Characteristics of the cellular response of the rat conjunctiva to topically applied leukotriene B4

Drug therapy for ocular allergy

The spectrum of ocular allergy ranges from mild, non-sight threatening disease, such as hay fever, to disorders such as atopic keratoconjunctivitis (AKC) which cause permanent ocular surface changes and reduced vision. The ideal treatment is with topical preparations. Launched topical preparations include anti-histamines and mast cell (MC) stabilisers, which are safe, but only moderately potent, steroids, which are very potent, but carry very serious side-effects, and cyclosporin A, which is not widely available and difficult to tolerate. There are a number of anti-histamines, MC stabilisers (and combinations thereof) and steroids in development which are of potential interest. Other possibilities for therapeutic intervention include inhibition of tryptase, cyclooxygenase (COX), leukotrienes (LTs), bradykinins (BKs), platelet activating factor (PAF) and immunoglobulin E (IgE). Therapies based on cytokine antagonism and agonism, T-cell inhibition and adhesion molecule antagonism might be expected to provide safe, but potent new modes of treatment. The increasing interest in research into the pathogenesis of ocular allergic inflammation may lead to more relevant approaches, such as eosinophil inhibition. Success will be highly dependent on the ability to produce suitable topical ophthalmic preparations.

Long-term Safety of Loteprednol Etabonate 0.2% in the Treatment of Seasonal and Perennial Allergic Conjunctivitis

PURPOSE

To determine the long-term safety of the topical steroid, loteprednol etabonate 0.2%, in the treatment of seasonal and perennial allergic conjunctivitis.

METHODS

A retrospective review of 397 patients from three private ophthalmologic practices treating seasonal and perennial allergic conjunctivitis with long-term loteprednol etabonate 0.2% was performed. Chart review of slitlamp findings and intraocular pressure measurements during follow-up visits was performed to determine the incidence of adverse effects, such as steroid-induced intraocular pressure increase, cataract formation, and any other possible topical steroid-induced adverse event. One hundred fifty-nine of the 397 patients had been continuously using loteprednol for more than 12 months.

RESULTS

There were no reported adverse effects of long-term loteprednol etabonate 0.2% use in any of the 159 patients, whose continuous use ranged from a cumulative total of 120 drops per eye to 3,741 drops per eye.

CONCLUSIONS

Loteprednol etabonate 0.2% is a safe topical steroid when used on a long-term basis for the treatment of seasonal and perennial allergic conjunctivitis.

Anti-inflammatory and antiallergic effects of ketorolac tromethamine in the conjunctival provocation model

AIM

To study the effect of the topical anti-inflammatory drug, ketorolac, on (1) the clinical allergic reaction induced by the conjunctival provocation test (CPT); (2) the release of tryptase in tears; and (3) the expression of adhesion molecules on the conjunctival epithelium.

METHODS

10 allergic but non-active patients were challenged in both eyes with increasing doses of specific allergen to obtain a positive bilateral reaction and rechallenged, after 1 week, to confirm the allergic threshold dose response. After 2 weeks, a third CPT was then performed bilaterally 30 minutes after topical application of ketorolac in one eye and placebo in the contralateral eye in a double blind fashion. Clinical symptoms and signs were registered 5, 10, 15, and 20 minutes after challenge. The following objective tests were performed: tear tryptase measurement; tear cytology; and conjunctival impression cytology for immunohistochemical expression of ICAM-1 on epithelial cells.

RESULTS

Compared with placebo, ketorolac significantly reduced the total clinical score and the itching score in the 20 minutes after challenge (p<0.0005). Tear levels of tryptase were significantly reduced in the ketorolac pretreated eyes compared with placebo (p<0.03). Eosinophils, neutrophils, and lymphocytes in tear cytology were significantly lower in ketorolac treated eyes compared with placebo. A significant difference in the epithelial expression of ICAM-1 was observed between placebo and ketorolac treated eyes (p<0.05).

CONCLUSION

Ketorolac proved to be effective in reducing mast cell degranulation, as indicated by significantly decreased tryptase tear levels, as well as the clinical and cytological allergic reaction.

Conjunctivitis of allergic origin: immunologic mechanisms and current approaches to therapy

The pathogenesis of ocular allergy involves multiple mechanisms, which lead to mast cell degranulation and the release of chemical mediators. Mast cell mediators that have been implicated in allergic ocular disease include histamine, eosinophil chemotactic factors, eosinophil granule major basic protein, platelet-activating factor, prostaglandin D2, and several other less well-defined preformed or newly synthesized mediators. The release of these chemical mediators ultimately results in conjunctival vasodilation, increased vascular permeability, leukocyte chemotaxis, and, rarely, ocular surface destruction. Current therapy of ocular allergy involves elimination of the offending allergen, modulation of the immune system, and pharmacologic inhibition of the chemical mediators. The purpose of this article is to provide a better understanding of the pathogenesis and current therapy of ocular allergic disorders and to review the central role of the mast cell and chemical mediators involved in ocular allergy.