What can I do to continue driving safely at night?

DEAR DOCTOR K: I am in my 60s. Over the last few years, my night vision has gotten worse, and I'm finding it increasingly difficult to drive at night. What can I do to continue driving safely after dark?

DEAR READER: Night vision does start to decline as we get older, usually after age 50. Perhaps you've noticed more difficulty seeing in dim light, or maybe you're more bothered by the glare from headlights. Problems with night vision are the result of several changes to the eye that occur with aging. The first change involves the iris and pupil. As we age, the iris muscle weakens and becomes less responsive.

How serious is Osgood-Schlatter disease?

DEAR DOCTOR K: My 12-year-old daughter has been doing gymnastics for years. Lately she's complained about pain in her knee. Her doctor says it's Osgood-Schlatter disease. How serious is this?

DEAR READER: This is a case where the name makes the condition sound worse than it is. Osgood-Schlatter disease is a common, temporary condition. It causes knee pain in older children and teenagers, especially those who play sports. About 20 percent of kids who play sports develop this condition. It starts when a kid's growth spurt starts, and major symptoms typically go away at the end of a teenager's growth spurt.

What is atherosclerosis?

DEAR DOCTOR K: You mention atherosclerosis in many of your columns. Could you explain what this word means?

DEAR READER: My readers ask me many questions about atherosclerosis, and for good reason: It is the No. 1 cause of premature death in developed nations, including the United States. Atherosclerosis is a narrowing of the arteries. Arteries are blood vessels that supply fresh, oxygen-rich blood to the heart, brain, intestines and other organs. The narrowing is caused by the buildup of plaques in artery walls. The plaques are filled with LDL cholesterol -- so-called "bad" cholesterol.

What can I do to make sure my children are safe while biking?

DEAR DOCTOR K: Summer is here, and my children are out all afternoon riding their bicycles. What can I do to make sure they're as safe as possible?

DEAR READER: Bicycling is a wonderful activity for children -- and for families. As with any sport, bicycling carries a risk of injury. Proper safety skills and equipment are essential for all children before heading out on the road. It can be tricky to find a safe place to teach your child to ride a bike. The streets near your home may be too busy.

I have osteoporosis — should I stop exercising to avoid another bone break?

DEAR DOCTOR K: Last year I broke my ankle while jogging. It turns out I was vulnerable to breaking a bone because I have osteoporosis. Should I stop exercising to avoid another break? If I should exercise, are there particular types of exercise I should do?

DEAR READER: Once you've broken a bone, it's natural to be cautious about exercise for fear of another injury. It's true that osteoporosis, a bone-thinning disease, increases your risk of bone fracture. But staying active is exactly what you should be doing right now. Why? Because the right exercises, done properly, will build up your bone strength and reduce the likelihood of another fracture.

What can I do to prevent migraines?

DEAR DOCTOR K: I suffer from excruciating migraine headaches. What can I do to prevent them?

DEAR READER: Migraines are severe, throbbing, often debilitating headaches. They can be accompanied by nausea or vomiting. It's no wonder that anyone who suffers from migraines would do anything to avoid them. Migraines can be triggered by certain activities, foods, smells or emotions. Common migraine triggers include:

How can I get my elderly mother to take her medications consistently?

DEAR DOCTOR K: My mother is supposed to take several medications each day, but she doesn't take them consistently. What can I do to get her back on track?

DEAR READER: I'll bet when you were a kid and your parents were hounding you about taking your medicine, you never imagined a day would come when you'd be doing the same to them. Nearly three out of four Americans report that they do not always take their medication as directed. So there are a lot of people who are in the same position as your mother. And, obviously, for the medicines to work, a person's got to take them.

Are there any new treatments for lowering cholesterol, besides statins?

DEAR DOCTOR K: I have high cholesterol, but I can't tolerate statins. Are there any new treatments for lowering cholesterol?

DEAR READER: I assume you're taking statins because your low-density lipoprotein (LDL) cholesterol (so-called "bad" cholesterol) is high. If so, that does increase your risk of having a heart attack or stroke. Lowering LDL cholesterol reduces that risk. Some people can bring down their cholesterol levels with diet and exercise alone. But many people need medication to get to their target levels.

What does it mean when someone “goes into shock”?

DEAR DOCTOR K: What does it mean when someone "goes into shock"?

DEAR READER: Shock occurs when there is not enough blood flowing through the body to supply the oxygen and nutrients your cells need to survive. People who go into shock can develop organ damage -- or even die -- if the condition is not treated promptly.

What can I do to ease the discomfort of hemorrhoids?

DEAR DOCTOR K: What can I do to ease the discomfort of hemorrhoids?

DEAR READER: Hemorrhoids are quite common, and they're not a "serious" medical problem. But, figuratively and literally, they're a real pain in the butt. Hemorrhoids develop when veins in the anus and rectum swell and widen. (I've put an illustration below) They can be extremely painful and uncomfortable, causing bleeding and painful bowel movements. There are surgical treatments that can help when you have recurrent, painful flare-ups of hemorrhoids.