Sunglasses or sun glasses are a form of protective eyewear designed primarily to prevent bright sunlight and high-energy visible light from damaging or discomforting the eyes.

1. About Sunglasses – Gkboptical.com
Sunglasses or sun glasses are a form of protective eyewear designed
primarily to prevent bright sunlight and high-energy visible light from
damaging or discomforting the eyes.
In the early 20th century they were also known as sun cheaters

2. History of Sunglasses
In prehistoric and historic time, Inuit people
wore flattened walrus ivory "glasses," that
came with narrow slits that block harmful
rays of the sun .
First Sunglass in History Which
Protect the eyes from Snow….
Inuit snow goggles function by reducing
exposure to sunlight, not by reducing its
intensity

3. Modern developments
In the early 1900s, the use of sunglasses
started to become more widespread,
especially among movie stars. It is commonly
believed that this was to avoid recognition by
fans, but an alternative reason sometimes
given is that they often had red eyes from the
powerful arc lamps that were needed due to
the extremely slow speed film stocks used
Foster in 1929. Foster found a ready market on
the beaches of Atlantic City, New Jersey,
where he began selling sunglasses under the
name Foster Grant from a Woolworth on the
Boardwalk

4. Visual clarity and comfort
∗ Sunglasses can improve visual comfort and visual clarity by
protecting the eye from glare.
∗Various types of disposable sunglasses are dispensed to patients
after receiving mydriatic eye drops during eye examinations.
∗The lenses of polarized sunglasses reduce glare reflected at some
angles off shiny non-metallic surfaces such as water. They are
popular among fishermen because they allow wearers to see into
water when normally only glare would be seen.
∗The glare is neutralized by blocking the vertical (magnetic)
components of light.
Functions of Sunglasses

5. Protection of Eyes from many Factors
∗Sunglasses offer protection against excessive exposure to light, including its
visible and invisible components.
∗The most widespread protection is against ultraviolet radiation, which can
cause short-term and long-term ocular problems
∗High-energy visible light (HEV) has been implicated as a cause of age-related
macular degeneration. before, debates had already existed as to whether
"blue blocking" or amber tinted lenses may have a protective effect.
∗Sunglasses are especially important for children, as their ocular lenses are
thought to transmit far more HEV light than adults
Functions of Sunglasses

6. Assessing the protection of sunglasses
∗The only way to assess the protection of sunglasses is to have the lenses
measured, either by the manufacturer or by a properly equipped optician .
∗Several standards for sunglasses allow a general classification of the UV
protection .
∗Manufacturers often indicate simply that the sunglasses meet the
requirements of a specific standard rather than publish the exact figures .
Functions of Sunglasses

7. Further functions of sunglasses
∗Sunglasses can also be used to hide emotions; this can range from hiding
blinking to hiding weeping and its resulting red eyes .
∗Fashion trends can be another reason for wearing sunglasses, particularly
designer sunglasses
∗People may also wear sunglasses to hide an abnormal appearance of their
eyes.
∗Fashion trends can also draw on the "cool" image of sunglasses.
∗Some lawbreakers have also been known to wear sunglasses during or after
committing a crime as an aid to hiding their identities.
Functions of Sunglasses

8. There are three major sunglass standards, which are popularly known mostly
as a reference for sunglass protection from UV radiation
∗The Australian Standard is AS/NZS 1067:2003 Sunglasses and fashion spectacles. The
five ratings for transmittance (filter) under this standard are based on the amount of
absorbed light
∗The European standard EN 1836:2005 has four transmittance ratings: "0" for
insufficient UV protection, "2" for sufficient UHV protection, "6" for good UHV
protection
∗The U.S. standard is ANSI Z80.3-2001, which includes three transmittance categories.
According to the ANSI Z80.3-2001 standard
Standards for sunglasses

9. Special use sunglasses
Sunglasses in Sports - Sunglasses have to meet
special requirements when worn for sports .
Strap or other fixing is typically used to keep
glasses in place during sporting activities, and
they have a nose cushion . Mountain climbing or
traveling across glaciers or snowfields requires
above-average eye protection, because sunlight
(including ultraviolet radiation) is more intense
in higher altitudes, and snow and ice reflect
additional light. Popular glasses for this use are a
type called glacier glasses or glacier goggles.
They typically have very dark round lenses and
leather blinders at the sides, which protect the
eyes by blocking the sun's rays around the edges
of the lenses.

10. Special-use sunglasses
Sunglasses in space - Special protection is
required for space travel because the sunlight is
far more intense and harmful than on Earth,
where it is always filtered through the
atmosphere. Sun protection is needed against
much higher UV radiation and even against
harmful infrared radiation, both within and
outside the spacecraft. Within the spacecraft,
astronauts wear sunglasses with darker lenses
and a thin protective gold coating.
During space walks, the visor of the astronauts'
helmets, which also has a thin gold coating for
extra protection, functions as strong sunglasses

11. Aviator sunglasses - are a style of sunglasses that were developed by
Bausch & Lomb and branded as Ray-Ban. They are characterized by dark, often
reflective lenses having an area two or three times the area of the eyeball, and
very thin metal frames with double or triple bridge and bayonet earpieces or
flexible cable temples that hook behind the ears.
The original design featured G-15 tempered glass lenses, i.e., neutral gray,
transmitting 20% of incoming light. The large lenses are not flat but slightly
convex. The design attempts to cover the entire range of the human eye and
prevent as much light as possible from entering the eye from any angle
Aviator sunglasses, or "pilot's glasses", were originally developed in 1936 by
Ray-Ban for pilots to protect their eyes while flying.
Type Of Sunglasses

12. Type Of Sunglasses
Mirrored sunglasses - Mirrored lenses,
having a metallic, partially reflective coating
on the outer surface, combined with a
tinted glass lens, are an alternative to
polarization for UV protection, improving
contrast when depth perception is
important such as seeing moguls and ice
while skiing or snowboarding. The mirrored
lens reflects glare to protect the eyes, but
improves the ability to see contrasts, and
mirrored lenses of different colors can
expand the range of fashion styles.

13. Type Of Sunglasses
Oversized sunglasses - Oversized sunglasses,
which were fashionable in the 1980s, are now
often used for humorous purposes. They
usually come in bright colors with colored
lenses and can be purchased cheaply.
Singer Elton John sometimes wore oversized
sunglasses on stage in the mid-1970s as part
of his Captain Fantastic act.
In the early 21stcentury moderately oversized
sunglasses had become a fashion trend. There
are many variations, such as the "Onassis",
discussed below, and Dior white sunglasses.

14. Type Of Sunglasses
Teashades - "Teashades" (sometimes also called
"John Lennon glasses", "Round Metal", or,
occasionally, "Granny Glasses") were a type of
psychedelic art wire-rim sunglasses that were
often worn, usually for purely aesthetic
reasons, by members of the 1960s
counterculture, as well as by opponents of
segregation.
Pop icons such as Mick Jagger, Roger Daltrey,
John Lennon, Jerry Garcia, Boy George, Liam
Gallagher and all wore teashades. The original
teashade design was made up of medium-sized,
perfectly round lenses, supported by pads on
the bridge of the nose and a thin wire frame.
When teashades became popular in the late
1960s

15. Type Of Sunglasses
Wayfarers - The Ray-Ban Wayfarer is a
plastic-framed design for sunglasses
produced by the Ray-Ban company.
Introduced in 1952, the trapezoidal lenses
are wider at the top than the bottom and
were famously worn by James Dean, Roy
Orbison and other actors and singers. The
original frames were black; frames in many
different colors were later introduced. There
is always a silver piece on the corners as
well.

16. Type Of Sunglasses
Wrap-around sunglasses - Wrap-arounds
(sometimes also called "Yoko Ono glasses")
are a specific design of sunglasses. They are
characterized by a single, smooth, semi-
circular lens that covers both eyes and much
of the same area of the face covered by
protective goggles.
The lens is usually combined with a minimal
plastic frame and single piece of plastic
serving as a nosepiece. As an alternative, the
glasses can have two lenses, but the design
evokes the same semicircle.