Definitions for "Diopters"
Refractive errors are measured in "diopters". Nearsighted people have negative diopters and farsighted people have positive diopters.
A measure of refreactive power. Hypermetropia is measured in positive diopters, myopia is measured in minus diopters. i.e. +3.50 or -3.50
A unit of measurement for myopia, hyperopia and astigmatism that usually falls within a scale of +14 to -14. A positive number indicates hyperopia and a negative number indicates myopia. Positive and negative numbers are also used to indicate astigmatism. Whether the number is positive or negative, the higher the number the greater the extent of the vision problem.