What could be the cause of unilateral eye pain upon touch, with no drainage or vision loss, and red inner eyelids in a patient?

Unilateral Eye Pain with Red Inner Eyelids: Differential Diagnosis and Management

Most Likely Diagnosis

This presentation most likely represents viral conjunctivitis (particularly adenoviral) or bacterial conjunctivitis, given the unilateral red inner eyelids (palpebral conjunctival injection), pain on touch (tenderness), absence of drainage, and preserved vision. 1

Critical Red Flag Assessment Required Immediately

Before proceeding with presumptive diagnosis, you must rule out vision-threatening emergencies:

• Check visual acuity in both eyes - any decrease requires same-day ophthalmology referral 1
• Perform fluorescein staining - this is mandatory in every case to detect corneal involvement that may not be clinically apparent 1
• Assess for moderate-to-severe pain - mild discomfort on touch is consistent with conjunctivitis, but severe pain suggests corneal involvement, uveitis, or acute angle-closure glaucoma 1, 2
• Check extraocular movements - painful movements suggest orbital cellulitis or scleritis 1
• Examine for proptosis - any forward displacement of the globe indicates orbital cellulitis requiring emergent hospitalization 1
• Evaluate pupil reactivity - abnormal pupils suggest uveitis, acute glaucoma, or optic nerve involvement 1

Primary Differential Diagnoses

Viral Conjunctivitis (Most Common)

• Adenoviral conjunctivitis presents with unilateral eyelid swelling and erythema, watery discharge (though patient may not notice drainage), bulbar conjunctival injection, chemosis, and follicular reaction of the inferior tarsal conjunctiva 1
• Associated with recent exposure to infected individuals or concurrent upper respiratory infection 1
• The "no drainage" reported by patient may reflect minimal watery discharge rather than purulent discharge 3

Herpes Simplex Virus (HSV) Keratoconjunctivitis

• HSV usually presents unilaterally with bulbar conjunctival injection, watery discharge, mild follicular reaction, and palpable preauricular lymphadenopathy 1
• Critical distinguishing feature: examine eyelids carefully for vesicles - presence of vesicles requires immediate ophthalmology referral and antiviral therapy 1, 4
• Can progress to epithelial keratitis, stromal keratitis, corneal scarring, perforation, and uveitis if untreated 1

Bacterial Conjunctivitis

• Can present unilaterally with bulbar conjunctival injection and purulent or mucopurulent discharge 1
• The absence of obvious drainage does not exclude bacterial etiology, particularly early in course 3
• More common in children with mucous discharge and eyelid swelling 4

Molluscum Contagiosum

• Typically presents unilaterally with mild to severe follicular reaction and punctate epithelial keratitis 1
• Characterized by single or multiple shiny, dome-shaped umbilicated lesions on eyelid skin or margin - examine eyelid margins carefully 1

Serious Conditions That Must Be Excluded

Preseptal vs. Orbital Cellulitis

• Preseptal cellulitis presents with eyelid erythema, edema, and tenderness WITHOUT proptosis, painful eye movements, or vision changes 1
• Orbital cellulitis is a severe infection with proptosis, ophthalmoplegia, vision loss, and fever requiring emergent hospitalization and IV antibiotics 1
• The key distinction is whether infection is anterior (preseptal) or posterior (orbital) to the orbital septum 5

Sebaceous Carcinoma

• Can masquerade as chronic unilateral blepharoconjunctivitis 1
• Biopsy is indicated for unifocal recurrent lesions, resistance to therapy, focal lash loss, or chronic presentation unresponsive to treatment 1
• May appear as yellowish discoloration of tarsal plate or subconjunctival multilobulated yellow mass 6

Acute Angle-Closure Glaucoma

• Presents with severe eye pain, decreased vision, mid-dilated fixed pupil, corneal edema, and elevated intraocular pressure 2, 7
• Requires immediate ophthalmology referral 7

Diagnostic Algorithm

Step 1: Perform mandatory baseline examination 1

• Visual acuity testing
• Fluorescein staining of cornea
• Extraocular movement assessment
• Pupil examination
• Check for proptosis

Step 2: Examine eyelids systematically 1

• Look for vesicles (HSV/VZV)
• Look for umbilicated lesions (molluscum)
• Assess for eyelid swelling and erythema
• Check eyelid margins

Step 3: Assess discharge character 1

• Watery suggests viral
• Purulent/mucopurulent suggests bacterial
• Minimal or absent discharge can occur in early viral conjunctivitis

Step 4: Palpate preauricular lymph nodes 1

• Enlarged nodes suggest viral (especially HSV) or Parinaud oculoglandular syndrome 3

Initial Management Approach

If No Red Flags Present (Presumed Viral Conjunctivitis)

• Cool compresses for symptomatic relief 1
• Mandatory follow-up in 3-4 days to assess improvement 1
• Strict hand hygiene to prevent transmission 4
• Avoid touching or rubbing the eye 7

If Red Flags Present - Immediate Ophthalmology Referral Required

• Visual changes 1
• Moderate-to-severe pain 1
• Corneal involvement on fluorescein examination 1
• Suspected HSV/VZV with vesicles 1
• Proptosis or painful extraocular movements 1
• Abnormal pupil reactivity 1

If Bacterial Conjunctivitis Suspected

• Start topical broad-spectrum antibiotic therapy immediately 4
• Common choices include fluoroquinolones (moxifloxacin, gatifloxacin) or trimethoprim-polymyxin B 7
• Follow-up in 3-4 days; if no improvement, refer to ophthalmology 4

If Preseptal Cellulitis Suspected

• High-dose amoxicillin-clavulanate with daily follow-up 1
• Hospitalization for IV antibiotics if no improvement in 24-48 hours or progressive infection 1

Common Pitfalls to Avoid

• Failing to perform fluorescein staining - corneal involvement may not be clinically apparent and changes management completely 1
• Missing eyelid vesicles - HSV requires antiviral therapy, not just supportive care 1, 4
• Assuming "no drainage" excludes infectious conjunctivitis - early viral conjunctivitis may have minimal watery discharge 3, 1
• Treating with topical steroids without ophthalmology consultation - can worsen HSV keratitis and lead to corneal perforation 7
• Delaying referral when red flags present - vision-threatening conditions require same-day ophthalmology evaluation 1, 2