Does 20/20 Vision Mean Perfect Vision?
Many of us have heard the term “20/20 vision” tossed about since the time we were children. In many instances, you likely heard that this was the optimal, or perfect kind of vision, and that those who had less than 20/20 vision basically had eye problems. 20/20 vision, or what could be called “normal” visual acuity, refers to the clarity of one’s vision, or how acute that vision is, and it is determined by both optical and neural factors.
- How sensitive is the interpretative faculty of the subject’s brain?
- How sharp is the retinal focus within the subject’s eye(s)?
- How in tact is the subject’s retina, and how well does it function, or perform its duties?
These are the factors that determine how clear a person’s vision is, and conversely, the types of corrective measures that should be taken if the person’s vision is less than normal when it comes to visual acuity. Let’s take a look at a few other ideas surrounding 20/20 vision, and visual acuity.
Determining Visual Acuity
Visual acuity testing is typically measured with the subject at a distance of twenty feet from the subject matter they are asked to focus on. To say that a person has 20/20 vision is to say that they can accurately see what is in front of them, from 20 feet away. When broken down in this way, it’s pretty clear that 20/20 vision doesn’t necessarily imply perfect vision, just how sharp a person can see from the distance of 20 feet.
But how far away from an object that a person can see clearly isn’t the only factor that affects the quality or ability of one’s vision. How well one can see and process information in the periphery of their vision is also a factor, as well as the coordination of their eyes. Think about sports, for instance – how important do you think it is for a basketball player to have accurate depth perception? Immensely important, given the fact that in order to shoot the ball through the hoop, the athlete must be able to accurately assess how far away the hoop is.
One’s ability to focus, as well as color vision, are two other important factors that impact the quality of a person’s vision.
Optical Factors That Might Affect Visual Acuity
There are several factors that impact one’s visual acuity on an optical level, including refractive error, or ametropia, which is related to how the eyeball refracts light; ametropia could be the result of something as simple as an abnormally shaped eyeball or cornea. Refractive error as it relates to the eyeball’s length can result in either hyperopia (farsightedness) or myopia (nearsightedness).
From an optical standpoint, other causes impacting visual acuity may include corneal irregularities of a more complicated nature, and astigmatism.
Neural Factors That Might Affect Visual Acuity
Negatively affected visual acuity as a result of neural factors will be found in either the retina or a person’s brain, with a common example being the case of macular degeneration. If a person has had brain damage, for instance, this could result in diminished visual acuity. This includes a stroke, as well.
How to Go About Determining Visual Acuity
A qualified eye doctor (doctor of optometry), through the administration of a comprehensive eye examination, can accurately assess your visual acuity. Furthermore, there are numerous tests by which a doctor of optometry can gauge the factors that might be affecting or reducing the quality of your vision. There are many remedies available, such as glasses, contact lenses, vision therapy, and surgery, depending on the type of vision problem, and its severity.
[Photo Credit: LCRF Wired]