Imagine Adjustable Prescription Glasses

Adlens glasses use removable knobs to adjust the prescription.

Adlens is about to introduce a pair of inexpensive eyeglasses with both celebrity cachet and a technology that lets you adjust the prescription by just turning a knob.

Its John Lennon Collection features glasses in the round style favored by Mr. Lennon (or Harry Potter, if you don’t know who Mr. Lennon is) with a variable lens that can be djusted for near, intermediate or distant sight. The sizable knobs that adjust the lenses are removable, but you would have to keep them handy if you often want to change prescriptions.

The glasses, which become available in April at a price of $80, are just one of several similar designs available from other companies, but Adlens claims its design has a greater range of adjustability than those of its competitors.

The glasses work by using fluid to change the shape of a membrane inside the lens, which changes the prescription. Different companies have taken a variety of approaches to variable focus lenses, including one that uses liquid crystals to make the adjustment.

The John Lennon Collection will be available in a variety of styles.

In a test, the ophthalmologist Ryan Beveridge, using a lensometer, found that the glasses delivered on the declared corrective power of minus 4.5 diopters to plus 3.5 diopters. That means correction from fine print to scenic overlooks.

The doctor said the glasses were good for people with presbyopia, an inability to focus, especially on items that are close, which is often addressed with bifocals or trifocals. Virtually everybody will get presbyopia, usually after age 40. “These will work for a majority of people,” Dr. Beveridge said of the Adlens glasses.

But not everybody. People with astigmatism, for instance, an abnormal curve of the cornea, will not be helped much by the adjustable focus.

Dr. Beveridge called th design “a good start,” although he noted some lens aberrations and distortions. For that reason, he said, the Lennon glasses may be best used as a backup.

To add a little Lennon-like social responsibility to the brand, for each pair purchased, Adlens will donate a pair of glasses to needy Rwandans through its Ministry of Health.