Transcript Optical dispensing

OPTICAL DISPENSING
FRAMES
 MATERIALS:
– Cellulose acetate or zylate is the most
commonly used material for plastic frames.
• Monel is a corrosion resistant alloy, and is
the most prevalent material used for
metal frames.
PLASTIC MATERIALS
 Cellulose acetate
 Cellulose propionate
 Carbon fiber graphite
 Polycarbonate
 Polyamide
 Optyl
 Nylon
Cellulose acetate
 Cellulose is mixture of cottonseed fibers,
wood flakes, stabilizers and plasticizers.
Zyl is east to adjust and has the unique
ability to slightly reduce in size to
accommodate a lens that is edged a bit
small or to stretch to house a lens that is
edged to large.
Cellulose propionate
 Cellulose propionate is another plastic
material used to produce injection molded
frames. Because it is lightweight and very
strong it lends itself well to the production
of ultra thin and over sized frame styles.
Carbon fiber graphite
 CFG is a light weight materials (about one
forth the weight of zyl and metal) that
consists of a carbon compound and a
textiles fiber called ceramic whisker.
Polycarbonate
 It is used in the manufacturing of bullet
proof glass and crash helmets. In eye care it
is used for sports and safety purposes.
Polyamide
 Polyamide is a type of nylon that is very
strong and light weight in nature. It is easily
tinted and is available in a wide range of
colors.
Nylon
 It is a virtually unbreakable, hypoallergenic
frame materials that in today's market, is
mostly used for injection molded sun
glasses as well as men’s frame styles.
Optyl
 It is a plastic frame materials that is
hypoallergenic, light weight, and keeps its
finish over time. It is a lasting durable
material known for returning to its original
shape when thoroughly heated.
METAL FRAME MATERIALS
 Monel
 Nickel
 Nickel –Silver
 Phosphorous bronze
 Stainless steel
 Titanium
 Aluminum
 Beryllium
 Cobalt
Monel &Nickel
 Monel is a combination of nickel and
copper. It is a strong stable material that
also lends itself to making nose pad arms,
bridges and end pieces.
 Nickel is a strong and generally bends
without breaking to making nose pad arms.
Patients are sometimes allergic to this
products.
Nickel-silver & phosphorous
 NS is a strong rigid material that is suitable
for hinges, end pieces, bridges and
decorative trims. This is brittle material.
 Also called phosphor-bronze is an alloy
comprised mostly of copper. Adjustments
can be a problem because of the “springy”
characteristics of the material.
Stainless-steel & Titanium
 It is very popular because this material is strong
even in thin streamlined applications. This metal is
alloy comprised of manganese, nickel, iron and
chromium.
 Titanium is a naturally occurring element that is
highly corrosion-resistant and is incredibly
lightweight. If the wearers allergic to other metals
and is purchasing a titanium frame to avoid
allergic skin reactions.
Aluminum, beryllium & cobalt
 Aluminum is very popular . This make it
even lighter than titanium, it is rigid
material that is difficult to adjust.
 Beryllium is used in the production of
temples by combining with other metals. It
is very expense.
 Cobalt offers a highly polished finished and
is often used in thin frame designs. It is also
expensive.
Types of frame
 Full frame
 Combination frame
 Semi-rimless
 Full rimless (or) Drill mount
 Half eye
Frames
Frame parts
 Frame front
The frame front has either a sculpted
bridge or a bridge device that is attached
to the frame. The bridge is an important
part of the frame because it connects the
two eye wires and it supports most of the
weight of the spectacles on the patients
nose.
Frame part
Bridge type
 Plastics:
– Saddle, modified saddle, keyhole, adjustable
bridge .
 Metal :
• Adjustable nose pad, uni – fit bridge,
saddle bridge
Nose pad
Nose pad
Temples
 There are five temple design used in frame
manufacturing
• Skull temples
• Library temples
• Convertible temples
• Comfort cable temples
• Riding bow temples
Temples
Frame selection
 The best frame for a patient complements
his or her facial structure, requires minimal
adjustments, and will securely hold the
lenses in place.
Frame styling
 The size and the shape of the frame greatly
affect the overall cosmetic appearance of
the finished prescription lenses. The best
way to control the finished look is to first
imagine the thickness and curves of the
lenses.
Determining facial wrap
 There are seven facial shapes:
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Oval
Triangle
Round
Long
Square
Inverted triangle
Diamond
Frame selection
Frame types vs. facial
proportions
 Oval shape faces
 Round face
 Square face
 Long face
 Triangle
- any frame shape
- angular frames
- round or oval shape
- deep vertical frame
}
 Inverted triangle } oval or rounded
. diamond face
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designs.
LENSES
Abbe value
 The abbe value (first describe by Ernest k.
abbe a German optical physicist) indicates
the ability of a lens material to purely
refract white light without chromatic
aberration.
Abbe value of common lens
materials.
INDEX
 MATERIAL
Glass , crown
CR 39
Spectralite
High index 1.56 (resin)
High index 1.60 (resin)
High index 1.66 (resin)
Polycarbonate
High index glass
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59
58
47
39
37
32
31
25
Lens types
 Lenses are classified as spheres, cylinder
and prisms.
Lens material
 CR-39
 Glass
 Transitions
 High index lenses
 Polycarbonate
Lens designs
 Single vision lenses
 Bifocals
 Trifocals
 Occupational segments
 Progressive
 Corrective curve lenses
 Aspherics
 Lenticular bowl
 Blended myodisc
 Safety lenses
 Slab off prism
Bifocals
Single vision lenses
 Single vision lenses correct vision for one
focal length. (focal length is the distance at
which the lens focuses an object that is 1
meter away from the lens). They could be
prescribed for distance vision only or for
near vision only.
Bifocals
 Bifocal lenses correct vision at two distances,
usually with a prescription for distance vision at
the top of the lens and a segment at the bottom of
the lens for close work.
 Bifocal segments are available in many designs
and sizes. There are round segments called
kryptok bifocals as well as flat top.
 Round segments are available in 22 – 24mm
sizes and flat top bifocals are made in 25,28 or 35
mm sizes.
Trifocals
 Trifocal lenses have three viewing distances
or segments. A conventional trifocal lens
has a distance portion and intermediate
segment and a bottom segment to correct
vision at 33 cms.
 Trifocal lenses can be prescribed to correct
vision at varying distance.
Trifocals
Progressive addition lenses
(PAL)
 PAL consists of distance, intermediate and near
zones. They cause less of an image jump than
lined segments because the power differences
between the zones are achieved thorough slight,
gradual changes in power, unlike that of
conventionally lined bifocals or trifocal. PAL are
sometimes called bifocals but in actuality perform
most like trifocals because they offer an
intermediate area.
PAL lens
PAL lens
PAL lens
Corrective curve lenses
 A lens which could produce the same
quality of vision through the periphery as
through the optic center of the lens would
need have a radius that corresponded with
the radius of the moving eyeball.
Corrective curve lens
Aspherics
 Aspheric lenses improves the peripheral
optics and the cosmetic appearance of the
lenses. The curvature of an aspheric design
change in the outer portion of the lens. This
is especially true with mid-to high-powered
lenses.
Aspheric lens
Aphakic lenses
 Cataract lenses are aspheric lenses that are
available as lenticular design. This means a
minus lenticular carrier is used to house the
high powered plus prescription. They
should be fit as a close to the eye as
possible in order to provide a wide field of
vision for the patient.
Aphakic lens
Blended myodisc
 A myodisc or blended myodisc lens is used for
patients who have very high myopia. It is a
lenticular lens with a carrier, and produce a clear
central area for vision with a significantly thinner
lens edge. It is available from -12.0 D
 Another lens for high myopes is the biconcave
lens. This lens is concave and ground on both the
front and back surface, resulting in an overall
thinner and lighter weight lens.
Myodisc
Safety lenses
– Special purposes lenses must also have an “S”
marked on the lenses to signify that the lenses
are for special purpose. An example of special
purpose occupational lenses would be those that
are needed by welders. Productive lenses for
someone in this occupation must have a filter
that guards the welder from damaging optical
radiations.
Safety lenses
Safety lenses
Slab off prism
 This is given for anisometropic patients. If
one eye having a plus correction and the
other eye having a minus correction often
needed glasses with a specially ground lens
treatment called slab off.
Slab of prism