Why do the muscles of the Iris contract and relax?

  • Google+ icon
  • LinkedIn icon

To alter the size of the pupil, so the correct intensity of light is allowed through. Enough light is let through to allow clear vision, but not so much light that the retina might become damaged.

Calum M. GCSE Biology tutor, GCSE Physics tutor, GCSE Chemistry tutor...

About the author

is an online GCSE Biology tutor who has applied to tutor with MyTutor studying at Warwick University

Still stuck? Get one-to-one help from a personally interviewed subject specialist.

95% of our customers rate us

Browse tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss