The term luxury eyewear extends beyond the aesthetics of the frame. Optical lenses are the heart of each pair of glasses, providing eyeglasses wearers with the gift of sight. When investing in a pair of glasses, it's important to invest in quality lenses. Optical quality in lenses equates to optical clarity, and it is because of this belief that we only carry camera-quality lenses by Zeiss and Pentax. The Zeiss name coincides with value and greatness, thus, the reason that we offer the best lenses available. Whether it is a single vision lens or a progressive lens, Zeiss has a lens for everyone. Progressive lenses can be a tricky habit to master, but Zeiss takes the guess work out of finding that sweet spot. Standard progressive lenses are designed to enhance the field of vision as well as reduce distortion. Zeiss stays current with all the frame trends, to ensure that progressive lenses can accommodate all lens shapes. Zeiss lenses offer cutting edge technology with free-form progressive. This latest addition in technology provides wearers with less peripheral distortion and a wider field of vision. Free-form progressive lenses provide high-definition vision. The ultimate in free-form technology is embedded in the Zeiss Individual, which is a 100% customized lens. The Individual is designed for both progressive and single vision lenses. Unlike most lenses, this free-form lens takes into account where the frame sits upon the face, how close it is to the eye, and the tilt and wrap of the frame. Our faces are not generic, so why should our lenses be? To prove just how custom each lens is, Zeiss will personalize your lenses with your initials. The initials are hidden within the lens, but when the lens is placed in water, the initials are exposed.
High-index eyeglass lenses are the right choice if you want thinner, lighter lenses and eyeglasses that are as attractive and comfortable as possible. Thinner, lighter high-index lenses are especially recommended if you have a strong eyeglass prescription for nearsightedness, farsightedness or astigmatism. Most eyeglass wearers are nearsighted, which requires corrective lenses that are thin in the center but thicker at the edge of the lens. Most of today's fashionable frames are made of plastic or metal with rims thinner than the lens itself. Also, popular rimless mountings mean that the edges of the lenses are completely exposed. In either case, the lens edges are highly visible, and thicker edges can detract from the appearance of your eyewear.
Eyeglass lenses correct refractive errors by bending (refracting) light as it passes through the lens. The amount of light-bending ability (lens power) that's needed to provide good vision is indicated on the eyeglass prescription provided by your eye doctor. Refractive errors and lens powers required to correct them are measured in units called diopters (D). If you are mildly nearsighted, your lens prescription might say -2.00 D. If you are highly myopic, it might say -8.00 D. If you are farsighted, you need "plus" (+) lenses, which are thicker in the center and thinner at the edge.
Regular glass or plastic lenses for high amounts of nearsightedness or farsightedness can be quite thick and heavy. Fortunately, chemists have created a variety of new "high-index" plastic lens materials that bend light more efficiently. This means less material can be used in high-index lenses to correct the same amount of refractive error, which makes high-index plastic lenses both thinner and lighter than conventional glass or plastic 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.
High-index glass lenses also have thinner edges, but high-index glass is heavier than conventional glass, so there is not as much weight savings with glass as there is with plastic lenses. Lightweight lenses are even more of a benefit for farsighted prescriptions, which can make conventional lenses very heavy. And most high-index lenses also have an aspheric design, which gives them a slimmer, more attractive profile and reduces the magnified "bug-eye" look that conventional lenses cause in strong farsighted prescriptions.
There is a wide variety of thin, lightweight high-index eyeglass lenses, based on how efficiently they bend light. The light-bending ability of eyeglass lenses is determined by the "index of refraction" of the lens material. This refractive index is the ratio of the speed of light when it travels through air to the speed of light when it passes through the lens material. The speed of light is reduced the more it is refracted as it passes through a lens material. Therefore, lenses that bend light more efficiently have a higher index of refraction than those that bend light less efficiently, and lenses with a higher refractive index are thinner than lenses of the same power made of materials of a lower refractive index.
In short: the higher the refractive index, the thinner the lens.
Conventional plastic lenses have a refractive index of approximately 1.50. For glass, it's 1.52. Any lens material with a refractive index that's higher than that of glass or plastic is considered to be high-index. High-index plastic lenses are now available in a wide variety of refractive indices, typically ranging from 1.53 to 1.74. Lenses with an index of refraction of 1.70 or higher typically are at least 50 percent thinner than conventional plastic lenses. Also, generally speaking, the higher the index, the higher the cost of the lenses. Your eyeglass prescription also determines what kind of high-index material you might want for your lens. The highest index materials are used primarily for the strongest prescriptions. If you want high-index lenses, be sure to ask for them. But rely on your eye doctor's or optician's advice regarding which index to use. Your eye care practitioner can explain which high-index lenses are the best choice for your needs and budget. Most of today's popular lens designs and features (single vision, bifocals, progressive, photochromic, etc.) are available in high-index materials. But there are exceptions, so ask your eye doctor or optician for details.
All lens materials block some light from passing through the lens. This light reflects back from the lens surface, causing distractions and reducing the clarity of night vision. Conventional glass or plastic lenses reflect about 8 percent of light that otherwise would reach the eye. High-index lenses reflect up to 50 percent more light than conventional glass or plastic lenses. For the best vision and appearance, it's a good idea to have an anti-reflective lens coating (AR coating) applied to high-index lenses. AR-coated high-index lenses transmit up to 99.5 percent of light to the eye for optimum vision. And because AR coating virtually eliminates lens reflections, it makes high-index lenses appear nearly invisible, so others see your eyes, not your lenses. Also, studies have shown that eyeglass lenses with anti-reflective coatings provide sharper night vision with fewer glares, which is a real advantage for night drivers.
Why progressive lenses? You may be maturing, but "mature" doesn't have to mean "old." If you are in your 40s (or older) and are having trouble reading fine print with your glasses, progressive lenses offer a younger-looking appearance and other advantages over the lined bifocal lenses your parents wore. Progressive lenses, sometimes called "no-line bifocals," eliminate the visible lines of traditional bifocals and trifocals and hide the fact that you need reading glasses. With progressive lenses, no one has to know whether you're wearing glasses; for fashion or because your arms have "grown too short" for you to see up close.
In addition to cosmetic advantages, progressive multifocal lenses provide a more natural correction of presbyopia than bifocal or trifocal prescription eyeglasses. Instead of having just two or three lens powers like bifocals or trifocals, progressive lenses are true "multifocal" lenses that provide a seamless progression of many lens powers for all viewing distances. With progressive lenses, you can look up to see clearly across the room and in the distance. You also can look ahead to view your computer in the intermediate zone and drop your gaze downward to read and do fine work comfortably through the near zone of the lenses. And it's easy to adapt to today's modern progressive lenses. A "corridor" of optimum lens power runs vertically down each progressive lens. Your eye care practitioner will take careful measurements of your eyes and eyeglass frame in order to place the corridor in just the right location so your eyes can naturally access the various powers within the lens for comfortable viewing at all distances. And progressive lenses eliminate an annoying problem caused by bifocal and trifocal lenses known as "image jump." With conventional bifocals and trifocals, images seem to "jump" as your eyes move past the sharply defined boundary between the distance and near parts of the lens. With progressive lenses, the transition between lens powers within the lens is smooth and seamless, letting you change focus from distance to near and back again more comfortably, with no image jump.
For all powers of progressive lenses to fit within a pair of eyeglasses, frames in the past had to be relatively large. If the frame was too small, the reading portion of the lens would sometimes end up uncomfortably small after the lens was cut to size and inserted in the frame. But lens manufacturers have overcome this problem by introducing "short corridor" progressive lenses with compact designs that provide larger reading zones for today's smaller, fashionable frames. The popularity of progressive lenses has exploded in recent years, making progressives the most widely purchased lenses for correcting presbyopia. Today there are many progressive lens designs to fit virtually any needs. The differences in lens design are related mainly to the length and width of the progressive power corridor and how much of it is devoted to different viewing distances. Different areas of the corridor may be expanded, depending on the design philosophy of the manufacturer and the intended purpose of the lens. Some progressive lenses are made especially for computer use, for example, and have a wider intermediate zone. Other progressive lens designs may have a larger reading portion. Your eye care practitioner is in the best position to evaluate which lens style will work best for you. Progressive lenses also are available in a wide variety of materials, including regular plastic and glass, polycarbonate, high-index and photochromic lenses.
When you are fitted with your first pair of progressive lenses, you may need a short adaptation period to become fully comfortable using the lenses. This might take only a few minutes, or it could take a few days. This is because blending lens powers in progressive lenses lets you see clearly at all distances, but also causes minor aberrations in the peripheral part of the lenses, to the left and right of the progressive power corridor (see diagram). If you glance to the far right or left, especially when looking down, you might notice your vision is slightly blurred. Peripheral aberrations also might cause you to experience a sensation of "swim" when you make quick head movements. Over the last several years, progressive lens designs have been continually improved to reduce peripheral aberrations. Today, most first-time wearers are comfortable with progressive lenses almost immediately. If you experience any peripheral blur or "swim" when wearing progressive lenses, you usually can eliminate the problem by learning to make slight head movements to look more directly at objects. But most peripheral vision problems caused by progressive lenses typically are mild and temporary, and disappear as you adapt to the lenses. If you have a lot of hyperopia, adapting to progressive lenses may take a bit longer than if you are only mildly farsighted or are nearsighted. But with todays lens designs, nearly everyone can wear progressive lenses successfully. To make sure you get the best value in progressive lenses, talk to a professional optician, who will be able to recommend a customized progressive lens solution for your specific needs and give you helpful tips on adapting to and caring for your new lenses.
Anti-reflective coating (also called AR coating or anti-glare coating) improves both your vision through your lenses and the appearance of your eyeglasses. Both benefits are due to AR coating's ability to eliminate reflections of light from the front and back surface of eyeglass lenses. AR coating is especially beneficial when used on high-index lenses, which reflect more light than regular plastic lenses. Generally, the higher the index of refraction of the lens material, the more light that will be reflected from the surface of the lenses. For example, regular plastic lenses reflect roughly 8 percent of light hitting the lenses, so only 92 percent of available light enters the eye for vision. High index plastic lenses can reflect up to 50 percent more light than regular plastic lenses (approximately 12 percent of available light), so even less light is available to the eye for vision. This can be particularly troublesome in low-light conditions, such as when driving at night. Today's modern anti-reflective coatings can virtually eliminate the reflection of light from eyeglass lenses, allowing 99.5 percent of available light to pass through the lenses and enter the eye for good vision. . By eliminating reflections, AR coating also makes your eyeglass lenses look nearly invisible so people can see your eyes and facial expressions more clearly. Anti-reflective glasses also are more attractive, so you can look your best in all lighting conditions. The visual benefits of lenses with anti-reflective coating include sharper vision with fewer glares when driving at night and greater comfort during prolonged computer use (compared with wearing eyeglass lenses without AR coating). Anti-reflective coating also is a good idea for sunglasses, because it eliminates glare from sunlight reflecting into your eyes from the back surface of tinted lenses when the sun is behind you. (Generally, AR coating is applied only to the back surface of sunglass lenses because there are no cosmetic or visual benefits to eliminating reflections from the front surface of dark-tinted lenses.) Most premium anti-reflective coatings include a "hydrophobic" surface layer that prevents water spots from forming and makes the lenses easier to clean. Some AR coatings also include an "oleophobic" surface layer that repels skin oils and makes it easier to remove smudges from the lenses. Some eyeglass lenses have factory-applied AR coating on both lens surfaces. Other lenses, particularly progressive lenses and other multifocal lenses (i.e., bifocals and trifocals), have the coating applied after the lenses have been customized to your eyeglass prescription by an optical lab.
Applying anti-reflective coating to eyeglass lenses is a highly technical process involving vacuum deposition technology. The first step in the AR coating process is to meticulously clean the lenses and inspect them for visible and microscopic surface defects. Even a tiny smudge, piece of lint or hairline scratch on a lens during the coating process can cause a defective AR coating. Typically, a production line includes multiple washing and rinsing baths, including ultrasonic cleaning to remove any traces of surface contaminants. This is followed by air drying and heating of the lenses in special ovens to further remove unwanted moisture and gases from the lens surface. The lenses are then loaded into special metal racks with spring-loaded openings so the lenses are held securely but with virtually all lens surfaces exposed for the coating application. The racks are then loaded into the coating chamber. The door of the chamber is sealed, and the air is pumped out of the chamber to create a vacuum. While the lens racks are rotating in the coating chamber, a power source within the machine focuses a beam of electrons onto a small crucible that contains a series of metal oxides in separate compartments. When bombarded by the beam of this electron "gun" in succession, the metal oxides are transformed into vapors that fill the coating chamber and adhere to the lenses in a specific order to form a precise multilayer AR coating. Each AR coating manufacturer has its own proprietary formula, but generally all anti-reflective coatings consist of multiple microscopic layers of metallic oxides of alternating high and low index of refraction. Depending on the AR coating formula, most lenses with anti-reflective coating have a very faint residual color, usually green or blue, that is characteristic of that particular brand of coating. Anti-reflective coatings are incredibly thin. The entire multilayer AR coating stack generally is only about 0.2 to 0.3 microns thick, or about 0.02 percent (two one-hundredths of 1 percent) of the thickness of a standard eyeglass lens.
When cleaning AR-coated lenses, use only products that your optician recommends. Lens cleaners with harsh chemicals may damage the anti-reflective coating. Also, don't attempt to clean AR-coated lenses without wetting them first. Using a dry cloth on a dry lens can cause lens scratches. And because anti-reflective coating eliminates light reflections that can mask lens surface defects, fine scratches often are more visible on AR-coated lenses than on uncoated lenses.