Using reading glasses for distance vision is not recommended, as they are designed for a completely different purpose than distance correction. Reading glasses are specifically engineered to help the eye focus on objects close up. Using them to view distant objects will interfere with the eye’s natural ability to see far away, resulting in blurred vision and potentially leading to uncomfortable physical symptoms.
The Purpose of Reading Glasses
Reading glasses compensate for a common, age-related condition affecting near vision. This involves the natural hardening and loss of flexibility in the eye’s crystalline lens. As the lens stiffens, the eye loses its ability to rapidly change shape and focus light rays properly onto the retina for close-up tasks.
The lenses used in reading glasses are convex, meaning they are thicker in the center and thinner at the edges. This shape, designated by a plus sign (+) in lens power measurements, works by increasing the eye’s overall focusing ability. The convex lens bends light rays inward, or converges them, effectively moving the focal point closer to the eye.
This added converging power allows the eye to focus on objects within an arm’s reach, such as a book or a phone screen. Standard over-the-counter reading glasses come in strengths measured in diopters, typically from +1.00 to +3.50. These generic strengths are standardized for a typical reading distance and are not intended for use beyond that range.
What Happens When Near Correction Is Used for Distance
Using the convex lenses of reading glasses to look at distant objects creates an artificial focusing error. When a person with normal distance vision puts on reading glasses, the lenses exert a constant converging force on light rays. While this force helps with close focus, it is too powerful for distant viewing.
Light from far-away objects should naturally focus directly on the retina for clear vision. However, the convex lens prematurely converges this light, causing the image to focus in front of the retina instead. This optical error is called induced myopia, or nearsightedness, which results in the distant view becoming significantly blurry.
Attempting to see through this blur can lead to several negative physical consequences. The eyes try to fight the added power of the lens, resulting in a conflict with the eye’s natural focusing mechanisms. This struggle often manifests as eye strain, fatigue, and a burning sensation in the eyes. Prolonged misuse can also trigger headaches and dizziness as the brain processes the distorted image.
When Distance Vision Correction is Needed
Correcting distance vision requires a different approach and lens type, depending on the specific refractive error. The two most common conditions requiring distance correction are myopia (nearsightedness) and hyperopia (farsightedness). Myopia is corrected using concave lenses, which are thinner in the center and designated by a minus sign (-) in the prescription.
A concave lens works by diverging light rays, pushing the focal point backward onto the retina to correct for an eye that focuses light too strongly. Hyperopia, where light focuses behind the retina, may also be corrected with a convex lens, but this lens is precisely prescribed for distance and is not the same as a generic reading glass power.
Unlike the standardized power of over-the-counter readers, distance correction is highly individualized. A comprehensive eye examination is necessary to measure the exact degree of refractive error and determine the precise power, or diopter strength, needed for each eye. This professional prescription ensures the lens correctly focuses light onto the retina, providing clear distance vision without strain.