I have a single round red spot on the inner surface of my eyelid while using topical erythromycin; what is the likely diagnosis and how should it be managed?

Round Red Spot on Inner Eyelid While Using Erythromycin

This is most likely a papillary reaction from either giant papillary conjunctivitis, medication-induced conjunctivitis from the erythromycin itself, or a follicular response to an underlying viral or chlamydial infection that is not responding to the antibiotic.

Most Likely Diagnoses

Medication-Induced Keratoconjunctivitis

• Topical antibiotics including erythromycin can cause conjunctival injection, papillary reactions, and follicular changes on the tarsal conjunctiva, particularly with prolonged use 1
• The appearance of a round red spot on the inner eyelid surface (tarsal conjunctiva) during antibiotic therapy strongly suggests either a papilla or follicle formation 1
• Gradual worsening with continued antibiotic use is characteristic of medication-induced conjunctivitis 1

Giant Papillary Conjunctivitis (GPC)

• Presents with papillary hypertrophy of the superior tarsal conjunctiva, often appearing as localized round elevated lesions 1
• Can occur with contact lens wear, exposed sutures, or ocular prostheses, but also develops spontaneously 1
• Characterized by mucoid discharge and chronic gradual increase in symptoms 1

Follicular Conjunctivitis (Viral or Chlamydial)

• Follicles appear as round, elevated lesions on the tarsal conjunctiva with a pale center and surrounding hyperemia 1
• Viral conjunctivitis (especially adenoviral) commonly causes follicular reactions that persist for weeks 1
• Chlamydial inclusion conjunctivitis causes follicular conjunctivitis with distinctive follicles on bulbar conjunctiva and semilunar fold 1

Immediate Management Algorithm

Step 1: Discontinue Erythromycin

• Stop the topical erythromycin immediately to rule out medication-induced conjunctivitis 1
• Medication toxicity can cause worsening inflammation and should be the first consideration when symptoms develop during antibiotic therapy 1

Step 2: Examine the Lesion Characteristics

• Evert the upper eyelid to visualize the tarsal conjunctiva fully and determine if the lesion is a papilla (vascularized central core) or follicle (avascular center with peripheral vessels) 2
• Check for laterality (unilateral suggests contact allergen or localized process; bilateral suggests systemic or medication-related cause) 1, 3
• Assess for discharge type: mucoid suggests GPC or allergic; purulent suggests bacterial; watery suggests viral 1

Step 3: Initiate Conservative Treatment

• Begin warm compresses for 5-10 minutes, 3-4 times daily, and eyelid hygiene with gentle cleansing once or twice daily 3
• Use preservative-free artificial tears 4-6 times daily to reduce surface irritation 3
• Avoid all topical medications except lubricants for 48-72 hours to allow assessment of natural course 1

Step 4: Reassess at 48-72 Hours

• If the lesion improves or resolves after stopping erythromycin, the diagnosis is medication-induced conjunctivitis 1
• If the lesion persists or worsens, consider viral follicular conjunctivitis (self-limited, supportive care) or chlamydial infection (requires systemic antibiotics) 1
• If marked papillary hypertrophy develops, diagnose GPC and continue conservative measures for 4-6 weeks 1

When to Refer to Ophthalmology

• Lesion persists beyond 2-3 weeks despite conservative management 3, 2
• Development of corneal involvement (punctate epithelial keratitis, pannus, or ulceration) 1
• Severe pain not relieved by conservative measures 4
• Vision changes or photophobia 4
• Chronic unilateral lesion resistant to therapy warrants biopsy to rule out sebaceous carcinoma or conjunctival malignancy 1, 3

Critical Pitfalls to Avoid

• Do not continue topical antibiotics when medication-induced conjunctivitis is suspected - this will worsen the condition and delay diagnosis 1
• Do not add topical corticosteroids empirically - while they may reduce inflammation, they can worsen infectious causes and should only be used after definitive diagnosis by an ophthalmologist 1
• Failing to evert the eyelid for complete examination misses tarsal conjunctival pathology 2
• Assuming all red spots are infectious and adding more antibiotics creates a cycle of medication toxicity 1

If Infection is Confirmed

• For chlamydial conjunctivitis: systemic therapy with azithromycin 1g single dose or doxycycline 100mg twice daily for 7 days is required (topical therapy alone is insufficient) 1
• For viral conjunctivitis: supportive care with cool compresses, artificial tears, and patient education about contagion for 10-14 days 1
• For bacterial causes not responding to erythromycin: consider MRSA and use fluoroquinolone or trimethoprim-polymyxin B 1