Tinted lenses

details about Tinted lenses

1. T I N T E D L E N S by :- Jeslin Jose

2. Absorptive lens -An absorptive lens is one that is used for the specific purpose of reducing the amount of transmitted light or radiant energy. -It acts as a filter. -Absorption may be uniform or selective. -Some lenses absorb mostly in IR region of spectrum. Eg Ray Ban. -Other absorb in UV region. Eg UV 400, UV 420

3. Tinted lens ( cosmetic lens) Natural vision and natural colour perception, even in glaring and diffuse light. Increased contrast perception for a pleasant vision experience. Ideal in road traffic, sports, nature or on the job. Full UVA, UVB and glare protection.

4. - Some Lenses are tinted by adding a substance such as a metal oxide to the lens material when the lens is being created. - Tints can also be applied to the surface of a lens. - Surface application allows a wide variety of tints and creates a uniform darkness across the entire lens, regardless of prescription strength. -- Modern technology has greatly increased the toughness of surface lens treatments.

5. C ol o u r s Metallic oxide Green Iron, chromium Pink Manganese, Didymium Blue Cobalt Pinkish brown Cerium Brown Nickel Yellow Uranium, Silver, Kalichrome Red Gold

6. Tinted lens

7. Tinted plastic lens(Organic) Plastic lenses are tinted by dipping them in a solution containing the appropriate organic dye. The resulting density depends on the nature of the dye and the length of time the lens is immersed in the solution. If the tint is too dark, for any reason needs to be changed, some tint can be removed by dipping the lens in a bleaching solutions .

8. Integral Tint ( Tinted solid glass lens) Various Metal oxides added to the basic batch materials to impart specific lens colour . Absorbs selected parts of the spectrum. Colour distributed evenly all over the lens. The principle ingredients of white ophthalmic crown glass are silica, soda lime to which small amount of potassium, aluminium and barium oxide are added to provide the desired physical and chemical properties.

9. Surface coated A lens is tinted by depositing a thin metallic oxide on the surface of the lens. The coating is deposited on the lens by an evaporation process conducted under a vacuum at high temperature. The density of coated lens depends on the thickness of the metallic oxide. The coating is deposited on the back surface of the glass.

10. Disadvantage Advantage Possible to have equi tint lenses in any prescription

11. Dye Tint Resin lenses can be tinted by immersing in a container of dye. Red, Yellow, blue are three primary dyes from with which almost all other colours can be made. The dye can be purchased either in powder or liquid from which are then mixed with previously boiled water. The longer the lens remain in the dye, the more dye will be absorbed. Dye tint are not affected by the power of the lens.

12. Tint Darkness In addition to colour , the intensity or darkness of a tint must be specified. It is expressed in percentage of light it blocks. Fashion tints are usually in 10-20% range. Sunglass tint should be atleast 60% intensity to provide adequate protection. For most of outdoor activities and daytime driving 70-80% works well. For sports like mountain climbing or snow skiing, 90% tints and above are recommended.

13. Tints are also described using “1 to 4” numbering system instead of percentages for darkness ratings. Number one is almost clear……number four is darkest. Sunglasses are usually produced in darkness number three. Darkness number four is too dark for most wearers, but can be an ideal choice for high-glare environments like mountain climbing.

14. Choosing Tint Colour Because white light is made up of many colours , picking tints carefully can improve the performance of your eyewear in specific environments and activities. ROSE TINT YELLOW TINT BROWN AND AMBER TINT GREEN TINT GREY TINT G-15 GRADIENT TINT DOUBLE GRADIENT TINT PURPLE BLUE

15. Cosmetically appealing, soothing to the eyes, and seems to provide a degree of relief when the wearer is working in brightly lit offices. A rose tint is often recommended for computer users to help reduce eyestrain and glare. Advisable for those having colour vision deficiencies. ROSE TINT

16. Objects appear sharper against a blue or green background. Blue light bounces or scatters the most and can create a kind of glare known as blue haze . Yellow tints are sometimes marketed as blue blockers because they are fairly opaque to blue light. Good for overcast, hazy or foggy conditions and are favourite of shooters, skiers and pilots. Generally not a good choice for any activity that depends on accurate colour perception. YELLOW TINT

17. Work well in variable light conditions and provide good contrast because they filter some blue light, although not as strongly as a yellow tint. Brown lenses are good general purpose lenses and work especially well for sports where judging distance is important like tennis and golf. BROWN AND AMBER TINT

18. Filter some blue light and enhance contrast in low-light conditions. The human eye is most sensitive to green wavelengths of light so green tints offer the highest contrast and greatest visual acuity of any tint. GREEN TINT

19. Provides good protection from glare and keeps distortion of colours to a minimum. Sometimes referred to as tru-colour tint. Available in a wide range of densities and is an excellent choice for general use and driving. Most popular sunglass tint. GREY TINT

20. This sunglass tint is sometimes called the Ray-Ban tint. Essentially a combination of grey and green tint that transmits 15% (blocks 85%) of the light. G-15

21. Balanced colour which provides natural colour perception while shading the eye. Can be a good choice for hunters. PURPLE

22. Can be a good choice for fashion tints in lighter shades. If the lenses are intended for outdoor use, remember that blue tints can increase glare . In this case, consider using a brown or grey lens combined with a blue mirror coating. BLUE

23. Describes a lens with a darker tint at the top, fading gradually to little or no tint at the bottom of the lens. This provides additional protection from light coming from above, without blocking too much light from straight ahead or below. Gradient sunglasses work particularly well for driving; glare coming through the windshield is blocked but the speedometer and other instruments are easy to see through the lighter bottom portion of the lens. GRADIENT TINT

24. Describes a lens with a darker tint at the top and bottom of the lens and a medium tint in the center of the lens . Double gradient tints are good for skiers, because glare coming from above (sun) and below ( snow) is heavily blocked but a clearer viewing area is present in the middle of the lens. DOUBLE GRADIENT TINT

25. Tinted lens and night driving A commonly occurring situation that demonstrates the hazards of too much tint for existing conditions is night driving. At night with eyes adapted to a light intensity of 0.1 mL through a clear glass windshield, the visual acuity of an individual who normally sees 20/20 will be reduced to 20/32. this is not because of looking through the windshield, but rather is simply a result of reduced illumination.

26. Any tinted material between the observer’s eye and the object being viewed will further reduce acuity. Even an 82% transmitting pink tinted lens worn at night reduces acuity to 20/40. a green tinted windshield by itself reduces acuity to 20/46. the combination of tinted windshield and tinted lens, however reduces acuity to 20/60.the level of tint desirable is therefore a function of the circumstances under which it is to be worn.

27. COMPANY The three major companies: ZEISS ESSILOR HOYA

28. Do as directed: Tinting of lenses________ the transmittance. a. Increases b. decreases c. Normal d. None 2. _______ tint is advisable for use by those having colour vision deficiencies. 3. The other name for yellow tint is____________ 4. Yellow tint help night driving because they eliminate blue haze. True or False. 5. ________ tint is advisable for night driving. 6. ________ tint have a uniform transmission across the visible spectrum. 7. Colour of Kalichrome is……………. QUESTIONS

29. 8. The tint may be removed and reapplied for…….. type of lenses. 9. Matching: i ) Light pink a) Blue absorbing ii) Grey b) Highest transmission of visible light found in the middle of the visble spectrum. iii) Green c) even absorption across the visible spectrum iv) Yellow d) good for colour defectives. 10. The tinting of lenses being denser in upper part and lighter in lower part, these lenses are known as............. a) Photochromatic Lenses b) Isochromatic lenses c) Gradient lenses d) None 11. Short note on tinted lens? (12 marks) 12. Explain various methods of tinting in detail? (10 marks)

30. 13. Important properties and uses of following tints? (7marks) (repeated ) Green, Yellow, Pink and Grey Tint. 14. Define gradient tint?(1 marks) 15. Explain tinted lens. Describe their principle characteristics of each group.( 10 marks) 16. Explain in detail tinted lenses?(10 Marks) 17. Explain solid integral tint, Green, Yellow, tint with its advantages and disadvantages. (10 marks)

31. ANSWER b) decreases 2. Grey tint Kalichrome False Grey Rose Yellow Vacuum coated or plastic lenses. i – c, ii – d, iii – b, iv - a c) Gradient lenses