See Change

Corrective lenses — what we call “glasses” — have a long history. In ancient Egypt, people realized that looking through a glass bowl filled with water would magnify print. By the 13th century, there were magnifying glasses to help with reading. In the 16th century, the magnifying glass was streamlined into lenses for people who were nearsighted. In 1775, Benjamin Franklin developed the first bifocal lens.

But nowadays, “glasses” usually aren’t glass. Most are plastic, although the word doesn’t really convey the qualities of the new materials. William “Sully” Sullivan describes some of the changes that have improved corrective lenses. Sully and his wife, Liz Sullivan, are owners of Hampton Vision Center and Kittery Opticians in Kittery, Maine.

The new materials are light and impact resistant. Flexon/Trivex, for instance, is lightweight and shatter resistant. It has superior optical quality, blocks ultraviolet rays and is a good choice for rimless glasses. Polycarbonate plastic is another of the new materials. It also is lightweight and shatter resistant, and a good choice for sports glasses and for children. It does scratch easily but can be coated for greater resistance.

High-density plastics make possible the thinnest of lenses. There is some loss of optical quality, but for the person with a very strong prescription, the trade-off in weight may be worth it.

Progressive lenses — changing in focus from distant to near — are popular. Most progressives have a distance focus in the upper lens, a small intermediate focus at mid-lens and a focus for reading in the lower lens. In the past, progressive lenses had to be fairly large, but new techniques now make it possible to use a smaller lens and still have full reading range at the bottom. While no lens replicates the shifting focus of the natural eye, these can work well for people who have to wear glasses in all situations. No more searching for the reading glasses to read labels while shopping, then switching again for the next task.

One specialized progressive lens is especially helpful for people who work at computers — there’s a small area for distance focus at the top, a larger mid-range for computer work and a small area at the bottom for reading. This solves the problem of looking down at text and trying to read with the intermediate range. Electricians may also need a special design to accommodate the time they spend looking up, working at arms’ length.

Sully recommends anti-reflective coating for lenses. Until recently, coated lenses (often called anti-glare) tended to be greasy and hard to keep clean. That is no longer the case, he says. Coated lenses improve vision both day and night. Reflection off the highway and from oncoming headlights is reduced. The glare of florescent lighting is less bothersome. Vision is actually improved, he says, because the coated lens lets in more light than regular lenses.

Frame materials have also improved in recent years. Titanium is the lightest of the new materials. Memory metal, which resumes its shape even after being twisted or bent, is titanium blended with nickel. Given the rough treatment glasses often get, this could be an advantage.

Contacts, too, have evolved since the early days of “hard” contacts. Now made of materials such as silicone hydrogel, they are more comfortable and easier to insert. These permeable materials let in more oxygen and reduce the dryness that made older contacts feel scratchy.

Progressive contact lenses and contacts for people with astigmatism are now available. There are disposable contacts that require no cleaning, but they do cost more. You can also choose contacts to change or enhance your eye color.

There are advantages to wearing contact lenses, but there can also be problems. Some wearers find the process a bother. There is the possibility of dry eyes and corneal abrasions. A person who lives or works in a dusty environment may not be able to wear contact lenses.

Sunglasses are growing in popularity. Sully says this is positive, but he urges caution. Poorly made sunglasses can distort vision. The best sunglasses are ground as if they were prescription, even if correction is not needed. They should be UVA- and UVB-protective and polarized.

They should fit so that the wearer is protected from glare from above and below. The glare from water, pavement, snow or sand is intense. People whose work or sports puts them in such situations should always use sunglasses. There are also light-weight sunglasses that fit over regular glasses that give good protection. Sunglasses with a built-in MP3 player in the temple are now available.

Glasses for industrial use must be thicker than conventional glasses and must meet standards of the Occupational Safety and Health Administration (OSHA). Frame materials also have to pass rigorous tests for approval. A “Z87” stamped on frames signifies approval. Sully suggests that safety glasses may also be needed at home. “More eye injuries occur at home than in industry,” he says. Brush cutting, weed-whacking, woodworking and other home projects can result in eye injuries.

Has Lasik surgery eliminated the need for glasses? “No,” says Sully, “not everyone with a vision problem is suitable for the procedure. And between the varied demands of modern life and the options for specialization, the use of glasses is growing.” Plus, he says, glasses — once seen as unattractive but necessary, and worn reluctantly — have become fashionable.

The Hampton Vision Center even gets requests for glasses from people who don’t need corrective lenses but want to be in style. NH