Theatrical contact lenses are colored contacts that you can often see in movies. You might have seen a vampire movie where the vampires have unnatural looking white eyes or maybe a character with cat eyes. Well, they use often theatrical contact lenses to get those eyes. Even though they are often used at movies and stuff, anyone can easily get those for themselves for their own use. Regular people often use them just for the fun of it or maybe at some events, like at Halloween. Using theatrical contact lenses that fit to your character, you can get your character much more alive. Because changing your eyes is something that one can't do themselves, you have to use color contacts to get that effect. Like I mentioned, Halloween is one event where theatrical contacts could be used.

Other events where they are often used are those where you cosplay (costume play) some character (i.e. Some character from a game or a comic) and often these characters some special eyes (sometimes it might be just different colored eyes, then just normal color contacts can do the job for you) which can be achieved only using theatrical contact lenses. One popular choice is to use sharingan contacts when role playing a character from the Japanese cartoon (anime/manga) series Naruto. You can also of course use them for your own movie or if you're going to do a play. Use your imagination.