What is Eyeglass prescription?
An '''eyeglass prescription''', '''glasses prescription''' or '''spectacle prescription''' is a [[prescription]] for corrective glasses [[Lens (optics)|lens]]es. It specifies what ''strength'' of lenses the patient needs to see clearly. These prescriptions use [[dioptre]]s as the measure. They usually have four sections. The first one is the ''base power'' (also called ''sphere power'') measured in [[Dioptre|diopter]]s (dioptres). Prescriptions for [[hyperopia]] have a + sign in front of the number, while prescriptions for [[myopia]] have a - sign. The second is the ''cylinder power'', which is particularly for people with [[astigmatism]]. The ''cylinder'' refers to the type of corrective lens that treats astigmatism, called a ''cylindrical lens''. The third is the ''axis component'', which measures the position of both the ''sphere'' and ''cylinder'' powers. *See also: [[Corrective lens]] [[Category:Eyeglasses]] [[Category:Ophthalmology]]