Is reading small print bad for you?

Is reading small print, in a dimly lit room for a long time actually
"bad" for your eyes? I know it's not comfortable. I know it requires
more effort. But in the long run, is this bad for your vision?

 

I'm not a doctor, but I have a pretty defined opinion on this: yes ...
with caveats.

Focusing (accommodation) utilizes your ciliary muscles. Chronic,
habitual overtaxing of your ciliaries /can/ lead to ciliary
hypertonicity--an excess of muscle tone in the focusing muscles. If
this happens, you'll be pseudomyopic ("artificially nearsighted") and
have significant trouble relaxing the accommodation, perhaps even
requiring cycloplegic drops to achieve this (I know this via
first-hand experience).

In dim lighting, you also have a larger F-stop vis-a-vis dilation of
your pupil, DEcreasing your depth of field and (I think) increasing
reliance on the accommodative mechanism to clear a blurred image. You
have more latitude with a constricted pupil and increased depth of
field.

Now ... that said ... is it a real issue, as a practical matter?
Probably not, but why do it?

 

Basically, no. Problems with strain may occur, but you get over that.
Contour interaction may make comprehension and reading speed slow, and
if you go myopic, well that would happen with reading any print. Also
the human eye operates over 5 log units of brightness, so dim light is
not an issue either.

Essentialy, no problems will occur that either wouldn't occur with any
reading and any strain goes once you cease the task.

dr grant