Will reading glasses make your eyes worse? The short answer is ‘No.’

Although we don’t know the exact mechanism by which humans have a decreased ability to focus up close as we age (a process called presbyopia), the fact remains that it will happen to all of us.

The leading theory of how this occurs is that the lenses in our eyes get stiffer and thicker as we age such that one of the muscles in the eye that contracts to change the shape of the lens does so less and less effectively because the lens itself gets less pliable.

The process of changing the focus of the lens from far away objects to up-close objects is called accommodation. If you have normal distance vision without glasses, then your eyes’ natural focus spot is far off in the distance. In order to focus on an object close to you, the lens in your eye has to alter its shape. The ability of your lens to do that is at its best when you are born and it slowly gets less and less pliable as the years go on. You have...

One of the most commonly asked questions in an eye exam comes right after the refraction, or glasses prescription check: “What is my vision?”

Almost invariably, people know the term “20/20”. In fact, it’s a measure of pride for many people. “My doctor says I have 20/20 vision.” Or, on the other side of that same coin, having vision that is less than 20/20, say 20/400, can be a cause of great concern and anxiety. In this discussion I will describe what these terms actually mean.

To lay the foundation, let’s discuss some common terms. Visual acuity (VA) is clarity or sharpness of vision. Vision can be measured both corrected (with glasses or contact lenses) and uncorrected (without glasses or contact lenses) during the course of an eye exam. The result of an eye exam boils down to two different but related sets of numbers: your VA and your actual glasses prescription.

The notation that doctors use to measure VA is based off of a 20-foot distance. This is where the first 20...