What is the likely diagnosis and treatment for a 40-year-old female patient with a 1-day history of itching, redness, watery discharge, and pus in her right eye?

Acute Bacterial Conjunctivitis with Likely Viral Component

This patient most likely has acute infectious conjunctivitis, and given the combination of watery discharge with purulent material in a unilateral presentation of 1-day duration, this represents either viral conjunctivitis with secondary bacterial infection or bacterial conjunctivitis alone—both of which are typically self-limited and can be managed with supportive care, though topical antibiotics may be considered for bacterial cases. 1

Diagnostic Reasoning

The clinical presentation points toward infectious conjunctivitis based on several key features:

• Unilateral involvement with itching, redness, and discharge suggests viral etiology, as viral conjunctivitis characteristically presents with abrupt onset, can be unilateral or sequentially bilateral, and features watery discharge 1
• Mixed discharge pattern (both watery and purulent) is diagnostically significant—pure watery discharge favors viral causes while mucopurulent discharge suggests bacterial infection 2
• Acute 1-day timeline fits the natural history of both viral and bacterial conjunctivitis, which present with rapid onset 1, 3

The presence of itching is particularly notable as it can occur in both viral and allergic conjunctivitis, though the purulent component makes pure allergic conjunctivitis unlikely 4.

Treatment Approach

For Presumed Viral Conjunctivitis (Primary Consideration)

Supportive care is the cornerstone of management:

• Artificial tears and cold compresses for symptom relief 5, 2
• Warm soaks may relieve itching and burning 5
• Strict hand hygiene and infection control measures are essential 1, 6

Critical infection control instructions:

• Avoid touching the eyes, wash hands frequently, use disposable towels 5
• Avoid sharing towels, pillowcases, eye makeup, or contact lens equipment 6
• Remain isolated from work/school until watery discharge resolves, typically 5-14 days from onset, with the most contagious period being the first 10-14 days 6

For Bacterial Component (If Clinically Indicated)

If bacterial conjunctivitis is strongly suspected based on purulent discharge:

• Topical antibiotic ointment can be considered, though bacterial conjunctivitis is often self-limited 3, 2
• Erythromycin ophthalmic ointment approximately 1 cm applied directly to the infected eye up to 6 times daily depending on severity 7
• Bacitracin ophthalmic ointment applied directly into the conjunctival sac 1 to 3 times daily 8
• Delayed antibiotic prescribing (providing prescription but instructing patient to wait 2-3 days before filling) has similar symptom control as immediate prescribing 2

What to Avoid

Do NOT use topical corticosteroids in this acute presentation, as they can mask serious conditions, lead to complications, and are not indicated for simple viral or bacterial conjunctivitis 5. Indiscriminate use of topical antibiotics or corticosteroids should be avoided 1.

Red Flags Requiring Immediate Ophthalmology Referral

Refer urgently if any of the following develop 3, 2:

• Severe pain not relieved with supportive measures
• Vision loss or significant visual changes
• Corneal involvement (opacity, ulceration)
• Copious purulent discharge suggesting hyperacute bacterial conjunctivitis
• Vesicular rash on eyelids or nose (suggesting herpes zoster)
• Recent ocular surgery
• Immunocompromised state
• Lack of improvement after 5-7 days

Expected Clinical Course

• Viral conjunctivitis: Self-limited with improvement within 5-14 days 1, 6
• Bacterial conjunctivitis: Generally self-limited with or without antibiotics 3, 2
• Patient should return if symptoms worsen, vision decreases, or no improvement occurs within one week 3

Common Pitfalls

The main diagnostic challenge is that no single sign or symptom accurately differentiates viral from bacterial conjunctivitis 2. The mixed presentation (watery plus purulent discharge) in this case makes definitive differentiation impossible on day 1. However, the unilateral presentation with itching and watery component favors a viral etiology with possible secondary bacterial colonization 1, 2.