Differential of eye allergy includes tear film dysfunction, infection, autoimmune/inflammatory conditions, blepharitis, dry eye.
Severe -2 of vision disturbance, impairment of daily activities (leisure, sport, school, work); troublesome symptoms.
Perennial conjunctivitis usually related to house dust mite (HDM), animal dander, moulds else multiple. Itch characteristic, as per seasonal conjunctivitis, findings non-specific eg tearing, redness, eyelid swelling, small papillary hypertrophy of tarsal conjunctiva. Neither has corneal involvement.
Beware pain, photophobia, visual disturbance, grittiness or foreign body sensation. These can indicated Vernal keratoconjunctivitis, which does affect the cornea (warm climates eg Mediterranean/Africa): typically boys aged 4-12yrs, T cell and IgE combined, improves after puberty. Severe itching, exacerbated by nonspecific stimuli eg wind, dust, sun. Cobblestone appearance of tarsal plate (ie inside upper eyelid) else limbic thickened and opacified +/- white/yellow gelatinous deposits (more typical of tropical form). Can get corneal ulcers.
Atopic keratoconjunctivits is also rare, the eye can be the only affected area cf atopic dermatitis. Hall mark is fissured eyelid. Staph colonization contributes. Limbus and cornea can be affected.
Giant papillary – associated with contact lenses.
Contact blepharoconjunctivitis is eyelid itching, oedema, eczema with less in the way of conj redness.
Investigations for ocular allergy
Skin prick testing incl moulds. Consider latex. Else IgE.
Conjunctival provocation test can be done with standardized allergens – defer if on local or systemic antihistamines or anti-inflammatories, contra-indicated if uncontrolled asthma. Ideally when asymptomatic and eye not inflamed! Dilute extract to obtain several lower concentration solutions (last up to 6 hours at room temp). Administer 20microl dose at 30 min intervals at infero-external quadrant of right eye. Left eye is control! Have local antihistamine and steroids available, in addition to usual systemic medicines. Only 1 reported case of anaphylaxis!
Patch test for non-IgE. Else Conjunctival cytodiagnosis eg eosinophil infiltrates.
Treatment and prevention –
- Avoid allergens, protect eye with sunglasses.
- Lubricants and cold compresses are good.
- Topical antihistamines eg azelastine, olapatadine but also Lodoxamide, ketotifen.
- Mast cell stabilizer (ie cromoglycate) needs 2/52 preloading and multiple doses per day, plus stings! So poor compliance.
- Systemic antihistamines if other symptoms else may be excessively drying.
- Topical steroids should be avoided except where cornea involved, ie VKC, AKC, and then only in short pulses. Twice daily steroids for a month or more raises concern about glaucoma, cataracts.
- Ciclosporin drops oily, supply probs – veterinary products used! Tacrolimus not available in drops; cream burns a little but gets better.
Nasal steroids work well for eye symptoms and appear to be safe.
For blepharitis, eyelid hygiene, emollients, 1% hydrocortisone.[Leonardi, Allergy 67 (2012):1327]