Vernal Keratoconjunctivitis

Evidence-based assessment and management of vernal keratoconjunctivitis (VKC). Comprehensive guide covering etiology, pathogenesis, classification, diagnosis, and treatment protocols including sight-threatening complications and optometry scope of practice.

Last updated: March 2026

Vernal keratoconjunctivitis: cobblestone papillae on everted superior tarsal conjunctiva, shield ulcer on superior cornea, and Horner-Trantas dots at the limbus

Vernal keratoconjunctivitis (VKC) is a severe, chronic, bilateral, recurrent inflammatory disease of the ocular surface predominantly affecting the conjunctiva and cornea. It is driven by a complex hypersensitivity response involving IgE-mediated mast cell degranulation and Th2-lymphocyte activation, resulting in eosinophil-rich tissue infiltration and progressive structural remodelling. VKC affects predominantly young males in warm, dry, or tropical climates, with a predilection for spring and summer seasons — hence the term “vernal” (Latin: spring). The condition is characterised pathognomonically by giant cobblestone papillae on the superior tarsal conjunctiva, limbal Horner-Trantas dots, and, in its most severe form, the vision-threatening shield ulcer. While most cases remit spontaneously by late adolescence or early adulthood, the risk of permanent corneal scarring and the complications of long-term topical steroid therapy necessitate careful, structured management — ideally in collaboration with an ophthalmologist. VKC accounts for a significant proportion of severe allergic eye disease in Sub-Saharan Africa, the Middle East, South Asia, and the Mediterranean basin, and is increasingly recognised in the tropics of Southeast Asia.

Immunological Basis

IgE-mediated (Type I) hypersensitivity: Allergen sensitisation triggers B-cell class switching to IgE production; mast cell–bound IgE cross-linking by re-exposure to allergens initiates rapid degranulation and release of preformed mediators (histamine, tryptase, prostaglandins, leukotrienes)
T-cell–mediated (Type IV) hypersensitivity: Th2 lymphocyte activation drives eosinophil recruitment and persistent tissue inflammation independent of allergen re-exposure; IL-4, IL-5, IL-13, and eotaxin are central cytokines; accounts for the chronic, non-remitting nature of VKC beyond simple allergic exposure
Atopic predisposition: Approximately 50–70% of VKC patients have a personal or family history of atopic disease (asthma, atopic dermatitis, allergic rhinitis); elevated total serum IgE is common; however, a significant proportion of VKC — particularly in tropical Africa — occurs without classical atopy, suggesting non-atopic immunological pathways

Triggering Factors

Seasonal allergens: Pollen (grass, tree, weed), fungal spores, and dust mite antigens are the most frequently implicated; seasonal exacerbations in spring and summer correspond to peak pollen counts
Environmental factors: Hot, dry, windy climates and high UV radiation index are strongly associated with disease activity; cold, humid environments typically produce remissions
Non-specific triggers: Physical stimuli including wind, dust, bright light, and mechanical irritation can provoke acute exacerbations independent of specific allergen exposure; this non-specific mast cell hyperreactivity distinguishes VKC from simpler allergic conjunctivitis
Hormonal influence: The marked male predominance and spontaneous remission after puberty implicate androgens and sex hormones in disease modulation; testosterone may suppress conjunctival mast cell activity

Genetic and Familial Factors

Family history of atopy in first-degree relatives confers two- to fourfold increased risk; HLA associations (HLA-A24, HLA-Bw35) have been reported in some populations
Filaggrin gene mutations (FLG), associated with atopic dermatitis and impaired epidermal barrier, may contribute to conjunctival epithelial barrier dysfunction in a subset of VKC patients

Cellular and Molecular Cascade

Allergen sensitisation: Antigen-presenting cells (Langerhans cells, dendritic cells) process allergens and present epitopes to naïve T-helper cells in regional lymph nodes, driving Th2 polarisation via IL-4 signalling; B-cells undergo class switching to IgE under IL-4 and IL-13 stimulation
Mast cell priming and degranulation: IgE antibodies bind to high-affinity FcεRI receptors on conjunctival mast cells (2–5× elevated in VKC vs. normal conjunctiva); allergen cross-linking of receptor-bound IgE triggers rapid degranulation releasing histamine, tryptase, chymase, prostaglandin D2 (PGD2), cysteinyl leukotrienes (LTC4, LTD4) and platelet-activating factor (PAF) — producing the acute phase response (itch, hyperaemia, chemosis)
Eosinophil recruitment and activation: IL-5 (from Th2 cells and mast cells) promotes eosinophil maturation and survival in the bone marrow; eotaxin-1 and eotaxin-2 (from conjunctival epithelium and fibroblasts) provide chemotactic signals; activated eosinophils release major basic protein (MBP), eosinophil cationic protein (ECP), eosinophil-derived neurotoxin (EDN), and reactive oxygen species — directly toxic to the corneal epithelium and responsible for shield ulcer formation
Fibroblast activation and tissue remodelling: TGF-β1, released by mast cells and Th2 cells, activates conjunctival fibroblasts to produce excess collagen, fibronectin, and extracellular matrix proteins; this subepithelial fibrosis and stromal hypertrophy creates the giant papillae of the superior tarsal conjunctiva
Giant papilla formation: Hyperplasia of the conjunctival epithelium overlying a fibrotic stromal core densely infiltrated by mast cells, eosinophils, lymphocytes, and plasma cells produces the characteristic cobblestone appearance; each papilla has a central fibrovascular core; papillae >1 mm are termed “giant”
Limbal inflammation and Trantas dot formation: Limbal VKC is characterised by accumulation of eosinophils and their degranulated products at the corneoscleral limbus, forming the gelatinous limbal thickening and discrete chalky-white Horner-Trantas dots (aggregates of degranulated eosinophils and epithelial cells)
Shield ulcer pathogenesis: Mechanical trauma from giant papillae abrading the superior corneal epithelium, combined with eosinophil-derived cytotoxic proteins (MBP, ECP) deposited in the corneal epithelium and Bowman’s layer, produces epithelial sloughing and the characteristic oval superior shield ulcer; subsequent stromal plaque formation from fibrin, MBP deposits, and mucus prevents epithelial healing

By Anatomical Location

Palpebral (tarsal) VKC: Predominant involvement of the superior tarsal conjunctiva with giant cobblestone papillae (>1 mm); papillae develop in a mosaic or cobblestone pattern; secretes thick ropy mucus; most commonly seen in non-African populations and patients with atopy; the mechanically traumatic papillae directly abrade the superior cornea, predisposing to shield ulcer
Limbal VKC: Predominant involvement of the corneoscleral limbus; gelatinous limbal thickening and Horner-Trantas dots at the superior limbus; more common in dark-skinned individuals (African, South Asian populations) and in non-atopic VKC; limbal pannus and pseudogerontoxon may develop with chronicity
Mixed VKC: Features of both palpebral and limbal VKC coexist; most severe clinical phenotype; highest risk of corneal complications; requires intensive management

By Disease Severity (Bonini Grading Scale)

Grade	Clinical Features	Corneal Involvement
Grade 1 (Mild)	Mild itch; small papillae (<1 mm); mild hyperaemia; no discharge	None
Grade 2 (Moderate)	Moderate itch; papillae 1–2 mm; mucoid discharge; limbal involvement possible	Superficial punctate keratitis (SPK); punctate epithelial erosions
Grade 3 (Severe)	Severe itch; giant papillae >2 mm (cobblestone); profuse ropy mucus; Trantas dots; blepharospasm	Diffuse SPK; superior corneal pannus; macroerosion
Grade 4 (Very Severe)	All Grade 3 features; severe photophobia; blepharospasm; vision loss	Shield ulcer; stromal plaque; corneal scarring; pseudogerontoxon

Male sex: Male-to-female ratio approximately 3–4:1 in childhood; this disparity equalises after puberty, implicating androgenic hormonal modulation of conjunctival mast cell activity and Th2 immune responses
Young age: Peak onset between 5 and 15 years; disease typically begins in the first decade and remits by the late teens to early twenties; onset before age 5 or after age 20 is atypical and warrants consideration of alternative diagnoses (e.g. atopic keratoconjunctivitis in adults)
Hot, dry, or tropical climate: VKC is endemic in Sub-Saharan Africa, the Middle East (particularly Saudi Arabia, Iran, Egypt), Mediterranean basin, Indian subcontinent, and parts of Southeast Asia and South America; incidence is substantially lower in cold, temperate, or humid regions
Personal history of atopic disease: Atopic dermatitis, allergic rhinitis (hay fever), and asthma are present in 50–70% of VKC patients; the atopic march — progression from atopic dermatitis in infancy to allergic rhinitis and asthma in childhood — is a recognised risk trajectory
Family history of atopy or VKC: First-degree relative with atopic disease or VKC; polygenic inheritance of atopic diathesis involving IgE regulation, cytokine gene polymorphisms (IL-4, IL-13 loci on chromosome 5q31), and HLA associations
Elevated total serum IgE: Marker of systemic atopic sensitisation; elevated in the majority of atopic VKC; less consistently elevated in non-atopic limbal VKC in African populations
Allergen sensitisation: Positive skin prick test or specific IgE to environmental allergens (grass pollen, Dermatophagoides species, fungal antigens) identifies sensitising triggers and guides avoidance strategies
Sub-Saharan African and dark-skinned ethnicity: Non-atopic limbal VKC predominates in African children; the mechanism is not fully elucidated but may involve heightened non-specific mast cell reactivity or different allergen exposure profiles
Keratoconus: VKC is a recognised risk factor for keratoconus, likely through repeated eye rubbing, eosinophil-mediated collagenolysis, and chronic mechanical trauma from giant papillae; the association is clinically important and should prompt corneal topography assessment

Conjunctival Signs

Giant cobblestone papillae: Pathognomonic of palpebral VKC; polygonal, flat-topped papillae >1 mm (often 2–8 mm) with a central fibrovascular core on the superior tarsal conjunctiva; arranged in a mosaic pattern resembling cobblestones; must be visualised on upper lid eversion — the most critical examination step; the inferior tarsal conjunctiva is typically spared or less severely affected
Horner-Trantas dots: Pathognomonic of limbal VKC; discrete, chalky-white, gelatinous accumulations of degenerated eosinophils and epithelial cells at the superior and perilimbal conjunctiva; transient — more prominent during active disease and may disappear during remission; size varies from 0.5 to 3 mm
Limbal gelatinous thickening: Broad, opaque, gelatinous swelling of the limbal conjunctiva — predominantly superior in limbal and mixed VKC; may encroach onto the peripheral cornea
Maxwell-Lyons sign: Fine, superficial, transverse white lines on the superior tarsal conjunctiva corresponding to the grooves between papillary ridges filled with mucus; seen in VKC and sometimes in AKC
Diffuse conjunctival hyperaemia: Pink-to-red palpebral and bulbar conjunctival injection; more prominent during acute exacerbation
Chemosis: Conjunctival oedema, particularly during acute flares; may be accompanied by eyelid oedema
Mucoid discharge: Ropy, stringy, whitish-grey mucus — characteristic of VKC; composed of mucin, eosinophil products, fibrin, and shed epithelial cells; forms threads and strands on the ocular surface and eyelid margins; visually and clinically distinct from the watery discharge of viral or the mucopurulent discharge of bacterial conjunctivitis

Corneal Signs

Superficial punctate keratitis (SPK): Fine punctate fluorescein-staining lesions predominantly in the superior cornea corresponding to the zone of contact with papillae; earliest corneal manifestation; reflects epithelial disruption from mechanical trauma and eosinophil-derived toxins
Macroerosion: Confluent superior epithelial erosion preceding shield ulcer formation; stains with fluorescein; patient experiences acute pain, photophobia, and reduced visual acuity
Shield ulcer (Togby’s ulcer): Oval or shield-shaped epithelial defect with a white stromal plaque at the superior one-third of the cornea; the plaque consists of fibrin, mucus, and eosinophil-derived proteins deposited in Bowman’s layer; prevents epithelial healing and may deepen into the anterior stroma; grades I–III based on depth (epithelial only → Bowman’s → anterior stroma)
Corneal pannus: Superficial fibrovascular ingrowth from the superior limbus onto the cornea; associated with chronic limbal VKC; may produce a grey-white arc of opacity in the superior peripheral cornea
Pseudogerontoxon: Lipid deposition at the superior peripheral cornea resembling arcus senilis but localised to the superior sector; a marker of chronic limbal VKC and associated chronic limbal ischaemia
Corneal scarring: Permanent anterior stromal haze resulting from resolved shield ulcers with Bowman’s layer involvement; reduces best-corrected visual acuity; location in the visual axis determines functional significance
Keratoconus: Corneal topography may reveal early keratoconic changes (inferior steepening, asymmetric bow-tie pattern, increased astigmatism) in VKC patients — particularly those who chronically rub their eyes; assessment with Scheimpflug or Placido topography is essential

Cardinal Ocular Symptoms

Intense bilateral itching (pruritus): The dominant and most diagnostically characteristic symptom; mediated by histamine acting on H1 receptors on conjunctival sensory nerves; typically described as an irresistible deep-seated itch that compels rubbing; more severe than in seasonal allergic conjunctivitis; present even outside peak allergen seasons in moderate-to-severe disease
Photophobia: Often prominent and can be disabling; results from corneal epithelial disruption (SPK, macroerosion, shield ulcer) and heightened nociceptor sensitivity in inflamed conjunctival and corneal tissues; severe photophobia with blepharospasm is a warning sign for corneal complications requiring urgent assessment
Foreign body sensation / burning: Gritty or sandy discomfort from giant papillae mechanically abrading the corneal surface with each blink; burning sensation from inflammatory mediators on the ocular surface; may be constant and severely affect quality of life and school attendance
Blepharospasm: Involuntary forceful eyelid closure in response to corneal pain and photophobia; a sign of severe corneal involvement (shield ulcer or macroerosion); may prevent adequate examination without topical anaesthetic
Profuse mucoid discharge: Ropy, stringy white-grey mucus; patients describe “strings” of mucus in the medial canthus on waking and throughout the day; attempts to remove the mucus by pulling produce long fibrous strands (Tenzel’s sign)
Blurred vision: Transient blurring from excessive mucus and tearing (clears with blinking) in mild-to-moderate disease; persistent blur suggests shield ulcer, corneal scarring, irregular astigmatism from keratoconus, or induced refractive change from corneal distortion
Ptosis: Mechanical ptosis (pseudoptosis) from the weight of hypertrophied tarsal papillae and repeated eye rubbing; should be distinguished from true ptosis; typically resolves with disease control

Seasonal and Diurnal Pattern

Seasonal exacerbation: Symptoms characteristically worsen in spring and summer (particularly March–September in the northern hemisphere), corresponding to peak pollen counts and elevated temperatures; patients may have a relatively symptom-free winter
Perennial disease: In moderate-to-severe VKC — particularly in tropical climates and limbal VKC — symptoms persist year-round with seasonal exacerbations superimposed on a continuous inflammatory baseline
Morning worsening: Accumulated mucoid discharge and papillary conjunctival trauma during sleep cause more pronounced morning symptoms; blinking on waking produces immediate discomfort

Sight-Threatening Corneal Complications

Shield ulcer (Togby ulcer): Most significant acute complication; oval superior epithelial defect with a white stromal plaque; results from combined mechanical trauma from papillae and eosinophil cytotoxin deposition; the plaque inhibits re-epithelialisation; requires ophthalmological management — may need surgical plaque debridement; risk of anterior stromal scarring if untreated or inadequately managed
Corneal scarring: Permanent anterior stromal opacity resulting from resolved shield ulcers that have breached Bowman’s layer; central scars reduce best-corrected visual acuity and may cause irregular astigmatism; a leading cause of preventable corneal visual impairment in children in endemic regions
Corneal plaque: Calcium-containing, chalky-white opacity adherent to Bowman’s layer at the site of a shield ulcer; further impairs epithelial healing; surgical excimer laser phototherapeutic keratectomy (PTK) or mechanical debridement required
Keratoconus: Progressive non-inflammatory ectatic corneal thinning associated with VKC, particularly in chronic eye rubbers; prevalence of keratoconus in VKC patients is significantly higher than in the general population (estimates range from 7–26%); may necessitate rigid gas-permeable contact lenses or corneal cross-linking (CXL)
Corneal neovascularisation and pannus: Superficial fibrovascular ingrowth from the limbus onto the peripheral cornea; reduces corneal clarity and compromises future penetrating keratoplasty by increasing vascularisation of the graft bed

Treatment-Related Complications

Steroid-induced ocular hypertension and glaucoma: The most clinically significant treatment complication; up to 30% of VKC patients on long-term topical steroids develop raised IOP; steroid responders are at risk of irreversible optic nerve damage; IOP must be monitored every 4–6 weeks during steroid therapy; appropriate non-contact tonometry and, where indicated, optic nerve and visual field assessment required
Posterior subcapsular cataract: Prolonged topical steroid use — particularly with potent agents such as dexamethasone and prednisolone — accelerates posterior subcapsular lens opacity; particularly damaging in the visually immature eyes of children, where it can cause deprivation amblyopia
Steroid-related ptosis and skin atrophy: Periocular skin atrophy, eyelid depigmentation, and dermal thinning from chronic topical or periocular steroid use
Amblyopia: Unilateral or bilateral amblyopia may develop from corneal scarring, shield ulcer-induced visual deprivation, anisometropia from corneal irregularity (keratoconus), or steroid-induced cataract — particularly in children under 8 years; regular visual acuity monitoring and refraction are essential

Other Complications

Secondary bacterial or herpetic infection: Compromised corneal and conjunctival epithelial barrier in active VKC predisposes to secondary bacterial keratitis and HSV reactivation; topical steroid use further impairs local immunity
Limbal stem cell deficiency: Chronic limbal inflammation, eosinophil-mediated cytotoxicity, and repeated papillary trauma may deplete the palisades of Vogt and limbal stem cell population, leading to conjunctivalisation of the cornea (pannus, goblet cell ingrowth onto corneal epithelium)

Atopic Systemic Associations

Atopic dermatitis (eczema): Present in approximately 40–60% of VKC patients; characterised by chronic pruritic eczematous skin lesions with IgE-mediated sensitisation; the shared Th2 immunological milieu links these conditions; periocular involvement (eczematous lid skin, Dennie-Morgan infraorbital folds, Hertoghe sign — lateral eyebrow thinning from chronic rubbing) is common
Allergic rhinitis: The most common systemic atopic association in VKC (50–70%); sneezing, rhinorrhoea, nasal congestion, and nasal pruritus from IgE-mediated inflammation of the nasal mucosa; shared allergen sensitisation (grass pollen, dust mites) often triggers both conditions simultaneously; assessment and treatment of co-existing rhinitis (intranasal corticosteroids, oral antihistamines) may reduce systemic allergic burden and indirectly improve VKC control
Asthma: Bronchial hyperreactivity and episodic wheeze present in 30–50% of VKC patients; the unified airway hypothesis proposes that the same Th2-driven allergic inflammation affects the entire respiratory mucosa; systemic anti-allergic therapy (oral antihistamines, allergen immunotherapy) targeting one condition may benefit the other
Food allergies: IgE-mediated sensitisation to food antigens (peanut, tree nuts, milk, egg, wheat) in a subset of atopic VKC patients; dietary avoidance may be relevant in reducing overall IgE burden and systemic mast cell priming
Elevated total serum IgE: Systemic marker of atopic sensitisation; markedly elevated IgE (>1000 IU/mL) is associated with more severe VKC and greater risk of corneal complications; IgE-targeted therapy (omalizumab) has shown promise in refractory atopic disease including severe VKC

Connective Tissue and Other Associations

Down syndrome (Trisomy 21): Significantly increased prevalence of VKC and keratoconus in Down syndrome; the combination of altered immune regulation and connective tissue laxity increases vulnerability to both conditions; requires proactive corneal screening and management
Leber congenital amaurosis (LCA): Association between LCA and keratoconus — itself associated with VKC — has been reported; the eye-rubbing behaviour in visually impaired children with LCA may contribute to keratoconus progression
Keratoconus systemic links: Conditions associated with connective tissue laxity (Marfan syndrome, Ehlers-Danlos syndrome, osteogenesis imperfecta) carry increased keratoconus risk, which may be compounded by VKC-associated chronic eye rubbing and eosinophil-mediated collagenolysis

Clinical Diagnosis

VKC is a clinical diagnosis based on characteristic signs and symptoms. No single laboratory investigation is diagnostic; the clinical triad of intense bilateral itch, giant cobblestone papillae on upper lid eversion, and/or Horner-Trantas dots at the limbus in a young atopic male from an endemic climate is pathognomonic.

History: Age of onset, sex, ethnicity, atopic history (personal and family), seasonal variation, geographic background (hot/dry/tropical), symptom severity (itch, photophobia, discharge character), prior treatments and their effect, contact lens use, history of eye rubbing
Visual acuity: Reduced BCVA raises concern for corneal complication (shield ulcer, scarring, keratoconus); serial VA monitoring is essential in children to detect amblyopia
Upper eyelid eversion (critical): Mandatory in all suspected VKC; cobblestone papillae are exclusively visualised on eversion of the upper lid; failure to evert the upper lid is the most common reason for missed or delayed VKC diagnosis; papillae may be so large as to cause mechanical difficulty in lid eversion
Slit lamp biomicroscopy: Assess papillae size and distribution; limbal gelatinous thickening and Trantas dots; corneal epithelium with fluorescein (SPK, erosion, shield ulcer); anterior chamber (exclude uveitis); lens (steroid-induced posterior subcapsular cataract if on treatment)
Fluorescein and sodium fluorescein staining: Maps corneal epithelial involvement (SPK, macroerosion, shield ulcer); assesses shield ulcer grade and extent; essential for monitoring corneal response to treatment
Corneal topography / Scheimpflug imaging: Mandatory in VKC patients with reduced BCVA, increasing astigmatism, or history of significant eye rubbing; screens for keratoconus; establishes baseline corneal morphology for longitudinal monitoring
Intraocular pressure measurement: Baseline IOP prior to steroid initiation; repeat every 4–6 weeks during steroid therapy; non-contact tonometry (air-puff) appropriate for screening; Goldmann applanation is the gold standard for accurate readings

Investigations

Conjunctival scraping cytology: Giemsa-stained conjunctival scraping reveals a predominantly eosinophilic infiltrate with scattered mast cells and lymphocytes; eosinophils (>2 per high-power field) and free eosinophil granules (MBP deposits) are characteristic; Charcot-Leyden crystals (from eosinophil lysophospholipase crystallisation) may be seen; differentiates VKC from bacterial (neutrophils) and viral (lymphocytes) conjunctivitis
Serum total IgE: Elevated in atopic VKC (>150 IU/mL; often >1000 IU/mL in severe disease); supports atopic diagnosis; useful for monitoring response to anti-IgE therapy; normal IgE does not exclude VKC (non-atopic limbal form)
Specific IgE (RAST / ImmunoCAP): Identifies sensitising allergens (grass pollen, dust mites, animal dander, fungi); guides environmental avoidance counselling and identifies candidates for allergen-specific immunotherapy (ASIT)
Skin prick testing: Gold-standard allergen sensitisation testing; performed by allergist; identifies specific environmental triggers; guides ASIT selection; inappropriate if patient is on antihistamines
Tear cytokine analysis (research): Elevated IL-4, IL-5, IL-13, eotaxin, tryptase, ECP, and MBP in tear fluid of VKC patients; not routinely used clinically but supports diagnosis and monitoring of therapeutic response in research settings

Singapore Optometry Scope Note: Optometrists in Singapore may perform comprehensive anterior segment assessment including slit lamp biomicroscopy, upper lid eversion, fluorescein staining, non-contact tonometry (IOP monitoring), corneal topography, and visual acuity assessment. Non-contact fundus assessment using slit lamp biomicroscopy with a condensing lens or approved diagnostic imaging equipment is within scope — dilation fundus examination is not performed by optometrists in Singapore. Topical corticosteroids, topical cyclosporine, and supratarsal steroid injections require initiation and monitoring by an ophthalmologist. Any case with shield ulcer, corneal scarring, reduced BCVA, suspected keratoconus, or inadequate response to non-steroidal therapy must be referred to an ophthalmologist promptly. Mast cell stabilisers and topical antihistamines are within optometric scope for mild-to-moderate disease management.

Environmental and General Measures

Allergen avoidance: Reduce exposure to identified triggers; stay indoors during high pollen counts; use high-efficiency particulate air (HEPA) filters; dust mite impermeable mattress and pillow covers; avoid known food allergens; remove or reduce animal dander exposure
Wraparound UV-blocking sunglasses: Reduce UV exposure (a non-specific trigger), wind and dust irritation, and photophobia; particularly important during outdoor activities in tropical or high-UV environments
Cold compresses: Cold packs applied to closed eyelids for 5–10 minutes several times daily reduce histamine release, mast cell activity, and itch; one of the most effective and safe non-pharmacological interventions
Eye rubbing cessation: Critical counselling point — eye rubbing perpetuates the itch-rub cycle, worsens mechanical trauma from papillae, promotes keratoconus progression, and redistributes allergens; patients (and parents) must be educated on strategies to break the habit (cold compress substitution, nasal antihistamines to reduce systemic itch drive)
Preservative-free lubricating drops: Frequent application (4–8 times daily) dilutes allergens and inflammatory mediators, reduces surface friction, and supplements mucosal defence; preservative-free formulations preferred to avoid additive surface toxicity

Pharmacological Management

Mast Cell Stabilisers (First-Line, Long-Term):

Sodium cromoglicate (cromolyn) 2–4% eye drops: Stabilises mast cell membranes, inhibiting degranulation; QID dosing; most effective as prophylactic/maintenance therapy; onset of full effect 2–4 weeks; safe for long-term use in children; first-line maintenance agent in mild-to-moderate VKC
Lodoxamide 0.1% eye drops: More potent mast cell stabiliser than cromoglicate; also inhibits eosinophil activation and reduces mediator release; QID dosing; superior efficacy to cromoglicate in clinical trials; effective for both acute and maintenance therapy in moderate VKC
Nedocromil sodium 2% eye drops: Dual mast cell stabiliser and anti-inflammatory; inhibits eosinophil and neutrophil activation; BD-QID dosing; useful adjunct in moderate disease

Dual-Action Antihistamine / Mast Cell Stabilisers:

Olopatadine 0.1% or 0.2% eye drops: Combined H1-antagonist and mast cell stabiliser; rapid onset (15 minutes) for itch relief; sustained anti-inflammatory effect; BD dosing (0.1%) or once daily (0.2%); first-line for acute itch management and maintenance; excellent safety profile; preferred first-line pharmacological agent in Singapore optometric practice for mild-to-moderate VKC
Ketotifen 0.025% eye drops: Dual antihistamine and mast cell stabiliser; also inhibits eosinophil migration; BD dosing; available OTC in many markets; effective for itch and mild-to-moderate disease
Azelastine 0.05% eye drops: Selective H1-antagonist with additional mast cell stabilising activity; BD dosing; effective rapid-onset itch relief

Topical NSAIDs:

Ketorolac tromethamine 0.5% eye drops: Inhibits prostaglandin synthesis; reduces itch and hyperaemia as an adjunct to mast cell stabilisers; QID dosing; short-term use; limited evidence compared with antihistamines and steroids in VKC specifically

Topical Corticosteroids (Ophthalmologist-Initiated):

Fluorometholone (FML) 0.1% eye drops: Preferred steroid for VKC; less penetrant to anterior chamber; lower IOP-raising potential than prednisolone; typically QID for 2–4 weeks then taper; suitable for moderate exacerbations
Prednisolone acetate 0.5–1% eye drops: More potent; reserved for severe acute flares or shield ulcers; short-course pulse therapy (1–2 weeks) to control acute inflammation; must monitor IOP every 4–6 weeks; long-term use carries significant steroid complication risk
Loteprednol etabonate 0.5% eye drops: A retrometabolic steroid with reduced systemic and IOP-related side-effect profile; emerging evidence supporting use in VKC; suitable for moderate disease where IOP sensitivity is a concern
Supratarsal corticosteroid injection: Methylprednisolone acetate (40 mg/mL) or triamcinolone acetonide (10 mg/mL) injected into the superior fornix conjunctival subspace; delivers sustained-release depot steroid directly to the most inflamed tissue; used for severe or steroid drop-resistant palpebral VKC; performed under topical anaesthesia by an ophthalmologist; may avoid frequent drop instillation in non-adherent patients

Topical Immunomodulators (Steroid-Sparing — Ophthalmologist-Initiated):

Topical cyclosporine A (CsA) 0.05–2%: Calcineurin inhibitor; inhibits T-cell activation and IL-2 production; reduces eosinophil infiltration and mast cell density; most evidence for 1–2% compounded formulation in VKC; reduces steroid dependence; well-tolerated with minimal systemic absorption; first-line steroid-sparing agent for moderate-to-severe VKC; may cause initial burning/stinging on instillation
Topical tacrolimus 0.03–0.1%: More potent calcineurin inhibitor than CsA; useful in refractory VKC unresponsive to CsA; limited approved topical ophthalmic formulation — typically compounded; case series and small trials support efficacy
Oral ciclosporin (severe, refractory VKC): Short-course systemic immunosuppression for sight-threatening or refractory VKC unresponsive to all topical therapy; requires systemic monitoring (renal function, blood pressure); specialist ophthalmology or immunology involvement

Systemic Agents:

Oral antihistamines (cetirizine, loratadine, fexofenadine): Reduce systemic histamine-driven itch; useful when VKC co-exists with allergic rhinitis or urticaria; second-generation agents preferred for reduced sedation; adjunct to topical therapy
Allergen-specific immunotherapy (ASIT): Subcutaneous or sublingual desensitisation to confirmed sensitising allergens; the only disease-modifying therapy; reduces IgE-mediated sensitisation and shifts immune response from Th2 toward Th1; recommended for atopic VKC patients with confirmed specific allergen sensitisation; course duration typically 3–5 years; requires allergy specialist collaboration
Omalizumab (anti-IgE monoclonal antibody): Binds free IgE, reducing mast cell sensitisation; shown to reduce VKC severity in small cohort studies and case series; reserved for severe atopic VKC refractory to standard therapy; specialist prescription

Shield Ulcer Management

Grade I (epithelial only): Intensive topical steroid (prednisolone acetate 1% QID) + mast cell stabiliser + preservative-free lubricant; bandage contact lens for epithelial support; close monitoring every 48–72 hours; managed by ophthalmologist
Grade II–III (plaque formation / stromal involvement): Mechanical debridement or surgical excision of the stromal plaque under topical anaesthesia; excimer laser PTK for residual stromal plaque; postoperative topical steroid, antibiotic prophylaxis, and bandage contact lens; supratarsal steroid injection to reduce papillary trauma during healing
Amniotic membrane transplantation: For recalcitrant shield ulcers failing standard measures; promotes re-epithelialisation and reduces inflammation; applied as a temporary graft or patch

Stepped Treatment Summary

Severity	Pharmacotherapy	Referral
Mild	Cold compress; PF lubricants; topical olopatadine or ketotifen BD; sodium cromoglicate or lodoxamide QID; oral antihistamine if co-existing rhinitis	Not required if responding
Moderate	Above + short-course FML 0.1% QID ×2–4 weeks (taper); consider topical CsA for steroid-sparing; monitor IOP	Ophthalmology for steroid initiation; corneal topography
Severe	Prednisolone 1% QID pulse; topical CsA 1–2%; supratarsal steroid injection; lodoxamide; systemic antihistamine; consider ASIT referral	Urgent ophthalmology; allergen testing
Shield ulcer / refractory	Plaque debridement / PTK; bandage CL; intensive steroid; amniotic membrane if needed; consider omalizumab	Same-day / urgent ophthalmology

Refer to Ophthalmology / Emergency Department for:

Immediate / same-day referral:

Shield ulcer (any grade) or macroerosion
Severe blepharospasm preventing examination
Significantly reduced visual acuity not attributable to discharge
Suspected corneal scarring or corneal perforation (rare)

Urgent / early referral:

Steroid initiation for moderate-to-severe disease
IOP elevation on topical steroid therapy
Suspected keratoconus on corneal topography
Suspected posterior subcapsular cataract
Disease refractory to mast cell stabilisers and antihistamines
Child with unilateral reduced VA — exclude amblyopia

Overall Prognosis

The natural history of VKC is generally favourable, with spontaneous remission occurring in the majority of patients by late adolescence or early adulthood (typically by age 20–25). The disease is self-limiting in most cases, driven by age-related changes in immune responsiveness, hormonal shifts, and altered mast cell reactivity. However, the prognosis for visual acuity is less uniformly good — a significant minority of patients sustain permanent corneal scarring, develop keratoconus, or suffer complications from long-term steroid therapy. Early, structured management with regular ophthalmological oversight is the most important determinant of visual outcome.

Prognostic Factors

Factor	Effect on Prognosis
Age at presentation	Younger onset with early treatment — favourable; disease remits by early adulthood
Corneal shield ulcer	Risk of permanent scarring if Bowman’s layer involved; visual prognosis depends on ulcer depth and central location
Keratoconus	Progressive corneal ectasia; visual rehabilitation with RGP lenses or CXL required; corneal transplant in advanced cases
Long-term unmonitored steroid use	Risk of steroid glaucoma and posterior subcapsular cataract — both potentially sight-threatening in children
Adherence to mast cell stabiliser therapy	Reduces exacerbation frequency and corneal complication risk; improves quality of life
Allergen immunotherapy (ASIT)	Disease-modifying; reduces allergen sensitivity and exacerbation frequency; may induce long-term remission
Chronic eye rubbing	Accelerates keratoconus progression; perpetuates the itch-rub cycle; important modifiable risk factor

Condition	Key Distinguishing Features	Differentiating Clue
Atopic Keratoconjunctivitis (AKC)	Adults (20–50 years); severe atopic dermatitis with periocular eczema; chronic perennial bilateral disease; inferior fornix scarring; corneal neovascularisation; stellate anterior subcapsular cataract; keratoconus; does not remit with age	Age (>20 years); periocular skin eczema; inferior fornix involvement; chronic non-remitting course
Seasonal Allergic Conjunctivitis (SAC)	Bilateral itch and redness; watery discharge; chemosis; papillary reaction; seasonal pattern; mild severity; no cobblestone papillae; no corneal involvement; complete remission out of season	Mild severity; no cobblestone papillae; no Trantas dots; complete seasonal remission
Perennial Allergic Conjunctivitis (PAC)	Year-round mild-to-moderate bilateral itch; papillary reaction; dust mite or animal dander sensitisation; no cobblestones or Trantas dots; no corneal involvement; far milder than VKC	Year-round but mild; no tarsal cobblestones; no corneal complications
Giant Papillary Conjunctivitis (GPC)	Contact lens or ocular prosthesis wearer; large tarsal papillae on upper lid; mucus and lens intolerance; itch less severe than VKC; no Trantas dots; no corneal complications; resolves with lens holiday	Contact lens or prosthesis history; resolves with lens cessation; no limbal signs
Viral Conjunctivitis (EKC)	Acute onset; watery discharge; follicular not papillary reaction; preauricular lymphadenopathy; URTI history; subepithelial infiltrates (not shield ulcer); self-limiting; no itch as dominant symptom	Acute self-limiting; follicles not papillae; preauricular LAP; watery discharge
Bacterial Conjunctivitis	Mucopurulent discharge; papillary reaction (fine); no itch; unilateral onset; responds to topical antibiotics; no cobblestone papillae; no Trantas dots	Mucopurulent discharge; itch absent; responds to antibiotics
Chlamydial Conjunctivitis (Trachoma)	Follicular reaction on superior tarsal (arlt’s line); superior pannus from limbus; Herbert’s pits at superior limbus (healed follicles); endemic in resource-limited settings; chronic mucopurulent discharge; STI form — follicular, inferior, chronic, in adults	Follicles not papillae; Arlt’s line; Herbert’s pits; chronic mucopurulent discharge
Toxic / Medicamentosa Conjunctivitis	Chronic inferior papillary or follicular reaction from topical medication preservatives (BAC); inferior SPK; history of multi-drop therapy; improves with withdrawal of offending agent; no itch as dominant symptom	Topical medication history; inferior pattern; no itch; improves with cessation
Dry Eye Disease (DED)	Bilateral burning/grittiness; reduced TBUT; interpalpebral SPK; no discharge; worsens in dry/airconditioned environments; no papillae or follicles; Schirmer reduced; no limbal signs	No itch; no papillae; reduced TBUT; responds to lubricants

Always evert the upper eyelid — cobblestone papillae on the superior tarsus are pathognomonic of palpebral VKC and are only visible on upper lid eversion; this single examination step is the most commonly missed and is the most diagnostically decisive in differentiating VKC from all other allergic eye diseases
Intense itch is the cardinal symptom — if the patient does not describe significant itch, reconsider the diagnosis of VKC; bacterial and viral conjunctivitis produce minimal itch, while dry eye produces burning rather than itch; the severity and bilaterality of itch is diagnostically discriminating
Shield ulcer is a sight-threatening emergency — a white oval plaque at the superior one-third of the cornea in a young atopic patient presenting with acute photophobia and reduced VA should be considered a shield ulcer until proven otherwise; refer same-day to ophthalmology; do not initiate steroid drops alone without ophthalmological assessment
Monitor IOP rigorously in every VKC patient on topical steroids — steroid responders can develop significant IOP elevation within weeks of commencing therapy; the risk is particularly high in children; failure to monitor IOP is the most preventable cause of steroid-induced glaucomatous optic neuropathy in VKC
Eye rubbing cessation is non-negotiable in keratoconus risk management — every VKC patient and their caregivers must be counselled on the mechanistic link between vigorous eye rubbing, progressive corneal thinning, and keratoconus; substituting cold compresses for rubbing breaks the cycle and reduces ectasia risk
Ropy mucus is a clinical hallmark of VKC — the stringy, fibrous mucoid discharge of VKC contrasts with the watery discharge of viral conjunctivitis, the mucopurulent discharge of bacterial infection, and the thin mucoid strands of dry eye; asking patients to describe whether the discharge forms long strings is a useful history-taking tip
Allergen immunotherapy is the only disease-modifying treatment — all other pharmacological therapies in VKC are symptomatic; for atopic patients with identified sensitising allergens, referral for ASIT consideration is appropriate and may achieve long-term reduction in disease activity and steroid requirement
Perform corneal topography in all VKC patients — particularly those with reduced or asymmetric BCVA, increasing astigmatism, or a history of vigorous eye rubbing; early keratoconus detection enables timely corneal cross-linking before significant ectasia compromises BCVA

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Clinical Illustration

Overview

Etiology

Immunological Basis

Triggering Factors

Genetic and Familial Factors

Pathogenesis

Cellular and Molecular Cascade

Classification