He has Irlens syndrome which is a visual processing disorder and his glasses help to combat this as many specialists have said. I struggle with this myself but these glasses help. His are red and yellow sometimes but they are made up of all different colours within one lense which are unique to every individual experiencing irlens as different colours work better for different people.
It is said that Elton wearing glasses at the beginning is just for emulating one of his childhood heroes. But the latter, he really need eyeglasses because he become nearsighted. So, eyeglasses is a part of him. Anyway, it is cool when he wear eyeglasses. You know, eyeglasses now become part of fashion accessorizes. No matter you are poor vision or perfect vision, you can choose some nice or cool eyeglasses to decorate yourself as some famous person do.
Well, generally speaking, many people wear eyeglasses to have good vision. It is maybe because they do not have good vision or they have some kinds of eye diseases. So that they have to wear eyeglasses to see things clearly and also can heal some eye diseases. But on the other hand, there are also more and more people who do not have any eye vision problem, but they still wear eyeglasses. Maybe Elton john is one of them. They just want for fun or make them look nice and cool. Anyway, fashion is their only concern.
He is not short sighted. What he wears is just to make him look cool and stylish. The eyeglasses for he are the accessory which may match with the clothing. In addition, wearing the eyeglasses will give the people the impression of stars. In a word, they just wear for the looks.
You should understand that Elton John is one of them most renowned musician in Britain and his excellent piano songs attracted a large number of fans. As he is a celebrity , he does not want his personal life to be affected by paparazzi, also perhaps by wearing those glasses, his looks will be enhanced. Meantime, maybe he has got a poor vision. So, the glasses he wears have become part of him.