DEAR DR. ROACH: When I lost the vision in my eye in an accident, I had Charles Bonnet syndrome hallucinations. I am 80 years old, and I went completely blind in one eye the day of the accident. There were patterns that I saw whenever my eye was unfocused, which pretty much obscured everything. I saw complicated figures like very bright TV. I have read Oliver Sacks’ explanation in his latest book, called “Hallucinations.” What I viewed is exactly how he described CBS. Seven months later, I am still having hallucinations, but they are much subdued and not very interesting. I think it is gradually disappearing. What concerns me is that none of the hospital personnel knew of the syndrome. The best that was offered was that it was from a bladder infection, which I did not think I had. I imagine that there are a lot of old blind folks who think they are crazy, and there is no one to tell them otherwise. I am hoping you might write an explanation for all of us who have failing eyesight and no explanation for what ails us. I had so many interesting visions, and since I knew it was not real, I rather enjoyed it. — L.R.

ANSWER: I can’t criticize the doctors at your hospital too much, since I had never heard about this type of hallucination before your letter. In fact, a brief survey of some colleagues, with hundreds of years’ worth of clinical experience, showed me that many of us, unlike Dr. Sacks, had never heard of this syndrome, so I am glad to be able to bring it up.

Charles Bonnet syndrome, also called visual release hallucinations, occur in people who are losing or have lost vision. It does seem to be more common in the elderly, but it has been reported in children. Most people who have had these hallucinations do not bring it up to their doctor, probably because they fear being labeled as having a psychiatric disease. It is thought to happen due to the firing of nerve cells in areas of the brain that process vision when they are deprived of visual input from the optic nerve.

There are treatments available, including moving eyes rapidly back and forth, which often can stop the hallucinations if they are bothersome. There are also medications to stop them in people who don’t enjoy them the way you have.

DEAR DR. ROACH: I’ve heard many medical providers say that they believe they get more accurate blood pressure readings from the old-fashioned manual method, rather than the automatic cuff machines. I wonder how true this can be, though, since the former is subject to human hearing ability. My excellent hearing lets me pick up on beats far beyond what someone who has average hearing can detect, so it stands to reason that there would be a difference in the reading. — C.B.

ANSWER: The very best machines are accurate at measuring blood pressure; however, a trained clinician remains the standard for blood pressure measurement. Fortunately, good, but not necessarily outstanding, hearing is required for accurate blood pressure measurement. Proper placement and inflation of the cuff, the correct slow deflation rate and, importantly, measuring both arms are as significant as good hearing. I was taught to take an average of three measurements.

Excellent hearing helps the clinician pick up on subtle heart murmurs and other noises, normal and abnormal, that the heart makes. If you decide to become a physician, consider cardiology. We physicians should take great care to protect our ears; sadly, some of us listened to music that was too loud at some points in our lives.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Health newsletters may be ordered from www.rbmamall.com.

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