RESUMO
OBJECTIVE: To investigate the effects of long-term and low dose ionizing radiation on ocular lens opacities of residents living in areas with high natural radiation background(HNRB) in Yangjiang City, China. METHODS: A total of 483 Han residents from Yangjiang City(HNRB area) and 517 from Enping City(control area) were selected as study subjects using a cluster random sampling method. Questionnaire survey and lens examination were carried out. The risk factors of lens opacity and its severity were analyzed by logistic regression analysis. RESULTS: The prevalence rates of lens opacity, cortical opacity and posterior subcapsular opacity in HNRB area were higher than those in control area(60.7% vs 51.6%, 53.4% vs 46.8%, 21.9% vs 9.3%, all P<0.05). There was no significant difference in karyotype turbidity between HNRB area and control area(52.4% vs 47.6%, P>0.05). After adjusting for confounding factors including age, gender, cardiovascular/metabolic diseases, smoking, alcohol drinking and tea drinking, the unconditional logistic regression analysis results showed that the risk of ocular opacity, cortical opacity and posterior subcapsular opacity in residents of HNRB area was higher than that in control area(all P<0.05). Multivariate disordered logistic regression analysis results showed that residents in the HNRB area had a higher risk of grade two karyotype turbidity than grade one karyotype turbidity(P<0.01). Ordered logistic regression analysis results showed that residents in HNRB area had an increased risk of developing severe cortical turbidity(P<0.01). CONCLUSION: Long-term and low dose ionizing radiation exposure may increase the risk of ocular lens opacity, especially cortical and posterior subcapsular cataract, and affect the severity of the disease.