With regards to modern eye exams then you should see that they have actually changed over the years and are now capable of dealing with much more than just your eyesight. They can now spot various conditions quite early on and then help to stop them from gradually getting a lot worse as well.
The machines that are used are now much more powerful than before and if you go for an examination you shall see it really has come on so much from the days of reading off a chart. Instead they now measure things such as the pressure in your eye and the entire thing does take a bit longer than it used to.
The exact things they do does depend upon where you are as various countries shall use slightly different techniques but they all generally do the same things. It means you will need to identify various things and they see how your eye actually reacts when dots appear and how early you see them appearing which then provides them with various pieces of information.
They are now able to work out if you suffer from things including the development of cataracts as well as glaucoma and how they are progressing over time. This does then mean they can see about making sure the lenses you get are the perfect ones to ensure you can see as well as possible even with these problems.
You are always best to get these examinations on a more regular basis and the actual optician can advise you on whether it would be every year or if every two years is fine depending on your eyesight. In some instances it may be determined you need to have them more regularly or your own doctor could refer you to someone as well.
What this costs does once again depend on where you are based as in some countries it is actually entirely free. This information shall be easy enough to find out however so look for it before you go and think about making an appointment.
So modern eye exams are able to be booked for the same day as the majority of companies will have spare slots available if you just call them up. Then all that is required is you get there and let them do all of the test so if you are needing glasses they can make sure that the lenses are the perfect strength for you.