If you haven’t bought glasses in a while, prepare to be overwhelmed by the number of lens materials and coatings available. (BIGSTOCK)

With eyeglasses, contacts, eye exams and laser surgery, U.S. adults spent more than $35 billion on vision care in the year ending June 2013, according to the Vision Council, a trade group. But not all of what we buy for our eyes is necessarily a good idea or worth the money. Consumer Reports reviewed the evidence and consulted experts for the latest on what helps, harms or has no effect.

Laser surgery update

First developed in the mid-1990s, laser vision correction involves using a laser to reshape the cornea (the circular portion on the front of the eye) and correct nearsightedness, farsightedness or astigmatism.

There are two main types: traditional Lasik, in which a surgeon cuts a flap on the surface of the cornea, then uses a laser to reshape the underlying cornea; and photorefractive keratectomy (PRK), in which a surgeon scrapes micro-thin layers of tissue off the cornea’s outermost layer instead of making a flap.

Newer techniques have allowed for results that can be better than those obtained in the past. Indeed, nine of 10 patients who undergo Lasik achieve vision of between 20/20 and 20/40.

There’s a caveat, though: Laser surgery might not free you from glasses or contacts if you’re 40 or older. That’s because the procedure can’t correct or prevent presbyopia, the natural loss of focusing power for close-up objects that happens with age. So you could have Lasik or PRK, only to find that you still need reading glasses. What’s more, laser surgery might hasten the development of presbyopia in some people who are nearsighted.

Eyeglasses go digital

If you haven’t bought glasses in a while, prepare to be overwhelmed by the number of lens materials and coatings available. What to get may depend on which type of lens you wear.

If you have a simple single-vision prescription, you can generally get by with inexpensive plastic CR-39 lenses, which Consumer Reports recently found for as little as $10 a pair. But with stronger prescriptions they can look thick (the Coke-bottle effect).

If you have a strong prescription, you may see more comfortably (and stylishly) with high-
index lenses, which are made of thin, lightweight glass or plastic.

If you have progressive lenses — which provide a gradual change in power for different viewing distances and are an alternative to bifocals and trifocals — it may be worth springing for the precision, diamond-cut, high-definition (digital) lenses. A newer option, they are made using computerized surfacing equipment that results in superior visual performance.

Food vs. supplements

There’s no definitive proof that specific foods, such as green leafy vegetables, can directly improve or protect vision in people who aren’t malnourished, says Neil Bressler, a professor of ophthalmology at the Wilmer Eye Institute at the Johns Hopkins School of Medicine.

But eating a healthful diet may help control weight gain. Being overweight increases the risk of developing Type 2 diabetes. This can cause a complication called diabetic retinopathy, which damages the blood vessels in the retina at the back of the eye.

Numerous dietary supplements are marketed for eye health, often with ingredients including zinc and antioxidant vitamins C and E. They might benefit some of the 1.8 million Americans age 40 and older who are affected by age-related macular degeneration (AMD).

Dry AMD occurs when the cells in the macula — the part of the eye involved in sharp, central vision — break down slowly, gradually blurring vision. If it isn’t halted, dry AMD can lead to wet AMD, in which blood vessels grow under the retina and leak, causing rapid and severe vision loss.

The Age-Related Eye Disease Study found that a supplement containing high levels of vitamins C and E, beta carotene and zinc decreased the five-year risk of progression from intermediate to advanced AMD by 25 percent compared with a placebo. But the pills had no apparent effect on the risk of developing cataracts or the loss of visual acuity.

In addition, high doses of certain antioxidant nutrients might be harmful to some. For example, taking beta carotene has been shown to increase the risk of lung cancer in smokers.

Regular eye exams

Even if your eyes look and feel fine, a periodic exam by an optometrist or ophthalmologist is important. An exam can detect early signs of eye problems that often have no warning symptoms, including diseases related to diabetes, glaucoma and macular degeneration, at a stage when they might be more treatable.

You should undergo an eye exam with dilation every two to four years from age 40 to 54, and every one to three years from age 55 to 64. People age 65 and older should go every year or two, depending on their eye health and other factors. If you have diabetes or a family history of eye problems, you may need more frequent checkups.

Copyright 2013. Consumers Union of United States Inc.

For further guidance, go to www.ConsumerReports.org/Health, where more detailed information, including CR’s ratings of prescription drugs, treatments, hospitals and healthy-living products, is available to subscribers.