Roughly 145 million of those people could have normal vision with the help of eyeglasses and are simply suffering from problems like nearsightedness, farsightedness, and astigmatism, and many are in low-income countries.
The purpose of eyeglasses and contact lenses is to correct or improve the vision of people with nearsightedness (myopia), farsightedness (hyperopia), presbyopia, and astigmatism.
These glasses contained convex lenses (lenses that bend outwards) that could correct farsightedness and the worsening of vision often seen as individuals age.
Farsightedness means the individual has problems seeing close-up and nearsightedness occurs when the individual has problems seeing far away.
There may be unequal amounts of nearsightedness, farsightedness, or astigmatism, so that one eye will be in focus while the other will not.