Vernal conjunctivitis is an inflammation of the membrane covering the inner eyelid (tarsal conjunctiva). The condition is labeled "vernal" because it most often produces symptoms in the spring and summer. The term vernal means relating to, or occurring in the spring. Children under 14 are most likely to experience vernal conjunctivitis, with boys afflicted far more often than girls. Most children outgrow the condition by early adulthood.

During flare-ups, severe eye itchiness (pruritus) afflicts the patient. Large bumps (papillae) may develop in a cobblestone pattern on the membrane covering the back of the eyelid. Occasionally, these bumps are abrasive enough to the eyeball to cause a noninfectious scar on the cornea.

Those with vernal conjunctivitis should not let the condition go untreated. The tissue around the cornea where the white part of the eye (sclera) and the cornea meet (limbus) can become inflamed (limbal vernal conjunctivitis). If this inflammation extends onto the cornea itself, scarring and decreased vision may result.

The cause of vernal conjunctivitis is unknown, but the condition appears to be related to allergies. It often occurs in those with a family history of allergies or those who also have symptoms of allergic rhinitis, eczema or asthma. These symptoms together are a condition known as atopy.

Vernal conjunctivitis tends to strike children who live in hot, dry, dusty and windy climates. It is most often found in the Mediterranean, Middle East and West Africa, and is much less common in North America and Europe.

In most cases, vernal conjunctivitis is found in both eyes of the affected person (bilateral), but symptoms may be worse in one eye than the other.