unit for lens power?, The unit of lens power is expressed in diopters (abbreviated as D). Diopters are a measure of the optical power of a lens. A positive diopter value indicates that the lens is convergent and is used to correct nearsightedness (myopia), thereby improving near vision. A negative diopter value indicates a diverging lens and is used to correct farsightedness, which improves distance vision.
For example:
– Glasses with a strength of +2.00 D correct myopia.
– Spectacles with a strength of -3.50 D correct hyperopia.
The optician or ophthalmologist will determine the correct diopter value based on an eye exam to ensure that the glasses provide the correct correction for the person’s specific visual needs.