Visual acuity is the measurement used by eye care professionals to quantify the clarity and sharpness of your distance vision. Receiving a fractional result, such as 20/150, often creates immediate confusion and concern. This score indicates how well you can distinguish fine details and shapes at a specific distance. Understanding this measurement system helps determine the functional impact of your vision score.
Decoding the Snellen Fraction
Visual acuity is most commonly measured using the Snellen fraction, a standardized system developed to assess sight clarity. This fraction compares an individual’s vision to what is considered average visual performance. The top number, or numerator, represents the standard distance at which the test is performed, which is typically 20 feet in the United States.
The bottom number, or denominator, is the distance at which a person with 20/20 vision can clearly read the line you read at 20 feet. For instance, 20/20 vision is the benchmark for normal clarity, meaning that at 20 feet, you can read the line of letters an average person can also read from 20 feet away. A larger denominator indicates a greater degree of distance vision impairment.
Interpreting 20/150 Vision
A result of 20/150 means you must be 20 feet away to clearly see an object that a person with 20/20 vision could see clearly from 150 feet away. This level of acuity signifies a moderate reduction in sight clarity. Distant objects like street signs or faces across a room would appear noticeably blurred.
This score is generally considered a significant visual impairment, affecting the ability to perform tasks that require sharp distance vision. It is important to note the distinction between this result and the definition of legal blindness. Legal blindness is typically defined in the U.S. as having visual acuity of 20/200 or worse in the better eye, even with the best possible correction.
Therefore, 20/150 vision falls just outside the most common threshold for legal blindness when measured without correction. It indicates that the individual’s sight is substantially reduced, but it is not categorized as severe vision loss. The functional impact can vary, but most daily activities requiring clear distance vision would be challenging without correction.
Common Causes of Reduced Acuity
The most frequent reasons for a visual acuity score of 20/150 are uncorrected refractive errors. These errors occur when the eye’s shape prevents light from focusing directly onto the retina, leading to blurred vision. Nearsightedness (myopia) is a common culprit where the eye is too long or the cornea is too steeply curved, causing distant objects to appear out of focus.
Farsightedness (hyperopia) and astigmatism can also contribute to reduced acuity, though hyperopia usually affects near vision more significantly. Astigmatism is caused by an irregularly shaped cornea or lens, which distorts vision at any distance. A score of 20/150 may also be an early indicator of a more complex eye health issue.
Conditions such as the beginning stages of cataracts, which cause the natural lens to cloud, can lead to reduced clarity. Corneal issues, which affect the transparent outer layer of the eye, can scatter light and degrade vision. A comprehensive eye examination is necessary to differentiate between a simple refractive error and a developing ocular disease.
Options for Correction and Next Steps
The immediate step following a diagnosis of 20/150 vision is the prescription of corrective lenses. Eyeglasses and contact lenses work by introducing a specific optical power to redirect light rays, ensuring they focus correctly onto the retina. For most people, this correction effectively restores vision to 20/20 or very near to it.
Refractive surgery options, such as LASIK or PRK, are available for eligible candidates. These procedures permanently reshape the cornea to correct the underlying refractive error, eliminating or significantly reducing the need for glasses or contacts.
Regardless of the correction method chosen, the most important next step is undergoing a thorough eye health evaluation. This comprehensive exam ensures that the reduced acuity is solely due to a simple refractive error and not an underlying medical condition. Addressing potential health issues early is a preventative measure for maintaining long-term sight and overall eye health.