Instead of "long-sighted" we ususally say "farsighted", and instead of "short-sighed" you can say "nearsighted". The words "short-sighted" and "farsighted" are adjetives that describe a person. Ex: I am farsighted, but my friend, Liana, is "short-sighted". The words "short-sightedness" and "long-sightedness" are nouns, which describe a condition. I suffer from short-sightedness, and my friend, Liana, suffers from long-sightedness.

Hi Liana, Both your expressions are correct, Here in Canada and the USA we commonly use: nearsighted farsighted Hope this helps?

Mr Wright is right. His answer is perfect and complete. Let me add one more example: I am nearsighted (adjective describing the condition of my vision (ability to see)) My nearsightness (noun - the problem with my vision) problem requires me to wear glasses to see far away. The interesting thing about the adjective "nearsighted" means that I can see well up close, but I can not see things well if they are far away.

Both are correct. Short-sighted = adjective 眼光短的 Short-sightedness = noun.眼光短 We say "eyesight", not "eyesighted".

short-sightedness = short-sighted. long-sightedness = long-sighted. Both of them are correct expressions that refer to certain medical conditions related to poor vision (eye sight). However there's nothing called 'eye-sighted' or 'eye-sightedness'. Check the following link for details: http://www.bbc.co.uk/health/physical_health/conditions/visionproblems1.shtml