BTW, Lin Dan wears contacts when playing .... I saw a recent social photo of him and XXF at a function, and he was wearing his glasses (not sun-glasses - normal glasses) ... so if he is myopic or astig, he must be wearing contacts when playing ...
Initially i wore contact lens but i have astigmatism, quite frequent unable to see birdie especially cross court play from opponent and birdie fly to left or right base line when I look direct to the light.
Then i ordered contact lens with power + astigmatism, but very thick and uncomfortable to wear. Drop off sometime during play.
End up, wearing glasses now and has to get used to the fogging and always need to adjust the position of my glasses due to sweating on my face.