The answer to whether you can get reading glasses with two different strengths is a definitive yes, and for many people, it is actually a requirement for comfortable vision. Reading glasses are used to correct presbyopia, a common age-related condition where the eye’s natural lens becomes less flexible, making it difficult to focus on close objects. This loss of focusing power typically becomes noticeable around age 40, requiring an additional lens power to effectively magnify near print. While many individuals rely on uniform-strength readers for convenience, a personalized approach often dictates that each eye needs a slightly different power for optimal clarity.
Why Prescriptions Differ Between Eyes
The need for different strengths in reading glasses often stems from an underlying condition called anisometropia. This describes a difference in the overall refractive error between the two eyes. For example, one eye might be slightly more nearsighted or farsighted than the other, meaning the eyes do not focus equally well without correction.
This inherent difference in vision persists even when the magnifying power for reading, known as the “ADD power,” is factored in. The final reading correction combines the base refractive error and the necessary reading addition, resulting in a unique total power for each eye. Trying to use readers with identical lenses when a difference exists can force the eyes to strain to compensate, frequently leading to symptoms like headaches or eye fatigue. Correcting this imbalance with a custom prescription ensures both eyes work together comfortably and effectively at reading distance.
Custom vs. Over-the-Counter Reading Glasses
The ability to incorporate two different lens strengths is the primary difference between custom prescription glasses and over-the-counter (OTC) reading glasses. OTC readers, commonly found at pharmacies and retail stores, are a one-size-fits-all solution mass-produced with the exact same magnifying power in both lenses, typically in increments like +1.00, +1.50, or +2.00 diopters.
Generic OTC readers are only suitable for people with symmetrical vision or a very minor difference between their eyes. They also do not correct for other common issues like astigmatism, which requires a highly specific lens shape. Prescription reading glasses are custom-tailored after a comprehensive eye examination, allowing them to accurately incorporate two distinct powers and ensure precise correction for each eye.
A custom prescription also accounts for the exact center point for each lens relative to the pupil, known as the pupillary distance. If the optical center of an OTC reader does not align with your pupils, it can induce unwanted prismatic effect, causing distortion and discomfort. For anyone with a measurable difference between their eyes, investing in a personalized lens is the only way to achieve clear, comfortable, and balanced near vision.
Monovision Correction Strategy
Monovision is an optical strategy that intentionally uses different powers in each eye to manage presbyopia, distinct from correcting a natural imbalance. This technique corrects one eye, usually the dominant one, for distance vision, and the other eye specifically for near vision, such as reading or close-up tasks.
The brain learns to automatically favor the eye that provides the clearest image, creating a blended vision where both near and far objects are generally clear without needing bifocals. While most commonly implemented with contact lenses or refractive surgery, monovision principles can also be applied to glasses. However, this intentional power difference can reduce the wearer’s depth perception because the eyes are not perfectly balanced for any single distance.
When to Consult an Eye Care Professional
If you rely on OTC readers for extended periods, seek a professional eye examination. Specific symptoms indicate that a generic reader is insufficient and a custom prescription is necessary. These symptoms include headaches, noticeable eye strain, or difficulty reading fine print even after trying several different OTC strengths.
A comprehensive eye exam is the only way to accurately measure the precise power needed for each eye and check for other vision issues like astigmatism. The resulting personalized prescription specifies the exact, often differing, powers required for each lens, ensuring the most comfortable and clearest possible near vision.