Unit for lens power?, The lens power unit is expressed in diopters (D). Diopters are a measure of the optical power of a lens and indicate how much the lens deflects light. In eyeglasses and contact lenses, diopters are used to indicate the correction needed to improve vision.
A positive diopter (eg +2.00 D) indicates a converging lens, which means the lens deflects light towards each other and is used to correct farsightedness. A negative diopter (eg -3.50 D) indicates a diverging lens, which deflects light away from each other and is used for myopia correction.
The right lens power is essential for clear vision and to prevent eye strain and other visual problems. It is therefore important to be regularly examined by an optometrist or ophthalmologist to prescribe the right glasses if necessary.