The Human Eye : Main Characteristics of the Sight (2)
Total 15M pixels over the FOV of 4/3PI steradians, most dense in fovea. (about 
  1/3rd of a full sphere : 4PI steradian)
Visual Acuity : between 30” to 2’ of angle ...  let's memorize 
  1'
Pixel resolution
  
    | 
         
          28 seconds of arc - highest resolution 
          50 seconds of arc - "20/20" vision 
          1.5 arc - minutes - "20/30" acceptable vision | 
        
          Lighty slot on Black Backgroung : 30'' of arc
          2 lighty spots on Black Background 1 ' of arc
          2 black spot on white background 2 ' of arc | 
1 ' : 0.1mn at 35 cm (0.0001/tan(1/60) = 0.34)
A screen at 35 cm, 25 cm, with a 40° FOV should have 2500 pixels (and 
  not only 1024) !
Stereoscopique Acuity : around 0.1 milliradian : Delta r = 0.001 . r2 (in 
  m)
  - 
     1mm at a distance of 1 m 
- 
    0.1 m at a distance of 10 m 
Maximim perceptible frequency : 25-30 hz
It is easier to perceive a slight difference than an absolute value
  - 
    Abslolute colour vs. comparaison of two colours
- 
    Perception of a distance vs comparaison of the depth of two close object 
      (within the fov)
What we "look at" is not about a simple picture printed on the retina
Before 70 philosophical (Kant) duality/separation between perception and interpretation 
  (eye/cortex)... now, more complex organisation, with specialised aera (frequency 
  perception, color contraste, color and low resolution intensities, move and 
  stereoscopic depth perception ...)
Average IPD (InterPupillary Distance) : 65 mm for adulte
  (between 50 and 70mm for european population)
The center-to-center distance between an adult person's 
  eyes averages. The binocular and of course HMD, should be capable of any setting 
  between those two measurements.