When purchasing reading glasses over the counter, there are a variety of different powers — ranging from +1.00 diopter to +3.00 diopters. Understanding what these powers mean and how they relate to the reading glasses allows for a better selection than the trial-and-error method many people use. The strength of the reading glasses will vary depending on your age, your prescription, and the distance at which you read.
To find the best power of reading glasses, you should have an eye exam with complete refraction by your eye doctor. This will allow you to have the prescription measured accurately and account for the distance at which you typically read.
What are Diopters and How Does the Strength Change?
A diopter is a unit of measurement for determining the strength of an optical lens.
All reading glasses have plus powered lenses which means that they will magnify things and help to see up close.
Reading glasses come in a variety of powers and are labeled by the diopter strength of the lenses.
The strength of the glasses will increase in quarter diopter steps from +1.00 to +3.00 with the higher numbers meaning a stronger power.
Power of Reading Glasses Based on Age
Often, using only your age, you can determine a rough idea of what power of reading glasses would be recommended. The following typically holds true if you have great vision while looking at things far away without glasses.
For individuals between forty and fifty, reading glasses that are between +1.00 and +1.50 will be best. These lenses are not too strong and will allow the eyes to still focus partially.
For individuals between fifty and sixty, reading glasses that are between +1.50 and +2.00 will be best. These stronger powers help compensate as the eye becomes weaker at focusing near.
For individuals between sixty and sixty-five, reading glasses between +2.00 and +2.50 will be best. This accounts for the fact that the eye is no longer focusing at near on its own.
For individuals over sixty-five, reading glasses of +2.50 or higher are best since the eye can no longer focus on its own and will provide some magnification as well.
Additional Factors to Determine Power
While age can give a guideline for what power of reading glasses may be needed, there are other factors that can contribute to deciding on the best power.
If your reading distance is closer or you have a specific task, such as threading a needle or tying a fly for fishing, reading glasses may need to have higher power than the age-based guidelines would suggest.
If you have an uncorrected prescription in the eye, it will contribute to choosing a power of reading glasses. If your eye is nearsighted, the reading glasses will be lower than expected. However, if your prescription is farsighted it will be higher than expected.
Choosing the Best Power
In the end, choosing the best power of reading glasses is a decision that can be difficult without professional help.
Having an eye doctor perform an eye exam and refraction will reduce the need for guesswork when choosing your reading glasses power.