How to Increase the Strength of Eyeglasses

To understand how an eye care practitioner increases the strength of your eyeglasses, you have to know a few basic optical principals. Adding strength to the lens is done by adding power, measured in diopters. This power is the amount of strength a lens needs to give you 20/20 vision. The more nearsighted or farsighted you are, the more prescription power is needed in your lenses. Adding strength means making a lens thicker in at least one area.

Instructions

• 1

  Add plus power to increase farsighted, or hyperopic, refractive power. Lenses that correct vision for farsightedness are thicker in the center and thinner at the edges. When you increase the strength of a plus lens, the center thickness increases.

• 2

  Increase the minus power of the minus lens to add additional strength for nearsightedness. While this may sound backwards for a minus number, the larger the number of the correction, the bigger the increase in the strength of the lens. A minus lens is thicker at the edges and thinner in the center, so increasing minus power makes the edges thicker.

• 3

  Add power to the cylinder, the part of the lens that corrects for astigmatism. Most people have some degree of astigmatism, which has to do with the shape of your cornea. However, not everyone has enough astigmatism to require glasses to correct for the irregular corneal curve. You increase astigmatism strength of your prescription by adding more cylinder power, which is also written in diopters. In addition to the diopter power, cylinder also includes an axis, a number between zero and 180 degrees and is the horizontal location on the lens where the correction is placed.