I do apologize that we seem to be playing holiday time zone tag.
Anyway, based on his photos, I'd be a wee bit concerned that Leo has a brewing upper respiratory tract infection causing a conjunctivitis. These are very common in breeding catteries because of the higher density of cats living in a shared airspace. And often the stress of life change (leaving mum, new home, new people/pets, neutering, etc) can trigger a flare up. The other concern of course would be whether he has had a wee trauma to the eye (ie scratch) but if we aren' t seeing those changes to the eyeball, then that is less likely.
Now it does depend on what antibiotics were used and who our culprit is. This is because for our common conjunctivitis or pink eye bacteria, they do usually respond to broad spectrum treatment. That said, if we have the bacteria Chlamydia present, they do tend to need 4-6 weeks of antibiotics to clear that sneaky bacteria. As well, we can see these issues caused by viruses (calicivirus, herpes) that can take 1-2 weeks to just settle. And those last 2 would notoriously take advantage of Leo's immune system in a time like this.
With all this in mind, it is good that the discharge is clear. If it had been snotty, then we'd be worried that the antibiotics weren't effective against any bacteria present. Though we do need to monitor for any relapses. Otherwise, since feline herpes is a common agent that can cause these signs, we can consider trying Leo with L-lysine (a nutritional supplement). This is available over the counter at vets, pet stores, health food stores, and online. It comes as a gel, powder, or crushable table to all be mixed with food. An average cat dose is 500mg a day. As well, we can also flush those eyes with sterile saline (ie OTC first aid eye wash, plain contact lens solution) to just help get any irritants/bacteria away,remove the discharge, and keep those eyes comfortable.
Overall, I would be most suspicious that we do have a cat flu agent causing these signs. Since the discharge is clear, the viruses are our main suspects. So, we want to flush those eyes +/- try the L-lysine and keep a close eye on him. If he has any relapses or doesn't totally settle, then we may need to have your vet swab the eyes to diagnose what is lurking and ensure we clear it for him.
All the best,