This document discusses various types of lenses and coatings used in eyeglasses. It describes unifocal lenses that provide single vision correction and multifocal lenses like bifocals and trifocals that correct for both distance and near vision. Progressive lenses provide a seamless transition between vision corrections. Hi-index and lightweight lenses reduce thickness. Photochromic lenses darken in sunlight and clear in low light. Polarized and tinted lenses reduce glare. Polycarbonate lenses are impact resistant. Anti-reflective coatings improve vision clarity and comfort.

1. SPECTACLES
Dr Saurabh Kushwaha
Resident (Ophthalmology)

2. SCOPE
 Introduction
 Eye glasses and Frame
 Unifocal, Bifocal and Trifocal
 Progressive lenses
 Hi Index lenses
 Photochromic lenses
 Polarazied lenses
 Polycarbonated lenses
 Anti refelective

3. SPECTACLE
 Spectacle is an optical appliance comprising
a lenses and a frame with sides extending
towards the ears.

4. SPECTACLE
FRAME
EYE
GLASSES

5. EYE GLASSES
 These optical appliance comprising of lenses
and a frame having no side.
 Eye glasses were used in the past and have
replaced spectacle.

6. 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

7. FRAME
TEMPLE
FRAME
FRONT

8. 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

9. BIFOCAL LENSES
 Bifocal lenses combine vision correction for
near-sightedness and far-sightedness.
 The top of the lens is for distance vision and
the bottom half is for near vision.
 Usually prescribed for presbyopic patients
 There are several types of bifocal:
• Two pieces bifocal
• Fused bifocal
• One piece or solid bifocal

10.  Fused bifocals are mostly used. Types are:
• Kryptok: suitable for hypermetropic patients
• Flat top/D shaped: suitable for myopic patients
• Executive: Best for pseudophakic paediatric
patients and also for presbyopic patients as well

11. 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

12. 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.

13. HI-INDEX LENS
 Hi-index lens material reduces lens thickness,
making these lenses more comfortable and better
looking by minimizing the size of visible lens edges for
nearsighted wearers and reducing the magnified “bug
eye” appearance associated with farsighted wearers.
 Variety of hi-index 1.67 and 1.74 lenses that are
thinner and lighter than plastic. High Index 1.74 lenses
are the thinnest, flattest, and most cosmetically
appealing lens ever developed.
 These ultra thin lenses are nearly 50% thinner than
plastic and 5% thinner than 1.67 high index lenses,
offering you the ultimate in technology and cosmetics

14. HI-INDEX LENS
 Advantages of High-Index Lenses:
• Thinner: Because of their ability to bend light more
efficiently, high-index lenses for nearsightedness
have thinner edges than lenses with the same
prescription power that are made of conventional
plastic material.
• Lighter: Thinner edges require less lens material,
which reduces the overall weight of the lenses.
Lenses made of high-index plastic are lighter than
the same lenses made in conventional plastic, so
they're more comfortable to wear.

15. 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.

16.  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.

17. 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).

18. PHOTOCHROMIC LENSES

19. 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.

20. POLARIZED LENSES

21. POLARIZED LENSES

22. TINTED LENSES
 Colored or tinted lens protects against UV
radiation.
 They can also give you a high-contrast vision
experience even in glaring or diffuse light.

23. POLYCARBONATE LENSES
 Polycarbonate lenses are resilient, impact-
resistant and a favorite among active individuals.
Savvy parents choose polycarbonate lenses for
children who may not take good care of their
glasses. The durability of polycarbonate lenses
makes them a good choice for rimless eyeglasses.
 Polycarbonate lenses have built-in UV filters to
help prevent eye problems such as macular
degeneration (breakdown of macula) and cataracts
(clouding of the eye lens).

24.  Polycarbonate lenses are up to 10 times more
impact-resistant than plastic or glass lenses and
they provide 100% protection from the sun's harmful
UV rays. They are also lightweight, adding to the
comfort of your eyeglasses, sunglasses, and sports
eyewear.

25. POLYCARBONATE LENSES

26. ANTI-REFLECTIVE
 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.

27. THANK YOU