Ophthalmic lense

Although the proposed appHcations for photochromic systems are numerous, few have received broad use. By far, the most successful commercial apphcation is the use of photochromic silver halide-containing glasses in prescription eyewear. The convenience of having lenses that darken automatically upon exposure to sunlight has proven appealing to spectacle wearers (35). With the increasing penetration of plastic lenses into the ophthalmic market, the desire for plastic photochromic ophthalmic lenses has also increased, and considerable effort has been spent on the discovery of photochromic systems for plastic eyewear. 

Photochromism Light Ophthalmic lenses, novelty printing, security printing, cosmetics, optical data storage, memories and switches, sensors... 

The soda-lime glasses are used for plate and window glass, containers, light bulbs and ophthalmic lenses. 

Additional azo intermediates, (I), were previously prepared by the authors (1) and used in ophthalmic lenses and are discussed. 

Functionalized diazo dye monomers, (II), were prepared by Hagting et aL (3) and used to prepare ophthalmic lenses that absorbed light between 400 and 550 nm. 

The low refractive index monomer, diethylene glycol bis allyl carbonate, was prepared by Khandel et al. (4) and used in plastic ophthalmic lenses. 

His research interests include the chemistry of benzopyrans and benzothiopyrans and various aspects of color chemistry. These have resulted in the development of a range of photochromic naphthopyrans which are in commercial use in ophthalmic lenses, security materials, and novelty items. 

J. C. Crano, T. Flood, D. Knowles, A. Kumar, and B. Van Gemert, Photochromic compounds chemistry and application in ophthalmic lenses, Pure Appl. Chem., 68, 1395-1398 (1996). 

Using poly(thiourethane) (PTU) as a polymer matrix for DHIs is a method for generating transparent polymers that may be used for different purposes, such as in ophthalmic lenses or information recording material. The compounds shown in the scheme (Scheme 23) were studied in such a PTU matrix. Typical fading or bleaching... 

Dr. Crano received a B.S. degree in Chemistry in 1957 from Notre Dame and M.S. and Ph.D. degrees from Case Western Reserve University in 1959 and 1962, respectively. He joined PPG Industries in 1961, and had spent his entire career with that firm, at first in various roles in the Chemical Research Development area. In 1974 PPG began research upon means to impart photochromic properties to ophthalmic lenses made from plastics, in particular from poly(allyl diglycol carbonate), CR-39 . Plastic lenses command over 85% of the total ophthalmic market in the US, principally because a lightweight plastic product is more comfortable to wear and permits more attractive fashion designs. 

He has a number of US patents in various areas of technology, including three during 1990-2 that cover the basic compositions and methods for producing the first generation of Transitions lenses. These were important in establishing a strong proprietary position in photochromic plastic ophthalmic lenses. In addition, he had published several reviews and invited lectures on photochromism and photochromic polymers. 

Photochromic Systems for Plastic Ophthalmic Lenses, J. C. Crano, 1997 Gordon Conference on Organic Photochemistry. 

Use Ophthalmic lenses, shields, instrument panels, marine and aircraft glazing. 

Variable-Transmission optical materials such as photochromic ophthalmic lenses or camera filters... 

It is clear that this volume is truly different from the preceding accounts. Photochemists will appreciate Volume 2 as a nice complement to Volume 1, although it can be read independently. Organic photochromic systems are known for their applications in variable-transmission optical materials, ophthalmic lenses, authentification devices (photochromic inks), and novelty items, but they also have great potential in any domain where reversible physical properties are desired (optical memories, gradation masking, optoelectronic systems, nonlinear optical devices, etc.). This book is thus strongly recommended to anyone interested in materials science. 

The two volumes of this new treatise are an outgrowth of the large increase in the number of publications and patents concerning photochromic compounds and their use in various applications (e.g., ophthalmic lenses, security printing, etc.) during the past 10 years. As a result of this increased interest, two successful International Symposia on Photochromism (ISOP) have been held ISOP-93, held in France on Les Embiez Island near Bandol (September 12-16, 1993), and ISOP-96, held in the United States in Clearwater, Florida (September 8-12, 1996). The number of countries represented at each of these symposia (17 and 16, respectively) attests to the international scope of the photochromic research community. This global interest is also exemplified by the authors of the chapters within this book. 

Photochromism has many potential and existing applications that take advantage of a change in colour or other physicochemical properties during the process, for example variable-transmission optical materials such as photochromic eyeglass or ophthalmic lenses that darken in sunlight (using spiropyran and spirooxazine systems in addition to... 

Crano, J. C., Flood, T., Knowles, D., Kumar, A., VanGemert, B., Photochromic Compounds Chemistry and Application in Ophthalmic Lenses, Pure Appl. Chem. 1996, 68, 1395 1398. 

G. A. Chase, T.R. Kozlowski and R.P. Krause, Chemical strengthening of ophthalmic lenses, Am. J. Optom., 50 (1973) 470 and Suresh T. Gulati, Frangibility of Tempered Soda-Lime Glass Sheet, Proc. Glass Processing Days, Tampere, Finland 1997, p. 72,... 

It is worth noticing that the principles ruling transdermal drug delivery are analogous to those occurring in ophthalmic lenses. Indeed, reservoir patches correspond to sandwich-type lenses [177], while matrix patches correspond to therapeutic lenses where the drng is combined with polymer [178]. 

Ophthalmic lenses F-theta lenses Fresnel lenses... 

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