Air New Zealand is the only airline ive come accross that has a restriction on unaided vision. Most airlines just expect that you can operate at a normal capacity should your vision aids fall ill in an emergency. A simple eye test will determine this during your aviation medical.
I wear O2 optix contact lenses by CIBAvision, they allow more oxygen to circulate under the contact lense and you can also rest in them for up to four hours - great for crew rest. The special eyedrops that come with them are great for when you wake up.