Visual acuity measures the clarity or sharpness of a person’s vision. This measurement is routinely taken during a comprehensive eye examination to determine how well an individual can see small details at a distance. The result provides an objective way to assess the current state of a person’s eyesight. Understanding the meaning of these numbers is the first step toward knowing if a prescription is necessary to achieve optimal sight.
Understanding Visual Acuity Measurements
Visual acuity is typically measured using the Snellen chart, which displays rows of letters that decrease in size. The result is expressed as a fraction, with the standard for normal vision being 20/20. The first number represents the distance, in feet, at which the test is performed (usually 20 feet).
The second number indicates the distance at which a person with normal 20/20 vision could read the same line of letters. For instance, 20/20 vision means a person can see clearly at 20 feet what a person with normal vision can also see at 20 feet. When a person has 20/50 vision, they must stand 20 feet away to read a line that a person with 20/20 vision could read clearly from 50 feet away.
What 20/50 Vision Means for Daily Life
The World Health Organization (WHO) classifies visual acuity between 20/30 and 20/60 as mild vision loss, or near-normal vision, placing 20/50 within this category. While 20/50 vision is not considered legally blind (typically 20/200 or worse), it can still present noticeable functional challenges in daily life. The most common cause of this reduced acuity is a refractive error like myopia (nearsightedness), where distant objects appear blurry.
Tasks requiring clear distance vision become more difficult with uncorrected 20/50 vision. Reading street signs and highway exit markers can be a struggle, particularly when traveling at speed, because the text appears blurred until the driver is much closer. Recognizing familiar faces from across a large room may also require more effort and time than for someone with 20/20 vision.
Driving is an activity where the functional impact of 20/50 vision is most apparent, often falling below the standard for an unrestricted license. Most jurisdictions require a visual acuity of 20/40 or better in at least one eye to drive without restrictions. A driver with uncorrected 20/50 vision is therefore likely to receive a restriction mandating the use of corrective lenses while operating a vehicle.
Some areas consider corrected vision worse than 20/50 a contraindication to driving a non-commercial vehicle. However, some states may grant a “daylight only” restriction to individuals with vision in the 20/50 to 20/70 range. While 20/50 is a mild impairment, it is generally insufficient for the demands of safe, unrestricted driving.
Options for Correcting 20/50 Vision
The good news is that 20/50 vision caused by a refractive error is highly treatable and usually corrected easily. The most common solution involves the use of corrective lenses, such as prescription eyeglasses or contact lenses. These lenses work by altering the way light enters the eye, ensuring that light focuses correctly onto the retina to create a sharp image.
An optometrist will determine the precise prescription, measured in diopters, needed to bring the vision to 20/20 or better. For nearsightedness, this prescription will be a negative number, indicating the lens power required to correct the distant blur. Wearing the prescribed corrective lenses not only sharpens vision but also reduces eye strain.
For those seeking a more permanent solution, refractive surgery is an option. Procedures like Laser-Assisted In Situ Keratomileusis (LASIK) reshape the cornea using a laser to correct the underlying refractive error. Photorefractive Keratectomy (PRK) is another surgical option that reshapes the cornea without creating a flap, suitable for individuals with thinner corneas. These procedures can often correct 20/50 vision effectively, eliminating the need for daily use of glasses or contacts.