Effects of volcanic ash on ocular symptoms: Results of a 10-year survey on schoolchildren
Received 8 July 2004; accepted 27 September 2004. published online 07 January 2005.
Objective
To study the effects of volcanic ash on the ocular symptoms of schoolchildren ages 6 to 15 residing near Mt. Sakurajima, an active volcano.
Design
Retrospective, cross-sectional study.
Participants
A total of 10 380 children ages 6 to 15, 1175 in a high-exposure area and 9205 in a low-exposure area, were studied.
Methods
High- and low-exposure areas for volcanic ash were selected. All subjects in both areas were examined annually each September in the decade from 1994 to 2003.
Main outcome measures
The frequency of positive ocular symptoms in years with and without active volcanic eruptions was compared. The association of ocular symptoms with volcanic ash dispersal was assessed with the Mantel–Haenszel test or chi-square test.
Results
Subjects in the high-exposure area showed ocular symptoms more often than those in the low-exposure area (P<0.0001). Years of active volcanic eruptions (volcanic ash of 5000 g/m2/year or more) were closely related to years with a high frequency of ocular symptoms in subjects in the high-exposure area (P<0.05) but related conversely in subjects in the low-exposure area (P<0.01). Major ocular symptoms were redness, discharge, foreign body sensation, and itching, all treated effectively with eyedrops.
Conclusions
Ocular symptoms in subjects were strongly influenced by volcanic eruptions in the Mt. Sakurajima area, but direct influence was limited to those living in areas very near the volcano (i.e., 4 km from the volcano's crater).
1Department of Ophthalmology, Faculty of Medicine, Kagoshima University Graduate School of Medicine and Dental Sciences, Kagoshima, Japan
2Department of Medical Information Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
Correspondence and reprint requests to Taiji Sakamoto, MD, Department of Ophthalmology, Faculty of Medicine, Kagoshima University Graduate School of Medicine and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima 890-8520, Japan
Manuscript no. 240540.
Supported by the Ministry of Education, Science, Sports and Culture, Tokyo, Japan (Grant-in-Aid for Scientific Research no.: 09671804), and the Japanese National Society for the Prevention of Blindness, Tokyo, Japan.
ABSTRACT