It's always handy having a spare pair of glasses on hand, but paying for a second set of prescription specs is something that most of us would prefer not to do. Well, that's where Adlens Adjustables come in. They're inexpensive glasses that can be focused by the user to (more or less) match their prescription. We recently gave them a try, and can tell you that they work ... but you probably won't want to use them as your primary glasses.

Adlens is best-known for its pricier AdlensFocuss glasses, which are designed to replace conventional bifocals.

That model incorporates two lenses for each eye – the wearer's prescription lens in the front, a deformable lens behind it, and a layer of clear silicone oil sandwiched between the two. Twisting a small dial on the temple arm squeezes the lenses together or pushes them apart, altering the magnification rate. This allows the glasses to instantly switch between three different settings – distance, mid and reading – that are preset with the user's prescription.

Well, that's not how the Adjustables work.

They do have two lenses per eye and dials that you twist, but there's no oil involved, and neither of the lenses are prescription. Instead, adjusting the dials causes the polycarbonate lenses to slide horizontally relative to one another, along with oval optical plates embedded in each one. As those plates move, thicker and thinner sections of the two are gradually brought in and out of alignment with one another, causing the lens' focus to incrementally change from near to far (or vice-versa).

To set up the glasses you just cover one eye with your hand, set the focus for the other eye, then repeat the process on the other side. It's a fairly simple process, although it's not one that you'd likely want to perform several times a day – so, unlike the AdlensFocuss, the Adjustables aren't well-suited to tasks where you're constantly changing focus back and forth.

Additionally, although objects seen straight through the optical plates are indeed in focus, everything in your peripheral vision is blurry. We also noticed some glaring in bright light, plus it was possible for dust to get between the two lenses, and the unpadded plastic frames weren't the most comfortable we've ever tried.

All that being said, prices do start at just US$30 for the standard clear-lens model. Sunglass and anti-screen-glare versions are also available.

Product page: Adlens Adjustables

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