How do the people who live in the country of blind lose their sight?

In H.G. Wells' short story "The Country of the Blind," the inhabitants lose their sight due to a combination of factors, including a disease and the isolation of their mountainous environment. Over generations, this led to a community where blindness became the norm, and the people adapted to their condition, developing heightened other senses and a unique culture. The loss of sight is portrayed as a natural evolution for the community, shaping their identity and way of life.