Vision is considered normal when a patient can see 20 size print at 20 feet. This is a patient that does not require glasses for distance or for near. Distance vision is defined as any distance over 20 feet. Functionally that means any task which is over 10 feet. This of course is driving or looking at once environment.
Farsightedness is when a patient can see better at far than at near. With a person who is under the age of 30 -40 farsightedness doesn’t affect reading either because that individual can overcome the out of focus condition of hyperopia which is farsightedness. However, as the patient grows older, between the ages of 40-45, they will need to wear reading glasses and often have to use glasses for distance. So when comparing farsighted and nearsighted, it is much better to be nearsighted because only one distance is affected. With farsightedness, after the age of 40-45, both distance and near are affected. Also, the most common condition of farsighted people approaching the older age group is tiredness because if they are not wearing glasses they are constantly using their reading eye muscles to compensate for the out of focus vision. Farsightedness can be corrected with glasses, contacts, LASIK, and Lens Exchange.
PA person who has nearsightedness or myopia is a person who can see well at near usually at any age but has difficulty as distance. This requires a lens that is concave and in higher powers usually makes the eye looks smaller when the glasses are on the face. People who have myopia are fortunate because only one of their distances is disturbed by being out of focus and that is at distance. At near, they can see perfectly fine because they are ‘nearsighted’. Nearsightedness can be corrected with glasses, contacts, LASIK, and Lens Exchange.
Astigmatism is interesting because it is irregularity of the cornea, sometimes the lens, but most often the cornea. This affects both reading and distance visions. Because the field of view is greater when looking at distance astigmatism most often affects the reading. Astigmatism can only be corrected by glasses, contacts, or LASIK.
Presbyopia is the age related farsightedness. That is to say that a person who has gone through their life seeing normal at distance and at near and have no underlying focus problem, the lens in their eye begins failing to increase the power for reading and they have difficulty with near functions. This happens to 100% of the population regardless of race, genetics or gender. This happens to people, on average, between the age of 40-45 and at first the person will be extending their arms out to read things and soon thereafter will require magnifying glasses to help bring the image closer. This can only be corrected with glasses, contacts, and LASIK. There is no exercise, drops or other medicine that can prevent this aging process.