Astigmatism – blurs vision due to the front of the eye (cornea) or the lens having an irregular shape. The common analogy is to imagine the cornea shaped more like a basketball, while an astigmatic cornea looks more like a football.
Myopia – or nearsightedness is when near objects appear clear but distant objects appear blurry. It is due to light being focused in front of the retina.
Hyperopia – or farsightedness is when distant objects are usually seen clearly but near objects are blurry. It is due light being focused behind the retina.
Presbyopia – begins around the age of 40 and results from the diminishing flexibility of the lens to focus at near objects.