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Classification of Ocular Allergy : General Classification of Inflammatory Disorders of the Conjunctiva


General Classification of Inflammatory Disorders of the Conjunctiva

Depending on the clinical presentation, allergic ocular disorders can be classified under a number of categories. The most common form of ocular allergy is seasonal allergic conjunctivitis (SAC), which is associated with seasonal rhinitis (hay fever) and sensitization/exposure to airborne allergens such as ragweed and grass pollen. Patients usually suffer from SAC in spring and fall seasons, when levels of pollens are at their peak. The perennial form (PAC), although less intense, is more of a chronic condition. This form of ocular allergy usually involves sensitization to antigens that are present year round, such as dust mites, animal dander, mold, and air pollutants.[3]

More severe types of allergic eye disease include vernal keratoconjunctivitis (VKC), atopic keratoconjunctivitis (AKC), and giant papillary conjunctivitis. VKC is a severe bilateral ocular allergic disease that has the capacity to become sight threatening. This disease is often chronic, occurring predominately in male children living in warmer climates such as India, Africa, and some parts of Asia. The disease often, but not always, resolves upon entrance into puberty.[4,5] VKC frequently involves inflammation of the cornea (keratitis) and is often associated with other allergic diseases.[6**] AKC is a severe bilateral allergic inflammation of the conjunctiva, eyelids, and cornea, affecting individuals with a history of atopic dermatitis. This condition is chronic, sight threatening, and has no geographical prevalence. The disease occurs predominantly in adults between 20 and 50 years old.[7**,8**] Symptoms of AKC usually become more severe in the winter season. Patients present with a ropy mucoid discharge, tearing, burning, photophobia, chemosis, papillary reaction of inferior tarsal conjunctiva, and intense bilateral pruritus of the eyelids, periorbital area, and conjunctiva. Complications of AKC include corneal disease, Staphylococcus aureus infection of the eyelid, and ocular herpes simplex in some patients of at least 30 years of age. Horner-Trantas dots, thick gelatinous infiltrates of epithelial cells and eosinophils, are also rarely present.[2,8**]

Giant papillary conjunctivitis (GPC) is a chronic ocular inflammatory condition resulting from constant mechanical irritation of ocular surfaces by contact lenses, ocular prostheses, or exposed ocular sutures. Constant use of soft, hard, or gas-permeable contact lenses can increase the incidence of GPC, especially in individuals simultaneously experiencing other forms of allergy. GPC is not a true form of allergic conjunctivitis, as it is a non-IgE-mediated inflammation of external ocular surfaces. Frequent use of contact lenses facilitates repetitive physical trauma to the upper tarsal conjunctiva, resulting in papillary hypertrophy indicated by the presence of abnormally large cobblestone papillae.[5,7**,8**] Other symptoms of GPC include intense itching, tearing, blurred vision, a mucous discharge in strips or sheets, foreign body sensation, conjunctival injection, and contact lens intolerance.[1,8**,9] Complications of GPC involve immune reactions against accumulated residue deposited on the contact lens, which may contain cellular debris, preservative deposits from contact lens solutions, microbial deposits, and mucous.[2,8**]

Although rare, drug-induced allergic conjunctivitis can occur in reaction to long-term use of topical ocular therapies (eye drops, ointments, contact lens solutions, etc.) and is often caused by an adverse reaction to chemical preservatives in the ophthalmic solution.[5] These reactions often occur in the lower eyelid and inferior conjunctiva, as liquid therapeutics tend to pool in these areas. Patients usually present with red-colored inflamed conjunctiva, papillae development, pinpoint keratitis, and chemosis.[2,5,9]

Dry eye syndrome (tear film dysfunction) is a common disorder that is frequently confused with seasonal and perennial allergic conjunctivitis. This condition results from a decreased production in tear volume and is most prevalent with long-term use of contact lenses, certain medications (chemotherapeutic agents, phenothiazines, first-generation antihistamines), computer use, and individuals with autoimmune disorders.[8**] This disorder frequently occurs concomitantly with ocular allergic disorders and may be exacerbated by use of antihistamines.[8**] Although not considered a form of ocular allergy, infectious conjunctivitis is frequently encountered and can have similar clinical presentation. Bacterial conjunctivitis can be caused by Haemophilus influenzae, Streptococcus pneumoniae, or Staphylococcus aureus.[10,11] This form of ocular disease can be very contagious, especially among small children and people living in close quarters such as dormitories. Symptoms of bacterial conjunctivitis include red eyes, yellowish green mucus discharge, follicle formation, and discomfort. Viral conjunctivitis can be caused by strains of adenovirus, enterovirus, or herpes virus. Symptoms of viral conjunctivitis include burning, watery discharge, chemosis, pretragal lymph node enlargement, ocular pain and light sensitivity.[8**]

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