Allergic conjunctivitis
Vernal keratoconjunctivitis (VKC, spring catarrh)
An uncommon recurrent, bilateral, external, ocular inflammation affecting children and yound adults, more common in males than in females. VKC is an allergic disorder in which IgE and cellmediated immune mechanisms play an important role. About ¾ of patients have associated atopy and 2/3 have a close family history of atopy. Atopic patients often develop athma and eczema in infancy. The onset of VKC is usually after the age of 5 and the condition eventually resolves around puberty, only rarely persisisting beyond the age of 25. As its name suggests the symptoms and signs of VKC may occur on a seasonal basis with a peak incedence between april and august but many patients have year round disease.
Clinical features
Main symptoms: intense ocular itching, may be associated with lacrimation, photophobia, foreign body sensation &burning. Thick mucus discharge from the eyes and ptosis also occur. The three main clinical types are: palpebral, limbal & mixed
Palpebral VKC in chronological order:
- conjunctival hyperaemia followed by a diffuse papillary hypertrophy, most marked on the superior tarsus
- the papillae enlarge and have a flat toped polygonal appearance reminiscent of cobblestones
clinical fetures
- in severe cases the connective tissue septa rupture, giving rise to giant papillae which may be coated by copious mucus
- active disease is characterized by redness, swelling& tightly packed papillae. As inflammation settles papillae become more seperated→limbal VKC has better prognosis
- it is characterized by mucoid nodules that have a smooth round surface