I am wearing contact lens from last 7 to 8 years. in my left eye I have a number of -2.75 and my right eye has - 2.25. is it ok if I purchase a contact lens of -2.50 which can be used for both of my eyes as visa me a difference of -25. I have checked with the local I shops and they told me its ok to wear -2.50 for both the eyes. I will be purchasing the contact lens of coopervision biofinity. you can also suggest which would be the best lens for me thank you.