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...

There is a common misconception that any adverse reaction to a drug is an allergy. That is definitely not the case.

Reporting to your doctors that you have an allergy to a medication when what you really had was a side effect could potentially create a substantial alteration to your medical care in the future. And this could mean a physician may avoid using a drug that could possibly save your life because of the fear of an allergic reaction.

An anaphylactic allergic reaction generally produces a very specific set of symptoms, including difficulty breathing due to constriction of windpipe, swelling of your tongue and/or a rash and hives that break out over your entire body. While an allergic reaction can present in other ways, these are the most frequent reactions that occur when you have a true allergy to something.

If that is not the type of reaction you had then it probably isn’t an allergy. If you are uncertain if your reaction to a medication is an allergy or not,...