Reading glasses are a necessity for most people older than 40, when the blurriness known as presbyopia overtakes their ability to focus. Soon enough, it seems, middle-aged Americans will catch up with the rest of the world. A corneal inlay product, which is already sold in other parts of the world, is now under review by the Food and Drug Administration (FDA).

Presbyopia, the gradual loss of our eyes' ability to focus on nearby objects, affects more than one billion people worldwide. As we age, the lens becomes less flexible and so fails to focus as smoothly. Generally, presbyopia becomes noticeable in the early to mid-40s and continues to worsen until around age 65. While age is the greatest risk factor for this common condition, being farsighted along with having diabetes, multiple sclerosis, or cardiovascular diseases increase your risk of developing presbyopia prematurely. Antidepressants, antihistamines, and diuretics also can raise your chances of developing presbyopia at an early age.

To address such issues of aging vision, scientists have developed a variety of new corneal inlay products. Currently, three different types are in development for the U.S. market and also under review by the FDA: Raindrop Near Vision Inlay; Presbia Flexivue Microlens; and the KAMRA inlay. However, other than Raindrop, the other two products already are available in Europe, South America, Israel, and Asia.

KAMRA is a flexible doughnut-shaped ring that acts like a camera aperture and adjusts the depth of field for both near and far distances. To help you understand how KAMRA is implanted, this YouTube video explains the procedure:

Tested in 507 patients, KAMRA has an 83 percent success rate in providing 20/40 vision or better, the standard for driving a car without corrective lenses — and also the usual requirement for reading a newspaper without glasses. A warning: Corneal inlays may come with complications for some patients. Among the side effects, some patients experience haziness. However, there's one big plus. Inlays can be removed.

"Corneal inlays represent a great opportunity to improve vision with a safety net of removability,” said Dr. John Vukich, a clinical adjunct professor in ophthalmology and vision sciences at the University of Wisconsin, who noted the KAMRA inlay allows vision to transition smoothly from near to far. Welcome to the future.