After using a binocular microscope recently for about 20 minutes, my vision went blurry and for an hour or so it was much harder to read small text. This occurs to a (far) lesser extent whenever I use it for a shorter time.

  • Why does this occur?
  • Which is the optimal microscope light intensity so this does not happen?
  • What other variables should I beware of?
  • 2
    $\begingroup$ Wow, I use microscopes daily and I never had this problem. What type of microscope / light source are we speaking about? $\endgroup$
    – nico
    Commented Nov 17, 2012 at 19:16
  • 1
    $\begingroup$ @nico It's an 'apex researcher' microscope. For lighting it's a small lamp mounted underneath the slide hole and lens. I don't know what's the standard for microscopes so I can't really comment if it's anything out of the ordinary. $\endgroup$
    – Meow
    Commented Nov 18, 2012 at 14:10
  • 2
    $\begingroup$ Could it be because you are focusing at a fixed distance for a long time? I would try changing my focus every 5 mins by looking someplace far away. $\endgroup$
    – Memming
    Commented Nov 18, 2012 at 15:56
  • $\begingroup$ @Alyosha: OK, that is a fairly standard brightfield microscope. The only thing I can think of is that your problem may be due to the fact that the lenses of the microscope are not top quality and may give some optical aberrations that your eyes got used to during the 20 minutes. $\endgroup$
    – nico
    Commented Nov 18, 2012 at 16:09
  • $\begingroup$ I'll try Memming's idea in the future. Thanks all. $\endgroup$
    – Meow
    Commented Nov 18, 2012 at 19:18


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