Any reason not to get inexpensive drugstore reading glasses instead of pricier versions?

DEAR DOCTOR K: My vision has been getting worse, and I definitely need reading glasses. Is there any reason not to get the inexpensive ones sold at the drugstore?

DEAR READER: If you're over 40, reading glasses can be a necessity. Many people end up buying several pairs at the drugstore. They are inexpensive and available in a wide variety of styles. (Not to mention that reading glasses tend to be easily misplaced.)

How can I adjust my walking routine to start losing weight again?

DEAR DOCTOR K: When I first started walking for exercise, I lost some weight. Since then, my weight has plateaued. How can I adjust my walking routine to start losing weight again?

DEAR READER: To reignite your weight loss, you need to keep challenging your body. That means walking farther, faster and more often. The more vigorous your workout, the longer you'll continue to burn calories after you stop exercising.

How does sun exposure damage our skin?

DEAR DOCTOR K: You've said many times that the sun can harm our skin and increase the risk for skin cancer. How does it do that?

DEAR READER: As you age, the single biggest cause of damage to skin is sun exposure. This damage is called "photoaging." Over the years, sun exposure causes fine and coarse wrinkles; baggy skin with a yellow, leathery appearance; and dry, scaly skin. It also reduces collagen, a natural chemical that gives strength to tissues and that supports a network of blood vessels in the skin. As a result, the skin bruises more easily.

I’m still in pain after a car accident. Why won’t my doctor prescribe more pain medication?

DEAR DOCTOR K: I have been in pain since a car accident a few years ago. My doctor is very conservative in prescribing pain medication. Why not just give me what I need to feel better?

DEAR READER: I don't know the particulars of your case, but I think you are talking about narcotic (opioid) pain medicines. And your doctor probably is reluctant to prescribe opioid medicines for chronic pain -- the kind I assume you now have if your accident was a few years ago.

What can I do to relieve burning mouth syndrome?

DEAR DOCTOR K: For some time, I've had a burning and tingling in my mouth. My dentist and doctor seem to be mystified. What could be causing my symptoms, and what can I do?

DEAR READER: Several things might be causing these bothersome symptoms. Some that come to mind are nutritional deficiencies -- particularly of B vitamins, iron and zinc. These problems can be detected by simple blood tests.

Do I need to get a Pap test every year?

DEAR DOCTOR K: I've had a Pap test every year for 20 years, since I was about 25. It's always normal. Do I still need one every year?

DEAR READER: The answer used to be yes. The reason was that doing the test often would help catch cancer of the cervix at its earliest and most curable stage. However, studies showed that less frequent Pap tests for younger women caught just as many early cancers. The studies also showed that many older women with repeatedly normal Pap smears (like you) had an extremely low risk of ever getting cancer of the cervix.

My father has Alzheimer’s disease. Does that mean my children and I will eventually develop it too?

DEAR DOCTOR K: My father has been diagnosed with Alzheimer's disease. Does that mean that my children and I will eventually develop Alzheimer's too?

DEAR READER: Many people worry that if a parent had Alzheimer's disease, they are doomed. But that's not true. Having a first-degree relative (parent, sibling or child) with Alzheimer's disease increases a person's risk by about 30 percent. That sounds like a lot, and therefore sounds scary. But what you really want to know is: What is my risk in the first place? If it's a very low number, then raising a low risk by 30 percent won't be a big deal.

Why do best practices get reversed so often in medicine?

DEAR READERS: In yesterday's column, I answered a reader's question about why doctors seem to change their minds about the best treatments for medical problems. I said that we doctors keep changing our minds because we're human. We sometimes believe things that seem reasonable and for which there is some evidence. But then we find out, as more and better research is done, that we were wrong.

Why do doctors keep changing their minds about the right thing to do?

DEAR DOCTOR K: I have diabetes, and my doctor used to tell me my fasting blood sugar level needed to be below a certain number. Now, he says it's OK if it's higher. Why do doctors keep changing their minds about the right thing to do?

DEAR READER: We doctors keep changing our minds because we're human. Which means that we sometimes believe things that seem reasonable and for which there is some evidence -- only to find out, as more and better research is done, that we were wrong.