Eye drops with "Dr. Grandson"

I watched my husband help his dad with eye drops and I was reminded of this picture. (A little blurry maybe, but you get the idea!) It's dated November 14, 2005, 6 1/2 years ago. (Dad was mostly healthy then, maybe showing a few random symptoms of the disease.) My son, at age 3, loved to help his Poppy with eye drops (notice Grammy's hand guiding the process!)

What is it about eye drops that are so intriguing to a little guy?
Here he is the same day, out "raking" leaves behind Grammy and Poppy's house:

Wow, Poppy was brave to let a 3 year old administer medication! Dad had just turned 72 the day before.