for hallcosplay you do not need color contact lenses. people rarely notice them in natural colours. if the eye colour is the only special thing about your character and the reason you are choosing to cosplay them in the first place over other characters is because you want attention from having cool/freaky looking eyes, you need to pick a new character rather than risk your vision.
Like everyone says, photoshop your pics if you really need them to be perfect and leave it at that. Always obey your doctors. They're the professionals, not anyone here.