This locution verbale as well defined Lidia means not see almost nothing or very badly. It has its origin in the rural Andalusia from the beginning of the 20th century, when ophthalmologists began to examine the view of people in the field. As almost everyone was illiterate lyrics but images not taught. A photograph of three children mounted on a donkey was popularized. Ophthalmologists found that those who had more than six diopters couldn't see neither children nor the donkey. Here was popularized this expression equivalent to less than Pepe milks or see less than a bat
