There are other forms of allergic eye disease that do not fully fit into this classification, as Contact Allergic Conjunctivitis (CAC):
Figure 7 – Puffy eyelid due to neomycin eye drops allergy
Contact allergic conjunctivitis is due to an agent causing an allergic or toxic effect. The causative agent may be ocular medications such as atropine, gentamicin, neomycin, tobramycin, antivirals, epi- nephrine, pilocarpine, etc., or a preservatives such as benzalkonium chloride, chlorhexidine, EDTA, thimerosal, etc., or chemicals in cosmetics and hair spray. Usually the patient presents with a puffy swollen eyelid (Figure 7). On examination, the pal- pebral conjunctiva may show a follicular reaction and corneal staining with fluorescein may show punctuate keratopathy.
IMPORTANT POINTS TO BE CONSIDERED:
Age SAC and PAC usually affect any age. VKC typically affects young males with onset generally in the first decade and duration up to one decade. Its symptoms usually peak prior to the onset of puberty and then subside. AKC typically affects adults (20 – 50 yrs) suffering from atopy.
Sex VKC has a significant male preponderance.
Race VKC occurs predominantly in areas with tropical and temperate climates such as the Mediterranean, the Middle East, and Africa. The limbal form of VKC commonly occurs in dark- skinned individuals from Africa and India.
Type of discharge A serous discharge is most commonly associated with viral or allergic ocular conditions. A mucoid (stringy) discharge is highly characteristic of allergy or dry eyes. A mucopurulent or p u r u l e n t d i s c h a r g e , o f t e n a s s o c i a t e d w i t h m o r n i n g c r u s t i n g a n d d i f f i c u l t y o p e n i n g t h e e y e l i d , s
strongly suggests a bacterial infection.
Itching Itching is the hallmark of allergic conjunctivitis, as well as other forms of allergic eye disease.
The itching may be mild to severe. In general, a red eye in the absence of itching is not cau- sed by ocular allergy. A history of recurrent itching or a personal or family history of hay fever, allergic rhinitis, asth- ma or atopic dermatitis is also suggestive of ocular allergy. In VKC, itching is the most impor- tant and most common symptom. Other commonly reported symptoms are photophobia,
foreign body sensation, tearing, and blepharospasm. In contrast to AKC, the eyelid skin usu- ally is not involved. In AKC, the single most common symptom is bilateral itching of the eye- lids, but watery discharge, redness, photophobia, and pain may be associated. Primary symp- toms in GPC are ocular itching with a mucoid or stringy discharge, very similar to that seen in VKC.
Bilateral nature Allergic conjunctivitis is almost always secondary to exposure to environmental allergens and,
therefore, usually presents with bilateral symptoms. Infections caused by viruses and bacteria (including Chlamydial organisms) are transmissible by eye-hand contact. Often, these infec- tions initially present in one eye, with the second eye becoming involved a few days later.
Family history of atopy More than 90 % of patients with VKC exhibit one or more atopic conditions such as asthma, eczema, or seasonal allergic rhinitis. AKC has a strong association with atopic dermatitis.
Onset of symptoms The onset of symptoms is important in diagnosis of allergic conjunctivitis. Individuals with SAC typically have symptoms of acute allergic conjunctivitis for a defined period of time; in spring when the predominant airborne allergen is tree pollen; in summer when the predominant all- ergen is grass pollen; or in autumn when the predominant allergen is weed pollen. Typically, persons with SAC are symptom-free during the winter months in cooler climates because of the decreased airborne transmission of these allergens. In contrast, individuals with PAC may have symptoms that last the whole year; thus, PAC may not be caused exclusively by seasonal allergens, although, they may play a role. Other common household allergens such as dust mite, cockroaches, and pet dander may be responsible for the symptoms of PAC.
Contact lens use A persistent foreign body sensation when using contact lenses, resulting in an inability to wear contact lenses for the desired length of time (dropout) is an important symptom in diagnosis of GPC.
History of medication/chemicals use Contact allergic conjunctivitis is due to an agent causing an allergic or toxic effect. The causa- tive agent may be an ocular medication such as atropine, gentamicin, neomycin, tobramycin, antivirals, epinephrine, pilocarpine, etc., or a preservative such as benzalkonium chloride, chlorhexidine, EDTA, thimerosal, etc., or chemicals in cosmetics and hair spray.
PHYSICAL EXAMINATION & DIAGNOSTIC TESTS
Patients with allergic conjunctivitis present with itching of the eyes, accompanied by tearing and a burning sensation. The reaction is usually bilateral, although unilateral conjunctivitis may occur in a patient who has had direct hand-to-eye contact with an allergen.The periocular tissues are usually swollen and reddened. The conjunctiva is injected, with mild to moderate
chemosis, and there is a stringy mucous discharge in the tear film.