The Best Eyeglasses

How can you tell if you need eyeglasses? If you’re squinting while you read this, the answer is probably “yes.” Knowing which kind of eyeglasses to buy, however, is a trickier question.

There are two basic kinds of eyeglasses: Prescription glasses or over-the-counter. Prescription glasses are made to correct a variety of vision issues and do it with precision. You might be nearsighted, suffer from double vision or even have a severe imbalance in the quality of eyesight from one eye to the other. If you do start to experience a decline in your sight, the first thing you should do is visit an optometrist who can diagnose the problem and get you set up with prescription lenses — if you even need them. Once you have your prescription, you can shop around for your choice of frames and lenses.

If you simply have trouble reading things up close, over-the-counter glasses might be all that you need. These type of glasses are also known as reading glasses or readers, and they correct one simple but common problem: Farsightedness. This condition is also known as hyperopia. When you suffer from it, you might be able to see things at a distance perfectly well but get blurred vision when focusing on closer objects. Reading glasses are an affordable and effective solution to this problem, since they simply magnify the page or screen that you’re looking at. Mind you, they may not work well if you have better vision quality in one eye than the other (and can even give you headaches if that’s the case).

So how strong do you need those glasses to be? The magnification power of over-the-counter glasses is expressed in numbers known as diopters. Diopters refer to the focusing ability, and the healthy human eye rates about 40 diopters. Reading glasses compensate for the loss in focusing ability that comes with hyperopia, and they typically come in diopter strengths from +1 to +4. You’ll find them in increments of .25, so try on different lens strengths to see where your sweet spot is.

It’s normal for vision to degrade a bit with age, and you may need to trade out your old readers for stronger ones every five years or so. Contrary to popular myth, regular use of reading glasses won’t harm your eyesight — but a variety of bad habits will, such as excessive screen time or overuse of eye drops.

Form can be just as important as function. Make sure that your glasses fit and stay secure on your face even when you’re active, though this is less important for reading glasses. When it comes to looks, it’s generally best to contrast the shape of your frames to the shape of your face. That means rectangular frames for round features and oval or circular glasses for those with a more square-jawed look. There are no hard and fast style rules, so try on different glasses until you find what works for you.

Finally, there are many modern filters you can add to eyeglass lenses that will help with eyestrain. UV filters are a popular choice for those who plan to be outdoors a lot. If you’re planning to be in front of a laptop for much of the day, blue light blockers can reduce the fatigue that comes from overexposure to glowing screens.

If you’re buying glasses online, you don’t have to roll the dice and hope that your glasses will fit. Before you go looking, make sure you size up the width between your temples. You can do this by holding a ruler in front of your face and measuring the length in millimeters from one side of your face to the other.

You’ll also want to see what bridge size you need. If the bridge of your nose comes up above your pupils, you’ll need a wider bridge on your glasses (between 19-21 mm). If it sits below your pupils, go for a smaller bridge of 16-18 mm.