Q4 LONG ANSWER 10M ★ High-yield

Classify allergic conjunctivitis. Describe vernal keratoconjunctivitis and its treatment.

Ophthalmology · 3rd Professional

Allergic conjunctivitis is the commonest of all conjunctival disorders, and comprises a spectrum from trivial seasonal itching to sight-threatening corneal disease
Seasonal and perennial allergic conjunctivitis (sac and PAC) — a pure type I (IgE-mediated) hypersensitivity to pollen, dust mite or animal dander. Bilateral itching, watering, chemosis and lid oedema, with a papillary reaction; often with rhinitis. It is uncomfortable but not sight-threatening
Vernal keratoconjunctivitis (VKC, spring catarrh) — the important one in India. A combined type I and type IV reaction. Affects boys between 5 and 20 years, in hot, dry, dusty climates, with a strong atopic family history; it is bilateral, seasonal (worse in summer) and self-limiting at puberty in most cases

Form	Features
Palpebral	Large, flat-topped giant papillae on the upper tarsal conjunctiva, giving the classical cobblestone appearance
Bulbar (limbal)	Gelatinous thickening and heaping of the limbal conjunctiva, with HORNER-trantas DOTS — discrete chalky-white spots at the limbus composed of degenerating eosinophils and epithelial debris. Commoner in dark-skinned and African patients
Mixed	Both, and the commonest presentation
Corneal complications	Punctate epithelial keratitis; a shield ulcer — a shallow, oval, sterile ulcer of the superior cornea with a plaque of mucus and fibrin in its base.

Symptoms — intense itching, which is the cardinal symptom and out of proportion to the signs; ropy, thick, stringy mucoid discharge which the child pulls out in strands; photophobia; and a burning, gritty sensation
The single most important piece of advice is TO stop rubbing. Persistent vigorous eye rubbing in these children causes keratoconus, which is far more damaging in the long run than the conjunctivitis itself and is entirely preventable

General measures — avoid the allergen where identifiable; cold compresses, which are simple and genuinely effective; dark glasses for photophobia; frequent lubricants to dilute allergen; and moving to a cooler climate, which is classically advised and rarely practicable
Mast cell stabilisers — sodium cromoglycate, nedocromil; slow in onset, so they are started early in the season and continued prophylactically
Dual-action agents — olopatadine, ketotifen, azelastine — antihistamine and mast cell stabilising, with rapid onset and a long duration; these are now first-line

Feature	Vernal (VKC)	Atopic (AKC)
Age	Children and adolescents, 5 to 20 years	Adults, 30 to 50 years
Sex	Boys predominate	Either
Associated disease	Asthma, hay fever, atopy	Atopic dermatitis, characteristically of the eyelids
Course	Seasonal, worse in summer; resolves at puberty	Perennial and progressive; does not resolve
Conjunctiva involved	Upper tarsus — giant cobblestone papillae	Lower tarsus, with smaller papillae
Limbal signs	Gelatinous thickening and HORNER-trantas dots	Less prominent
Scarring	Uncommon; the conjunctiva usually recovers	Cicatrisation, symblepharon and fornix shortening
Corneal involvement	Shield ulcer; keratoconus from rubbing	Persistent epithelial defect, vascularisation, keratoconus
Cataract	Only if steroid-induced	Anterior subcapsular shield cataract, characteristic
Prognosis	Good — burns out	Guarded — sight-threatening and lifelong

Tell the child to stop rubbing, and tell the parents why; keratoconus from rubbing causes more permanent visual loss than the vernal disease does
Measure the intraocular pressure at every visit in a child on topical steroids, and ask specifically whether drops are being bought without prescription
Use dual-action drops and ciclosporin as the mainstay, and reserve steroids for short supervised pulses in severe exacerbations
Look for tuberculosis and malnutrition in phlyctenular disease; in India this association remains real and the eye sign may be the presenting feature
Suspect drug allergy when an eye deteriorates on treatment; neomycin, gentamicin, atropine and preservatives are the usual culprits and the answer is to stop, not to add
Reassure that vernal disease resolves at puberty in most children; it is a long haul but it ends.
Distinguish vernal from atopic disease — upper tarsus in a boy that resolves, against lower tarsus in an adult that scars — because the prognosis and the surveillance differ entirely
Vernal disease affects boys in hot dry climates and resolves at puberty; atopic disease affects adults and progresses

All questions in Diseases of the Conjunctiva