Allergic conjunctivitis and the impact of allergic rhinitis.

Although nasal allergy has been prominent in allergy research, ocular allergy is increasingly recognized as a distinct symptom complex that imposes its own disease burden and reduction in patients' quality of life. In the past year, knowledge of the relationships between allergic conjunctivitis and allergic rhinitis has increased. Allergic conjunctivitis is highly prevalent and has a close epidemiologic relationship with allergic rhinitis. Both conditions also exhibit similar pathophysiologic mechanisms. Pathways of communication are thought to increase the likelihood of an inflammatory reaction at both sites following allergen exposure of nasal or ocular tissue. Clinical trials of intranasal therapies have demonstrated efficacy in allergic conjunctivitis and rhinitis. Newer intranasal steroids decrease ocular symptoms, potentially achieving efficacy by suppressing the naso-ocular reflex, downregulation of inflammatory cell expression, or restoration of nasolacrimal duct patency. Proposed pathophysiologic interactions between allergic rhinitis and ocular allergy underscore the need for therapies with efficacy in both symptom sets.