I wear glasses at night to watch TV and read in bed. I am wondering when it is beneficial to get high index lenses vs. traditional polycarbonate lenses. I am guessing that the increased cost of high index would be a waste of money for someone like me who only wears glasses one or two hours a day. Anyone knowledgeable as to what the cost differential is in high index over traditional materials and at what prescription level does it make sense to go high index. I am about -4.75 in both eyes, and have just selected glasses with a very small frame size so hopefully centering on the lens material will make them thin.