ALLERGIC CONJUNCTIVITIS

Allergic Conjunctivitis

Very varied allergens can give rise to superficial conjunctival reactions.
Allergens such as dust, pollens, cosmetics and eye drops can be
responsible. Spring and summer outbreaks are most common from
pollens. A diagnostic feature is itch, especially near the medial canthi.

Treatment
Topical vasoconstrictor and antihistamine eye drops (antistine-provine),
oral antihistamines, desensitisation.

(a) Spring Catarrh (Vernal Conjunctivitis) - a bilateral chronic allergic
condition is more common in hot climates. It begins in pre-pubertal years;
boys are more commonly affected. The major complaint is itching, worse
in hot weather. Two areas predominantly affected, usually of different inten-
sity: - Palpebral - the upper tarsus is pale pink, thickened and contains
irregular swellings - "cobblestones".

Limbal - a pink, vascularised swelling close to the limbus in the palpebral
aperture.

- stringy mucoid conjunctival discharge contains eosinophils.
- corneal ulcer may occur, especially from rubbing by the rough upper lid.

Treatment consists of local instillation of minimal amounts of corticosteroids,
or sodium cromoglycate 2% (Opticrom) eye drops, to suppress the hypersen-
sitivity. The condition tends to disappear with time, but may continue for
several years.

(b) Giant Papillary Conjunctivitis - a complication of soft lenses, chronic sensi-
tivity, resembles spring catarrh; change or stop lenses, poor response to medi-
cations.

(c) Drug Sensitivity - to the topical application of atropine and similar alkaloids,
antibiotics, adrenaline and similar substances e.g. phenylephrine, antivirals
(I.D.U.), miotics. It is prone to occur with prolonged administration especially
where there is chronic or recurrent disease, but some drugs can cause sensiti-
vity quickly e.g. Neomycin.

It occurs more readily with a seborrhoeic background. When sensitivity occurs
the drugs cannot be used again even after an interval so the use of ocular topical
medications must be viewed very circumspectly.

Onset of drug sensitivity may be acute or gradual, with lacrimation redness,
chemosis and a watery discharge. The skin becomes red, hot and dry. Some
toxic drugs such as the antivirals and powerful miotics can cause scarring sub-
conjunctivally and closure of the lacrimal canaliculi.

Treatment - cease administration of the drug. Topical corticosteroids usually
expedite resolution.

Adrenaline administered repeatedly as eyedrops as for the treatment of glaucoma,
leads to the deposits of black spots in the conjunctiva, especially of the lower
fornix. These are harmless, but may be mistaken for foreign bodies.

(d) Phlyctenular Keratoconjunctivitis

Appears as a small gray, elevated lesion at the limbus. It is considered a delayed
hypersensitivity to bacterial protein, particularly tuberculoprotein.