Signs in phlyctenular keratoconjunctivitis include small yellow nodules that develop over the cornea, which ulcerate after a few days.A study by Klein et al. showed that in addition to the physical discomfort allergic conjunctivitis causes, it also alters patients routines, with patients limiting certain activities such as going outdoors, reading, sleeping, and driving. Therefore, treating patients with allergic conjunctivitis may improve their everyday quality of life. Causes
The cause of allergic conjunctivitis is an allergic reaction of the bodys immune system to an allergen. Allergic conjunctivitis is common in people who have other signs of allergic disease such as hay fever, asthma and eczema.Among the most common allergens that cause conjunctivitis are:
Pollen from trees, grass and ragweed
Animal skin and secretions such as saliva
Perfumes
Cosmetics
Skin medicines
Air pollution
Smoke
Dust mites
Balsam of Peru (used in food and drink for flavoring, in perfumes and toiletries for fragrance, and in medicine and pharmaceutical items for healing properties)
Eye drops (A reaction to preservatives in eye drops can cause toxic conjunctivitis)
Contact lens solution (some preservatives can irritate the eye over time resulting in conjunctivitis)
Contact lens (conjunctivitis is also caused by repeated mechanical irritation of the conjunctiva by contact lens wearers)Most cases of seasonal conjunctivitis are due to pollen and occur in the hay fever season, grass pollens in early summer and various other pollens and moulds may cause symptoms later in the summer. Pathophysiology
The ocular allergic response is a cascade of events that is coordinated by mast cells.
People treated with H1 antihistamines exhibit reduced production of histamine and leukotrienes as well as downregulation of adhesion molecule expression on the vasculature which in turn attenuates allergic symptoms by 40–50%. Dual Activity Agents
Dual-action medications are both mast cell stabilizers and antihistamines. They are the most common prescribed class of topical anti allergy agent. Olopatadine (Patanol, Pazeo) and ketotifen fumarate (Alaway or Zaditor) are both commonly prescribed. Ketotifen is available without a prescription in some countries. Corticosteroids
Ester based "soft" steroids such as loteprednol (Alrex) are typically sufficient to calm inflammation due to allergies, and carry a much lower risk of adverse reactions than amide based steroids. A systematic review of 30 trials, with 17 different treatment comparisons found that all topical antihistamines and mast cell stabilizers included for comparison were effective in reducing symptoms of seasonal allergic conjunctivitis. There was not enough evidence to determine differences in long-term efficacy among the treatments.Many of the eye drops can cause burning and stinging, and have side-effects. Proper eye hygiene can improve symptoms, especially with contact lenses. Avoiding precipitants, such as pollen or mold can be preventative. Immunotherapy
Allergen immunotherapy (AIT) treatment involves administering doses of allergens to accustom the body to substances that are generally harmless (pollen, house dust mites), thereby inducing specific long-term tolerance. Allergy immunotherapy can be administered orally (as sublingual tablets or sublingual drops), or by injections under the skin (subcutaneous). Discovered by Leonard Noon and John Freeman in 1911, allergy immunotherapy represents the only causative treatment for respiratory allergies.