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Focusers Explanation of Diopter Strength |
 | | Because the formula is based on the reciprocal of the focal length, a 2 diopter lens is not 2 meters but 1/2 meter, a 3 diopter lens is 1/3 meter and so forth. |
| | By age 25 this accommodation is usually reduced to about 10 diopters and by age 50 to a mere 1 diopter. |
| | Generally, the eye care industry classifies reading glasses lenses in diopter strengths that increase by a factor of.25 (e.g., +.75; +1.00: +1.25; +1.50; +1.75; +2.00; +2.25; +2.50; +2.75; +3.00 etc.). |
| www.focusers.com /diopter2.html (848 words) |
