Understanding Allergic Conjunctivitis
By: Paul M. Karpecki, OD, FAAO
Clinical Director – PECAA
If you are anything like me, your eyes tend to gloss over when you’re presented with lecture slides of pathophysiology and the associated immunology. However, in the case of allergic conjunctivitis, an improved understanding of basic immunology will help you select the best treatment option. With March being a key month for ocular allergies in many states, it makes sense to visit this condition.
If you look at the typical illustrations, you’ll see that allergen binding to immunoglobulin E (IgE) antibodies and crosslinking of IgE on the mast cell surface results in degranulation during the early stages of allergic conjunctivitis. This process causes a release of histamine, chymase/tryptase and platelet activating factors, which subsequently yields a variety of symptoms, such as itching in particular.
Likewise, the late phase involves the release of newly synthesized mediators, including leukotrienes, prostaglandins, cytokines, etc. This produces an inflammatory response, causing chemosis, increased hyperemia and the recruitment of more inflammatory cells.
So, how can be we apply this knowledge in daily clinical care? In general, during the acute or early phase—when symptoms like itching are present—the ideal medication would be an antihistamine/mast cell stabilizer agent. This would include patients who present with severe itching. Examples include Bepreve (bepotastine besilate, Bausch + Lomb), Pazeo (Olopadadine 0.7%, Alcon ), or Lastacaft (Alcaftadine 0.25%, Allergan). Also ketotifen (Zaditor, Alaway) over the counter are other options should branded medications be cost-prohibitive. Keep in mind that many company’s offer patient discounts and coupons during the allergy season making branded medications similar in cost so be sure to ask you reps about those.
If, however, allergic conjunctivitis has been present for some time, and thus the late phase is involved, the best medications to treat leukotrienes, prostaglandins and cytokines are topical corticosteroids, such as Alrex (loteprednol etabonate, Bausch + Lomb).
Another way to look at this to make it very straight forward is if symptoms of itching are the primary complaint with few other symptoms or signs, then an anti-histamine/mast cell stabilizer is the best option. If however there is more than itching or signs such as chemosis, injection and edema are present, a topical steroid is likely to be the more effective option.
It’s also valuable to include palliative therapies for these patients such as cool compresses (Bruder Healthcare Cool Compress mask as an example) for the edema and inflammatory responses and preservative free artificial tears to wash away the allergens.