What are the likely causes and recommended evaluation and management for a unilateral periorbital dark circle with concurrent lower eyelid swelling?

Unilateral Periorbital Dark Circle with Lower Eyelid Swelling

This presentation requires urgent ophthalmologic evaluation to rule out vision-threatening infectious causes (HSV, VZV, gonococcal infection) and orbital complications, while simultaneously considering allergic, inflammatory, and malignant etiologies based on associated clinical features. 1

Immediate Red Flag Assessment

Perform these evaluations immediately before considering benign causes:

• Check visual acuity using any available eye chart—any vision change mandates same-day ophthalmology referral 1
• Perform fluorescein staining in every case to detect corneal involvement that may not be clinically apparent 1
• Assess for proptosis and painful extraocular movements—these indicate orbital cellulitis requiring emergent hospitalization and IV antibiotics 1
• Examine for vesicular lesions on the eyelid—pathognomonic for HSV/VZV and requires immediate ophthalmology referral due to risk of corneal perforation 1
• Evaluate discharge character—copious purulent discharge suggests gonococcal infection, which can cause corneal perforation within 24-48 hours 1

Most Likely Diagnostic Considerations

Infectious Etiologies (Most Common)

Adenoviral conjunctivitis is the leading cause when presenting with:

• Unilateral eyelid swelling that may become sequentially bilateral within days 1
• Watery discharge with bulbar conjunctival injection 1
• Follicular reaction on inferior tarsal conjunctiva 1
• Preauricular lymphadenopathy (distinctive when present) 1
• Recent exposure to infected individuals or concurrent upper respiratory infection 2, 1

Herpes Simplex Virus (HSV) presents with:

• Usually unilateral bulbar conjunctival injection and watery discharge 1
• Palpable preauricular lymphadenopathy 1
• Can progress to epithelial keratitis, stromal keratitis, corneal scarring, and perforation if untreated 1
• Triggers include stress, febrile illness, UV exposure, surgery, or trauma 1

Varicella Zoster Virus (VZV) demonstrates:

• Vesicular dermatomal rash or ulceration of eyelids (distinctive sign) 1
• Conjunctival injection with watery discharge and follicular reaction 1
• Risk of conjunctival scarring, cicatricial ectropion, late corneal anesthesia, and dry eye 1

Allergic Etiology

Chronic allergic conjunctivitis characteristically shows:

• Dark infraorbital swollen semicircles (allergic facies) 2
• Morgan-Dennie's lines (accentuated horizontal skin folds on lower eyelid running parallel to lid margin) 2
• Pale boggy turbinates on nasal examination 2
• Clear, watery secretions (may be pale yellow with extreme inflammation) 2
• Itching, redness, lid swelling, and tearing as main symptoms 3

Critical distinction: Allergic conjunctivitis typically presents bilaterally, but unilateral presentation can occur when associated with non-specific factors such as contact lens intolerance, local infection, trauma, astigmatism, or heterophoria 3

Serious Conditions Requiring Urgent Evaluation

Preseptal cellulitis presents with:

• Eyelid erythema, edema, and tenderness without proptosis or painful eye movements 1
• Requires high-dose amoxicillin-clavulanate with daily follow-up 1
• Hospitalization for IV antibiotics if no improvement in 24-48 hours 1

Orbital cellulitis (life-threatening) shows:

• Proptosis, ophthalmoplegia, vision loss, and fever 1
• Requires emergent hospitalization and IV antibiotics 1

Sebaceous carcinoma can masquerade as:

• Chronic unilateral blepharoconjunctivitis 1
• Hard, non-mobile tarsal mass with yellowish discoloration 1
• Biopsy indicated for unifocal recurrent lesions, resistance to therapy, focal lash loss, or chronic presentation unresponsive to treatment 1

Practical Diagnostic Algorithm

Step 1: Rule Out Vision-Threatening Emergencies

• Visual acuity testing 1
• Extraocular movement assessment 1
• Pupil reactivity and afferent pupillary defect testing 2
• Fluorescein staining (mandatory) 1

Step 2: Characterize the Presentation

• Discharge character: Watery (viral), purulent (bacterial), clear (allergic) 2, 1
• Eyelid examination: Vesicles (HSV/VZV), umbilicated lesions (molluscum), erythema/warmth (cellulitis) 1
• Laterality: Strictly unilateral suggests infection or malignancy; bilateral or sequential suggests viral or allergic 1, 3
• Duration: Acute (<2 weeks) versus chronic (>4 weeks) 3
• Associated symptoms: Upper respiratory infection (viral), itching (allergic), pain (infection/cellulitis) 2, 1

Step 3: Examine for Allergic Facies

• Dark infraorbital swollen semicircles 2
• Morgan-Dennie's lines on lower eyelid 2
• Transverse nasal crease from constant nose itching 2
• Pale boggy nasal turbinates 2

Step 4: Assess Lymphadenopathy

• Preauricular lymphadenopathy suggests viral (especially HSV) or Parinaud oculoglandular syndrome 1

Initial Management Approach

For Presumed Viral Conjunctivitis (No Red Flags)

• Cool compresses for symptomatic relief 1
• Mandatory follow-up in 3-4 days to assess improvement 1
• Self-limited course with improvement expected within 5-14 days 1

Immediate Ophthalmology Referral Required For:

• 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
• Copious purulent discharge (rule out gonococcal) 1

For Suspected Preseptal Cellulitis

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

For Suspected Allergic Etiology

• Topical antihistamines or mast cell stabilizers 3, 4
• Allergen avoidance (house dust mites most common in perennial cases) 3
• Consider skin-prick testing for confirmation 3

Common Pitfalls to Avoid

• Never assume unilateral presentation excludes allergy—non-specific factors can trigger unilateral allergic conjunctivitis in atopic patients 3
• Do not skip fluorescein staining—corneal involvement may not be clinically apparent and changes management 1
• Avoid starting corticosteroids before ophthalmology evaluation—may worsen herpetic infections or mask accurate diagnosis 2
• Do not dismiss chronic unilateral blepharoconjunctivitis—sebaceous carcinoma can masquerade as benign inflammation and requires biopsy if unresponsive to treatment 1
• Puffy eyelids with pain, erythema, and warmth indicate preseptal cellulitis—requires systemic antibiotics, not just topical treatment 2