Treatment of Unilateral Eye Redness, Pain, and Watery Discharge in Older Adults
In an older adult with unilateral eye redness, pain, and watery discharge, you should NOT routinely prescribe antibiotics—this presentation is most consistent with viral conjunctivitis, which requires supportive care only. 1
Critical First Step: Rule Out Vision-Threatening Conditions
Before deciding on treatment, you must immediately assess for these red flags that require urgent ophthalmology referral:
- Examine the cornea with fluorescein staining to detect corneal involvement (ulcer, infiltrate, or keratitis), which can indicate bacterial keratitis, HSV keratitis, or gonococcal infection 2
- Check visual acuity—any vision loss requires immediate referral 3, 4
- Assess pain severity—severe pain unrelieved by topical anesthetics suggests corneal involvement, iritis, or acute glaucoma 3, 4
- Look for vesicular lesions on the eyelid or dermatomal distribution suggesting herpes zoster ophthalmicus 1, 2
- Examine the pupil—distorted pupil or painful pupillary reaction indicates intraocular inflammation 3, 5
Distinguishing Viral from Bacterial Conjunctivitis
Watery discharge strongly suggests viral etiology, while mucopurulent or purulent discharge indicates bacterial infection 1, 4:
Viral Conjunctivitis Features (Most Likely in This Case):
- Watery discharge (key distinguishing feature) 1, 4
- Unilateral initially, often becomes sequentially bilateral 1
- Follicular reaction on inferior tarsal conjunctiva 1
- Preauricular lymphadenopathy (highly specific for viral) 1
- Recent upper respiratory infection or sick contacts 1
- Self-limited course, improving within 5-14 days 1
Bacterial Conjunctivitis Features:
- Mucopurulent or purulent discharge with eyelids matted shut in morning 1, 4
- More common in children than adults 1, 4
- No preauricular lymphadenopathy (unless gonococcal) 1
Recommended Treatment Algorithm
For Viral Conjunctivitis (Watery Discharge):
Supportive care is the appropriate treatment 4:
- Artificial tears 4-6 times daily for symptomatic relief 4
- Cold compresses for comfort 4
- Topical antihistamine drops if significant itching 4
- Strict hand hygiene to prevent transmission 4
- Avoid contact lens wear until resolution 6
- Symptoms resolve in 5-14 days without antibiotics 1
For Bacterial Conjunctivitis (Purulent Discharge):
If the discharge is clearly purulent rather than watery, consider:
- Delayed antibiotic prescribing (prescription given but patient waits 2-3 days before filling) has similar outcomes to immediate prescribing 4
- If antibiotics are prescribed: Moxifloxacin 0.5% one drop three times daily for 7 days provides broad-spectrum coverage 6
- Alternative: Fusidic acid 1% twice daily for 7 days (better compliance, equal efficacy) 7
Critical Pitfalls to Avoid
Do not prescribe antibiotics empirically for watery discharge—this represents overtreatment of viral conjunctivitis and contributes to antibiotic resistance 4, 5:
- There is no specific test to differentiate viral from bacterial conjunctivitis, but discharge character is the most reliable clinical indicator 3, 4
- Viral conjunctivitis accounts for the majority of adult conjunctivitis cases 5
- Most bacterial conjunctivitis is self-limited in adults 1
In older adults specifically, consider these additional diagnoses:
- Herpes zoster ophthalmicus—look for vesicular rash, severe pain, and dermatomal distribution 1, 2
- Dry eye syndrome—chronic irritation can mimic conjunctivitis 1
- Medication toxicity—long-term use of preserved eye drops causes toxic conjunctivitis 5
Immediate ophthalmology referral is mandatory if: