Locating New Lenses In The Frame Question ?

Hello,

Was wondering about this a bit.
Had a "discussion" with my Optician re.

When new lenses are put into the frame, is the center of curvature of
the lens supposed to be directly in line with the eyeball's center (I
guess thru the middle of the Iris ?) ?

Or, as he said, the geometric center of the lens, in the vertical
dimension, is just put 1/2 way vertically in the frame ?
The horix. apparently he felt should be in line with the eye's center;
only the vertical that
we disagreed about.

I might not be all that clear in phrasing this.
So, if not, could someone please explain how the lens' optic center is
determined, and how it should be
located and placed in the frame ?

Much thanks,
Bob

 

If the optical center of the lens is 1/2 vertically in the frame, then it
will usually be near the center of the pupil. However, for most frames the
fitting height (where the optical center of the lens is placed in the frame)
is a little above the center of the frame.

A lens is never put 1/2 way the distance in either direction without first
measuring. It depends on the frame and how it sits on your face. This is
measured by first fitting the frame on your face and adjusting the nose pads
and temples, etc (with the temporary plastic lens in the frame). Then with
you looking straight ahead, the optician observes where your pupil is on the
temporary lens and they mark it with a pen and then measure the fitting
height. Pupil distance is measured without wearing the frame and is the
distance from the center of your nose to the pupil..