Abstract
Purpose: :
To evaluate the impact of sugar cane burning on the ocular surface of sugar cane workers and healthy controls during the burning and the non-burning periods.
Methods: :
101 sugar cane workers and 80 healthy controls were recruited from the rural city of Mendonça, located in the State of São Paulo, Brazil. Clinical evaluation was performed during the burning (April 2009) and the non-burning periods (October 2009) .We evaluated biomicroscopy -hyperemia, meibomitis, papillae and particulate matter on eyelid margins; tear film break-up time (TBUT); corneal and conjunctival vital staining with fluorescein and lissamine green; and Schirmer I test during both periods for both groups.
Results: :
Sugar cane workers presented significantly lower TBUT values during the burning period (mean 10.5, sd±6.1), when compared to the non-burning period (mean 8.5, sd±3.5)(p=0.005).There was a significant increase in the frequency of hyperemia (p=0.009), meibomitis (p<0.001), papillae (p<0.001)and particulate matter (p<0.001) in sugar cane workers during the burning period when compared to the non-burning period and to controls. There were no differences between biomicroscopic findings between periods for the control group. The Schirmer I test values and the vital staining patterns were within the normal range and there were no differences between periods or between groups.
Conclusions: :
These findings indicate that sugar cane workers present greater tear film instability during the burning period. The presence of particulate matter on the eyelid margins of a great number of sugar cane workers indicates a direct contact of the highly irritative air pollutants with the tear film and the ocular surface. The increase in the frequency of papillae in these individuals reinforces the presence of increased ocular irritation and inflammation. The reported effects of air pollution on the eyes of the sugar cane workers and the controls are important elements on defining safe limits for health protection and quality of life maintenance.
Keywords: cornea: tears/tear film/dry eye • ocular irritants