Bifocals and trifocals result in more complex lens shapes.
One of the lens shapes is catching up.
On landing, a stairway and two conveyor-loading ramps swing down at an angle from the central base of the bottom lens shape.
It causes streaks and lens shapes to form in the quartzite.
They range from flat, counter shaped to the typical lens shape.
They range from thinner flat-bottomed style, to a symmetrical lens shape.
In the 1980s, the lens shape was re-designed to the "S9".
The accommodative response of the eye results in changes to the lens shape and substantially affects the Wavefront aberration pattern.
These vertical members must also transfer some load between the two girders, so as to maintain their lens shape.
There is also a minimum lens thickness required to support the lens shape.
