S.B.
At 3 1/2, this might not work...I know my 3 1/2 year old would still put up a fight....but it may be worth a try. When my little one was younger, she had pink eye too. THe Dr. told us to lay her down, have her closer her eyes, then put the drop in the corner of her eyes and have her open them. This will get the eye drops into her eyes, and it did work! I don't know if it would work now, but still worth a shot! Hope it helps! You could always try bribing him too!
Good luck!
S.