what is the difference between a 2 and a -2 eye glasses specification? which one!
Question: I want to know which one sees far and which one sees near, negative number eye glasses (eg -3) or positive number eye glasses.
Answers:
Negatives are prescriptions for near-sightedness (can't see far away) also known as myopia. This happens when the eye is longer then normal from the front to the back. Postives are for far-sightedness (can't see up close), also known as hyperopia. This occurs when the eye is shorter than normal from front to back. The same symptoms of hyperopia occur in most aging people due to a inability of the aging eye to focus properly - a condition known as presbyopia. It is often confused with hyperopia because the first symptoms are blurry vision up close, but the two conditions have different causes, and presbyopia worsens to include blurry vision at all distances. Presbyopia is believed to be caused by a loss of flexibilty in the lens of the eye over time.
Astigmatism is caused by an irregularly shaped cornea or lens, and causes blurred vision as well. Please refer to the site listed if you would like to know more.
Other Answers:
2 is a magnifier for long-sighted people. -2 is for short-sighted people who need assistance in focusing on distant objects.
I think mine's a -3.5 and I can't see things far away.
Answers: