Near sightedness or myopia is a condition where near vision is clear, but far vision or distance objects appear blurry. A near sighted person require glasses to see clearly for far
Far sightedness or hyperopia is a condition where far vision is better than near vision. A far sighted person requires plus prescription glasses to see well for near and sometime even for distance.
Astigmatism is a condition where the cornea is not perfectly round causing distortion of vision ,eye strain, headache.