Based on what you've described (mucousy discharge and haze over the eye, with no redness or signs of other discomfort such as rubbing at the eye or squinting), this doesn't seem like infection or inflammation, so an antibiotic is unlikely to help; besides, you would need a special antibiotic ointment for the eye, which isn't something that's available over the counter.
I think you may be dealing with either of the following:
1. Glaucoma (increased pressure within the eye)
3. Corneal dystrophy
(gives the eye a hazy or bluish appearance)
4. Dry eye
(lack of adequate tear production)
5. Old, healed eye injury
It's not likely that you'd be able to treat this successfully at home, unfortunately. If this is a cataract, corneal dystrophy or an old injury, it's unlikely that it's causing pain or discomfort and you can wait a week or so to see what happens. Glaucoma unfortunately is quite painful and results in blindness. Dry eye is treated pretty easily and also can lead to blindness if not treated.
My recommendation is to get eye saline drops at a drugstore (make sure there is nothing else in the ingredient list) and apply 1 drop into the affected eye 3-4 times a day without touching the tip of the bottle. This should help soothe and lubricate the eye until you can get him seen by your vet.
Hope this helps; please let me know if you have any other questions; best of luck!