$40 for Comprehensive Eye Exam Package at Northline Vision ($330 Value)
$40 for comprehensive eye exam package ($330 total value)
- Eye exam ($100 value)
- Dry eye evaluation ($80 value)
- $150 credit toward glasses
20/20 Vision: An Imperfect Ratio
The included eye exam will determine your visual acuity, which compares your vision to the 20/20 standard. Read on to find out what this metric really means.
Possessing 20/20 vision may be considered perfect, a level of visual acuity reserved for Navy pilots and the bald eagles that train them, but in fact it-s not even close to average. Developed by Dutch optometrist Hermann Snellen in the 1860s, the 20/20 standard is a somewhat arbitrary distinction. After inventing his now-iconic eye chart—which consists of lines of standardized letters that get progressively smaller—Snellen also instituted the concept of a ratio to define the clarity of a patient-s vision. The denominator represents how many feet away a person of normal visual acuity could stand while still discerning the letters with the same level of clarity as the patient. In other words, 20/40 vision means the patient needs to stand 20 feet away to make out the same size letters as a person with standard vision can from 40 feet.
Because the 20/20 standard is arbitrary, many people actually have considerably better eyesight, represented by such ratios as 20/15 or 20/10. In fact, in the United States, the average visual acuity is sharper than 20/20 until about age 60 or 70, when people-s vision naturally starts to decline as their bangs finally grow past their eyes. Also, though it-s useful for determining basic shortcomings of vision, an eye chart can-t diagnose a proper glasses or contact prescription. To determine that, optometrists test many other factors, including depth perception, peripheral vision, x-ray vision, and focusing skills.