Though the first attempts to make spectacles date back to the 13th century, there's no question that more changes have occurred in the last 100 years than during the seven centuries preceding it. While all the 20th century developments could not possibly be included on these pages, the OLA invites you to track lens evolution by looking at some of the great moments in 10 major areas of advancement between 1900 and 2000.

1. Kryptok and the Bifocal Battles

The new century finds the lens industry in a state of turmoil dating back to Ben Franklin, reputed inventor of bifocals. From his time on, there are numerous attempts to provide better vision for presbyopes. Most are ineffective or too expensive. One of the few that works is the cement bifocal with a thin reading segment cemented to the inside of a distance lens. Following that is the Kryptok -- from the Greek "krypte" (hidden) and "tok" (eye) -- the first successful near-invisible bifocal.

1900: The Kryptok story actually starts a year earlier, in 1899, when Dr. John Borsch invents the original cemented Kryptok bifocal and quickly confines its sale to large retail dispensing opticians. Borsch sells marketing rights in almost every state, and a lot of money quickly changes hands. For example, Columbian Optical Company pays $8,000 for exclusive rights to market Kryptok in Colorado, Kansas, Nebraska, and California. Two weeks later, it sells just the California rights for $10,000. Nonetheless, manufacturing these complicated lenses is difficult, and problems are magnified when holes are drilled for rimless mountings.

1904: Knowing there has to be a better way, Dr. John L. Borsch, Jr. develops a fused Kryptok. The biggest thing to hit the young industry, the lens produces unheard-of profits and ushers in $12 to $20 lenses when others sell for a few dollars. Bootlegging the lenses quickly becomes big business. In response, the Kryptok Association files hundreds of litigation suits.

1910: The first blanks use primitive fusing techniques, and spoilage is frequent. With prices fixed, even retailers are told what to charge. Labs pay $2.50 a pair for flat blanks, and they must charge retailers $7.50 for finished lenses. Retailers in turn must charge $13, and anyone cutting price is dropped from the authorized list. B&L and AO are granted manufacturing rights. Kryptok becomes the first optical product featured in national consumer advertising.

1921: Kryptoks are a technical improvement over previous bifocals but exhibit a drawback every patient notices: Colored rainbows are seen around objects viewed through the segment. Bausch & Lomb starts working on the problem.

1925: The last Kryptok patent expires and now anyone can make them. Kryptoks continue to be the most-used bifocal for years.

1926: Flat top bifocals are conceived in Great Britain and exported to the U.S. The Univis Lens Company is organized to sell them, and, as World War II breaks out, Univis gets manufacturing rights, launching major efforts to convert the professions to flat tops. Soon, every manufacturer is producing them.

1929: As an improvement to flat tops, the Panoptik bifocal is designed, with AO and B&L getting manufacturing licenses. When AO drops the lens, Panoptik becomes B&L's flagship multifocal.

1931: Like Panoptiks, Fulvue is designed to compete with flat tops, avoiding patent infringement. Expensive to produce, they gradually fade into disuse.

1931: B&L develops a color-free Nokrome fused bifocal called Orthogon D. Before long, most manufacturers are producing Nokrome bifocals.

1932: A fused trifocal called Quintex is developed with five separate focal areas. The designer considers this a universal multifocal "age lens," with early advertising reading remarkably like ads for modern PALs.

2. The PAL Generation

1907: The concept of a progressive addition lens is patented this year. Though the first U.S. patent is issued to American Optical in 1924, the first successful PAL doesn't come out until 1959 in Europe. The first PALs -- pioneers, if you will -- were: Varilux I, launched by Essilor in 1959; Omnifocal by Volk, in 1965; Varilux II by Essilor in 1972, and Ultravue 25mm in 1976 by AO.

1975: Essilor and AO are the first to market PALs in the U.S. AO claims its Grohlman Device -- a Rube Goldberg contraption clamped to the patient's frame during dispensing -- is the best way to take PD and pupil measurements. It does, to say the least, confuse the neophyte dispenser. Progressive designs evolve slowly. Early designs are symmetrical; that is, identical for each eye. Next comes separate designs for right and left, followed by variations by add, PALs designed differently for myopes and hyperopes, and then the all-aspheric PAL.

1998: Two manufacturers put atoric surfaces on the backside, claiming enhanced acuity and wider field of view. Processed in Europe, they are shipped uncut to U.S. labs. Another European lens manufacturer introduces its version of an atoric progressive.

1999: At least 100 progressive lenses are now selling in the U.S., and one development involves "as worn" PAL designs. Here, the fitter's prescription is computed and modified to compensate for inequities introduced when lenses are positioned before the eyes.

3. Converting to Corrected Curve Lenses

1913: Lens designers know larger lenses produce inherent visual shortcomings. "Marginal astigmatism" is the term coined for these distortions. Germany's Carl Zeiss Company reduces these problems with its Punktal lenses, concluding that by changing front curves for each power, marginal astigmatism is minimized. Punktal lenses are remarkably advanced, and B&L introduces them to the American market. They do, however, have one shortcoming -- every correction demands a change in base curve, and, therefore, requires labs to stock blanks in hundreds of variations. Partly because of this, Punktal lenses are never commercially successful and are replaced by corrected curve lenses.

1919: AO's Dr. Edgar Tillyer is told to find a compromise between the Punktal approach and toric lenses. He calls his solution "corrected curve" because they minimize marginal astigmatism by changing base curves for every one to two diopters of power, thus limiting the range of semi-finished blanks to less than 10. AO calls them Tillyer lenses; B&L follows suit with Orthogon lenses; and, soon, every manufacturer offers standard 6-base and corrected curve lenses.

1935: Now comes the tough job -- convincing retailers to prescribe corrected curve instead of toric lenses. The cost difference is minimal -- AO charges $1.80 per pair for +0.50 +0.50 Tillyer stock lenses, and the same correction in Centex (toric) is $1.55 a pair. That may only be a difference of 25 cents, but converting the professions took some 30 years. Finally, in the late 1950s, manufacturers begin dropping toric lenses.

4. Plastic's Popularity

1930s: In England, there is considerable research to develop plastic lenses. I-Gard produces acrylic single vision lenses that are distributed by McLeod Optical. However, the acrylic lenses -- the same material that's widely used in aircraft windshields -- are brittle, subject to scratching and yellowing, and soon drop out of sight.

1947: During the war, Pittsburgh Plate and Glass Company (PPG) produces a material called CR 39 -- the 39th experimental cast resin produced by its subsidiary, Columbia Resin Chemical Company. Dr. Robert Graham and his Armorlite Company find that CR 39 produces lightweight lenses that scratch less than acrylic. These lenses enjoy limited sales, however, because the material is difficult to process, expensive at all levels, and its quality is perceived as less than glass. Armorlite is the only company committed to CR 39, and it looks like plastic lenses will never replace glass.

1972: Circumstances change dramatically. First, the federal government rules that all glass lenses must be tempered and impact-tested and, therefore, must be made thicker to withstand the test. Two, the popularity of larger frame styles -- demanding larger, and thus heavier, lenses -- increases. Labs and retailers find a new profit center in plastic lenses. They're more expensive than glass and can be easily tinted to any color.

1994: It takes 20 years, but CR 39 becomes the standard. By 1994, plastic lenses constitute more than 70 percent of domestic lens sales.

5. Photochromics Heat Up

1964: Corning develops glass lenses that darken in the sun. They take the industry by storm. Eyecare professionals now have a premium lens that consumers want, and every lens manufacturer begins producing photochromic lenses. Initially only in single vision, Corning later develops a fusible photochromic glass for multifocals and produces several varieties of photochromic glass.

1981: Corning's success indicates a photochromic plastic lens will be successful, and developing one becomes a quest for the next 15 years. AO launches one, but it is unsuccessful because of poor activation. Rodenstock produces another that works, but is marginally successful because of non-traditional colors.

1990: PPG Industries spends many man-years of R&D during the 1980s and ultimately develops an imbibition process to make plastic lenses photochromic. It forms a joint venture with Essilor International and names the new company Transitions Optical, Inc. The first Transitions lens doesn't darken much and is highly temperature-dependent, but it gets everyone's attention.

1992: Transitions Plus is released, and, finally, the industry has what it wants: a lightweight lens that effectively darkens in the sun. The ensuing consumer advertising campaign helps make Transitions the success story of the 1990s.

1999: While most lens manufacturers now include Transitions in their product line, new competition from other suppliers -- Seiko, Rodenstock, and Corning, to name just three -- is heating up the market like never before.

6. Getting High on HI

1970: The original high index lens, polycarbonate becomes available during the 1970s but dress lenses in poly don't hit the market until the 1980s. The initial product is primitive, and dispensers object to specks of carbon seen in the lens. Polycarbonate lenses are injection molded and a common complaint with early product is distortion from its low Abbe value. Most of the problems, however, come from distortion created during molding, not from the Abbe properties.

1970: High index glass lenses made of flint are now available, but excessive weight minimizes their value. Two years later, FDA impact resistance requirements make them illegal.

1973: Schott Glass produces the 1.70 index High-Lite that can be strengthened chemically. Corning develops a 1.60 photochromic high index glass. Later 1.80 and 1.90 index become available in glass, but the latter cannot be tempered and is only legal in the U.S. if waivers are signed by both doctor and patient.

1981: Poly gets a boost from an unexpected place -- a cowboy who breaks his glasses during a roping accident and sues. The jury rules the accident could have been prevented if polycarbonate lenses had been used. Other lawsuits follow that produce judgments based on patients not being informed about lens materials.

1985: Major improvements take place in poly as resin suppliers improve the raw material, and lens manufacturers find better ways to design molds.

1986: The first plastic high index is 1.56 and is introduced by two companies. By the late 1980s, several importers are bringing in high index plastic lenses, and most manufacturers begin adding high index to their product line.

1989: The index war is on. Optima is the first to introduce 1.60 lenses from Japan and later a 1.66 index.

1991: With less than 15 percent of U.S. labs processing poly, the main problem has been coating back surfaces. This year, however, UV coating equipment becomes available, and labs are now able to produce poly as fast as conventional plastic. Sola takes a different direction with its 1.54 index material called Spectralite, and a new category -- "mid-index" materials between 1.54 and 1.57 -- is born.

1999: Hoya launches the highest index plastic yet -- 1.71 lens. And, as the year ends, close to half of all lenses sold have a higher refractive index than conventional glass or plastic.

7. Adding Up Add-Ons

1913: Color becomes the first lens add-on, introduced initially for treatment of disease and improvement of vision. Dr. William Crookes, a British scientist, develops a colored glass to filter infrared rays called "Crookes." It is a cool blue/gray shade, effective but unattractive in appearance. Then AO's Dr. Edger Tillyer produces an attractive pink color called "Cruxite" which becomes AO's primary cosmetic tint. B&L follows, with, among others, its Soft Lite and Ray-Ban Lenses.

1937: Though Carl Zeiss introduces the first AR coating for optical systems in Germany, it's not used as a lens coating in the U.S. until 1958.

1999: Sales of anti-reflection coatings are steadily increasing. Market share exceeds 10 percent, but many experts believe AR numbers will eventually rival the 60 percent wear rate in Europe. Why? For one thing, after years of slow growth, sales of AR coating equipment are soaring, and many labs now offer in-house service. For another, light transmission has vastly improved. Early single-layer coatings transmitted 96 percent of light. Later two-layer coatings transmitted 97 percent, and the current generation of multi-layer coatings transmit 99.5 percent of light.

8. A Peek at Polarized

1932: A young Harvard student named Edwin Herbert Land produces the first man-made material to polarize light, and AO signs a contract with him to produce Polaroid Day Glasses.

1990s: Increasing consumer interest makes polarized sunwear the fastest growing consumer sunwear product. Polarized prescription lenses are now available in a wide range of lens materials.

9. Aspherics All Around

1950s: Aspheric lenses continue the ongoing quest for improved vision. The first use of aspheric curves is for post-cataract glasses, strong plus lenses worn after cataract removal. In the early 1950s, Dr. David Volk introduces Conoids, primarily for low vision uses.

1958: American Optical introduces Aolite Aspheric Cataract Lens, and other producers followed suit, including the famous Welsh 4-Drop. This important market is later wiped out as surgeons begin implanting interocular lenses.

1991: Rodenstock introduces aspheric curves for conventional dress lenses. Available only in plus, their success leads other manufacturers to follow; and within a year, minus aspheric lenses are also available.

Mid-1990s: Sola creates a mid-index line of all-aspheric lenses, calling the material Spectralite, and Seiko launches an all-aspheric photochromic line.

1998: By adding aspheric design, vendors move their products into the premium category. Vision-Ease introduces an all-aspheric polycarbonate line (Tegra�). And a new company, 2C Optics, is formed to produce uncut ophthalmic lenses by casting them to prescription utilizing aspheric designs.

10. The Atoric Challenge

1998: Backside aspheric lenses are introduced by two manufacturers and are available in stock lens form as laboratories here do not surface atoric curves. Atoric progressives -- boasting a widened field of view -- are also introduced. Whether single vision or bifocal, one of the major lens changes during the last 25 years has been the gradual erosion of brand identification. Between 1930 and 1970, brand identity was important. Today, however, few offices know which brand of single vision or bifocal lenses they dispense. The two exceptions are progressives and photochromics.

And looking ahead, experts say that as manufacturers begin advertising directly to consumers, recognition will increase in other categories as well. That, they say, will create a new marketplace in the new millennium. EB