— by Cate Stevenson, BA
There are a surprising number of things to consider when buying a pair of eyeglasses. The most important decision to be made is probably in regards to the lens. Most people get either single- vision lenses or bifocals. Single-vision lenses are used to correct nearsightedness. Bifocals and other multifocals correct more than one vision problem, such as myopia and presbyopia (an age-related inability to focus on close work).
For those who do need bifocals or multifocals, there’s also the option to get progressive lenses. Progressives have a smooth progression of optical power, helping you to see at intermediate distances as well as near and far. Also, progressives don’t have bifocal lines. For those with double vision, a special prism in eyeglasses may be necessary. This lens enables light to be bent or reflected in certain ways and can also split white light into different wave lengths and colors, helping to correct any vision problems.
If you fall into the “multifocal” category, you’ll want to take note of a recent study conducted at the Prince of Whales Medical Research Institute. According to researchers there, older people might avoid falls if they take off their bifocal or multifocal eyeglasses while taking part in outdoor activities and rely on single-vision lenses instead.
For their study, the research team recruited 606 people over the age of 65 who were at risk of falling and who used multifocal lenses when walking outdoors. The researchers prescribed a pair of single-lens distance glasses to about half of the participants to use when outdoors and in unfamiliar places.
Over the course of 13 months of follow-up, all falls among those who used the single-lens distance glasses fell by eight percent compared to the control group. Among those who regularly spent time outdoors, falls decreased by about 40%. One word of caution from the researchers: outside falls increased among those who rarely went outdoors, suggesting that the single-lens glasses aren’t the way to go if you find yourself in this category.
Remember: when it comes to lenses, you also have some choices to make about the materials they are made from. Most likely you’ll want your lenses as thin as possible, in which case you’ll want to consider getting high-index lenses. If you need a strong prescription, you’ll find that these lenses can get rid of the hated “Coke-bottle” look, and that they are lighter to wear.
And don’t forget to look into photo-chromic lenses. These are lenses that automatically darken when you step outside and return to normal when you go back indoors. And finally, if safety is an issue, go for polycarbonate — it’s an extremely impact-resistant material.