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P. Novaes, N. Kara-José, M. Macchione, M. Matsuda, L. A. A. Pereira, A. J. Lichtenfels, R. M. Santo, P. H. N. Saldiva, A. Berra; Chronic Urban Conjunctivitis by Air Pollution: Individual Measures of Air Pollution, Measures of Ocular Discomfort and Clinical Tests. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2372. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To estimate the effect of different levels of air pollution on the ocular surface by comparing individual measures of pollution exposure, subjective measures of ocular discomfort and clinical tests.
A panel study was carried out involving 55 volunteers in São Paulo, Brazil, where there are high detected levels of air pollution. Each subject received an individual pollution passive monitoring device with filters for nitrogen dioxide (NO2) and kept it for 7 days. Mean daily pollution concentration was estimated by dividing the accumulated dose by 7. All subjects answered the Ocular Symptom Disease Index (OSDI) validated for the Portuguese language and a symptoms inventory which addressed symptoms of dryness, irritation, heaviness and itching. Subsequently, they underwent Schirmer I test, biomicroscopy, vital staining with fluorescein and rose Bengal, and tear break-up time (BUT) measures. Exposure to NO2 was categorized in quartiles : Q1: 10.0 to 20.1 µg/mm3, Q2: 20.1 to 26.1 µg/mm3, Q3: 26.1 to 35.4 µg/mm3 , and Q4: 35.4 to 53.8 µg/mm3 . Statistical analysis was performed using one-way ANOVA, Tukey HSD test and Chi-Square test.
Mean OSDI scores were 11.7±12.4, 20.1±13.8, 23.2±17.7, 32.9±15.3 for Q1, Q2, Q3 and Q4 respectively, and when computed across gradients of NO2 levels a clear dose-response pattern was detected, with a significant difference among the quartiles (p=0.01). There was a significant correlation between NO2 levels and reported ocular irritation (X2=9.2, p=0.03), with a frequency of 38.5%, 64.3%, 71.4% and 92.9% in Q1, Q2, Q3 and Q4 respectively. No significant correlations between NO2 levels and Schirmer I values (means 22.3±13.9 mm and 23.6±13,5 mm, right and left eye respectively), Rose Bengal and Fluorescein scores. Mean BUT values were 6.8±4.6s, with a tendency towards lower levels in the third and fourth quartiles.
Subjects exposed to higher levels of air pollution report more symptoms of ocular discomfort and present a tendency to greater tear film instability. The results suggest that inhabitants of cities with high air pollution levels could develop an urban chronic conjunctivitis by air pollution.
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