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Brides have a lot of concerns about the aesthetics of their weddings, and for some, the idea of a couple of bridesmaids wearing glasses is completely unacceptable. Still, not being able to see while walking on an uneven surface is a safety hazard. And the safety of your bridesmaids should definitely come before the aesthetic of your wedding!
Above all, you should prioritize safety no matter what event you are hosting, even if it is your wedding. The bride had other priorities in this case, and I think it is clear that she gets her shallow nature from her mother. I hope they at least managed to take all the pictures without breaking anything!