Question: How can short sighted people see short objects but not long. Surely they wouldn't be able to see either

Savannah Clawson answered on 24 Nov 2020:

When we talk about “short-sighted” and “long-sighted” people , we are referring to how good their vision is when looking at things close to them and when looking at things far away. Short-sighted people can see things close to them well but things far away look blurry. It is the opposite for long-sighted people.

The science behind this comes down to the shape of the lens in our eye and where it focuses incoming light. When the light coming into our eyes is focused slightly behind the retina (the light-sensitive part at the back of our eye), people are long-sighted and things close to them look blurry. When the light is focused slightly in front of the retina, people are short-sighted and things far away look blurry. Wearing glasses can help focus the light exactly on the right spot so that we can counteract the effects of being short- or long-sighted.