A single-vision prescription corrects one type of vision issue, providing clarity for either near or far sight. It addresses four common vision problems: nearsightedness (myopia), where objects in the distance appear blurry and are corrected with a negative (-) prescription; farsightedness (hyperopia), where close-up objects are hard to see and are corrected with a positive (+) prescription; astigmatism, which causes blurred vision due to an irregularly shaped cornea and is corrected with cylindrical lenses; and presbyopia, an age-related condition that makes it difficult to focus on nearby objects, usually requiring reading glasses or a prescription with near correction.