How to get/what brands make flat lens glasses? Others make me dizzy?

How to get/what brands make flat lens glasses? Others make me dizzy? - 1
Added (1). I have a pair of aviators but they make me feel dizzy. I've worn other glasses and tried on my brother's (which are smaller). They all make me feel dizzy. If I look at something but move my head back and forth the thing i am looking at moves too. I think this is normal and most people probably get use to it. However I wear contacts most of the time so I haven't gotten use to it. I'd think lens that are flat would correct this. I wear -4.50 in both eyes. Next pair will be -5.50.

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