This refers to nearsightedness, farsightedness, and astigmatism, which can be corrected with eyeglasses, contact lenses or refractive surgery.
When you are nearsighted, things in the distance look blurry. Doctors call it myopia. You are more likely to be myopic if your parents have the same condition, or you do a lot of close-up reading. Nearsightedness can make it harder to drive, play sports, or see a blackboard or TV.
Most people are born with mild farsightedness and outgrow it in childhood. This condition is referred to as hyperopia medically. When it persists, you may see distant objects well, but books, knitting, and other close objects are a blur. This problem runs in families. Symptoms include trouble with reading, blurry vision at night, eyestrain, and headaches. As we age, farsightedness begins to affect distance vision as well.
If you have astigmatism in one or both eyes, your vision may be out of focus at any distance. It happens when the cornea, the clear “window” that covers the front of the eye, is misshapen. Light rays can scatter to different points on the retina, rather than focus on a single point. Glasses or contact lenses may correct it. Surgery can be another option.