20/5 is the theoratical limit of the retina! We have the potential of a hawk!

Discussion in 'Optometry Archives' started by Ace, Oct 25, 2006.

  1. Ace

    Ace Guest

    The theoretical limits of God's masterpiece is a retinal 20/5. We have
    same rod and cone density as a hawk. We just don't have the same

    *the above is what one expert said. Very interesting tibit! This shows
    that optical imperfections, astigmatism and high order aberrations
    results in most humans having a BCVA of 20/15 to 20/30(mine is 20/25
    and 20/30) I did read that a healthy human retina should have a
    potential of at least 20/8 to 20/10 and in fact over 99% of human
    retinas are capable of 20/10 or better. But because of optical
    limitations, 20/10 with or without glasses/contacts(non wavefront) is
    rare, encomposing between 1% and 2% of people. Sorry but straining to
    pump out a couple 20/10 letters doesnt count. I have gotten a couple
    20/20 letters before by straining but my BCVA isnt true 20/20(due to
    complex astigmatism and HOAs)
    Ace, Oct 25, 2006
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  2. Ace

    otisbrown Guest

    Nice Analysis, Ace.

    The practical value was established by a number of
    people, notably Snellen, Helmholtz, Donders and others.

    By practical testing (and use of the minus lens) they
    determined that most retinas could resolve 1 minute-of-arc.

    Snellen, converted this to a chart with 5 minute-of-arc letters --
    has become the "world" standard for visual-acuity testing.

    Finally, the Army (about 1914), gave up on naked-eye
    visual acuity of 20/20, and to avoid the use of a
    "lens", which might produce a "flash" in sunlight,
    determined to make the visual-acuity requirement
    20/40 in the better eye, or 20/40 with both eyes open.

    In fact that is probably how the DMV requirement
    came about.

    The people who have better-than 20/20 tend to
    be baseball players and other "out-door" types.

    20/15 in indeed superior, with some to about
    20/12 and even 20/10. But that is rare.

    As always, most ODs will prescribed for
    "Best Visual Acuity", which means that the
    person will get the sharpest vision possible
    from the minus lens prescribed.


    otisbrown, Oct 25, 2006
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  3. Ace

    serebel Guest

    Nothing like a retard and his mentor to solve the world's ills for all.
    serebel, Oct 26, 2006
  4. Ace

    Liz Day Guest

    We have the same rod and cone density as a hawk. We just don't have the same
    Hawks have a protrusion in the middle of their retina that makes their
    cone density effectively higher than ours.

    Liz Day, Nov 1, 2006
  5. Ace

    Ace Guest

    what im thinking is while both humans and hawks have retinas capable of
    20/5, hawks have their retina set up to be more effecient, such as a
    central protrusion. Humans have a fovea and perhaps that part of the
    retina is capable of 20/5 while hawks have a larger part of the retina
    capable of 20/5. Humans have much more aberrations than hawks so its
    rare for humans to see better than 20/15. If we removed all aberrations
    and other optical imperfections, would they still see as well as a hawk
    or at least nearly so? Ive heard the 20/8 figure thrown alot as the
    retinal limit of the average human
    Ace, Nov 1, 2006
  6. Ace

    eric_8_7_5 Guest

    I think that we have also some advantages over Hawks.

    Hawk = predator? --> bad peripheral vision, good distance vision
    man = prey? --> better peripheral vision, not so good distance vision

    Our peripheral vision is better than that of the hawk. So that we can
    see predators from the angle of our eye and run away. Typically men
    have more of the predator type eye. And women more of the prey-type
    eye. Does not mean that men hunt women. But means that women like to be
    hunted (??). I guess that's why we don't get along.
    eric_8_7_5, Nov 2, 2006
  7. Ace

    Ace Guest

    LOL this makes no sense. Humans are predators and have no natural
    enemies unless they are doing something really stupid like being at a
    place they shouldnt be such as swimming with shaks and aligators or
    playing with snakes and lions. We dont have the peripheral vision that
    pray like mice and rabits do.
    Ace, Nov 3, 2006
  8. Ace

    The Real Bev Guest

    Probably has to do with women being able to multi-task way than men.
    Grub the roots, keep your eye on the kids, and don't forget to watch out
    for the sabre-tooth hiding in the rocks.
    Underneath all the sophisticated trappings of civilization, we're still
    stone-age people. I would think that having a lion or tiger sneak up
    on you would have definitely been a problem at the time, and those who
    didn't notice probably didn't pass on many of their genes.
    The Real Bev, Nov 6, 2006
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