While the simple answer is no, the practical reality is often yes. Nearsightedness and farsightedness refer to distinct structural errors in the eye that cannot coexist in their pure form in a single eye. However, two common optical conditions—one structural and one age-related—frequently result in a person experiencing the symptoms of both blurred distance and blurred near vision.
Basic Refractive Errors: Myopia and Hyperopia
Nearsightedness, medically termed myopia, occurs because the eyeball is slightly too long from front to back, or the cornea is too steeply curved. This structural variation causes incoming light to focus at a point in front of the retina, the light-sensitive tissue at the back of the eye. Consequently, distant objects appear blurry, while near vision typically remains clear.
Conversely, farsightedness, or hyperopia, results from the eyeball being too short or the eye’s focusing power being too weak. In this condition, the light rays converge at a theoretical point behind the retina. Hyperopia causes close-up objects to appear out of focus. In more severe cases, it can also lead to blurred distant vision because the eye constantly strains to bring the focal point forward. These two conditions are opposite refractive errors, defined by where the light focuses relative to the retina.
The Definitive Answer: When Overlap Occurs
A single eye cannot be simultaneously too long and too short, meaning simple myopia and simple hyperopia are mutually exclusive conditions. The primary refractive error in any given eye will be either myopic or hyperopic.
However, the experience of needing correction for both distance and near vision is common due to two separate optical phenomena. These phenomena introduce a secondary focusing error that compounds the original condition, creating the effect of both nearsightedness and farsightedness symptoms. This dual visual difficulty arises from either an irregularity in the eye’s shape or a loss of functional flexibility.
Astigmatism: The Simultaneous Error
The clearest technical example of both errors coexisting in one eye is a specific form of astigmatism. Astigmatism is a refractive error caused by an irregularly shaped cornea or lens, which is shaped more like a football than a baseball. This irregular curvature causes light entering the eye to focus at multiple points instead of a single, sharp focus.
In the eye, astigmatism creates two principal meridians. In a condition called “mixed astigmatism,” the two meridians have opposing refractive errors. One meridian focuses light in front of the retina (myopic error), while the perpendicular meridian focuses light behind the retina (hyperopic error). Because the light is split between focusing too early and too late, vision is blurry at all distances. Mixed astigmatism is the only true structural condition where a single eye exhibits both nearsighted and farsighted components simultaneously.
Presbyopia: The Age-Related Layer
The most common reason for a person to experience both distance and near vision problems is the onset of presbyopia, a natural part of the aging process. Presbyopia is a functional loss caused by the hardening and loss of flexibility of the eye’s natural lens. This loss of flexibility reduces the eye’s ability to “accommodate,” or change focus, for close-up tasks.
Presbyopia typically begins to affect people in their 40s, regardless of their existing refractive error. A person who is already hyperopic will find that presbyopia severely worsens their near vision and may make their distance vision more challenging as the eye loses its ability to strain and compensate. The combination of existing hyperopia and new presbyopia creates a significant need for both distance and reading correction.
A person who is already myopic and requires corrective lenses for distance will also develop presbyopia. Once the lens hardens, they will find that while their distance correction helps them see far away, they may need to remove those same glasses or use a different part of a multifocal lens to see clearly up close. This functional need for two different corrections—one for distance and one for near—creates the symptom of being both nearsighted and farsighted, even though the original structural error is only myopia.