752:
948:. This design gives the best achievable optical quality and least sensitivity to lens fitting. A flatter base-curve is sometimes selected for cosmetic reasons. Aspheric or atoric design can reduce errors induced by using a suboptimal flatter base-curve. They cannot surpass the optical quality of a spherical best-form lens but can reduce the error induced by using a flatter-than-optimal base curve. The improvement due to flattening is most evident for strong farsighted lenses. High myopes (-6D) may see a slight cosmetic benefit with larger lenses. Mild prescriptions will have no perceptible benefit (-2D). Even at high prescriptions, some high myope prescriptions with small lenses may not see any difference, since some aspheric lenses have a spherically designed center area for improved vision and fit.
744:
952:
share the same base curve characteristics, but the spherical form is only best for a -4.25D prescription. In this case, the error will be imperceptible to the human eye. However, some manufacturers may further cost-reduce inventory and group over a larger range which will result in perceptible error for some users in the range who also use the off-axis area of their lens. Additionally, some manufacturers may verge toward a slightly flatter curve. Although if only a slight bias toward plano is introduced it may be negligible cosmetically and optically. These optical degradations due to base-curve grouping also apply to aspherics since their shapes are intentionally flattened and then asphericized to minimize error for the average base curve in the grouping.
485:, found on the front surface of the lens. Steeper and more convergent than the base curve, the add segment combines with the back surface to deliver the person's near correction. Early manufacturing techniques fused a separate lens to the front surface, but modern processes cut all the geometry into a single piece of lens material. There are many locations, profiles, and sizes of add segments typically referred to as segment type. Some "seg type" examples include Flat top, Kryptok, Orthogon, Tillyer Executive, and Ultex A. Trifocals contain two add segments to achieve a lens that corrects the person's vision for three distinct distances.
974:(1.6 in), and although they are quite rare, can reduce lens weight to about half of the 50 mm versions. The curves on the front and back of a lens are ideally formed with the specific radius of a sphere. This radius is set by the lens designer based on the prescription and cosmetic consideration. Selecting a smaller lens will mean less of this sphere surface is represented by the lens surface, meaning the lens will have a thinner edge (myopia) or center (hyperopia). A thinner edge reduces light entering into the edge, reducing an additional source of internal reflections.
407:, in any direction. Switching between distance and near vision is accomplished by re-adjusting the lens, instead of by tilting and/or rotating the head. The need for constant adjustment when the person's attention switches to an object at a different distance is a design challenge of such a lens. Manual adjustment is more cumbersome than bifocals or similar lenses. Automated systems require electronic systems, power supplies, and sensors that increase the cost, size, and weight of the correction.
2574:
736:
133:
322:
915:
518:
come into contact with the back of the lens, smudging the lens and causing annoyance for the wearer. A skilled frame stylist will help the wearer select a good balance of fashionable frame size with good vertex distance to achieve ideal aesthetics and field of view. The average vertex distance in a pair of glasses is 12-14mm. A contact lens is placed directly on the eye and thus has a vertex distance of zero.
2998:
1518:
lens. Standard polycarbonate with an Abbe number of 30 is one of the worst materials optically if chromatic aberration intolerance is of concern. Along with Trivex and the high-index plastics, polycarbonate is an excellent choice for rimless eyeglasses. Similar to the high-index plastics, polycarbonate has a very low Abbe number, which may be bothersome to individuals sensitive to chromatic aberrations.
2724:. Designs that feature "flatter" curves trade optical quality for cosmetic appearance. By using a non-spheric lens shape, an aspheric lens attempts to correct the error induced by flattening the lens. Typically, the design focuses on reducing the error (OAE) across the horizontal and vertical lens axis edges. This is of primary benefit to farsighted individuals, whose lenses have a thick center.
1060:
532:
36:
2662:
than aspherics for an ophthalmic lens application. Aspherics are only used for corrective lenses when, in order to achieve a flatter lens for cosmetic reasons, the lens design deviates from the best-form sphere; this results in degradation of the visual correction, degradation which can, in some part, be compensated for by an aspheric design. The same is true for atoric and bi-aspheric.
966:
294:
1270:
greatly reduces color-fringing of edge-wise viewed contrasty objects, compared to all available plastics. But glass lenses are much heavier, and making them requires specialized glass grinding equipment no longer common in ordinary prescription lens labs: At present, one is often hard-pressed to find an optical laboratory that has the machinery needed shape custom glass lenses.
452:
940:
actually due to color shifting. Chromatic aberration can be improved by using a material with improved ABBE. The best way to combat lens induced power error is to limit the choice of corrective lens to one that is in the best spherical form. A lens designer determines the best-form spherical curve using the
999:
which can result in a truly lighter lens. These materials can be found in a material property table. Reducing frame lens size will give the most noticeable improvement in weight for a given material. Ways to reduce the weight and thickness of corrective lenses, in approximate order of importance are these:
2665:
While it is true that aspheric lenses are used in cameras and binoculars, it would be wrong to assume that this means aspherics/atorics result in better optics for eyewear. Cameras and telescopes use multiple lens elements and have different design criteria. Spectacles are made of only one ophthalmic
2661:
improve vision over traditional spheric lenses. This statement could be misleading to individuals who do not know that the lenses are being implicitly compared to "a spheric flattened away from best-form for cosmetic reasons". This qualification is necessary since best-form spherics are always better
985:
The index can improve the lens thinness, but at a point, no more improvement will be realized. For example, if an index and lens size is selected with center to edge thickness difference of 1 mm then changing index can only improve thickness by a fraction of this. This is also true with aspheric
866:(2 mm vs. 1.5 mm thickness typical on newer materials) 58 @ 1.5, Sola Spectralite (47 @ 1.53), Sola Finalite (43 @ 1.6), and Hoya Eyry (36 @ 1.7). For impact resistance safety glass is offered at a variety of indexes at high Abbe number, but is still 2x the weight of plastics. Polycarbonate
369:
or varifocal lenses provide a smooth transition from distance correction to near correction, eliminating segment lines and allowing clear vision at all distances, including intermediate (roughly arms' length). The lack of any abrupt change in power and the uniform appearance of the lens gives rise to
258:
will not be accounted for. People with little to no need for correction in the distance may find off-the-shelf glasses work quite well for seeing better during near vision tasks. But if the person has a significant need for distance correction, it is less likely that the over-the-counter glasses will
2743:
In the United States, laws at the federal and state level govern the provision and effective dates of prescriptions for contact lenses and eyeglasses. Federal law requires that eyeglass and contact lens prescriptions be given to every consumer and that the prescriptions be for a minimum of one year.
2669:
It is worth noting that aspheric lenses are a broad category. A lens is made of two curved surfaces, and an aspheric lens is a lens where one or both of those surfaces is not spherical. Further research and development is being conducted to determine whether the mathematical and theoretical benefits
998:
Material density typically increases as lens thickness is reduced by increasing index. There is also a minimum lens thickness required to support the lens shape. These factors result in a thinner lens which is not lighter than the original. There are lens materials with lower density at higher index
242:
Ready-made single-vision reading glasses go by many names, including over-the-counter glasses, ready readers, cheaters, magnifiers, non-prescription readers, or generic readers. They are designed to lessen the focusing burden of near work, such as reading. They are typically sold in retail locations
1517:
Polycarbonate is lighter weight than normal plastic. It blocks UV rays, is shatter resistant, and is used in sports glasses and glasses for children and teenagers. Because polycarbonate is soft and will scratch easily, a scratch-resistant coating is typically applied after shaping and polishing the
1468:
vs. polycarbonate's 1.586 may result in slightly thicker lenses depending upon the prescription. Along with polycarbonate and the various high-index plastics, Trivex is a lab favorite for use in rimless frames, owing to the ease with which it can be drilled and its resistance to cracking around the
337:
is a lens with two sections, separated by a line (see image to the right). Generally, the upper part of the lens is used for distance vision, while the lower segment is used for near vision. The area of the lens that caters to near vision is called the add segment. There are many different shapes,
939:
Barring contacts, a good lens designer does not have many parameters that can be traded off to improve vision. The index has little effect on error. Note that, although chromatic aberration is often perceived as "blurry vision" in the lens periphery and gives the impression of power error, this is
935:
As corrective power increases, even optimally designed lenses will have distortion that can be noticed by a user. This particularly affects individuals that use the off-axis areas of their lenses for visually demanding tasks. For individuals sensitive to lens errors, the best way to eliminate lens
905:
of a lens as the eye looks through various points on the area of the lens. Generally, it is least present at the optic center and gets progressively worse as one looks towards the edges of the lens. The actual amount of power error is highly dependent on the strength of the prescription as well as
846:
Restrict the choice of lens material to the highest Abbe value at an acceptable thickness. The oldest most basic commonly used lens materials also happen to have the best optical characteristics at the expense of corrective lens thickness (i.e., cosmetics). Newer materials have focused on improved
842:
Try to use the smallest vertical lens size that is comfortable. Generally, chromatic aberrations are more noticeable as the pupil moves vertically below the optical center of the lens (e.g., reading or looking at the ground while standing or walking). Keep in mind that a smaller vertical lens size
488:
The optical center of the add segment may be placed on the lens surface or may hang off into an empty space near the lens surface. Although the surface profile of a bifocal segment is spherical, it is often trimmed to have straight edges so that it is contained within a small region of the overall
480:
Bifocals and trifocals result in a more complex lens profile, compounding multiple surfaces. The main lens is composed of a typical ophthalmic lens. Thus the base curve defines the front surface of the main part of the lens while the back surface geometry is changed to achieve the desired distance
471:
may choose to specify a particular base curve when prescribing a corrective lens for either of these reasons. A multitude of mathematical formulas and professional clinical experience has allowed optometrists and lens designers to determine standard base curves that are ideal for most people. As a
1269:
so the expensive, high-end optical glass types mentioned above have little value for central vision; however, the wearer's view through the side of a glass lens is not comparable to central vision through the eye: Low dispersion glass definitely makes optically superior corrective lenses since it
951:
In practice, labs tend to produce pre-finished and finished lenses in groups of narrow power ranges to reduce inventory. Lens powers that fall into the range of the prescriptions of each group share a constant base curve. For example, corrections from -4.00D to -4.50D may be grouped and forced to
714:
Theoretically, off-axis optical quality degrades (oblique astigmatic error). In practice this degradation should not be perceptible – current frame styles are much smaller than they would have to be for these aberrations to be noticeable to the patient, the aberration occurring some distance away
517:
is the space between the front of the eye and the back surface of the lens. In glasses with powers beyond ±4.00D, the vertex distance can affect the effective power of the glasses. A shorter vertex distance can expand the field of view, but if the vertex distance is too small, the eyelashes will
1045:
People with very high-power corrective lenses can benefit socially from contact lenses because these distortions are minimized and their facial appearance to others is normal. Aspheric/atoric eyeglass design can also reduce minification and magnification of the eye for observers at some angles.
837:
In contrast, the eye moves to look through various parts of a corrective lens as it shifts its gaze, some of which can be as much as several centimeters off of the optical center. Thus, despite the eye's dispersive properties, the corrective lens's dispersion cannot be dismissed. People who are
779:
In practice, an Abbe number change from 30 to 32 will not have a practically noticeable benefit, but a change from 30 to 47 could be beneficial for users with strong prescriptions that move their eyes and look "off-axis" of the optical center of the lens. Some users do not sense color fringing
1339:
Plastic lenses are currently the most commonly prescribed lens, owing to their relative safety, low cost, ease of production, and high optical quality. The main drawbacks of many types of plastic lenses are the ease by which a lens can be scratched, and the limitations and costs of producing
989:
The lens's minimum thickness can also be varied. The FDA ball drop test (5/8" 0.56-ounce steel ball dropped from 50 inches) effectively sets the minimum thickness of materials. Glass or CR-39 requires 2.0 mm, but some newer materials only require 1.5 mm or even 1.0 mm minimum
891:
Use contact lenses in place of or as well as eyeglasses. A contact lens rests directly on the surface of the cornea and moves in sync with all eye movements; consequently, a contact lens is always almost perfectly aligned on center with the pupil, and there is never any significant off-axis
435:
Although corrective lenses can be produced in many different profiles, the most common is ophthalmic or convex-concave. In an ophthalmic lens, both the front and back surfaces have a positive radius, resulting in a positive/convergent front surface and a negative/divergent back surface. The
2587:
Anti-reflective coatings help to make the eye behind the lens more visible. They also help lessen back reflections of the white of the eye as well as bright objects behind the eyeglasses wearer (e.g. windows, lamps). Such a reduction of back reflections increases the apparent contrast of
973:
The greatest cosmetic improvement on lens thickness (and weight) benefits from choosing a frame that holds physically small lenses. The smallest of the popular adult lens sizes available in retail outlets is about 50 mm (2.0 in) across. There are a few adult sizes of 40 mm
271:, usually results in better visual correction and fewer headaches and visual discomfort. Another criticism of over-the-counter glasses is that they may alleviate symptoms, causing a person to forgo the other benefits of routine vision exams, such as early diagnosis of chronic disease.
505:
that begins using one spherical surface base curve and ends at another, with the radius of curvature continuously varying as the transition is made from one surface to the other. This shift in curvature results in different powers being delivered from different locations on the lens.
279:
Although lenses are normally prescribed by optometrists or ophthalmologists, there is evidence from developing countries that allowing people to select lenses for themselves produces good results in the majority of cases and is less than a tenth of the cost of prescription lenses.
2591:
One problem with anti-reflective coatings is that historically they have been very easy to scratch. Newer coatings try to address this problem by combining scratch resistance with the anti-reflective coating. They also offer a measure of dirt and smudge resistance, due to their
1450:
and
Younger Optics, PPG announced the availability of Trivex for the optical industry in 2001. Trivex is a urethane-based pre-polymer. PPG named the material Trivex because of its three main performance properties: Superior optics, ultra lightweight, and extreme strength.
843:
will result in a greater amount of vertical head movement, especially while performing activities that involve short and intermediate distance viewing, which could lead to an increase in neck strain, especially in occupations involving a large vertical field of view.
308:
Reading glasses are single vision lenses designed for near work and include over the counter glasses. They come in two main styles: full frames, in which the entire lens is made in the reading prescription, and half-eyes, style glasses that sit lower down on the
838:
sensitive to the effects of chromatic aberrations, or who have stronger prescriptions, or who often look off the lens's optical center, or who prefer larger corrective lens sizes may be impacted by chromatic aberration. To minimize chromatic aberration:
2666:
lens, and the best-form spheric lens has been shown to give the best vision. In cases where best-form is not used, such as cosmetic flattening, thinning or wrap-around sunglasses, an aspheric design can reduce the amount of induced optical distortions.
776:). Generally, lower Abbe numbers are a property of mid and higher index lenses that cannot be avoided, regardless of the material used. The Abbe number for a material at a particular refractive index formulation is usually specified as its Abbe value.
1179:
of 1.9) and in certain occupations where the hard surface of glass offers more protection from sparks or shards of material. If the highest Abbe number is desired, the only choices for common lens optical material are optical crown glass and CR-39.
234:. Eyecare professionals (optometrists and ophthalmologists) are trained to determine the specific corrective lenses that will provide the clearest, most comfortable, and most efficient vision, avoiding double vision and maximizing binocularity.
2751:
State laws vary. For example, California law also requires prescriptions to be provided to clients whether demanded or not. Eyeglass prescriptions must be for a minimum of two years, and contact prescriptions must be for a minimum of one year.
1016:
It is not always possible to follow the above points, because of the rarity of such frames, and the need for a more pleasing appearance. However, these are the main factors to consider if ever it should become necessary and possible to do so.
755:
Close-up of color shifting through corner of an eyeglass lens. The visible colored fringing along the light and dark borders between color swatches are not actually on the color chart: They are the result of dispersion of colors by the
353:
are similar to bifocals, except that the two focal areas are separated by a third area (with intermediate focus correction) in the middle. This segment corrects the wearer's vision for intermediate distances roughly at arms' length,
1030:
For extreme nearsightedness, the eyes appear small and sunken into the face, and the sides of the skull can be visible through the lens. This gives the wearer the appearance of having a very large or fat head in contrast with their
2734:
is designed to compensate for the astigmatism of a patient's eye. Even though this lens is technically "aspheric", the terms "aspheric" and "atoric" are reserved for lenses which correct errors induced by cosmetic lens flattening.
1566:
High-index plastics allow for thinner lenses. The lenses may not be lighter, however, due to the increase in density vs. mid- and normal index materials. A disadvantage is that high-index plastic lenses have a much higher level of
1297:, some of which are toxic. The need for special venting to protect technicians from exposure to powdered toxic glass further limits the number of optical labs that can safely grind super-low dispersion / large Abbe number glass.
906:
whether a best spherical form of lens or an optically optimal aspherical form was used in the manufacture of the lens. Generally, the best spherical form lenses attempt to keep the ocular curve between four and seven diopters.
402:
can be changed to suit the needs of the wearer. A typical application of such a lens is to refocus the correction allowing clear vision at any distance. Unlike with bifocals, near-vision correction is achieved over the entire
809:
Moves to keep the visual axis close to its achromatic axis, which is completely free of dispersion (i.e., to see the dispersion one would have to concentrate on points in the periphery of vision, where visual clarity is quite
390:. Multifocal contact lenses are typically designed for constant viewing through the center of the lens, but some designs do incorporate a shift in lens position to view through the reading power (similar to bifocal glasses).
2678:
Optical terms are used to describe errors in the eye's lens and the corrective lens. This can cause confusion since "astigmatism" or "ABBE" has a drastically different impact on vision depending on which lens has the error.
828:
428:
1025:
Eyeglasses for a high-diopter nearsighted or farsighted person cause a visible distortion of their face as seen by other people, in the apparent size of the eyes and facial features visible through the eyeglasses.
222:. The prescription consists of all the specifications necessary to make the lens. Prescriptions typically include the power specifications of each lens (for each eye). Strengths are generally prescribed in quarter-
981:
to reduce flaring out of the very thick edge. Thick myopic lenses are not usually mounted in wire frames, because the thin wire contrasts against the thick lens, to make its thickness much more obvious to others.
926:
value increases. In a spherical lens, especially one with a strong correction whose base curve is not in the best spherical form, such increases can significantly impact the clarity of vision in the periphery.
338:
sizes, and positions for the add segment, such as rounded bifocals and D segment bifocals, that are selected for functional differences as well as the visual demands of the patient. Bifocals allow people with
2636:, naturally block most UV light; they have UV-cutoff wavelengths just outside the visible range and do not benefit from the application of a UV coating. Many modern anti-reflective coatings also block UV.
2577:
The effects of an anti-reflective coating applied (as seen on the bottom picture) as compared to regular eyeglass lens (notice how the reflection of the photographer in the top lens is clearly visible)
2727:
An atoric lens design refers to a lens with a more complex aspheric lens design. An atoric lens design can address errors over more corners of the lens, not just the horizontal and vertical axis.
791:
produce chromatic aberrations which can be perceptible to a user in lenses larger than 40 mm in diameter and especially in strengths that are in excess of ±4 D. At ±8 D even glass
472:
result, the front surface curve is more standardized and the characteristics that generate a person's unique prescription are typically derived from the geometry of the back surface of the lens.
243:
such as pharmacies and grocery stores but are also available in book stores and clothing retailers. They are available in common reading prescriptions with strengths ranging from +0.75 to +3.50
467:(usually determined from the profile of the front surface of an ophthalmic lens) can be changed to result in the best optic and cosmetic characteristics across the entire surface of the lens.
969:
Crude relationship between lens size and its thickness for the same radius of curvature. In addition to its smaller surface area, the small lens is also much thinner and so is much lighter.
1330:
workplace with bright recessed can lighting or other darkened room lighting, concentrated on a small areas, shining on bright reflective surfaces (e.g. display counters at jeweler stores).
888:
is also heavily marketed as an impact-resistant alternative to
Polycarbonate, for individuals who do not need polycarbonate's index. Trivex is also one of the lightest materials available.
1003:
Choose glasses frames with small lenses; that is to say so that the longest measurement across the lens at any angle is as short as possible. This gives the greatest advantage of all.
2996:, Slagel, Edwin C., "Impact resistant polyurethane, and meteor of manufacture thereof", published 3 October 2000, issued 3 October 2000, assigned to Simula, Inc.
2712:
Example: A patient with astigmatism (or no astigmatism) of the eye and a high prescription may notice astigmatism of the lens (OAE) when looking through the corner of their glasses.
751:
743:
1273:
A further complication for seeking lenses made of better, even-lower dispersion glass, is that the specialty glass is often expensive. Also, many exotic glass types, with
1175:
plastic lenses. They still remain in use for specialised circumstances, for example in extremely high prescriptions (currently, glass lenses can be manufactured up to a
1114:
659:
values that are at or above 1.60 can be referred to as "high-index". Likewise, Trivex and other borderline normal / mid-index materials may be referred to as mid-index.
1042:
due to some facial distortions. This can result in the low self-esteem of the eyeglass wearer and lead to difficulty in making friends and developing relationships.
419:. Some people with good natural eyesight like to wear eyeglasses as a style accessory, or want to change the appearance of their eyes using novelty contact lenses.
501:(PAL, also commonly called a no-line or varifocal lens) eliminates the line in bi/tri-focals and is very complex in its profile. PALs are a continuously variable
1575:. Aside from the thinness of the lens, another advantage of high-index plastics is their strength and shatter resistance, although not as shatter resistant as
802:
produces chromatic aberration that can be noticed by a user. Chromatic aberration is independent of the lens being of spherical, aspheric, or atoric design.
2709:
and is induced when the eye looks through the ophthalmic lens at a point oblique to the optical center (OC). This may become especially evident beyond -6D.
772:(i.e., color fringes above/below or to the left/right of a high contrast object), especially in larger lens sizes and stronger prescriptions (beyond ±4.00
247:. While these "magnifiers" do indeed make the image of the viewed object bigger, their main advantage comes from focusing the image, not magnification.
305:
to see up close. If the person cannot accommodate, they may need a separate correction for near distances, or else use a multifocal lens (see below).
1586:
atoms in the polymer being responsible for the high refractive index. The sulfur content can be up to 60 percent by weight for a material with index
2939:
1458:
while at the same time offering far superior optical quality (i.e., higher Abbe number) and a slightly lower density. Its lower refractive index of
2588:
surroundings. At night, anti-reflective coatings help to reduce headlight glare from oncoming cars, street lamps, and heavily lit or neon signs.
230:
smaller increments (e.g., eighth-diopter steps / 0.125 D). The use of improper corrective lenses may not be helpful and can even exacerbate
3051:
747:
Prismatic color distortion shown with a camera set for nearsighted focus, and using -9.5 diopter eyeglasses to correct the camera's myopia.
415:
A corrective lens with a power of zero is called a plano lens. These lenses are used when one or both eyes do not require correction of a
313:. Full frame readers must be removed to see distance clearly, while the distance can be clearly viewed over the top of half-eye readers.
3088:
1099:
571:
119:
1077:
549:
342:
to see clearly at distance and near without having to remove the glasses, which would be required with single vision correction.
53:
3118:
936:
induced aberrations is to use contact lenses. Contacts eliminate all these aberrations since the lens then moves with the eye.
259:
be perfectly effective. Although such glasses are generally considered safe, an individual prescription, as determined by an
100:
2919:
1081:
553:
57:
2745:
72:
444:
the opposite is true: the divergent back surface is greater in magnitude than the convergent front surface. To correct for
3038:
2698:
1324:
occupations that involve work with very high contrast elements (e.g. reading dark print on white paper under bright light)
923:
760:
Of all of the properties of particular lens material, the one that most closely relates to its optical performance is its
1224:
848:
1165:
1150:
79:
1926:
399:
2993:
1171:
Glass lenses have become less common owing to the danger of shattering and their relatively high weight compared to
3141:
2964:
2551:
227:
1070:
542:
46:
2891:"Progressive Memories & Calculus - Varilux progressive spectacle lenses - Werner Köppen - Progressive Lenses"
86:
851:
ball-drop impact test, and depending on needed index these seem to currently have "best in class" Abbe vs Index
440:
a convergent lens is needed; therefore, the convergent front surface overpowers the divergent back surface. For
448:, the lens, or section of the lens, must be more convergent or less divergent than the person's distance lens.
847:
cosmetics and increased impact safety, at the expense of optical quality. Lenses sold in the US must pass the
329:
are upside down as they rest on the surface. The add segment of the lens for near vision is the D-shaped area.
2582:
922:
As the eye shifts its gaze from looking through the optical center of the corrective lens, the lens-induced
705:
68:
1034:
For extreme farsightedness the eyes appear very large on the face, making the wearer's head seem too small.
805:
The eye's Abbe number is independent of the importance of the corrective lens's Abbe, since the human eye:
358:
computer distance. This lens type has two segment lines, dividing the three different correcting segments.
3146:
436:
difference in curvature between the front and rear surface leads to the corrective power of the lens. In
2771:
945:
211:
205:
2573:
301:
Single vision lenses correct for only one distance. If they correct for far distance, the person must
2670:
of aspheric lenses can be implemented in practice in a way that results in better vision correction.
1568:
1327:
construction work that requires viewing contrasting dark building elements against a cloudy white sky
1220:
769:
768:. Higher Abbe numbers mean a better lens material, and lower Abbe numbers result in the presence of
694:
3018:
1118:
1257:
761:
302:
1454:
Trivex is a relative newcomer that possesses the UV-blocking properties and shatter resistance of
941:
3151:
3059:
2847:
1307:) in excess of Crown Glass and CR-39 are mainly warranted only for unusual special uses, such as
1184:
502:
366:
193:
2915:
2839:
2786:
2687:
Astigmatism of the eye: Patients who are prescribed a sphere and a cylinder prescription have
2540:
1876:
1469:
drill holes. One other advantage that Trivex has over polycarbonate is that it can be tinted.
735:
701:
153:
132:
3096:
93:
2831:
1559:
1527:
1510:
1478:
1447:
1432:
1400:
1381:
1349:
1176:
1161:
1126:
593:
498:
416:
383:
378:
Multifocal contact lenses (e.g. bifocals or progressives) are comparable to spectacles with
251:
231:
185:
157:
2543:
for normal waves against air on two interfaces. This is a reflection without an AR coating.
1879:
for normal waves against air on two interfaces. This is a reflection without an AR coating.
780:
directly but will just describe "off-axis blurriness". Abbe values even as high as that of
2563:
818:
601:
514:
350:
260:
215:
1009:
Choose a lens as near round as possible. These are less commonly found than other shapes.
2816:
1443:
965:
585:
387:
914:
3135:
2851:
2796:
2721:
2702:
2658:
1576:
1455:
1039:
902:
589:
404:
165:
2744:(FTC Section 456.2 "Separation of examination and dispensing" was reviewed in 2004:
700:
Poorer light transmission and increased backside and inner-surface reflections (see
2865:
2761:
321:
181:
2628:. DNA damage from UV light is cumulative and irreversible. Some materials such as
1188:
1006:
Choose a frame that allows the pupil to occupy the exact middle point of the lens.
2909:
2720:
In ophthalmic terminology, "aspheric lens" specifically refers to a subclass of
2688:
2621:
2613:
2609:
1572:
1540:
1491:
1413:
1362:
1274:
1139:
1059:
765:
730:
690:
676:
531:
468:
264:
255:
169:
35:
1223:
such as the best optical quality low dispersion glass currently in production,
652:
This is a general classification. Often for marketing purposes, materials with
250:
These glasses are not tailored to a person's individual needs. A difference in
17:
2731:
2692:
2605:
2593:
464:
456:
451:
445:
339:
310:
293:
173:
2791:
2776:
2617:
1294:
822:
437:
219:
2843:
1582:
These high-refractive-index plastics are typically thiourethanes, with the
180:
or "spectacles" are worn on the face a short distance in front of the eye.
1217:
1158:: 2.56 g/cm³ (the heaviest corrective lens material in common use, today)
379:
334:
326:
268:
189:
1012:
Choose as high a refractive index for the lens material as cost permits.
136:
A pair of contact lenses, positioned with the concave side facing upward
2781:
2766:
1553:
1504:
1439:
Trivex was invented by Edwin C. Slagel and patented in
September 1998.
1426:
1375:
1312:
1290:
1155:
1084: in this section. Unsourced material may be challenged and removed.
978:
773:
608:. Lens materials are classified by their refractive index, as follows:
556: in this section. Unsourced material may be challenged and removed.
244:
223:
177:
2890:
2835:
1318:
very large size lenses, such as might cover a good portion of the face
2625:
1583:
1227:
made by the German company Schott with the following characteristics
814:
813:
Is very insensitive, especially to color, in the periphery (i.e., at
597:
441:
161:
817:
points distant from the achromatic axis and thus not falling on the
2963:
Code of
Federal Regulations Title 21 "Food and Drugs" Sec. 801.410
2550:
Indices of refraction for a range of materials can be found in the
2572:
1388:
1172:
964:
913:
892:
misalignment between the pupil and the optical center of the lens.
863:
750:
742:
734:
450:
426:
320:
292:
131:
2817:"Correcting refractive error in low income countries (editorial)"
1429:: 1.1 g/cm³ (the lightest corrective lens material in common use)
1579:. This makes them particularly suitable for rimless eyeglasses.
1550:): 42–32 (higher indexes generally result in lower Abbe numbers)
877:
is very dispersive but has excellent shatter resistance. Trivex
427:
145:
2701:
of the corrective lens: This phenomenon is called lens-induced
2978:
Refractive surgery or contact lenses – how and when to decide?
1053:
525:
149:
29:
481:
power. The "bifocal" is a third spherical segment, called an
2706:
2966:
Use of impact-resistant lenses in eyeglasses and sunglasses
1775:
X-Cell, Phillips, VisionEase, Zhong Chuan
Optical (China)
711:
Manufacturing defects have more impact on optical quality.
1216:
which is commonly used in telescopes and binoculars, and
1183:
Higher-quality optical-grade glass materials exist (e.g.
2674:
Optical aberrations of the eye lens vs. corrective lens
1256:
One must bear in mind that the human eye itself has an
3012:
3010:
3008:
2644:
Resists damage to lens surfaces from minor scratches.
2933:
2931:
226:
steps (0.25 D) because most people cannot generally
2980:, Clinical Optometry, Dove Press, p 68, 10 Nov 2011
2608:is used to reduce the transmission of light in the
931:
Minimizing power error and lens induced astigmatism
60:. Unsourced material may be challenged and removed.
1253:and are commonly used in high-end camera lenses).
3083:
3081:
3079:
3077:
3034:
3032:
3041:MAFO Ophthalmic labs & Industry, April 2009
2428:PPG, Augen, HOYA, Thai Optical, X-cel, Younger
825:responsible for color vision are concentrated.
715:from the optical centre of the lens (off-axis).
2648:Confusing corrective lens industry terminology
1423:): 43–45 (depending on licensing manufacturer)
596:is generally specified concerning the yellow
188:are surgically implanted most commonly after
184:are worn directly on the surface of the eye.
8:
1446:for the military as transparent armor. With
739:Chromatic aberration caused by a convex lens
693:, meaning, amongst other things, increased
1887:
1604:
459:require varying the back surface curvature
2739:U.S. legal requirements for prescriptions
1391:lenses are inherently scratch resistant.
1100:Learn how and when to remove this message
977:Extremely thick lenses for myopia can be
669:
572:Learn how and when to remove this message
455:Constant corrective power with different
120:Learn how and when to remove this message
27:Type of lens to improve visual perception
2988:
2986:
704:equation), increasing the importance of
3017:Bruneni, Joseph L. (1 September 2001).
2807:
2525:
1868:
1289:contain oxides of heavy metals such as
2616:radiation increases the likelihood of
2397:Tegra (Vision-Ease) Airwear (Essilor)
1321:low wearer tolerance of color fringing
1943:
1937:
1931:
1925:
1921:
1917:
1912:
1906:
1899:
1895:
1654:
1645:
1639:
1635:
1631:
1626:
1621:
1614:
1610:
1571:, which can be seen from their lower
297:Typical pair of single vision glasses
7:
3089:"MR™ Series | Products Line up"
1082:adding citations to reliable sources
829:Anatomy and Physiology of the Retina
554:adding citations to reliable sources
254:between the eyes or the presence of
58:adding citations to reliable sources
1803:Zeiss, Zhong Chuan Optical (China)
1599:Ophthalmic material property tables
1522:High-index plastics (thiourethanes)
1021:Facial distortion and social stigma
668:Thinner, sometimes lighter lenses (
2914:. SLACK Incorporated. p. 62.
2716:Aspheric and atoric disambiguation
2653:Spheric vs. aspheric, atoric, etc.
2633:
684:Disadvantages of increased indices
156:. The most common use is to treat
25:
1875:Reflected light calculated using
901:Power error is the change in the
862:Glass (2× weight of plastics) or
200:Prescription of corrective lenses
2746:FTC 2004 review of section 456.2
2532:Reflected light calculated from
1442:Trivex was developed in 2001 by
1058:
910:Lens induced oblique astigmatism
530:
210:Corrective lenses are typically
34:
2703:oblique astigmatism error (OAE)
1069:needs additional citations for
1038:Either situation can result in
541:needs additional citations for
275:Self-selected corrective lenses
45:needs additional citations for
2911:The Eye Exam: A Complete Guide
2657:Lens manufacturers claim that
2620:, while long-term exposure to
1:
1311:extreme positive or negative
398:The power or focal length of
2815:Keay L, Friedman DS (2011).
2487:(also Vision 3456 (Kodak)?)
1747:X-Cel, VisionEase, Phillips
849:Food and Drug Administration
764:, which is specified by the
679:over CR-39 and glass lenses.
663:Advantages of higher indices
431:Common lens optical profiles
400:adjustable or variable focus
370:the name "no-line bifocal".
192:removal but can be used for
3019:"Alternative lens material"
2629:
2541:Fresnel reflection equation
1877:Fresnel reflection equation
604:, commonly abbreviated as n
386:because they have multiple
238:Over-the-counter correction
146:transmissive optical device
3168:
2908:Schwartz, Gary S. (2006).
2683:Astigmatism disambiguation
2580:
2561:
2552:list of refractive indices
1185:Borosilicate crown glasses
728:
232:binocular vision disorders
203:
194:purely refractive purposes
3119:"WAIS Document Retrieval"
2624:radiation can damage the
2156:Daemyung Optical (Ramia)
499:progressive addition lens
2940:"Ophthalmic Lens Design"
2308:Hyperindex 174 (Optima)
642:Very high index: 1.76 ≤
267:and made by a qualified
2583:Anti-reflective coating
961:Reducing lens thickness
706:anti-reflective coating
2994:US Expired 6127505
2689:astigmatism of the eye
2600:Ultraviolet protection
2578:
970:
919:
918:Effects of astigmatism
757:
748:
740:
476:Bifocals and trifocals
460:
432:
330:
298:
137:
3039:Is the sky the limit?
2895:www.wernerkoeppen.com
2772:Eyeglass prescription
2691:, and can be given a
2576:
2402:PPG Trivex (average)
1569:chromatic aberrations
1340:higher-index lenses.
1113:Optical crown glass (
968:
917:
754:
746:
738:
612:Normal index: 1.48 ≤
454:
430:
324:
296:
206:Eyeglass prescription
135:
3056:www.essilorpro.co.uk
2342:Nikon 5 Plastic NL5
2313:Nikon 4 Plastic NL4
1078:improve this article
956:Cosmetics and weight
770:chromatic aberration
695:chromatic aberration
550:improve this article
423:Lens optical profile
367:Progressive addition
148:that is worn on the
54:improve this article
3062:on 25 February 2017
2281:MR-174 1.74 Plastic
2221:MR-10 1.67 Plastic
2130:MR-7 1.665 Plastic
1892:
1607:
1359:): 1.498 (standard)
632:High-index: 1.60 ≤
228:distinguish between
3123:www.leginfo.ca.gov
3093:www.mitsuichem.com
2872:. All about vision
2640:Scratch resistance
2579:
2251:MR-20 1.6 Plastic
2161:MR-7 1.67 Plastic
2042:Essilor Ormix 1.6
1888:
1719:VisionEase, X-Cel
1605:
971:
946:Tscherning ellipse
920:
758:
749:
741:
702:Fresnel reflection
622:Mid-index: 1.54 ≤
503:parametric surface
461:
433:
384:progressive lenses
331:
299:
186:Intraocular lenses
138:
3142:Corrective lenses
3099:on 6 October 2017
2938:Meister, Darryl.
2866:"Reading Glasses"
2836:10.1136/bmj.d4793
2787:Photochromic lens
2520:
2519:
2462:SOLA Spectralite
2191:MR-8 1.6 Plastic
2101:MR-6 1.6 Plastic
1986:CR-39 Hard Resin
1863:
1862:
1562:: 380–400 nm
1556:: 1.3–1.5 (g/cm³)
1110:
1109:
1102:
582:
581:
574:
158:refractive errors
154:visual perception
130:
129:
122:
104:
69:"Corrective lens"
16:(Redirected from
3159:
3127:
3126:
3115:
3109:
3108:
3106:
3104:
3095:. Archived from
3085:
3072:
3071:
3069:
3067:
3058:. Archived from
3048:
3042:
3036:
3027:
3026:
3023:Eyecare Business
3014:
3003:
3002:
3001:
2997:
2990:
2981:
2975:
2969:
2961:
2955:
2954:
2952:
2950:
2935:
2926:
2925:
2905:
2899:
2898:
2887:
2881:
2880:
2878:
2877:
2862:
2856:
2855:
2821:
2812:
2544:
2535:
2530:
2501:1.49 g/cm³
2471:1.21 g/cm³
2442:1.22 g/cm³
2411:1.11 g/cm³
2380:1.20 g/cm³
2351:1.46 g/cm³
2322:1.35 g/cm³
2291:1.47 g/cm³
2282:
2260:1.30 g/cm³
2230:1.37 g/cm³
2200:1.30 g/cm³
2170:1.35 g/cm³
2139:1.35 g/cm³
2110:1.34 g/cm³
2080:1.41 g/cm³
2051:1.30 g/cm³
2025:1.28 g/cm³
1995:1.31 g/cm³
1981:
1976:
1971:
1966:
1959:
1954:
1893:
1891:
1890:Optical plastics
1880:
1873:
1846:2.41 g/cm³
1837:
1817:2.54 g/cm³
1789:4.02 g/cm³
1761:3.37 g/cm³
1733:2.93 g/cm³
1705:2.62 g/cm³
1691:
1686:
1681:
1676:
1669:
1664:
1652:
1608:
1595:
1590:
1546:
1533:
1528:Refractive index
1497:
1484:
1479:Refractive index
1467:
1462:
1448:Hoya Corporation
1419:
1406:
1401:Refractive index
1368:
1355:
1350:Refractive index
1335:Optical plastics
1303:
1288:
1286:
1280:
1267:
1262:
1252:
1250:
1246:
1241:
1237:
1232:
1215:
1213:
1209:
1204:
1200:
1195:
1177:refractive index
1145:
1132:
1127:Refractive index
1105:
1098:
1094:
1091:
1085:
1062:
1054:
887:
882:
876:
871:
861:
856:
801:
796:
790:
785:
655:
645:
635:
625:
615:
594:refractive index
577:
570:
566:
563:
557:
534:
526:
522:Refractive index
493:Progressive lens
417:refractive error
394:Adjustable focus
252:refractive error
125:
118:
114:
111:
105:
103:
62:
38:
30:
21:
3167:
3166:
3162:
3161:
3160:
3158:
3157:
3156:
3132:
3131:
3130:
3117:
3116:
3112:
3102:
3100:
3087:
3086:
3075:
3065:
3063:
3050:
3049:
3045:
3037:
3030:
3016:
3015:
3006:
2999:
2992:
2991:
2984:
2976:
2972:
2962:
2958:
2948:
2946:
2937:
2936:
2929:
2922:
2907:
2906:
2902:
2889:
2888:
2884:
2875:
2873:
2864:
2863:
2859:
2819:
2814:
2813:
2809:
2805:
2758:
2741:
2718:
2695:to correct it.
2685:
2676:
2659:aspheric lenses
2655:
2650:
2642:
2602:
2585:
2571:
2569:Anti-reflective
2566:
2564:Optical coating
2560:
2548:
2547:
2538:
2533:
2531:
2527:
2280:
1979:
1974:
1969:
1964:
1962:
1957:
1952:
1950:
1945:
1941:
1939:
1935:
1933:
1929:
1923:
1919:
1914:
1910:
1908:
1903:
1901:
1897:
1889:
1884:
1883:
1874:
1870:
1836:PhotoGray Extra
1835:
1689:
1684:
1679:
1674:
1672:
1667:
1662:
1660:
1650:
1649:
1647:
1643:
1641:
1637:
1633:
1628:
1623:
1618:
1616:
1612:
1601:
1593:
1588:
1587:
1549:
1544:
1536:
1531:
1524:
1500:
1495:
1487:
1482:
1475:
1465:
1460:
1459:
1422:
1417:
1409:
1404:
1397:
1371:
1366:
1358:
1353:
1346:
1337:
1306:
1301:
1284:
1283:
1278:
1277:
1265:
1260:
1259:
1248:
1247:
1244:
1239:
1238:
1235:
1230:
1228:
1214:= 2.51 g/cm³ ),
1211:
1210:
1207:
1202:
1201:
1198:
1193:
1191:
1148:
1143:
1135:
1130:
1123:
1119:Soda/lime glass
1106:
1095:
1089:
1086:
1075:
1063:
1052:
1023:
996:
986:design lenses.
963:
958:
933:
912:
899:
885:
880:
878:
874:
869:
867:
859:
854:
852:
799:
794:
792:
788:
783:
781:
733:
727:
722:
720:Optical quality
686:
665:
658:
653:
648:
643:
638:
633:
628:
623:
618:
613:
607:
602:Fraunhofer line
578:
567:
561:
558:
547:
535:
524:
515:Vertex distance
512:
510:Vertex distance
495:
478:
425:
413:
396:
376:
364:
351:Trifocal lenses
348:
319:
291:
286:
277:
261:ophthalmologist
240:
216:ophthalmologist
208:
202:
142:corrective lens
126:
115:
109:
106:
63:
61:
51:
39:
28:
23:
22:
18:Reading glasses
15:
12:
11:
5:
3165:
3163:
3155:
3154:
3149:
3144:
3134:
3133:
3129:
3128:
3110:
3073:
3043:
3028:
3004:
2982:
2970:
2956:
2944:OptiCampus.com
2927:
2920:
2900:
2882:
2857:
2806:
2804:
2801:
2800:
2799:
2794:
2789:
2784:
2779:
2774:
2769:
2764:
2757:
2754:
2740:
2737:
2717:
2714:
2684:
2681:
2675:
2672:
2654:
2651:
2649:
2646:
2641:
2638:
2601:
2598:
2581:Main article:
2570:
2567:
2562:Main article:
2559:
2556:
2546:
2545:
2536:
2524:
2523:
2522:
2521:
2518:
2517:
2515:
2513:
2510:
2508:
2505:
2502:
2499:
2496:
2493:
2489:
2488:
2485:
2483:
2480:
2478:
2475:
2472:
2469:
2466:
2463:
2459:
2458:
2456:
2454:
2451:
2449:
2446:
2443:
2440:
2437:
2434:
2433:SOLA Finalite
2430:
2429:
2426:
2423:
2420:
2418:
2415:
2412:
2409:
2406:
2403:
2399:
2398:
2395:
2392:
2389:
2387:
2384:
2381:
2378:
2375:
2372:
2371:Polycarbonate
2368:
2367:
2365:
2363:
2360:
2358:
2355:
2352:
2349:
2346:
2343:
2339:
2338:
2336:
2334:
2331:
2329:
2326:
2323:
2320:
2317:
2314:
2310:
2309:
2306:
2304:
2301:
2298:
2295:
2292:
2289:
2286:
2283:
2277:
2276:
2274:
2272:
2269:
2267:
2264:
2261:
2258:
2255:
2252:
2248:
2247:
2245:
2243:
2240:
2237:
2234:
2231:
2228:
2225:
2222:
2218:
2217:
2215:
2213:
2210:
2207:
2204:
2201:
2198:
2195:
2192:
2188:
2187:
2185:
2183:
2180:
2177:
2174:
2171:
2168:
2165:
2162:
2158:
2157:
2154:
2151:
2148:
2146:
2143:
2140:
2137:
2134:
2131:
2127:
2126:
2124:
2122:
2119:
2117:
2114:
2111:
2108:
2105:
2102:
2098:
2097:
2095:
2092:
2089:
2087:
2084:
2081:
2078:
2075:
2072:
2068:
2067:
2065:
2063:
2060:
2058:
2055:
2052:
2049:
2046:
2043:
2039:
2038:
2036:
2034:
2032:
2030:
2028:
2026:
2023:
2020:
2017:
2013:
2012:
2010:
2007:
2004:
2002:
1999:
1996:
1993:
1990:
1987:
1983:
1982:
1977:
1972:
1967:
1960:
1955:
1947:
1946:
1942:
1936:
1930:
1924:
1920:
1916:
1911:
1905:
1898:
1882:
1881:
1867:
1866:
1865:
1864:
1861:
1860:
1858:
1856:
1853:
1850:
1847:
1844:
1841:
1838:
1832:
1831:
1829:
1827:
1824:
1821:
1818:
1815:
1812:
1809:
1805:
1804:
1801:
1799:
1796:
1793:
1790:
1787:
1784:
1781:
1777:
1776:
1773:
1771:
1768:
1765:
1762:
1759:
1756:
1753:
1749:
1748:
1745:
1743:
1740:
1737:
1734:
1731:
1728:
1725:
1721:
1720:
1717:
1715:
1712:
1709:
1706:
1703:
1700:
1697:
1693:
1692:
1687:
1682:
1677:
1670:
1665:
1657:
1656:
1653:
1644:
1638:
1634:
1630:
1625:
1620:
1613:
1600:
1597:
1591:
1564:
1563:
1557:
1551:
1547:
1538:
1537:): 1.600–1.740
1534:
1523:
1520:
1515:
1514:
1508:
1502:
1498:
1489:
1485:
1474:
1471:
1463:
1444:PPG Industries
1437:
1436:
1430:
1424:
1420:
1411:
1407:
1396:
1393:
1386:
1385:
1379:
1373:
1369:
1360:
1356:
1345:
1342:
1336:
1333:
1332:
1331:
1328:
1325:
1322:
1319:
1316:
1304:
1300:Abbe numbers (
1281:
1263:
1251:= 3.65 g/cm³ )
1242:
1233:
1205:
1196:
1169:
1168:
1159:
1153:
1146:
1137:
1133:
1122:
1111:
1108:
1107:
1066:
1064:
1057:
1051:
1050:Lens materials
1048:
1036:
1035:
1032:
1022:
1019:
1014:
1013:
1010:
1007:
1004:
995:
992:
962:
959:
957:
954:
932:
929:
911:
908:
898:
895:
894:
893:
889:
886:= 43 @ 1.53 ),
883:
872:
857:
844:
835:
834:
811:
797:
786:
729:Main article:
726:
723:
721:
718:
717:
716:
712:
709:
698:
685:
682:
681:
680:
673:
664:
661:
656:
650:
649:
646:
640:
636:
630:
626:
620:
616:
605:
580:
579:
538:
536:
529:
523:
520:
511:
508:
494:
491:
489:lens surface.
477:
474:
424:
421:
412:
409:
395:
392:
375:
372:
363:
360:
347:
344:
318:
315:
290:
287:
285:
282:
276:
273:
239:
236:
204:Main article:
201:
198:
182:Contact lenses
128:
127:
42:
40:
33:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
3164:
3153:
3150:
3148:
3147:Ophthalmology
3145:
3143:
3140:
3139:
3137:
3124:
3120:
3114:
3111:
3098:
3094:
3090:
3084:
3082:
3080:
3078:
3074:
3061:
3057:
3053:
3047:
3044:
3040:
3035:
3033:
3029:
3024:
3020:
3013:
3011:
3009:
3005:
2995:
2989:
2987:
2983:
2979:
2974:
2971:
2968:
2967:
2960:
2957:
2945:
2941:
2934:
2932:
2928:
2923:
2917:
2913:
2912:
2904:
2901:
2896:
2892:
2886:
2883:
2871:
2867:
2861:
2858:
2853:
2849:
2845:
2841:
2837:
2833:
2829:
2825:
2818:
2811:
2808:
2802:
2798:
2797:Visual acuity
2795:
2793:
2790:
2788:
2785:
2783:
2780:
2778:
2775:
2773:
2770:
2768:
2765:
2763:
2760:
2759:
2755:
2753:
2749:
2747:
2738:
2736:
2733:
2728:
2725:
2723:
2722:aspheric lens
2715:
2713:
2710:
2708:
2704:
2700:
2696:
2694:
2690:
2682:
2680:
2673:
2671:
2667:
2663:
2660:
2652:
2647:
2645:
2639:
2637:
2635:
2634:Polycarbonate
2631:
2627:
2623:
2619:
2615:
2611:
2607:
2599:
2597:
2595:
2589:
2584:
2575:
2568:
2565:
2558:Lens coatings
2557:
2555:
2553:
2542:
2529:
2526:
2516:
2514:
2511:
2509:
2506:
2503:
2500:
2497:
2494:
2491:
2490:
2486:
2484:
2481:
2479:
2476:
2473:
2470:
2467:
2464:
2461:
2460:
2457:
2455:
2452:
2450:
2447:
2444:
2441:
2438:
2435:
2432:
2431:
2427:
2424:
2421:
2419:
2416:
2413:
2410:
2407:
2404:
2401:
2400:
2396:
2393:
2390:
2388:
2385:
2382:
2379:
2376:
2373:
2370:
2369:
2366:
2364:
2361:
2359:
2356:
2353:
2350:
2347:
2344:
2341:
2340:
2337:
2335:
2332:
2330:
2327:
2324:
2321:
2318:
2315:
2312:
2311:
2307:
2305:
2302:
2299:
2296:
2293:
2290:
2287:
2284:
2279:
2278:
2275:
2273:
2270:
2268:
2265:
2262:
2259:
2256:
2253:
2250:
2249:
2246:
2244:
2241:
2238:
2235:
2232:
2229:
2226:
2223:
2220:
2219:
2216:
2214:
2211:
2208:
2205:
2202:
2199:
2196:
2193:
2190:
2189:
2186:
2184:
2181:
2178:
2175:
2172:
2169:
2166:
2163:
2160:
2159:
2155:
2152:
2149:
2147:
2144:
2141:
2138:
2135:
2132:
2129:
2128:
2125:
2123:
2120:
2118:
2115:
2112:
2109:
2106:
2103:
2100:
2099:
2096:
2093:
2090:
2088:
2085:
2082:
2079:
2076:
2073:
2070:
2069:
2066:
2064:
2061:
2059:
2056:
2053:
2050:
2047:
2044:
2041:
2040:
2037:
2035:
2033:
2031:
2029:
2027:
2024:
2021:
2018:
2015:
2014:
2011:
2008:
2005:
2003:
2000:
1997:
1994:
1991:
1988:
1985:
1984:
1978:
1973:
1961:
1949:
1948:
1928:
1894:
1886:
1885:
1878:
1872:
1869:
1859:
1857:
1854:
1851:
1848:
1845:
1842:
1839:
1834:
1833:
1830:
1828:
1825:
1822:
1819:
1816:
1813:
1810:
1807:
1806:
1802:
1800:
1797:
1794:
1791:
1788:
1785:
1782:
1779:
1778:
1774:
1772:
1769:
1766:
1763:
1760:
1757:
1754:
1751:
1750:
1746:
1744:
1741:
1738:
1735:
1732:
1729:
1726:
1723:
1722:
1718:
1716:
1713:
1710:
1707:
1704:
1701:
1698:
1695:
1694:
1688:
1683:
1671:
1659:
1658:
1609:
1603:
1602:
1598:
1596:
1585:
1580:
1578:
1577:polycarbonate
1574:
1570:
1561:
1558:
1555:
1552:
1542:
1539:
1529:
1526:
1525:
1521:
1519:
1513:: 385 nm
1512:
1509:
1506:
1503:
1493:
1490:
1480:
1477:
1476:
1473:Polycarbonate
1472:
1470:
1457:
1456:polycarbonate
1452:
1449:
1445:
1440:
1435:: 394 nm
1434:
1431:
1428:
1425:
1415:
1412:
1402:
1399:
1398:
1394:
1392:
1390:
1384:: 355 nm
1383:
1380:
1377:
1374:
1364:
1361:
1351:
1348:
1347:
1343:
1341:
1334:
1329:
1326:
1323:
1320:
1317:
1315:prescriptions
1314:
1310:
1309:
1308:
1298:
1296:
1292:
1276:
1271:
1268:
1254:
1226:
1222:
1221:crown glasses
1219:
1190:
1186:
1181:
1178:
1174:
1167:
1163:
1160:
1157:
1154:
1152:
1141:
1138:
1128:
1125:
1124:
1120:
1116:
1112:
1104:
1101:
1093:
1083:
1079:
1073:
1072:
1067:This section
1065:
1061:
1056:
1055:
1049:
1047:
1043:
1041:
1040:social stigma
1033:
1029:
1028:
1027:
1020:
1018:
1011:
1008:
1005:
1002:
1001:
1000:
993:
991:
987:
983:
980:
975:
967:
960:
955:
953:
949:
947:
943:
937:
930:
928:
925:
916:
909:
907:
904:
903:optical power
896:
890:
865:
850:
845:
841:
840:
839:
832:
830:
824:
820:
816:
812:
808:
807:
806:
803:
777:
775:
771:
767:
763:
753:
745:
737:
732:
724:
719:
713:
710:
707:
703:
699:
696:
692:
688:
687:
683:
678:
677:UV protection
674:
671:
667:
666:
662:
660:
641:
631:
621:
611:
610:
609:
603:
599:
595:
591:
587:
576:
573:
565:
555:
551:
545:
544:
539:This section
537:
533:
528:
527:
521:
519:
516:
509:
507:
504:
500:
492:
490:
486:
484:
475:
473:
470:
466:
458:
453:
449:
447:
443:
439:
429:
422:
420:
418:
410:
408:
406:
405:field of view
401:
393:
391:
389:
385:
381:
373:
371:
368:
361:
359:
357:
352:
345:
343:
341:
336:
328:
323:
316:
314:
312:
306:
304:
295:
289:Single vision
288:
283:
281:
274:
272:
270:
266:
262:
257:
253:
248:
246:
237:
235:
233:
229:
225:
221:
217:
213:
207:
199:
197:
195:
191:
187:
183:
179:
175:
171:
167:
166:hypermetropia
163:
159:
155:
151:
147:
143:
134:
124:
121:
113:
102:
99:
95:
92:
88:
85:
81:
78:
74:
71: –
70:
66:
65:Find sources:
59:
55:
49:
48:
43:This article
41:
37:
32:
31:
19:
3122:
3113:
3101:. Retrieved
3097:the original
3092:
3064:. Retrieved
3060:the original
3055:
3046:
3022:
2977:
2973:
2965:
2959:
2949:November 12,
2947:. Retrieved
2943:
2910:
2903:
2894:
2885:
2874:. Retrieved
2869:
2860:
2827:
2823:
2810:
2762:Contact lens
2750:
2742:
2729:
2726:
2719:
2711:
2697:
2686:
2677:
2668:
2664:
2656:
2643:
2603:
2596:qualities.
2590:
2586:
2549:
2528:
2425:1.0 mm
2394:1.0 mm
2239:100 °C
2209:118 °C
2153:1.2 mm
2094:1.5 mm
2009:2.0 mm
1871:
1808:Crown Glass
1581:
1573:Abbe numbers
1565:
1516:
1453:
1441:
1438:
1387:
1378:: 1.31 g/cm³
1338:
1299:
1272:
1258:Abbe number
1255:
1182:
1170:
1096:
1090:January 2015
1087:
1076:Please help
1071:verification
1068:
1044:
1037:
1024:
1015:
997:
988:
984:
976:
972:
950:
942:Oswalt curve
938:
934:
921:
900:
836:
826:
821:, where the
804:
778:
759:
651:
583:
568:
562:January 2015
559:
548:Please help
543:verification
540:
513:
496:
487:
482:
479:
469:Optometrists
462:
434:
414:
397:
388:focal points
377:
365:
355:
349:
332:
307:
300:
278:
249:
241:
209:
141:
139:
116:
110:January 2015
107:
97:
90:
83:
76:
64:
52:Please help
47:verification
44:
3052:"Ormix 1.6"
2707:power error
2699:Astigmatism
2610:ultraviolet
2594:hydrophobic
2300:78 °C
2179:85 °C
1541:Abbe number
1507:: 1.2 g/cm³
1492:Abbe number
1414:Abbe number
1363:Abbe number
1275:Abbe number
1199:= 1.51680 ,
1140:Abbe number
990:thickness.
924:astigmatism
897:Power error
766:Abbe number
731:Abbe number
725:Abbe number
691:Abbe number
483:add segment
457:base curves
362:Progressive
303:accommodate
265:optometrist
256:astigmatism
220:optometrist
170:astigmatism
152:to improve
3136:Categories
2921:1556427557
2876:2010-06-14
2803:References
2732:toric lens
2693:toric lens
2612:spectrum.
2606:UV coating
2071:Hoya EYRY
1780:1.9 Glass
1752:1.8 Glass
1724:1.7 Glass
1696:1.6 Glass
1136:): 1.52288
823:cone cells
762:dispersion
465:base curve
446:presbyopia
374:Multifocal
340:presbyopia
284:Lens types
212:prescribed
174:presbyopia
80:newspapers
3152:Optometry
2852:220113341
2830:: d4793.
2792:Pince-nez
2777:Lorgnette
2618:cataracts
1940:thickness
1932:Reflected
1651:typ / min
1648:thickness
1640:Reflected
1560:UV cutoff
1511:UV cutoff
1433:UV cutoff
1382:UV cutoff
1295:lanthanum
1245:= 90.90 ,
1236:= 1.456 ,
1208:= 64.17 ,
1162:UV cutoff
875:= 30–32 )
675:Improved
670:See below
639:< 1.74
629:< 1.60
619:< 1.54
438:hyperopia
3103:14 March
3066:14 March
2844:21828208
2756:See also
1975:(g/cm³)
1938:Minimum
1915:gravity
1913:Specific
1896:Material
1685:(g/cm³)
1629:gravity
1627:Specific
1611:Material
1594:= 1.74 .
1488:): 1.586
1466:= 1.532
1410:): 1.532
1218:fluorite
1187:such as
588:and the
380:bifocals
346:Trifocal
327:bifocals
269:optician
245:diopters
190:cataract
2870:Over 40
2782:Monocle
2767:Dioptre
2512:15.16%
2453:10.65%
2391:10.27%
2362:14.59%
2333:12.59%
2303:14.36%
2271:10.65%
2242:12.34%
2212:10.43%
2182:12.26%
2150:12.45%
2121:10.57%
2091:13.44%
2062:10.65%
1900:Refrac-
1798:18.85%
1770:16.47%
1742:13.47%
1714:10.68%
1646:Minimum
1624:number
1615:Refrac-
1554:Density
1505:Density
1427:Density
1376:Density
1372:): 59.3
1313:diopter
1291:arsenic
1266:≈ 50.2
1156:Density
979:beveled
944:on the
815:retinal
584:In the
335:bifocal
317:Bifocal
224:diopter
178:Glasses
94:scholar
3000:
2918:
2850:
2842:
2630:Trivex
2626:retina
2539:using
2492:Tokai
2482:8.96%
2422:8.70%
2374:1.586
2133:1.665
2016:NK-55
2006:7.97%
1909:number
1904:index
1855:8.59%
1840:1.523
1826:8.59%
1811:1.525
1783:1.893
1755:1.800
1727:1.706
1699:1.604
1655:Notes
1619:index
1606:Glass
1584:sulfur
1395:Trivex
1225:N-FK58
1166:320 nm
994:Weight
800:≤ 58 )
789:≤ 45 )
689:Lower
592:, the
442:myopia
325:These
218:or an
214:by an
172:, and
162:myopia
96:
89:
82:
75:
67:
2848:S2CID
2820:(PDF)
2507:100%
2504:100%
2495:1.76
2474:100%
2465:1.54
2448:100%
2445:100%
2436:1.60
2417:100%
2414:100%
2405:1.53
2386:100%
2383:100%
2357:100%
2354:100%
2345:1.74
2328:100%
2325:100%
2316:1.67
2297:100%
2294:100%
2285:1.74
2266:100%
2263:100%
2254:1.60
2236:100%
2233:100%
2224:1.67
2206:100%
2203:100%
2176:100%
2173:100%
2164:1.67
2145:100%
2142:100%
2116:100%
2113:100%
2086:100%
2083:100%
2074:1.70
2057:100%
2054:100%
2019:1.56
1998:100%
1989:1.49
1980:(mm)
1944:Notes
1934:light
1849:100%
1792:100%
1764:100%
1736:100%
1708:100%
1690:(mm)
1642:light
1501:): 30
1389:CR-39
1344:CR-39
1173:CR-39
1031:eyes.
864:CR-39
827:See:
819:fovea
810:poor)
756:lens.
411:Plano
144:is a
101:JSTOR
87:books
3105:2022
3068:2022
2951:2008
2916:ISBN
2840:PMID
2632:and
2622:UV-A
2614:UV-B
2477:98%
2194:1.6
2104:1.6
2045:1.6
2001:90%
1907:Abbe
1902:tive
1852:97%
1823:20%
1820:79%
1795:76%
1767:81%
1739:76%
1711:61%
1622:Abbe
1617:tive
1287:65 ,
1151:58.5
1115:B270
497:The
463:The
356:e.g.
311:nose
73:news
2832:doi
2828:343
2824:BMJ
2748:).
2705:or
2498:30
2468:47
2439:42
2408:44
2377:30
2348:33
2319:32
2288:33
2257:42
2227:32
2197:41
2167:32
2136:32
2107:36
2077:36
2048:41
2022:38
1992:59
1927:HDT
1922:UVA
1918:UVB
1843:57
1814:59
1786:31
1758:25
1730:30
1702:40
1636:UVA
1632:UVB
1293:or
1189:BK7
1149:):
1080:by
600:-d
552:by
382:or
263:or
196:.
150:eye
56:by
3138::
3121:.
3091:.
3076:^
3054:.
3031:^
3021:.
3007:^
2985:^
2942:.
2930:^
2893:.
2868:.
2846:.
2838:.
2826:.
2822:.
2730:A
2604:A
2554:.
1970:)
1958:)
1680:)
1668:)
1229:(
1192:(
1164::
1117:-
879:(
868:(
860:):
853:(
793:(
782:(
672:).
598:He
590:US
586:UK
333:A
176:.
168:,
164:,
160::
140:A
3125:.
3107:.
3070:.
3025:.
2953:.
2924:.
2897:.
2879:.
2854:.
2834::
2537:d
2534:N
1968:d
1965:V
1963:(
1956:d
1953:n
1951:(
1678:d
1675:V
1673:(
1666:d
1663:n
1661:(
1592:d
1589:n
1548:d
1545:V
1543:(
1535:d
1532:n
1530:(
1499:d
1496:V
1494:(
1486:d
1483:n
1481:(
1464:d
1461:n
1421:d
1418:V
1416:(
1408:d
1405:n
1403:(
1370:d
1367:V
1365:(
1357:d
1354:n
1352:(
1305:d
1302:V
1285:≳
1282:d
1279:V
1264:d
1261:V
1249:D
1243:d
1240:V
1234:d
1231:n
1212:D
1206:d
1203:V
1197:d
1194:n
1147:d
1144:V
1142:(
1134:d
1131:n
1129:(
1121:)
1103:)
1097:(
1092:)
1088:(
1074:.
884:d
881:V
873:d
870:V
858:d
855:N
833:)
831:.
798:d
795:V
787:d
784:V
774:D
708:.
697:.
657:d
654:n
647:d
644:n
637:d
634:n
627:d
624:n
617:d
614:n
606:d
575:)
569:(
564:)
560:(
546:.
123:)
117:(
112:)
108:(
98:·
91:·
84:·
77:·
50:.
20:)
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