Clinical Presentation of Allergic Conjunctivitis
Allergic conjunctivitis presents with bilateral eye involvement where itching is the predominant and most consistent symptom, accompanied by conjunctival injection, chemosis, watery discharge, and eyelid edema. 1
Cardinal Symptoms
- Intense ocular itching is the hallmark symptom that distinguishes allergic from other forms of conjunctivitis 1, 2
- Tearing and watery discharge are prominent, often with mild mucoid component 3
- Red eyes with conjunctival injection occur bilaterally 3, 1
- Eyelid swelling develops in most cases 3
- Symptoms typically worsen at night and persist throughout exposure periods 4
Physical Examination Findings
Eyelid Changes
- Periorbital edema affecting both eyes 3
- Periorbital hyperpigmentation ("allergic shiners") present in up to 60% of atopic patients 3, 5
- Dennie-Morgan lines (infraorbital folds) appear in 60-80% of atopic children 5
Conjunctival Signs
- Chemosis (conjunctival swelling) is characteristic 3
- Papillary reaction on the palpebral conjunctiva, particularly upper tarsal surface 3, 6
- Conjunctival injection with diffuse redness 3, 2
- Watery to mild mucous discharge without purulent material 3, 2
Corneal Involvement (Severe Forms)
- Vernal keratoconjunctivitis presents with giant papillary hypertrophy of superior tarsal conjunctiva, limbal Horner-Trantas dots, and potential corneal epithelial erosions 3
- Shield ulcers and corneal plaques may develop in chronic vernal disease 3
- Photophobia and pain indicate corneal involvement requiring ophthalmology referral 2, 6
Seasonal vs. Perennial Patterns
Seasonal Allergic Conjunctivitis
- Symptoms appear during defined pollen seasons (spring for trees, summer for grasses, fall for ragweed) 3
- More than 75% of seasonal allergic rhinitis patients report concurrent ocular symptoms 3, 1
- Pollen sensitivity correlates with rhinoconjunctivitis more than perennial allergens 3
Perennial Allergic Conjunctivitis
- Year-round symptoms triggered by indoor allergens, particularly house dust mites 3, 1
- Less severe ocular symptoms compared to pollen-induced disease 3
- Common triggers include house dust, cockroaches, and animal dander 4
Associated Conditions
- Allergic rhinitis accompanies allergic conjunctivitis in the majority of cases, creating allergic rhinoconjunctivitis syndrome 3, 1
- Atopic dermatitis, asthma, and eczema frequently coexist, requiring assessment for systemic atopy 3, 6
- Meibomian gland dysfunction and dry eye may exacerbate symptoms 3
- 95% of patients have other allergic diseases, and 66% have family history of atopy 4
Distinguishing Features from Other Conjunctivitis Types
- Lack of itching strongly argues against allergic etiology and favors bacterial cause 2
- Bilateral presentation is typical, whereas unilateral disease suggests other etiologies 3, 2
- Absence of purulent discharge distinguishes from bacterial conjunctivitis 2
- No preauricular lymphadenopathy, which is common in viral conjunctivitis 2
- Preserved visual acuity unless corneal involvement occurs 2
Severe Forms Requiring Ophthalmology Referral
Vernal Keratoconjunctivitis
- Onset in childhood with chronic course and acute exacerbations during spring/summer 3
- Giant papillae on superior tarsal conjunctiva with stringy mucoid discharge 3
- Horner-Trantas dots at the limbus 3
- Risk of corneal neovascularization, ulceration, and vision loss 3
Atopic Keratoconjunctivitis
- Associated with eczematous lesions of lids and skin 3
- More common in older adults 3
- Chronic inflammation with potential for corneal scarring and visual impairment 6
Red Flags Requiring Immediate Ophthalmology Consultation
- Visual loss or blurred vision indicates corneal involvement 2, 1
- Moderate to severe pain suggests more serious pathology 2
- Photophobia indicates corneal epithelial defects 2
- Suspected vernal or atopic keratoconjunctivitis based on giant papillae or chronic severe symptoms 1
- Disease uncontrolled with topical medications and oral antihistamines 1