On a sunny day, a person wears dark glasses (light-protective) to reduce the light flux falling on the retina. Fishermen wear polarized glasses to prevent reflections from the water when fishing. But to read books, many people who have visual impairments – myopia and farsightedness – wear glasses with lenses: scattering – with myopia, collecting – with farsightedness.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.