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Click here to download the
Fitting Guide Pdf
•Pentax Retina Forward Design provides wider visual field for
comfortable, effortless viewing.
•Greater asphericity for a more natural appearance and a slimmer
lens profile.
•Optimized position-of-wear optics for crystal clear,
aberration-free (AF) vision.
•Superior optics in a short corridor design.
•Available 14mm corridor design for smaller frame sizes.
The innovative design of Pentax AF Progressives creates a new level
of optical performance in progressive multifocal lenses. This Pentax-exclusive
technology, called Retina Forward Design, enhances performance in
three ways. |
Optimized for the
position of wear
Changes in viewing angle, lens tilt, and vertex distance in
different positions of gaze create optical aberrations that reduce
clarity and comfort. This is especially true with aspheric lenses,
which have flatter curves. Since these optical errors are caused by
position of wear factors, they are not detected by conventional
lensometry.
Pentax AF Progressives are specifically designed for how lenses are
actually worn. In Retina Forward Design, lens surface power is
precisely calculated at 5,000 points on each AF Progressive to
optimize optical performance and reduce aberrations caused by
pantoscopic tilt, vertex distance variations, and object distance.
Though these power adjustments are small, they pay huge dividends by
improving image quality at the retina in all directions of gaze for
greater clarity and wearing comfort.
Smoother power changes
The surface power optimization of Retina Forward Design gives Pentax
AF Progressives smoother power transitions and wider viewing zones.
This creates a more natural viewing experience virtually free of
swim or distortion.
Slimmer aspheric profile
Retina Forward Design makes it possible for Pentax AF Progressives
to have a slimmer, more attractive profile without compromising
optical performance. Base curves are flattened up to 1.5 diopters to
create the slimmest, most attractive lens possible. In plus powers,
the flatter curves of Pentax AF Progressives also reduce unwanted
magnification and give a more natural appearance to the wearer?s
eyes.
Retina Forward Design Means No Swim!
The position of a lens when worn in front of the eye affects its
optical performance. One variable in lens position is vertex
distance. Vertex distance is the distance from the back surface of
the lens to the apex of the cornea of the eye.
The effective power of lenses changes with vertex distance. With
increasing vertex distance, plus lenses effectively get stronger,
while minus lenses effectively get weaker. Conversely, when vertex
distance is shortened, minus lenses effectively get stronger, while
plus lenses effectively get weaker. Therefore, control of vertex
distance (or making lens power compensations for changes in vertex
distance) is important to maintain the effective power of a lens
when it is worn in front of the eye.
Vertex distance also affects field of view. The shorter the vertex
distance, the wider field of view. A shorter vertex distance also
enhances the cosmetic appearance of eyewear. Therefore, spectacle
lenses should be fit with a vertex distance of approximately 12mm.
This distance provides wide fields of view and a cosmetically
pleasing appearance, while providing adequate separation from the
face to prevent the wearer?s eyelashes from touching the back
surface of the lens.
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| A second factor that affects the optical performance
of a lens is pantoscopic tilt. Pantoscopic tilt is the
angle between the plane of the spectacle lens (and frame
front) and the frontal plane of the face when the
superior edge of the lens is farther away from the
frontal plane than the inferior edge. Pantoscopic tilt
brings the front of the frame into proper relationship
with the wearer?s eyebrows and cheeks. It also provides
the widest field of view for reading, since the vertex
distance of the lower half of the lens is minimized.
However, tilting a lens in front of the eye induces a
lens aberration called marginal astigmatism. Pantoscopic
tilt changes the effective sphere power of the lens and
induces cylinder power at axis 180?. For compound
prescriptions with axis other than 180?, pantoscopic
tilt changes the effective axis of the cylinder power.
And pantoscopic tilt reduces vertex distance for the
lower half of the lens, but increases vertex distance
above the 180 line. |
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Pentax Brand Single Vision Lenses
As a world leader in single-vision lens design and manufacturing,
Pentax continues to provide outstanding value and quality.
In every PENTAX branded lens, you'll see attention to detail. These
lenses offer an unbeatable combination of clarity, performance,
durability, and value. |
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