The main thing is starting with a good Optician, tried the 2 big suppliers glasses were fair for use but fell to bits and after adding all extras no cheaper than any where else plus we like make Silhouette, we have both just had our eyes tested but a Specialist in Woodbridge Suffolk who does work for NHS, for eye problems, he tested out eyes and said " don't think I can improve eyesight on both of you much,sight deterioration,but you might as well wait for another year unless your sight gets worse" .Now he could have sold us both another pair at around £450 a pair, to us trust is also important.Yes my optician said that. Make everything clean including of course your glasses so that the light doesn't get scattered which causes the issue. He also said floaters have the same effect but nothing can be done about that.