis. Relaxation methods like talking with family or friends or listening to music can help alleviate these feelings.
• During the active phase of infectious conjunctivitis (e.g., viral or bacterial conjunctivitis), practice contact isolation, wash hands frequently, maintain hand hygiene, separate personal items from family members, and avoid public places.

Are there any dietary precautions for conjunctivitis patients?

Patients are advised to eat a light diet and avoid spicy or irritating foods, as these may trigger conjunctivitis recurrence, irritate the gastrointestinal tract, and hinder digestion and absorption.

It is recommended to consume fresh vegetables, fruits, and protein-rich foods. These provide essential nutrients for the body and aid in recovery, such as celery, carrots, blueberries, milk, and black beans.

What should I do if conjunctivitis is very itchy but I can't rub my eyes?

Use clean cotton swabs or cotton balls to remove eye discharge and apply antibiotic, antiviral, or antihistamine eye drops prescribed by a doctor to relieve symptoms.

Can I buy eye drops from a pharmacy for red eyes without consulting a doctor?

No.

The cause of eye redness must be identified. It is advisable to seek medical attention, especially if experiencing symptoms like redness, blurred vision, tearing, light sensitivity, pain, swelling, or increased discharge.

Can frequent conjunctivitis lead to blindness?

Generally, no.

Frequent conjunctivitis requires consultation with an ophthalmologist to determine the cause and receive appropriate treatment. With timely treatment, blindness is extremely rare.

PREVENTION

How to prevent the spread of conjunctivitis?

Conjunctivitis is mostly transmitted through contact, so patients should wash their hands and face frequently, avoid rubbing their eyes with hands or clothing, isolate and disinfect used toiletries, and avoid crowded places such as barbershops, schools, nurseries, and swimming pools.

How to prevent allergic conjunctivitis?

The best way to prevent allergic conjunctivitis is to identify the allergen and avoid exposure.

For allergic conjunctivitis caused by plant pollen or weeds, desensitization therapy can be considered. Although the treatment process is cumbersome, the efficacy is relatively good. Cold compresses on the eyelids can improve patient comfort.

How to prevent viral conjunctivitis?

Viral conjunctivitis is highly contagious. Patients should isolate themselves and avoid public places to prevent infecting others.

Avoid touching the eyelids and tears—use cotton swabs for wiping, wash hands frequently with soap, and keep personal towels, handkerchiefs, washbasins, and other toiletries separate.