Quote:
Originally Posted by kenchan
sounds good, mr.alcheng!  i remember taking a pair of glasses i bought locally in the US to some optical place in japan and they measured my lens and later told me that the centering of the lens was completely off. 
does that mean my eyeballs are like lopsided or on the wrong side of the head or something?  
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... Mr.kenchan, for sure I won't go back to that eyeglasses store anymore or at least they have to redo the job...
Each lenses have an optical center which has the least prism effect, we call that the focal point of the lens.
When the lenses are being cut and mounted onto the frame, we have to decenter the lenses thus the position of that focal point will align in front of the pupil of the eyes when the person is wearing the glasses.
Depends on the prescription, the 'X' mini-meter off from the focal-point-distance will generate an 'X' amount of prism effect, thus the person will feel like 'swimming' when wearing the glasses.
Regarding your experience, your eyes are completely normal (I believe...
), that pair of eyeglasses..... most likely not...
