How do you distinguish viral from bacterial conjunctivitis clinically?

The discharge character is a key differentiator: bacterial conjunctivitis produces thick, purulent (yellow-green) discharge that causes the lids to stick together, especially in the morning. Viral conjunctivitis produces watery or mucoid discharge. Preauricular lymphadenopathy (a tender node in front of the ear) strongly favors viral conjunctivitis, particularly adenoviral. Viral conjunctivitis is often associated with a recent upper respiratory infection. Itching is not prominent in either bacterial or viral conjunctivitis (unlike allergic).

What is epidemic keratoconjunctivitis (EKC) and why is it important to recognize?

Epidemic keratoconjunctivitis (EKC) is a severe form of adenoviral conjunctivitis that is highly contagious. It can involve the cornea, causing subepithelial infiltrates that may persist for months and reduce vision. It spreads easily in clinics, schools, and workplaces. Stringent infection control is essential: hand hygiene before and after every patient contact, disinfecting contact tonometer probes between patients, and advising infected patients to avoid sharing towels, pillowcases, or eye drops. Infected healthcare workers should not perform eye examinations during the acute phase.

What is tear break-up time (TBUT) and what is a normal value?

Tear break-up time measures the stability of the tear film. After instilling fluorescein dye, the patient blinks, and the examiner watches through the slit lamp with cobalt blue light for the first dark spot to appear in the fluorescein pattern, indicating the tear film has broken. The time from the last blink to this break is the TBUT. Normal TBUT is 10 seconds or more. A TBUT below 10 seconds suggests an unstable tear film, and below 5 seconds is considered diagnostic of evaporative dry eye.

What is the difference between a chalazion and a hordeolum (stye)?

A hordeolum (stye) is an acute infection of a Meibomian gland (internal hordeolum) or Zeis or Moll gland (external hordeolum). It presents as a red, tender, inflamed nodule on the eyelid margin with purulent discharge. Treatment includes warm compresses and sometimes topical or oral antibiotics. A chalazion is a chronic, non-infectious granulomatous inflammation of a blocked Meibomian gland. It presents as a firm, painless, rubbery lump within the lid, usually away from the lid margin. Chalazia are treated with warm compresses initially; persistent ones require intralesional steroid injection or surgical drainage.

How is a corneal abrasion treated and how long does it take to heal?

Corneal abrasion management focuses on pain control and infection prevention. Treatment typically includes: lubricating drops or ointment, topical antibiotic drops or ointment to prevent secondary infection, and sometimes a bandage contact lens for comfort in larger abrasions. NSAIDs may be used for pain. Most uncomplicated corneal abrasions heal within 24 to 72 hours because the corneal epithelium regenerates rapidly. Contact lens-related abrasions carry a higher infection risk (Pseudomonas is a concern) and should be treated more aggressively. Patching is no longer routinely recommended as it does not speed healing and can increase infection risk in some cases.

Conjunctivitis & External Eye Disease for the CPO Exam

External eye disease encompasses conditions affecting the eyelids, conjunctiva, and cornea, the visible and exposed structures of the eye. These are among the most common reasons patients seek eye care. As a CPO, you will regularly triage, assess, and assist in treating these conditions.

Conjunctivitis: Types and Features

Conjunctivitis is inflammation of the conjunctiva, the clear mucous membrane covering the inner eyelids and anterior sclera. It presents with redness, discharge, and varying degrees of discomfort. Distinguishing bacterial, viral, and allergic conjunctivitis is a key clinical skill.

Feature	Bacterial	Viral	Allergic
Discharge	Purulent (thick, yellow-green)	Watery or mucoid	Watery, stringy mucus
Itch	Mild or absent	Mild	Prominent (hallmark)
Laterality	Often bilateral (starts unilateral)	Often starts unilateral, spreads	Bilateral
Lymphadenopathy	Uncommon	Common (preauricular node)	Absent
Associated symptoms	None specific	URI, fever, sore throat	Allergies, seasonal pattern
Treatment	Topical antibiotics	Supportive (artificial tears, cool compresses)	Topical antihistamines, mast cell stabilizers

Viral conjunctivitis, particularly epidemic keratoconjunctivitis (EKC) caused by adenovirus, is highly contagious and can survive on surfaces for days. Strict hand hygiene, avoiding shared towels, and advising patients to stay home from school or work during the acute phase are critical infection control measures.

Gonococcal Conjunctivitis

A special category is gonococcal conjunctivitis, caused by Neisseria gonorrhoeae. It presents with copious purulent discharge, marked lid edema, and can progress rapidly to corneal perforation. It requires urgent systemic antibiotic treatment (not just topical drops). This is a reportable sexually transmitted infection.

Dry Eye Disease

Dry eye disease (DED) is extremely prevalent, particularly in older adults, contact lens wearers, and patients using screens for extended periods. It results from either insufficient tear production (aqueous deficient dry eye) or excessive evaporation (evaporative dry eye, usually from Meibomian gland dysfunction). Symptoms include burning, grittiness, fluctuating vision, and paradoxically, reflex tearing.

Diagnosis is supported by slit lamp findings (staining of the cornea and conjunctiva with fluorescein and lissamine green), reduced tear meniscus, and reduced tear break-up time (TBUT). Treatment ranges from artificial tears to cyclosporine or lifitegrast drops, punctal plugs, and lid hygiene for Meibomian gland dysfunction.

Instruct dry eye patients to use preservative-free artificial tears if they are applying drops more than 4 times per day. Preservatives in multi-dose bottles (especially benzalkonium chloride) can damage the corneal epithelium and worsen dry eye with frequent use.

Blepharitis

Blepharitis is chronic inflammation of the eyelid margins. There are two types:

Anterior blepharitis: Affects the eyelash bases; associated with Staphylococcus or seborrheic dermatitis. Presents with collarettes (waxy scales encircling lashes).
Posterior blepharitis: Meibomian gland dysfunction with obstructed oily secretion. The lid margin may appear thickened, and the Meibomian gland orifices may be capped or inspissated (blocked with waxy secretion).

Treatment includes warm compresses, lid scrubs, and omega-3 fatty acid supplementation. Topical or oral antibiotics may be added for recalcitrant cases.

Corneal Abrasion

A corneal abrasion is a disruption of the corneal epithelium from trauma (fingernail, paper, contact lens, foreign body). Symptoms include sudden severe pain, photophobia, tearing, and foreign body sensation. The abrasion is identified with fluorescein staining under cobalt blue light on the slit lamp. Treatment includes lubricating drops, topical antibiotics to prevent infection, and possibly a bandage contact lens for comfort. Most abrasions heal within 24 to 72 hours.

Key Takeaways

Itch is the hallmark of allergic conjunctivitis; purulent discharge favors bacterial; preauricular lymphadenopathy favors viral.
Viral conjunctivitis (especially adenoviral EKC) is highly contagious; hand hygiene and isolation precautions are important.
Dry eye disease presents with burning, grittiness, and fluctuating vision; Meibomian gland dysfunction is the most common cause.
Blepharitis is chronic and managed with warm compresses and lid hygiene rather than cured.
Corneal abrasions are identified with fluorescein staining under cobalt blue light; most heal within 24 to 72 hours.