hi... puffiness in lids can be because of eye infction or systemic disease lkie kidney
or heart problem. if he also has discharge from eyes or increased watering and redness
in eyes( not lids) than it is mostly infection. he will nedd antibiotic eye drops. but you should show him to eye specialist.
if he does not have discharge/redness...and his general condition(sleep,apetite, bowel,bladder habits) is not normal..kindly take him to peadiatrician.