polycarbonate eyeglass lenses found significantly safer in study - polycarbonate plastic
Susan Gilbert Zhan
1997 when buying glasses, most people concentrate on the style and fit of the frame.
But eye doctors encourage consumers to look carefully at lens materials for prescription glasses, non-prescription sunglasses, and safety goggles.
A new study has found that a material, the polyester plastic, is more likely to break.
More resistant than others
Although all glass and plastic lenses tested in the study met the federal crushing standards
Resistance, only when the force generated in the event of a common accident, such as falling off the bike, does not break, is hit by an inflatable airbag or is hit by metal debris, this may happen in the manufacturing plant.
The findings questioned the safety of many safety glasses in certain accidents, Dr. Paul F.
Vinger is an eye doctor at the School of Medicine at the University of taftz and the lead author of the study, published today in the Journal of the American Medical Association.
His research suggests that most regular glasses may increase the risk of serious eye injuries by breaking and penetrating the eyes, he said. Dr.
Louis Pizzarello, spokesman for the American Academy of Ophthalmology, also believes that many of the causes of eye injuries may be broken lenses.
The Consumer Product Safety Board estimates that 2,417 cases of eye injuries in 1995 were related to goggles and other eye protection devices, and 2,651 cases were related to glasses.
The new study is the first to put the lens in a series of real shots.
Life accident, doctor.
Air gun bullets, golf, tennis, hockey and baseball are fired at the lens at a gradual increase until the lens breaks.
Some of the lenses in this study are designed for daily use, while others are thick lenses designed for industrial safety glasses and goggles.
Daily and industrial lenses made of acrylic plastic, high
Index plastic and glass are both broken by impact, which is weaker than the test object generated during normal use-
For example, in a tennis match.
Propylene resin cut 1.
9mm thick, the most commonly used plastic for regular glasses, was smashed by a tennis ball of about 55 miles an hour. High-
The thinnest plastic lens index plastic was smashed by a tennis ball about 40 miles an hour.
The glass has withstood the tennis shock of up to 89 miles an hour.
The study found that only polycarbonate plastic designed for daily or safe use remained intact when the object under test was bombed at normal speed.
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Inferred from these tests
In any common accident, regular glasses and safety goggles are broken, such as falling off a bicycle, tripping over a sidewalk or being hit on the face by an inflatable bag, Vinger said.
According to his findings,
Vinger recommends the crushing of federal standards
Strengthen the resistance of wearing glasses and protective lenses.
S. National Standards Institute, a New York company responsible for setting standards, is already considering revising standards for industrial glasses and goggles. Dr.
Pizzarello believes that the standard of wearing glasses should also be revised. Also, doctor.
Vinger urged people to ask for the use of polyfat lenses when ordering glasses.
According to the American Society of optometrists, only 20% of ordinary glasses are currently made of polycarbonate.
The main reason is the need for special equipment, many glasses are not available, doctorVinger said.
"Many opticians are trying to convince patients not to use polycarbonate lenses because they have to put them outdoors," he said . ".
Another factor is cost.
Opticians typically charge between $20 and $75 more for a pair of polyester lenses than for glass or acrylic plastic. Vinger said. But high-
Index plastic is more expensive. Dr. Vinger, Dr.
Pizzarello and other doctors say that for children, adults who exercise or ride bicycles, and anyone with a vision on one eye, the resin lens is essential. Dr.
Vinger recommended these lenses for all his patients.
But some experts say it is excessive for people with low risk of accidents.
Dan Tomson, technical director of the Optical Laboratory Association, a trade association based in Va Fairfax.
It is pointed out that there are some shortcomings in polyfat.
For example, it produces slight peripheral visual distortion in strong prescription lenses and cannot be used in some popular glasses styles, such as some progressive double focus glasses.
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A version of this article appears on page 8 of the national edition of the January 8, 1997 CSRP, titled: it was found in the study that polycarbonate glasses lenses are safer.