3. SPECTACLE FRAME
The portion of spectacle which holds the
lenses containing the ophthalmic prescription
in their proper position in front of the eyes.
There are two part in a frame:
• Frame front
• Temples
10. Bridge
1. Regular bridge-rests on nose with full support.
2. Inset Bridge-it protects behind the frame plane
,so that the area of contact lies behind the lens
space
3. Saddle Bridge-combination of regular and insert
bridge
21. 1. GLASS LENSES
2. NORMAL INDEX LENSES :1.48-1.54
->Standard plastic CR-39
lenses
3. MEDIUM INDEX LENSES:1.54-1.64
->Polycarbonate lenses
->Trivex lenses
4. HIGH INDEX LENSES :1.64-1.74
5. ULTRA-HIGH INDEX LENSES :>1.74
->Plastic lenses
COMMON EYEGLASS LENS
MATERIALS
29. LENS FORMS
● FLAT LENSES
1. Biconcave or biconvex
2.Plano-concave or plano-
convex
● CURVED LENSES
1. Meniscus lens
2.Toric lens
3. Lenticular lens
4.Apheric lens
30. MENISCUS LENS
● Base curve
-SEMIFINISHED LENS
Base curve is added to
anterior surface and
optician grinds its
other surface to get
required power
● DEEP MENISCUS
LENS
● PERISCOPIC LENS
31. TORIC LENS
• Where one surface is spherical and other
surface is toroidal.
• What is toroidal surface?
if we visualise a cylinder its one axis is curved while
other is straight which is the axis of cylinder-> now
straight axis is also curved then surface will become
toroidal.
• Spherical lens is ground on anterior surface
and posterior surface is made toroidal
• Base curve used 6D
• Difference between base curve and curvature of
toric surface equals the cylindrical power
32. LENTICULAR LENSES
● Used for high power
● Central portion –
power
– aperture – 30mm
● Peripheral portion –
carrier – 1.2-2 mm
thinner than central
part
● Reduce the
weight of
spectacle and
aberrations
33. ASPHERIC LENSES
● used to make high plus
aphakic lenses by
modifying the lens
curvature peripherally to
reduce aberration and
provide better
peripheral vision
● Base curve for aphakic
lens is relatively flat.
35. SINGLE VISION OR UNIFOCAL
This lens provides correction only for a given
distance. This means that the optical power is
the same at every point on the lens’s surface.
Prescribed only for single vision:
• Myopia
• Hypermetropia
• Astigmatism
• Presbyopia
36.
37.
38.
39.
40. TRIFOCAL LENSES
Trifocals are eyeglasses with lenses that have
three regions which correct for distance,
intermediate (arm's length) and near vision
John Isaac Hawkins developed the trifocal lens
in 1827
Trifocals are mostly used by people with
advanced presbyopia who have been prescribed
2 diopters or more of reading addition
41. PROGRESSIVE LENSES
Progressive lenses are line-free multifocals
that have a seamless progression of added
magnifying power for intermediate and near
vision.
The junction between these distinctly different
power zones is defined by a visible "bifocal line"
that cuts across the center of the lens.
45. ANTI-REFLECTIVE COATING
Anti-reflective coating can reduce eyestrain caused from
glare, reflections, and the "halos" you see around lights at
night. It helps protect your lenses from scratches and
smudges, and can repel dust and water. This coating makes
your vision sharper and your eyes appear clearer behind
your lenses.
Some anti-reflective coatings reduce the amount of
reflected UV from the back of your lenses, providing the
best overall UV protection possible.
46. • Copper and gold coating reflect approximately 98%
of IR above 750 nm
Anti reflective coating glasses for IR
47. SCRATCH- RESISTANT COATING
• They are distracting and
can affect thr ability to see
clearly.
• Many have built in scratch
resistant coating nowadays
including high-index lense,
polycarbonate and trivex
lenses.
• These type of lenses are
treated front and back with
a clear, scratch-resistant
coating and have harder
surface wchich benfit
kidsfor greater durability.
48. UV COATING
• The cumulative exposure to UV radiation is harmful and
associated with age related eye problems->Cataract
and macular degeneration.
• Lenses that block 100% of both UV-A and UV-B help to
ward off Uv damaging effect.
• Nearly all high index plastic lenses and basic CR-39
plastic lenses require an added coating to provide
equal UV protection.
49. PHOTOCHROMIC LENSES
Photochromic lenses are optical lenses that darken on
exposure to specific types of light of sufficient intensity,
most commonly ultraviolet (UV) radiation. In the
absence of activating light the lenses return to their
clear state. Photochromic lenses may be made of
glass, polycarbonate, or another plastic. They are
principally used in eyeglasses that are dark in bright
sunlight, but clear in low ambient light conditions. They
darken significantly within about a minute of exposure
to bright light, and take somewhat longer to clear. A
range of clear and dark transmittances are available.
50. In one sort of technology, molecules of silver
chloride or another silver halide are embedded in
photochromatic lenses. They are transparent to
visible light without significant ultraviolet component,
which is normal for artificial lighting. In another sort of
technology, organic photochromic molecules, when
exposed to ultraviolet (UV) rays as in direct sunlight,
undergo a chemical process that causes them to
change shape and absorb a significant percentage of
the visible light, i.e., they darken. These processes
are reversible; once the lens is removed from strong
sources of UV rays the photochromic compounds
return to their transparent state.
51. PHOTOCHROMIC LENSES
A photochromic eyeglass lens (polymer film),
after exposure to sunlight with part of the lens
covered by paper.
Note the two levels of coloration around the
dark-light interface, arising from the fact that the
photochromic molecules are located in two thin
films (on the front and back surfaces of the lens).
53. ANTI- FOG COATING
• During cold climatic
conditions or during sports
activities or while wearing
masks, the spectacle
lenses may fog up.
• The anti-fog coatings
negates this problems by
eliminating the
condensation of moisture
on lenses that causes
fogging
54. TINTED LENSES
or tinted lens protects against UV
Colored
radiation.
They can also give you a high-contrast vision
experience even in glaring or diffuse light.
55. MIRROR COATING
• It is designed for a
purely cosmetic
purpose that allows
the eyes to remain
hidden from view
and adds glamour to
the glass.
• it comes in a variety
of colours such as
silver, gold and blue.
56. POLARIZED LENSES
Polarized lenses reduce glare reflected off surfaces,
making images appear sharper and clearer. They are
available for non-prescription and prescription
sunglasses, and can be worn indoors by light-sensitive
people, including post-cataract surgery patients and those
continually exposed to bright sunlight through windows.
Most polarized lenses provide UV protection, which is
important to maintaining healthy eye sight.
