How Does Pupil Size Affect Refraction?

I have read that lage pupil size aids near vision (accomodation) and that
narrow pupils aid distance vision. iam myopic and I have at baseline large
pupils. This is independent of amount of light. In fact I'm sensitive to
sunlight i think because my pupil tends to stay large even in brigtness.What
is the optics of this. Is there a refraction effect independent of the
lens. Is this just the pinhole effect. Is there a reference somewhere, I'm
not an optometrist but i think I can follow a fairly technical explanation.
Why do contacts (RGP) make me even more ligt sensitive?

Mike Samsel

 

If smaller pupils equal better vision (well better visual acuity) near and
far, and myopes have large pupils, it seems desireable to reduce pupil size
on average if one has larger pupils. What are the mechanisms/techniques that
can do this?? Sunning the eyes? Decreasing anxiety?? Something else.??
What is the mechanism by which myopes pupils become/stay larger? Is it a
response to blur or the cause (partial) of blur?

Mike

 

Pupils become smaller with age and are larger with emotions (good and bad --
ie happiness, excitement, anxiety and fear all have pupil enlarging
effects). I would suggest that myopes don't have "larger" pupils but that
hyperopes have "smaller" pupils due to the accommodation that they exert
100% of the time. The pupil constricts with accommodation. Since 75% of
people are slightly hyperopic, they would skew the average towards smaller.

There isn't much you can do to affect your pupil size, outside of various
drugs.

Dr Judy