For example, American baseball star Mark McGwire is widely reported to use contact lenses that improve his 20/500 vision to be better than 20/10 5.ĭistinguising details at 150ppd would require 20/8 vision. However, corrective eyewear can often achieve this level. Anecdotally, my eye doctor told me that in all of his 20+ years in practice he has only seen one person (a teenager) who measured at this level without glasses. The graph on page 489 of 1 shows that only one or two individuals in the 100+ of tested 17-18 year olds got close to this limit (shown as -0.3 logMAR). Seeing details at 120ppd is equal to '20/10' vision (or '6/3' in Europe). Visual acuity peaks at around 25 years old and then slowly declines, but even then the average 75 year old has better eyesight than 20/20. While visual acuity changes per person and over time, the average acuity in adults is about 1.6 times better than 20/20, roughly 20/15 vision, or 80ppd. This is defined as the 'normal' visual acuity for adults, but it is actually not the average.

'20/20' vision (or '6/6' in Europe) corresponds to being able to resolve details 1 arcminute in size, or 60 pixels per degree.

limit of high contrast feature detection 4 limit of alignment detection (hyperacuity) 4Īpprox.

Visual Density pixels per degree (ppd) at center (~ 123 at edge)Ģ0/10 vision practical upper limit of visual acuityĢ0/8 vision theoretical upper limit of visual acuity 3Ģ0/4 vision approx.

The perceived 'visual density' of a screen-and thus the amount of anti-aliasing possibly needed to make computer graphics look convincing and smooth-is dependent on the pixel density of the screen (the 'ppi') and the distance from the user's eyes.Īdjust values below to calculate the visual density, or select a different value to control and instead enter the desired ppd.

Pixel resolution calculator