How to protect your eye? With sunglasses? Mirror glasses? Tinted or polarized glasses? What is right tint colour for you? What are antireflection coat glasses?

1. Absorptive lenses
BY: ASMAA J.
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2. Absorptive lenses
• Absorptive lenses are tinted lenses that improve a person’s visual
clarity by reducing glare and increasing contrast.
• Classification:
Absorptive lenses are classified by two variables:
1. the tint of the lens itself
2. the lens transmission
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Examples:
32% medium gray
10% medium amber
2% dark gray-green
20% medium plum
65% yellow
49% orange
16% amber
52% light orange
• The number refers to the
amount of light passing
through
• The color refers to the
tint

3. Absorptive lenses
• The main advantages and functions of the absorptive lens that it
can protect eye from ultraviolet rays, filter out excess light and
transmit only a certain amount of visible light through the lens.
• Tint is more comfortable in plastic than the glass because tint in
glass is varied from area to area. (In high minus lens tint is more
in peripheral compared to central and vice versa with high plus
lens)
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4. Types of the Absorptive Nature
1. Anti-reflective coating (ARC)
2. Anti-fog coating
3. Mirror coating
4. Edge coating
5. Photochromic lenses (Transition lenses)
6. Polarized lenses
7. Custom tints and colors
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5. 1. Anti-reflective coating (ARC)
• It is dielectric thin layer and it is applied on the surface of the lens to:
(1) reduce unwanted reflections from the lens surface
(2) increase the amount of light that passes through the lens to the eye.
• The main problem that the it is brittleness and scratch easily
• Fine scratches often are more visible on ARC lenses than on uncoated
lenses
• With high refractive index lens, ARC material must always be used
• The best solution for headlight glare at night is an ARC prescription
• ARC made of metals oxide such as magnesium floride and silicon nitride
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Reflections of spectacle lenses
that may cause troublesome to
the wearer.
The reflection could occur on the
front or back surface, or even an
internal reflection and corneal
reflection

7. 1. Anti-reflective coating (ARC)
Advantages:
₋ They improve your vision by reducing reflections, glare, and halos
₋ They can provide comfort during computer and mobile use (but they don't
prevent all glare and light, which may cause eye strain or headaches with
prolong use of screens)
₋ They allow more light to reach your eyes, improving visual acuity
₋ They can reduce the effects and symptoms of digital eye strain
₋ They make your eyes more visible behind your lenses
₋ They provide less glare when driving at night
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8. 1. Anti-reflective coating (ARC)
• A standard AR coating is typically comprised of two layers:
1. Anti-reflective
2. Scratch-resistant
• Premium AR coatings have multiple layers, such as:
1. Improved scratch resistance
2. Hydrophobic: Anti-water
3. Oleophobic: Reduces fingerprints
4. Anti-static: Repels dust
5. UV protection
6. Blue light protection: Protects your eyes from harmful effects of digital
devices
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11. 2. Anti-fog coating
• Prescribed to wearer who has to move in different temperature with
spectacle
• Anti fog coating is made up of ‘resin film’
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Resin film

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3. Mirror coating
This coating is applied on the anterior surface of the spectacle lens
It is made up of metalized and dielectric coating
The use of the mirror coating on the spectacle lens make the observer not
able to see the wearer eyes
Mirror coating

13. 4. Edge coating
Here colour is applied at the bevel area of the lens to reduce the concentric
rings
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Lens bevel coating

14. 5. Photochromic lenses
• They’re the type of lens that changes to a
darker color automatically when exposed to
the sun or other sources of UV light
• It changes the amount of the light
transmission
• In case of glass lens ‘silver halide crystal’ is
used, and in case of plastic lens organic dyes
are used
• In general, these lenses work by using
chemical reactions that are triggered by UV
exposure. The result of the chemical
reaction is a color change in the lens
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15. 5. Photochromic lenses
Advantages:
⁻ Can be used indoors and outdoors
⁻ They offer continuous UV protection
⁻ They can save you money and they are permenent
⁻ They reduce headache and eye strain
Disadvantages:
⁻ You can not control the transmission and the darken amount, some lenses
also take longer than others to adjust to brightness
⁻ These lenses can take longer to adjust in cold weather
⁻ They don’t darken well inside cars because cars glass contain UV protection
⁻ They don’t protect from blue light (some of them contain anti-blue light) or
Infrared (IR) radiation
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16. 6. Polarization lenses
• Polarized lenses have a special chemical applied to them to filter light and
that block certain vibration of light waves.
• Mainly polarized lens is used to cut the glare and block the ultra violate
rays.
• On polarized sunglasses, the filter creates vertical openings for light. Only
vertical light can pass to the eyes, and the horizontal light will be blocked.
And they also block the UV ray (but not all of it).
• As a result of this filtering, the image will be a bit darker than usual, but
sharper and clearer.
• They are helpful to reduce eye fatigue, reduce glare, and they increase
visual clarity and comfort.
• If the wearer tilts his or her head, the polarized lens will not work.
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18. 6. Polarization lenses
• When to use:
⁻ Fishing and boating
⁻ Snowing environment (Although snow tends to reflect light equally in
all directions, so this lens will not be very effective)
• When NOT to use:
⁻ With LCD screen (Cell phones, car dashboard, ATM machine…)
⁻ Night driving
⁻ Pilots can not use it
⁻ When you are working with colours (especially white)
⁻ Working with heavy machines
⁻ It is dangerous with skiing
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20. 7. Tints and colours
• A colour tint can enhance the visual performance of spectacles for certain
sports or activities.
• Tinting done by different methods:
1. Surface coating: mostly used with glass lens.
2. Dye tinting: mostly used with plastics by placing the lens on a dye bath.
• The tint is permanent, but it could become darker or lighter
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21. 7. Tints and colours
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• Good absorption for the green glass lens in both the IR and UV regions
• Best for some sports such as golf and tennis
• Helps in bright shadow
• Most popular for sun protection
• Natural contrast in mid. to high sunlight and provide true color perception
• Equal transmission through the whole visible spectrum This characteristic allows
colors to be seen in their natural state relative to one another
• Good choice for driving
• Useful for photophopia
• Increase contrast in hazy, foggy, or low-light conditions, and in snow
• Filters the blue light without reducing the luminance

22. 7. Tints and colours
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• Bright fluorescent lighting or glare in the work area
• Increase contrast by blocking blue light
• Red filter is very helpful for (Retinitis pigmentosa)
• A higher absorption of shorter visible wavelengths
• Improve contrast on bright
• Enhance contrast
• Hazy, or smoggy days
• They're useful against green and blue backgrounds, like grass and sky
• Very useful with those disease (Developing cataracts, Aphakes and pseudophakes
Macular degeneration, Corneal dystrophy, Optic atrophy)
• Dark brown is useful for photophobia

23. Sunglasses:
• The ideal pair of sunglasses should do the following:
1. Reduce the intensity of sunlight
2. Visual comfort and visual performance
3. Eliminate parts of the optical spectrum that are not required for vision and are
hazardous to the eyes
4. Provide enough protection and reduce glare
5. Maintain normal color vision and allow the wearer to distinguish traffic signals quickly
and correctly
6. Resist impact and scratching and only require minimum of care
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24. Lens Caring
1. Rinse first, it is better to use warm water (dry cleaning may
cause scratches)
2. You can use an alcohol-free lens cleaning solution (drop of dish
detergent can work), do not use saliva, ammonia, or normal
window and mirror cleaners
3. Wipe with a lint free microfiber cloth
4. Put the spectacle with the frame up
5. Avoid touching the lenses
6. Avoid wearing glasses during sports and tough activties
7. Keep them in their cases, not directly in your bag or your pocket
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1. Rinse
4. Don’t touch the lens
2. Use alcohol free cleaner
5. Put the frame up
3. Use the lens cloth
6. Remove during sport