When driving at night, I am often blinded by lights as I pass by (streetlights, oncoming cars etc.) I have gone to an optometrist and was given glasses to bring the lights into better focus, but I still suffer the same symptoms. What could be causing this problem? Is there anything I can do other than not driving at night?

B.M.

Night-vision problems can be caused by a variety of conditions. By far, the most common cause of nighttime glare and symptoms is cataracts. Since I do not know your age, I can not determine the likelihood of you having cataracts -- a clouding of the eye's lens that nearly everyone will develop if he or she lives long enough.

However, it's important to keep in mind that cataracts are not limited to older patients. Even people in their 20s can develop various types of cataracts that can affect vision. The most common kind is a posterior subcapsular cataract, which starts in the rear of the lens. Posterior subcapsular cataracts are sometimes associated with the use of medications (such as the steroid Prednisone). Like other types of cataracts, the standard treatment is surgery to remove the clouded lens and replace it with a plastic lens, which greatly improves vision and reduces nighttime glare.

Another possible cause of night-vision problems could be uncorrected or undercorrected nearsightedness (myopia). While you indicate that your current eyeglasses have improved your ability to focus, you may want to visit an ophthalmologist to doublecheck the strength of your glasses and to see if you might be able to get an even better lens prescription.