13. The 3T-015A is a measuring tools for
measuring the Pantoscopic Angle and the
Back Vertex Distance, especially for
Progressive Lenses.
14.
15.
16.
17. Pantoscopic: The lens bottom is rotated
towards the cheeks.
Retroscopic: The lens bottom is rotated away
from the cheeks. Rotation of the lens, around
the horizontal axis occurs in frames at the
hinge so temples mounted at the top of a
frame are rotated like the above illustration
18. In addition, proper pantoscopic tilt will help maximize the amount of
bridge surface resting on the nose.
Retroscopic may at times be needed to maximize the amount of bridge
surface touching the nose, but generally the purpose of retroscopic is
to remove the lower rim of the frame from a protruding cheek.
Pantoscopic Tilt - When the bottom of the frames is angled toward the
cheeks. Orthoscopic Tilt - When the frames have no angle.
Retroscopic Tilt - When the bottom of the frames is angled away from
the cheeks.
19. Lens tilt improves the way a lens works and contributes
to how good a pair of glasses looks on the patient. Tilt is
dependent on the interaction of the heights of the ears
and bridge of the nose. So, even though a new frame has
about seven degrees of tilt when manufactured once
lenses are added the frame may not appear to have any
tilt at all unless it is well adjusted to the
wearer before any measurements are taken.
So, when taking measurements for free-form or digitally
enhanced lenses, place the frame on the patient, make
sure the frame front is straight and lenses have about 8
degrees of tilt. The amount of tilt should look good i.e.,
correct for the way that this patient wears this frame