I think what the OP is explaining is that he is having trouble following the map, not seeing data screens so I think the suggestion to use bifocal safety glasses is a good one. Something I did was get the stick on bifocal lenses on Amazon to put in my Oakley sunglasses. I also lately have been riding with a pair of butt ugly prescription safety sunglasses my employer provided.
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"It is the unknown around the corner that turns my wheels." -- Heinz Stücke