Final answer:
The medical assistant should hand the physician an ophthalmoscope to check the pupils of the eyes, which allows examination of the interior surface of the eye, including the retina and optic disk.
Step-by-step explanation:
If a medical assistant were to hand an instrument to the physician for checking the pupils of the eyes, she should provide an ophthalmoscope. An ophthalmoscope is a device used to look through the pupil and examine the interior surface of the eye, including the retina, optic disk, and the blood vessels that serve the retina. This is vital in assessing the health of the eye and for determining changes in vision, especially when a patient presents with symptoms like impaired vision or issues related to the optic nerve.