"We have literally busted the myth that people who wear glasses are introverted or have particular personality characteristics. They are more likely to be agreeable and open, rather than closed and introverted," said Prof Paul Baird of the University of Melbourne's Centre for Eye Research Australia.

The researchers, who say that shortsightedness affects about one in four Australians, insist that theirs is the world's biggest study into factors linked to the condition.

In the study, which took more than four years to complete, the researchers involved 633 twins and a comparative group of 278 family members. They used the University's Australian Twin Registry for the purpose.

The study participants were analysed using a state-of-the-art measure of the five major personality factors administered by psychologists from the university - viz. openness, conscientiousness, extroversion, agreeableness and neuroticism.

The researchers observed that comparison of family members and twins did not show any link between myopia and introversion, though there was a significant but small association with myopia and agreeableness.

"Working together we have been able to generate more comprehensive and consistent results than previously obtained regarding personality and myopia, "said Nick Haslam from the School of Behavioural Science at the University of Melbourne.