Medical Author: John Sheppard, MD
Medical Editor: Melissa Conrad Stöppler, MD
It is common for pharmacies, supermarkets, airports, and even dollar stores today to carry nonprescription eyeglasses, sunglasses, and magnifiers. We hope this review will assist consumers with valuable information about these eye products.
Nonprescription eyeglasses are primarily for people who can no longer read fine print. This condition, called presbyopia or "old vision," usually begins at about the age of 35 and progresses until about the age of 55. This inability to focus clearly at near distances is a universal human aging condition.
Although over-the-counter (OTC) glasses do not appear to harm vision, if they are not appropriate for a person's eyes, they can cause eyestrain after prolonged use.
Most vendors offer standard and bifocal lenses, and some vendor locations also offer transitional lenses that lighten up indoors and darken when outdoors. The reading glasses may be available in both full reading vision or in bifocals. Bifocals, invented by Benjamin Franklin, have a lower segment to see up close, with an upper segment consisting simply of clear glass for distance.
The quality and durability of OTC eyeglasses vary widely. Cheap models—costing as little as a few dollars—may have lenses that scratch easily and distort vision. Expensive models—costing $50 or more—may incorporate some or all of the desirable characteristics of high-quality prescription lenses. There is no permanent harm to the eyes from wearing poorly focused or distorted lenses. However, eye strain, computer vision problems, and poor quality vision from cheap or improperly fitted eyeglasses can reduce productivity and accuracy.
Manufacturers rate the power of nonprescription glasses from weakest (+1.0 diopters) to strongest (+3.5 diopters or more). When making a selection, the customer tries on eyeglasses and reads fine print while standing 12 to 14 inches from the print, or simply holding the printed material at a comfortable, customary reading distance. The customer keeps trying on glasses with different power ratings until the print comes into sharp focus. Suppose, for example, the print comes into focus when the customer is wearing eyeglasses with a power rating of +2.0. The customer then knows that a +2.0 rating is correct and can select from styles with that rating.
As we age, our eyes continue to lose the ability to focus up close. This phenomenon (presbyopia) is a result of many factors, including loss of elasticity of the natural human lens with time. Thus, a younger person first requiring reading glasses may require only +1 diopter lenses, which may progress with time to +2.50 diopter lenses.
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