They constrict: By constricting they allow less light to enter, preventing damage to your eyes.
Answered 10/23/2018
5.4k views
A doctor has provided 1 answer
13 doctors weighed in across 2 answers
3 doctors weighed in across 2 answers
90,000 U.S. doctors in 147 specialties are here to answer your questions or offer you advice, prescriptions, and more.
Ask your question