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Thank you for the question. I am Dr.A.S.Desai, certified ophthalmologist and I look forward to answering this question for you.
Actually these are very small errors and it would hardly make much of difference in the vision with either. In case the vision in your left eye is pretty blurred for distance ( say 20 feet and beyond) then I guess you can go ahead with either 0.25 or 0.50 D whichever gives you clear vision.
Hope this helps you to take the right decision. Take care.
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No, I don't think you need to worry about this subtle change.