During a Zombie Apocalypse, all people with the goal of survival in the long term will need all of their senses working at optimum potential. Glasses are mediums used by many people but most have little experience maintaining them over long periods of time, almost like shoes, bicycles, or knives. Things such as these may seem trivial but in the event of encountering one (or more) zombies, it is very desirable to be able to see them as crisply ten months after the outbreak as when one was spotted ten days after.
Repair and ReplacementsEdit
Glasses repair kits can be found in many places such as pharmacies and dollar stores. They will probably be one of the last things left in a raided store due to its low caloric content and lack of immediate usefullness. Simply take one (or as many as possible) and run; but eventually all things need to be replaced and what if the supply of screws run dry before the factories producing them are started up again?
Opticians' shops may have plenty of supply considering most survivors may not care for designer glasses in that awful hue of pink or may not need replacements yet. Not many, if any, zombies are likely to be there, and it would most likely have a ready supply of screws and maybe lenses if you are lucky.
However, if the glasses have disappeared, one might find a pair on a zombie. However, there may be problems involving the retrieval and the integrety of the glasses given how it would be on (or possibly embedded in) the head of the last thing most self-preserving people would willingly want to approach and may have been exposed to the elements for extended periods of time.
If the frame is simply broken, one could simply use a foolproof combination of steel wire and solder to repair it and save the effort of the aformentioned methods of getting one that may or may not help. If it is made of plastic, it may be possible to melt it together with the flame of a candle.
If all else fails, use gauze and epoxy.