Treating the Ocular Component of Allergic Rhinoconjunctivitis and Related Eye Disorders

Leonard Bielory, MD; C. H. Katelaris, MD; Susan Lightman, FRCP, FRCOphth, PhD; Robert M. Naclerio, MD

Disclosures
In This Article

Epidemiology of Ocular Allergy

Allergy is a common hypersensitivity disorder that affects 15% to 20% of the population in the western world,[6,7] and its prevalence is increasing worldwide. In the United States, ocular allergies are known to affect more than 20% of the general population[7] and in the United Kingdom, a prevalence of 18.2% has been reported.[6] The combination of allergic nasal and ocular symptoms (rhinoconjunctivitis) is extremely common in adults[7] and children. The International Study of Asthma and Allergy in Childhood (ISAAC) has shown that the prevalence of rhinitis with itchy-watery eyes varied between countries from 0.8% to 14.9% in 6- to 7-year-old children and from 1.4% to 39% in 13- to 14-year-old children (Figure 1).[8] However, it is not clear whether the prevalence of rhinitis and conjunctivitis were similar or if 1 symptom was more common than the other. There is a paucity of international data evaluating the prevalence of ocular allergies within adult populations; however, the incidence of nasal allergy has been determined to be 24% to 29%, 28% to 34%, 13% to 23%, 12% to18%, and 13% to 17% in the United Kingdom, France, Germany, Spain, and Italy, respectively,[9] and 14% in the United States.[10] A recent analysis of US Third National Health and Nutrition Examination Survey (NHANES III) data has shown that ocular symptoms, defined as 'episodes of watery, itchy eyes,' affected 40% of the adult population of the United States during a 12-month period, and prevalence of ocular symptoms did not change significantly with age.[11] The survey showed that cat exposure triggered ocular, nasal, or ocular and nasal symptoms in about one fifth of sufferers.[11] Household dust and pollen were the most common trigger for combined ocular and nasal symptoms across all regions of the country,[11] although household dust was a greater trigger for ocular symptoms in the South compared with other regions of the United States.[12] Ocular symptoms are also increasingly prevalent in Eastern countries; in Mongolia, allergic rhinoconjunctivitis was found to affect 9.3%, 12.9%, and 18.4% of the population surveyed in villages, rural towns, and cities, respectively.[13] In Pakistan, allergic conjunctivitis (AC) affected 3.7% of the surveyed village population.[14] A study in Thailand, involving 445 patients with a history of ocular symptoms or suspected AC, was performed to analyze the clinical features, risk factors, and clinical course of various types of AC among Thai people.[15] Patients were evaluated by slit-lamp evaluation and a skin-prick test; 81.8% were diagnosed with perennial allergic conjunctivitis (PAC), 4.7% with AKC, 10.6% with VKC, and 2.9% with GPC. The mean age of onset of AC was 20.3 years, and the most common trigger was house dust. Patients with PAC were most commonly sensitized to house-dust mites (Dermatophagoides pteronyssinus) (70.2%), house dust (67.5%), cockroaches (44.3%), grass (42.2%), and insects (29.2%).[15]

Prevalence of rhinoconjunctivitis in children aged 13-14 years from a selection of countries worldwide. Data from the International Study of Asthma and Allergies in Childhood (ISAAC) study.[115]

Traditionally, allergy investigations have focused on nasal symptoms; however, recent studies have highlighted the prevalence and significance of ocular symptoms. Evidence suggests that ocular symptoms are particularly prevalent in seasonal allergic rhinitis (SAR) sufferers,[16] and in accordance, the NHANES III survey showed that during the summer months (May to August) in the United States, isolated ocular symptoms were more prevalent than isolated nasal symptoms[11] (Figure 2). Another study found that the incidence of conjunctivitis was high in patients experiencing allergic rhinitis (AR) in response to cypress pollen (approximately 88%).[17] Furthermore, an investigation of hay fever sufferers showed that ocular symptoms were experienced alone (8%) or in combination with nasal symptoms (85.3%) more often than nasal symptoms without conjunctivitis (6.7%).[18] This study also concluded that ocular symptoms were as severe or more severe than nasal symptoms in approximately 70% of patients.[18]

Comparison of symptoms exacerbated by pollen in the US adult population (US Third National Health and Nutrition Examination Survey; NHANES III). OS, ocular symptoms; NS, nasal symptoms.[11]

Ocular symptoms are not only common, but also distressing for sufferers. Over 50% of nasal allergy sufferers stated that watering and red/itching eyes were moderately to extremely bothersome in the recent Allergies in America survey,[10] and for 15% of sufferers the ocular component of the allergic hypersensitive reactions was the most bothersome symptom. Similarly, seasonal allergic conjunctivitis (SAC) sufferers have been shown to have a significantly reduced quality of life score as determined by the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) compared with age-matched non-SAC patient controls.[19] SAC sufferers also score significantly lower than controls who do not suffer from ocular allergy symptoms in several domains of the Visual Functioning Questionnaire 25 (VQF-25), including mental health, social function, and overall vision.[19,20]

It is not known why the combination of symptoms varies among allergic patients; however, the reported symptom variation may arise from underestimation of the association between rhinitis and conjunctivitis in epidemiologic studies. Several signs of involvement of the external eye can be documented only with an accurate eye examination, which is not part of the protocol in most studies of rhinitis patients.[8] Moreover, several forms of conjunctivitis of varying severities exist, which may complicate assessments. A standardized format that integrates immunopathophysiology and symptom severity is yet to be developed; however, recent studies have used a measurement of ocular symptoms called the Total Ocular Symptom Score (TOSS), which integrates individual ocular symptom components including itching, redness, and tearing.[21,22,23] In addition, some AR patients may not suffer from ocular symptoms as a result of more efficient washing mechanisms in the eye than the nose, or less contact with the allergen. Indeed, ocular washing mechanisms can vary between individuals, as demonstrated by the changing tear flow rate and composition observed with age.[24,25]

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