Here is how the eye is supposed to work: tears are produced in a gland at the outer/upper corner of the eye – the lacrimal gland. The moisture flows over the eye, keeping it from drying out – this is aided by blinking. Any excess fluid then drains out of the inner corner and down the nasolacrimal duct (also call the tear duct) into the nose. When somebody cries, there can be an overflow of tears out of the eye and down the cheek. Many infants are born with plugged tear ducts, and have tears running down their cheeks even without crying (click here for more info on this). I have seen plenty of kids crying, but without tears rolling down the cheeks. This is probably because their tear ducts work very well (I do see the tear in their eyes, just not running down the cheek). It is unusual for a child to not produce any tears at all. Next time he cries, look for the eyes to become extra moist – if you don’t see this, then you probably should see an eye doctor to measure the level of tear production.