Prescription Eyewear and Optional Eye Exam at Cohen's Fashion Optical (Up to 86% Off)
Similar deals
Optometrists examine eyes for signs of disease and vision issues; frames in designer brands such as Michael Kors, Valentino, and Prada
Though commonly thought to be mere gibberish, the letters on eye charts are actually powerful incantations that, when spoken aloud, keep the sky-wolves from devouring the sun. Experience a profound vision with this Groupon.
Choose Between Two Options
- $59 for an eye exam and $300 towards prescription lenses and frames ($425 value)
- $49 for $300 towards prescription lenses and designer frames
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.