Answer: Let's deal with polycythemia (POL-ee-sigh-THEME-ee-uh) first. It's the condition where the bone marrow produces too many blood cells — red, white and platelets, the clotting cells. No one knows why it starts, but quite often, it progresses slowly. Many have no symptoms for decades. It's often discovered because a person happens to have a blood count done for some unrelated reason.

In time, the thick blood brings on symptoms, such as dizziness, ear noises, headaches, vision problems, increased blood pressure and clots forming in veins. It can even lead to strokes. And what seems paradoxical is a tendency to bleed in spite of having an abundance of clot-forming cells. That's because the platelets, the clotting cells, often are ineffective.

When polycythemia produces no symptoms, people usually are not prescribed any treatment. If and when symptoms occur, then treatment consists of drawing blood to get the blood count to a normal level. That relieves symptoms. If your driver's license was taken away because of polycythemia symptoms, treatment should alleviate the symptoms, and you could get your license back.

If your license was taken for other reasons, let me know what those reasons were. I understand how loss of a driver's license makes a person feel like his or her freedom is lost, especially if that person is living in a place with nonexistent public transportation. I need more details. Things are not hopeless.

Dear Dr. Donohue: My daughter is pregnant with her second child. She had a miscarriage after the birth of her first child. Now she has hyperemesis gravidarum. She is in her second trimester. She has lost about six pounds. Her doctor has her on a medicine used for chemotherapy patients, but it has reduced her vomiting only a little. Many people think she simply suffers from morning sickness, but this is more serious. Can you suggest anything? — K.R.

Answer: Many pregnant women suffer from morning sickness — more or less constant nausea with vomiting every now and then. Most are able to maintain body weight and nutritional health. And most get over morning sickness by the fourth month of pregnancy.

Hyperemesis ("hyper" — excessive; "emesis" — vomiting) gravidarum (of pregnant women) is a much greater problem than morning sickness. It happens to one in 200 to 300 pregnant women. It's nonstop nausea and vomiting with significant weight loss. It can be of such consequence that hospitalization is necessary to provide nutrition intravenously or through a tube. Your daughter's condition sounds like it's approaching that level.

The medicine your daughter takes is a medicine to quell vomiting, something that many people on chemotherapy have to take for the same reason.

I'm sure she's tried the standard treatments of eating small amounts but doing so frequently and filling up on dry foods like crackers.

Dear Dr. Donohue: Please advise when is the right time to have cataract surgery. I am a healthy, 79-year-old man in a retail business that requires color recognition. I have difficulty distinguishing between black and navy. Other than that, I have no eyesight concern. My eye doctor is pressuring for early removal of a "beginning" cataract. I feel I am being pushed into surgery. — L.S.

Answer: The patient is the one to judge when cataract surgery should be done. When the cataract interferes with accomplishing daily tasks, makes it difficult to read or watch TV, or puts one at risk of having a driving accident, then the cataract should be removed.

Can brighter lights help you distinguish between black and navy?