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Eyewear Manuel

1.??????Everything you always wanted to know about eyewear but were too afraid to ask

2.??????Nomenclature

3.??????We will be going over the introduction, anatomy of eyewear, technical elements (including bridges, nose pieces and pads, temples, and hinges), and aesthetics (which include rim types and frame shapes)

4.??????Eyewear has a specific, technical language used to define the individual parts that glasses are made of. This includes elements which are further divided into variations and sub-categories.

5.??????The anatomy of eyewear

6.??????The hinge is a functional element which allows the temples to open and close. The bridge is the structure that supports the two rims of a frame front. The temple is the lateral part of the frame that is attached to the frame front at the end piece. The temple tip Is the final part of the temple that is positioned behind the ear to provide stability. The end piece is the order part of line frame front that connects to the temple. The rim is the part of the frame front that holds the lens. Nose pads are pieces in plastic or silicone that rest on the nose for a comfortable fit. Lenses are the optical element that either concentrates or diverges rays of light. The ornament is a decorative element normally found on the frame front or temple.

7.??????Technical elements. Depending on the design of eyeglasses, different elements can have different aesthetic connotations. In particular, there are different types of bridges, nose pieces, temples, and functionally different hinges.

8.??????Bridges. Single bridges are the most common bridge, formed by an arch that connect the two rims. The keyhole is a bridge design resembling old door locks. Double bridge is a bridge with a double structure, generally made of metal or a combination of metal and plastic.

9.??????Nose pieces and nose pads. A fixed nose piece is generally found on plastic frames, included as part of the mold or shaped afterwards, in materials such as acetate or injected plastic. An arm mount nose piece is adjustable and usually composed of metal arms with or without screws, with pads in silicone or plastic.

10.??Temples. Skull is when the temple is straight nearest the frame front and shaped at the ear. Library is generally an injection molded temple that is slightly curved or straight. Curlicue is a temple characterized by an almost circular earpiece. Fork is when the temple is split into two pieces at the frame front and becomes a single piece at the ear.

11.??Hinges are a continually evolving eyewear element. There are many types with different designs or technical solutions. They can often be personalized. Classic hinges are visible and attached to the frame front on one end and to the temple on the other. Integrated hinges are hidden in the temple, nested directly in the frame front, and allow for a cleaner temple design. Flex or spring are classic or integrated in which the flex (or spring) hinge can bend beyond the perpendicular angle with the frame front for a more comfortable fit.

12.??Aesthetics. Eyewear design is constantly evolving. There are, however, some well-defined types that permit us to categorize the accessories’ nomenclature.

13.??Types of rims. A full rim refers to eyeglasses in which the rim completely surrounds the lens. Half rim or nylor frame fronts have only the upper part of the frame structure, while the lower part of the lens is attached with a special nylon thread. Rimless eyeglasses are eyeglasses without rims in which the lenses are attached directly to the hinges and the bridge, which connects them to each other. Many shapes are possible and depend on the modeling of the lenses.

14.??Frame front shapes. The design of the frame front characterizes the eyewear and often determines its name. Teardrop-shaped rims, for example, are called “aviator” eyeglasses. Even though constantly evolving, frame fronts are often based on well-established types, each with a different nomenclature. As shown, you can see the different shapes of frame fronts.

15.??Lenses and sun.

16.??We will be going over the definition, lenses and materials, mountings, vision protection, colors, treatments, and polarized lenses.

17.??The European Union has classified sunglasses as “personal protective equipment” (PPE) worn to protect from the risks associated with solar radiation. The European Directive of reference for this definition is 89/686/CEE and is connected to the harmonized standard EN ISO 12312-1: 2013: “Eye and face protection – sunglasses and related eyewear – part 1: sunglasses for general use”

18.??Sunglass lenses can be made of different plastic materials besides glass, including thermoplastics and thermosetting polymers.

19.??The types of materials used. The thermosetting materials used for making lenses are CR39 and polyurethane. The thermoplastic materials used for making lenses are polyamide, polycarbonate, and polymethyl methacrylate. The other material used for making lenses is glass.

20.??Thermosetting polymers cross-linked structure when heated to high temperatures and thus, cannot be recycled. Generally, they are highly resistant to impact, solvents, and high temperatures but are difficult to work. Thermoset lenses are made by casting. Thermoplastic polymers are plastic materials that become pliable or moldable at a fairly high temperature. It softens when heated and hardens to a glass transition state when sufficiently cooled. The nature of thermoplastic polymers makes them recyclable. Glass is a homogenous, transparent solid obtained from the fusion, at a temperature between 1300 and 1700 degrees Celsius, of silica (silicon dioxide SiO2), alkaline carbonates, and lime generally in the from of pure calcium carbonate. If these substances are pure, the glass is colorless.

21.??How are plastic lenses made? Lenses in thermosetting materials are made by a casting process. Monomers are mixed by special machines (known as monomer mixing). The monomers are then pushed into molds (called filling). The lenses are polymerized in special kilns (known as kiln polymerization). Transparent lenses are created which can be colored by dipping with special colorants and then treated.

22.??Thermoplastics. Granules of a transparent material are colored with pigments. They are then mixed, melted, extruded, and cut. The colored granules are ready for injection molding. The material is injected into special molds and the thermoplastic lenses are then made.

23.??There are advantages, limitations, and compatibilities of the materials used. The advantages to glass are that it has exceptional resistance to scratches, is thin, is transparent, has dimensional stability, and has aesthetic quality. The limitations are its fragility and weight. The advantages to CR39 have good impact resistance, are extremely lightweight, and have optimal chemical resistance (which can be cleaned with alcohol).The limitations are that it has poor mechanical resistance and elasticity (which is not suitable for use in rimless mountings if the thickness is less than 4-5 mm). It also has poor resistance to scratches (which must be treated with a special coating). PC (or polycarbonate)?is very resistance to impact (50 times that of CR39 and 250 times more than untampered glass and for this reason often used for children’s lenses) and lightweight. The limitations are that the mechanical resistance is reduced when there are holes or cuts (which is not suitable for rimless and acetate frames) and it has mediocre optical quality. PA (nylon) (also known as polyamide) is lightweight, compatible with all mounting materials, and can have holes drilled in it.

24.??Not all lenses are compatible with all materials from which eyeglasses can be made. Below is a table showing the compatibility with the lenses and the materials.

25.??Physical characteristics of the materials. According to the materials from which they are made, lenses can have different physical qualities. The important attributes for lenses are density (the weight of the material), ABBE number (chromatic aberration), refractive index (the number that quantifies the refractive effect of a lens), impact resistance, scratch resistance, and design freedom. The characteristics of each material make each type of lens more or less suitable for different uses. Below is a chart describing how valuable the different materials are for the different uses.

26.??The ABBE number is the value that indicates the amount of chromatic aberration caused by the lens material. The higher the Abbe number, the lower the chromatic dispersion. The refractive index is the ratio between the velocity of light in a vacuum and the velocity of light passing through a material. The lower the number is, the less refraction there will be.

27.??Mounting. If the lenses are not shaped or mounted perfectly, their structure can become deformed, causing optical and mechanical problems. The tension is created can even cause breakage or chipping of the lens.

28.??Post-mounting stress. If the lenses are not cut or mounted correctly, the structure can become deformed, causing optical and mechanical problems. The tension can even cause breakage or chipping of the lens.

29.??Vision protection. Not only is direct light harmful, but even reflected light can cause damage. So, staying in the shade is not always enough, which is why sunglasses are necessary to protect your vision.

30.??The electromagnetic spectrum. UV rays are the most dangerous part of the electromagnetic spectrum, because they have sufficient energy to cause irreversible damage to the eyes. The principal problems caused by UVA, UVB, and UVC rays concern the cornea, the lens, and the retina. The most common vision problem caused by UV rays is a cataract. About 80% of lifetime exposure to UVA and UVB rays occurs before 18 years of age, so it is important for children to wear sunglasses also.

31.??Protection. There are different categories of transmission provided by sunglass lenses. Protection is indicated by numbers that range from 0 to 4, independent of filter color. The protection category (stamped on the inside of the left temple) depends on the quantity of light that passes through the lens. 4 refers to very dark lenses, not suitable for driving. It is for use only on snow or glaciers. 3 is dark lenses which are for general use, suitable for protection from bright light. 2 refers to medium protection lens which allows a fair amount of light to pass and is for general use. 1 is slightly colored lens with poor filtering capacity and mainly for fashion. 0 is suitable only for fashion. Caution: the indication of the filter category of a lens is not an indication of protection from UVA and UVB rays.

32.??Colors. The perception of color, which also relates to lens color, depends on many factors (the observer, lighting conditions, the amount of light, the background, the direction of viewing, and the distance between the two lenses). For this reason, objective methods for measuring color have been invented, providing an unambiguous definition of the lint.

33.??According to its color, the lens has different characteristics relative to the eyes. Grey is optimal in extreme light conditions or for prolonged use. For green, light is attenuated, and normal depth perception is maintained. Brown improves contrast and depth perception but can tire eyes if worn for lengthy periods.

34.??In pink, this also ensures good visibility in poor light and increases depth perception. Yellow assures the transmission of a large part of light and is the perfect color for use on cloudy days. Blue helps distinguish between objects with soft colors and white details. Orange is a filter that increases contrasts which is ideal for low light situations.

35.??Treatments. There are many types of treatments produced with various methods.

36.??Types of treatment. Hard coating is applied by immersion, spray, spinning or flow technology. It is anti-scratch and anti-fog. Thin coating is applied in a high vacuum. It has the mirror treatment, is anti-reflective, is water repellent, and is oleophobic.

37.??An anti-scratch coating is a film or coating that can be applied without interfering with lens function or disturbing the wearer’s vision. Even if not 100% resistant to scratches, this coating helps prevent minor scratches that could damage the surface and cause vision problems. Anti-fog treatments are made from a special resin that disperses the condensation which forms on lens surfaces when going from cold to warm temperatures.

38.??Mirror treatment is applied to sunglasses and is a mirror coating that creates a brilliant and highly reflective outer surface on the lens. Some mirrorings coatings completely hide the eyes of the person wearing them. Some like mirrored glasses just for aesthetic reasons, but mirrored lenses are also very functional. Anti-reflective coating deposits a very thin layer of special metallic or dielectric on the lens surface by highvacuum. They diminish the parasitic light reflections that reduce an image’s sharpness as it is processed through the optical system.

39.??Water repellent coating allows water drops to slide easily from the lenses. Oleophobic refers to the application of a clean coat which provides excellent anti-static properties that keep lenses cleaner longer which allow dust, dirt, and water to slide from the lenses.

40.??Polarizing lenses. Light, especially if intense and reflected, is not only annoying but also is a potential danger for the eyes, which do not develop a tolerance for UVA and UVB rays and become more sensible with each exposure. To reduce glare, we can use polarizing lenses.

41.??Intro. Clouds are not a protective barrier against solar radiation because almost 80% of the rays are transmitted even on a cloudy day (the effect increases when near water, snow, concrete, and sand – all surfaces that reflect UVA and UVB rays). The intensity of the sun’s rays increases significantly as altitude increases, reaching 12% every 1,000 meters at higher elevations.

42.??Eye protection. Non-polarizing lenses let all light, both horizontal and vertical rays, pass through. Polarizes lenses, on the other hand, let only the vertical component of light through, which is preferable for clearer vision. Polarizing lenses advantages. The use of polarizes lenses has various advantages. It improves visual comfort by absorbing reflected light, improves contrast and clarity with higher definition for images, reduces eye strain, allows better color perfection, and reduces/eliminates glare and reflections.

43.??Polarizing lenses – when not to use them. For some activities, polarizing lenses are not the best choice. For example: When skiing in icy conditions (To the naked eye, icy areas are easily identifiable because they reflect more light than snow. However, using polarizes lenses make it more difficult to distinguish ice from snow), when there is oil or ice on the road (again, in this case, reducing reflections created by the contrast between oil or ice and the rest of the street makes it difficult to distinguish between these two hazards), and when looking at some liquid crystal screens (LCD) (Polarized lenses can make some liquid crystal displays (LCD) difficult to read).

44.??How to recognize polarizing lenses. Polarizing lenses can be identified by overlapping the two lenses and rotating the closer one 90 degrees. If the view through the two lenses become obscured, then the lenses are polarized. There are also gadgets or mirrors with “hidden” backgrounds that become visible only when seen through polarizing lenses.

45.??How do I look?

46.??We will be going over the introduction, fit, eyes, face shape, colors, and macro categories.

47.??The choice of eyewear should always take aesthetics into consideration. Eyewear fashion (for sunglasses or spectacles) is one of the key purchase motivators, along with price, brand, and technical solutions.

48.??There are many factors that determine a correct match between person and eyer: fit, the eyes, face shape, and colors. Note: to correctly choose a frame, there are 2 main rules to follow. Eyewear shape should always contrast with the shape of the face, and the frame front dimensions should always be proportional to the face of the wearer.

49.??Fit. Like clothing, eyewear comes in different sizes and must fit perfectly. This also guarantees quality vision and comfort. Wearing correctly sized sunglasses, for example, helps properly filter UV rays.

50.??Choosing “the size”. But how do you determine if the eyewear is the correct size? The frame front must not extend beyond the temples and the sides of the face should not be visible. For the temples, the earpieces should not show beyond the curve of the ear and should not begin to curve much before the ear.

51.??The eyes. The choice of eyewear greatly influences the image a person projects, and the area around the eyes will therefore greatly be affected by or benefit from it.

52.??When choosing a frame, there are three factors to consider: eyebrows, eye shape, and distance between the eyes.

53.??Eyebrows. Whatever the shape of the eyebrows (balanced, rounded, angled, or straight), eyewear should always follow their shape to create harmony with the face. Especially for spectacles, half the eyebrow should be visible above the frame front.

54.??Eye shape. With spectacles in particular, different eye shapes can be associated with different frame shapes. Almond eyes should choose shapes that call attention to the eyebrows. Round shapes should choose cat eyes and avoid square shapes. Average eye shapes can choose any. Narrow eye shapes should choose soft shapes and avoid rectangular.

55.??Distance between the eyes. Imagine there is a third eye between the two. The distance between the eyes can be defined as: normal (a hypothetical third eye that fits perfectly between the two real eyes), wide set (there is more space between the two real eyes than that occupied by the imaginary third eye), and close set (there is less space between the two eyes than that of a hypothetical third eye). For normal set eyes, you can choose any. For wide set eyes, you should choose wide and keyhole bridges and avoid small bridges. For close set eyes, you can choose small bridges and bright colors and avoid wide and keyhole bridges.

56.??Face shape. The main parameter when identifying the eyewear shape most suitable for a person is the harmony it creates with his or her face.

57.??The face can be defined by precise geometric shapes. The most common shapes are oblong, oval, round, square, rectangular, triangular, reverse triangle, heart-shaped, and diamond.

58.??A face can be called oblong when the distance between the chin and forehead is significant. The features are soft, and the cheeks are not very pronounced. Sometimes an oblong face is associated with a long nose. An oblong face should choose shapes that widen the face, horizontal and slightly upturned shapes, and/or eyewear with decorative or contrasting temples which call attention to the sides of the face. They should also avoid narrow shapes and shapes that generally are too narrow at the sides and further lengthen the face. The best shapes for this type of face are aviator and square shapes with a low bridge (to shorten the appearance of the nose).

59.??The oval face is defined by soft, well-balanced features, and the chin is narrower than the forehead. The cheekbones are typically high. An oval face can choose practically any shape. The best shapes for this type of face are practically any, if proportional to the dimensions of the face.

60.??The round face features a circular shape, without angles or squared lines. The distance between the temples is well-balanced. A round face should choose shapes that bring volume to the lower part of the cheekbones, shapes with lines which are well-defined square, or geometric, and/or eyewear with strong temples. They should avoid oversize shapes and shapes that are too round. The best shapes for this type of face are rectangular and strongly geometric eyewear.

61.??The square face is known for its decisive, square shape both vertically and horizontally. The length and width of the face are perfectly equal. Someone with a square face should choose softly curved shapes, lower frame fronts, and/or upward-angled shapes. They should avoid eyewear that is flat on bottom, squared, or with strong geometrical shapes. The best shapes for this type of face are round, panthos, cat eye, and aviator.

62.??A rectangular face is long with squared angles. The cheekbones and jaw are usually pronounced. People with this face should choose lower frame shapes, eyewear which is wider at the bottom, a bridge with a strong design, and/or curved shapes. They should avoid very narrow lenses. The best shapes for this type of face are round, panthos, lenses with soft shapes, and aviator.

63.??A face Is considered triangular when the chin and jaw are wide, and the forehead is very narrow. Someone with this shape should choose shapes that call attention to the upper part of the face and/or half rim glasses that balance the pronounced jaw. They should also avoid very wide temples and frames which are wide at the bottom. The best shapes for this type of face are half rim, soft shapes, and soft cat eye.

64.??The inverted triangle face is characterized by a wide forehead, narrow cheekbones, and usually, a pointed chin. People with this shape should choose shapes that contrast that of the face (wider at the bottom) eyewear with thin temples and/or light colors and rimless in general. They should avoid eyewear that is too “decorative” or with a heavy upper part of the frame. The best shapes for this type of face are rimless and soft shapes.

65.??The heart-shaped face features a wide forehead, accentuated cheekbones, and a narrow chin. This face should choose shapes that narrow the forehead (wider at the bottom), light colors and materials, and/or rimless in general. They should avoid half rims that call attention to the upper part of the face and frames which are wide at the bottom. The best shapes for this type of face are rimless, cat eye, and butterfly.

66.??The diamond shaped face is narrow at the extremes (between the forehead and chin, as well as between the temples), and the cheekbones are very pronounced. People with this shape should choose shapes emphasizing the upper part, eyewear with very high temples, and/or frames with decoration on the upper part. They should also avoid eyewear with low temples. The best shapes for this type of face are oval, squared, rimless, and cat eye.

67.??Colors. Each person has their color. There are people characterized by warm colors and others by cool colors.

68.??But how are these distinctions made? Principally based on three elements: skin color, eyes, and hair.

69.??Skin color. Carotene refers to a yellowish pigment. Hemoglobin is the molecule in blood that transports oxygen. Melanin is a combination of black, brown, and red pigments. These three factors together determine a person’s complexion.

70.??In 1975, Harvard dermatologist, Thomas B. Fitzpatrick created the Fitzpatrick Scale to estimate the reaction of various types of skin to UV rays. Type 1 is a white or very pale skin. Type 2 refers to light or fair skin. Type 3 refers to medium light skin. Type 4 refers to medium dark, “Mediterranean”, or olive skin. Type 5 refers to dark of brown skin. Type 6 refers to very dark and deeply pigmented skin. However, the undertone of the skin determines if a person’s coloring is warm or cool. Coloring falls into two categories: tending toward yellow if warm, or blush if cool.

71.??The eyes. Even the eyes are a factor in determining a person’s color characteristics. Eye color is a polygenic trait determined mainly by the quantity of melanin and type of pigment in the iris. Eye color can vary within a wide range from dark brown to the lightest shades of blue. It can be classified as: dark brown eyes, brown eyes, light brown eyes, hazel eyes, amber, green, grey, and blue.

72.??Dark eyes are the most common throughout the world. Brown is the dominant color in humans, and in many areas of the world it is the only eye color found. Dark eyes include: dark brown eyes which are the absolute darkest (they tend to become lighter brown with age and can be found with phototypes 3 and higher), brown eyes which contain a large quantity of melanin (they can be medium brown or darker, similar to dark chocolate), light brown eyes which have less melanin with respect to medium and dark brown eyes (they are found with phototypes 3 and higher), and hazel eyes which give the impression of various shades of light brown to dark green gold (they derive from a combination of brown and green and the dominant color can be either green, light brown, or gold).

73.??Light eyes (such as amber, green, grey, and blue) are the rarest eye colors in the world. Individuals with light eyes are more exposed to damage caused by ultraviolet rays with respect to those with dark eyes. Amber eyes are at times considered yellow. These are characterized by intense color and a yellow gold or reddish/copper shade. Green eyes are a product of a lower quantity of melanin and are more common in women than men. Grey eyes have more melanin compared to blue eyes. Blue eyes are due to a reduced quantity of melanin and are linked to the density of proteins in the stroma.

74.??Every hair color is determined by melanin. There are two types of eumelanin: dark (black hair) and pheomelanin. Ligh (red or blond hair). Black hair is the most common hair color in the world, also found in Europe. Brown hair refers to colors ranging from brown to dirty blonde, similar to a chestnut color. It is typical of European populations. Red hair is linked to a recessive gene, also associated with other physical characteristics, in particular, white skin with freckles.

Blonde hair tends toward yellow (with various possible shades and gradations). Grey hair refers to hair that turns grey with the passage of time. The average age for its appearance is between 30 and 40 years old for both men and women. The principal factors that influence the growth of grey hair in an individual may be genetic, metabolic, nutritional, and psychological.

75.??Macrocategories. The combinations of skin, eye, and hair colors create 4 macro characterizations for complexions into which every person can be placed. These categories are based on the 4 seasons which they are named after: winter, autumn, spring, and summer.

76.??Winter. Snow white perfectly represents this phototype, known for its characteristic contrasting colors. The “winter” person typically has dark hair, from intense chestnut to jet black. Eye color can be dark brown, hazel, grey-green, or rarely, emerald or blue topaz. Complexion varies greatly from ivory to ebony, but the undertone of the skin is always a cool pinkish. A “winter” person should choose decisive, strong colors like burgundy, electric blue, bright green and yellow. Fluorescent colors and contrasting colors would be okay. They should avoid warm or Earth tones.

77.??Autumn. Fall types are more variable and are characterized by red in all shades. Hair color varies from chestnut with mahogany highlights to copper red. These blondes tend to have warm, golden shades. Eye color is usually green with gold flecks, but it is also possible to find bright blue, olive, and golden brown. Skin is always light, and the undertone is always warm. Autumns should choose Earth colors like khaki, brick red, beige, gold, sand, grown, and green. They should avoid colors that are too contrasting, such as dark tones of black or blue, or pastel colors like lilac, light blue, and pink.

78.??Spring. Spring types are characterized by harmony and a lack of contrast. Hair tends to be light, from blonde to red with warm highlights. Eye color is light blue, green, or hazel. Skin is peach-colored with warm undertones. They should choose neutral colors like beige, ivory, gold, or copper, or warm pastel colors and decisive colors which are partially cold (dark blue, coral, electric blue, and violet). They should avoid black colors.

79.??Summer. This is the most delicate and cold complexion type. Hair is often ash blonde, and at times, dark chestnut. Eyes are indecent because they interact with the weather and the principal colors are sky blue, petroleum green, and hazel grey. Skin color is light with a cool pinkish undertone. They should choose light colors, pastels, and cool tones like light blue and violet, but also green, lilac, and pearl grey. They should avoid orange at all costs.