Shining light on night blindness

Animals renowned for their outstanding night vision include owls, cats, tarsiers (a tiny primate in Southeast Asia) — and even the dung beetle.

But humans? Not so much.

Over time, many people suffer from night blindness, also known as nyctalopia. This condition makes seeing in dim or dark settings difficult because your eyes cannot adjust to changes in brightness or detect light.

What are the dangers for those experiencing night blindness?

Night blindness is especially problematic and dangerous when driving. Your eyes cannot adjust between darkness and the headlights of oncoming vehicles, other cars may appear out of focus, and your depth perception becomes impaired, which makes it difficult to judge distances.

Night blindness also may affect your sight at home by making it hard for your vision to quickly adjust to a dark room after turning off the lights. “This can cause people to bump into furniture or trip and suffer an injury,” says Dr. Isabel Deakins, an optometrist with Harvard-affiliated Massachusetts Eye and Ear.

What happens in the eye to create night blindness?

The ability to see in low-light conditions involves two structures in the eye: the retina and the iris.

The retina, located in the back of the eye, contains two types of light-detecting cells called cones and rods. The cones handle color vision and fine details while the rods manage vision in dim light.

The iris is the colored part of your eye. It contains muscles that widen or narrow the opening of your pupil to adjust how much light can enter your eyes.

If your irises don’t properly react, the pupils can dilate and let in too much light, which causes light sensitivity and makes it hard to see in bright light. Or your pupils may remain too small and not allow in enough light, making it tough to see in low light.

What causes night blindness?

Night blindness is not a disease but a symptom of other conditions. “It’s like having a bruise on your body. Something else causes it,” says Dr. Deakins.

Several conditions can cause night blindness. For instance, medications, such as antidepressants, antihistamines, and antipsychotics, can affect pupil size and how much light enters the eye.

Eye conditions that can cause night blindness include:

• glaucoma, a disease that damages the eye’s optic nerves and blood vessels
• cataracts, cloudy areas in the lens that distort or block the passage of light through the lens
• dry eye syndrome.

However, one issue that raises the risk of night blindness that you can’t control is age. “Our eyes react more slowly to light changes as we age, and vision naturally declines over time,” says Dr. Deakins.  “The number of rods in our eyes diminish, pupils get smaller, and the muscles of the irises weaken.”

What helps if you have night blindness?

If you notice any signs of night blindness, avoid driving and get checked by an eye care specialist like an optometrist or ophthalmologist. An eye exam can determine if your eyeglass prescription needs to be updated.

“Often, a prescription change is enough to reduce glare when driving at night," says Dr. Deakins. “You may even need separate glasses with a stronger eye prescription that you wear only when driving at night.”

Adding an anti-reflective coating to your lens may help to cut down on the glare of the headlights of an oncoming car. However, skip the over-the-counter polarized driving glasses sold at many drug stores. "These may help cut down on glare, but they don't address the causes of night blindness," says Dr. Deakins.

An eye exam also will identify glaucoma or cataracts, which can be treated. Glaucoma treatments include eyedrops, laser treatment, or surgery. Cataracts are corrected with surgery to replace the clouded lens with an artificial one. Your eye care specialist can also help identify dry eye and recommend treatment.

Ask your primary care clinician or a pharmacist if any medications that you take may cause night blindness. If so, it may be possible to adjust the dose or switch to another drug.

Three more ways to make night driving safer

You also can take steps to make night driving safer. For example:

• Wash the lenses of your glasses regularly. And take them to an optician to buff out minor scratches.
• Keep both sides of your front and rear car windshields clean so that you can see as clearly as possible.
• Dim your dashboard lights, which cause glare, and use the night setting on your rearview mirror.

About the Author

Matthew Solan, Executive Editor, Harvard Men's Health Watch

Matthew Solan is the executive editor of Harvard Men’s Health Watch. He previously served as executive editor for UCLA Health’s Healthy Years and as a contributor to Duke Medicine’s Health News and Weill Cornell Medical College’s … See Full Bio View all posts by Matthew Solan

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

Could men with advanced prostate cancer avoid chemotherapy?

When we think about radiation therapy, we typically picture treatments directed at tumors by a machine located outside the body. Now imagine a different scenario — one in which radioactive particles injected into the bloodstream find and destroy individual cancer cells, while leaving healthy cells unscathed.

The drug

One such “radioligand” is already available for certain patients with prostate cancer. Called Lu-PSMA-617 (trade name Pluvicto), it carries a lethal payload of radioactive atoms. The drug binds with a cell protein known as prostate-specific membrane antigen (PSMA), which is abundant on most prostate cancer cells but absent on most normal cells. After sticking to that protein, Lu-PSMA-617 delivers its radioactive cargo, and then the targeted cell dies.

As it currently stands, Lu-PSMA-617 is approved only for very a specific circumstance: eligible patients must have been treated already with chemotherapy for metastatic castration-resistant prostate cancer (mCRPC). During this advanced stage of the disease, prostate-specific antigen (PSA) levels rise despite treatments that block testosterone, a hormone that fuels prostate cancer growth (rising PSA indicates the cancer is progressing).

Doctors will often respond by switching to second-line hormonal treatments that block testosterone in other ways. If those drugs don’t work or become ineffective, then chemotherapy is typically the next option.

But could men with mCRPC bypass chemotherapy — along with its challenging side effects — and start on Lu-PSMA-617 right away? Investigators evaluated that potential strategy during a newly-completed clinical trial.

The study

The PSMAfore phase 3 trial enrolled 468 men with mCRPC. All the men had PSMA-positive tumors, and each of them had been treated already with a second-line testosterone blocker. For most men, that drug was abiraterone; the rest had been treated with a drug called enzalutamide. None of the men had yet been given chemotherapy.

The investigators randomized all the enrolled men into two groups. Men in the treatment group were given infusions of Lu-PSMA-617, while men in the control group were switched to a second testosterone-blocker that they hadn’t yet received.

The findings

After nearly a year and a half of follow-up, Lu-PSMA-617 treatment generated promising results. Crucially, the treated men avoided further cancer progression for a year on average, which was six months longer than progression was avoided in the control group.

Lu-PSMA-617 also produced significant drops in PSA: in 58% of the Lu-PSMA-617-treated men, PSA levels declined by half or more. Just 20% of men in the control group experienced comparable PSA declines. Lu-PSMA-617 was also well tolerated. The most common side effects were dry mouth and minor gastrointestinal symptoms, and treated men also reported less pain and better quality of life.

Commentary

Researchers still need to show that using Lu-PSMA-617 before chemotherapy actually lengthens survival before the FDA will approve this new indication. The enrolled subjects are still being followed, and “hopefully with further follow up, this sequence of treatments may become more widely available,” says Dr. Marc B. Garnick, the Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center.

Added Dr. Garnick, “This study marks another advance in our emerging treatment options for men with advanced prostate cancer, and underscores the methodical progression of pharmaceutical development. When new therapies are introduced, they are studied in patients in whom the treatment options are limited. Fortunately, Lu-PSMA-617 showed excellent results in this population, and the study outlined here suggests that it may be able to move this therapy to even earlier forms of advanced prostate cancer. We anxiously await longer-term follow-up of this important research.”

About the Author

Charlie Schmidt, Editor, Harvard Medical School Annual Report on Prostate Diseases

Charlie Schmidt is an award-winning freelance science writer based in Portland, Maine. In addition to writing for Harvard Health Publishing, Charlie has written for Science magazine, the Journal of the National Cancer Institute, Environmental Health Perspectives, … See Full Bio View all posts by Charlie Schmidt

About the Reviewer

Marc B. Garnick, MD, Editor in Chief, Harvard Medical School Annual Report on Prostate Diseases; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Marc B. Garnick is an internationally renowned expert in medical oncology and urologic cancer. A clinical professor of medicine at Harvard Medical School, he also maintains an active clinical practice at Beth Israel Deaconess Medical … See Full Bio View all posts by Marc B. Garnick, MD

Icy fingers and toes: Poor circulation or Raynaud’s phenomenon?

If your fingers or toes ever turn pale (or even ghostly white) and go numb when exposed to cold, you might assume you just have poor circulation. That’s what I used to think when I first started noticing this problem with my own hands many years ago.

It usually happened near the end of a long hike on a spring or fall afternoon, when the temperature dropped and I didn’t have any gloves handy. My pinkie, third, and middle fingers would turn white, and the fingernails took on a bluish tinge. As I soon discovered, I have Raynaud’s phenomenon, an exaggeration of normal blood vessel constriction.

Raynaud’s phenomenon: Beyond poor circulation

When you’re exposed to a cold environment, your body reacts by trying to preserve your core temperature. Blood vessels near the surface of your skin constrict, redirecting blood flow deeper into the body. If you have Raynaud’s phenomenon, this process is more extreme.

Is wintry weather the only trigger for Raynaud’s phenomenon?

“Cold weather is the classic trigger for Raynaud’s phenomenon," says rheumatologist Dr. Robert H. Shmerling, senior faculty editor at Harvard Medical School's Harvard Health Publishing.

"But it can occur any time of year — for example, when you come out of a heated pool, walk into an air-conditioned building, or reach into the freezer section at the supermarket. Even slight changes in air temperature can trigger an episode.”

What happens when an episode occurs?

During an episode, the small arteries supplying the fingers and toes contract spasmodically, hampering the flow of oxygen-rich blood to the skin. Some of these vessels even temporarily collapse, and the skin becomes pale and cool, sometimes blanching to a stark white color.

In addition to the hands, Raynaud’s can also affect the feet. Less often, the nose, lips, and ears.

Is Raynaud’s phenomenon a circulation problem?

Technically, Raynaud’s phenomenon is a circulation problem, but it’s very different than what doctors typically mean by poor circulation, says Dr. Shmerling. Limited or poor circulation usually affects older people whose arteries are narrowed with fatty plaque (known as atherosclerosis). This condition is often caused by high cholesterol, high blood pressure, and smoking.

In contrast, Raynaud’s usually affects younger people (mostly women) without those issues. And the circulation glitch is generally temporary and completely reversible, he adds.

How can you prevent episodes?

As I can attest, the best treatment for this condition is to prevent episodes in the first place, mainly by avoiding sudden or unprotected exposure to cold temperatures. I’ve always bundled up in the winter before heading outside, but now I bring extra layers and gloves even when the temperature might dip even slightly, or the weather may turn rainy or windy. Preheating the car in winter before getting in, and wearing gloves in chilly grocery store aisles, can also help.

Generally, it’s best to avoid behavior and medicines that cause blood vessels to constrict. This includes not smoking and not taking certain medications, such as cold and allergy formulas that contain pseudoephedrine and migraine drugs that contain ergotamine. Emotional stress may also provoke an episode of Raynaud’s, so consider tools and techniques that can help you ease stress, such as mindfulness techniques.

If necessary, your doctor may prescribe a medication that relaxes the blood vessels, usually a calcium-channel blocker such as nifedipine (Adalat, Procardia). If that’s not effective, drugs to treat erectile dysfunction such as sildenafil (Viagra) may help somewhat. Other treatment options include losartan (Cozaar), fluoxetine (Prozac), and topical nitroglycerin. You may only need to use these medications during the cold season, when Raynaud’s tends to be worse.

What steps may help during an episode?

Once an episode starts, it’s important to warm up the affected extremities as quickly as possible. For me, placing my hands under warm running water does the trick.

When that’s not possible, you can put them under your armpits or next to another warm part of your body. When the blood vessels finally relax and blood flow resumes, the skin becomes warm and flushed — and very red. The fingers or toes may throb or tingle.

Is Raynaud’s phenomenon linked to other health problems?

Some people with Raynaud’s phenomenon have other health problems, usually connective tissue disorders such as lupus or scleroderma. Your doctor can determine this by reviewing your symptoms, performing a physical exam, and taking a few blood tests. But most of the time, there is no underlying medical problem.

About the Author

Julie Corliss, Executive Editor, Harvard Heart Letter

Julie Corliss is the executive editor of the Harvard Heart Letter. Before working at Harvard, she was a medical writer and editor at HealthNews, a consumer newsletter affiliated with The New England Journal of Medicine. She … See Full Bio View all posts by Julie Corliss

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

Discrimination at work is linked to high blood pressure

Experiencing discrimination in the workplace — where many adults spend one-third of their time, on average — may be harmful to your heart health.

A 2023 study in the Journal of the American Heart Association found that people who reported high levels of discrimination on the job were more likely to develop high blood pressure than those who reported low levels of workplace discrimination.

Workplace discrimination refers to unfair conditions or unpleasant treatment because of personal characteristics — particularly race, sex, or age.

How can discrimination affect our health?

“The daily hassles and indignities people experience from discrimination are a specific type of stress that is not always included in traditional measures of stress and adversity,” says sociologist David R. Williams, professor of public health at the Harvard T.H. Chan School of Public Health.

Yet multiple studies have documented that experiencing discrimination increases risk for developing a broad range of factors linked to heart disease. Along with high blood pressure, this can also include chronic low-grade inflammation, obesity, and type 2 diabetes.

More than 25 years ago, Williams created the Everyday Discrimination Scale. This is the most widely used measure of discrimination’s effects on health.

Who participated in the study of workplace discrimination?

The study followed a nationwide sample of 1,246 adults across a broad range of occupations and education levels, with roughly equal numbers of men and women.

Most were middle-aged, white, and married. They were mostly nonsmokers, drank low to moderate amounts of alcohol, and did moderate to high levels of exercise. None had high blood pressure at the baseline measurements.

How was discrimination measured and what did the study find?

The study is the first to show that discrimination in the workplace can raise blood pressure.

To measure discrimination levels, researchers used a test that included these six questions:

• How often do you think you are unfairly given tasks that no one else wanted to do?
• How often are you watched more closely than other workers?
• How often does your supervisor or boss use ethnic, racial, or sexual slurs or jokes?
• How often do your coworkers use ethnic, racial, or sexual slurs or jokes?
• How often do you feel that you are ignored or not taken seriously by your boss?
• How often has a coworker with less experience and qualifications gotten promoted before you?

Based on the responses, researchers calculated discrimination scores and divided participants into groups with low, intermediate, and high scores.

• After a follow-up of roughly eight years, about 26% of all participants reported developing high blood pressure.
• Compared to people who scored low on workplace discrimination at the start of the study, those with intermediate or high scores were 22% and 54% more likely, respectively, to report high blood pressure during the follow-up.

How could discrimination affect blood pressure?

Discrimination can cause emotional stress, which activates the body’s fight-or-flight response. The resulting surge of hormones makes the heart beat faster and blood vessels narrow, which causes blood pressure to rise temporarily. But if the stress response is triggered repeatedly, blood pressure may remain consistently high.

Discrimination may arise from unfair treatment based on a range of factors, including race, gender, religious affiliation, or sexual orientation. The specific attribution doesn’t seem to matter, says Williams. “Broadly speaking, the effects of discrimination on health are similar, regardless of the attribution,” he says, noting that the Everyday Discrimination Scale was specifically designed to capture a range of different forms of discrimination.

What are the limitations of this study?

One limitation of this recent study is that only 6% of the participants were nonwhite, and these individuals were less likely to take part in the follow-up session of the study. As a result, the study may not have fully or accurately captured workplace discrimination among people from different racial groups. In addition, blood pressure was self-reported, which may be less reliable than measurements directly documented by medical professionals.

What may limit the health impact of workplace discrimination?

At the organizational level, no studies have directly addressed this issue. Preliminary evidence suggests that improving working conditions, such as decreasing job demands and increasing job control, may help lower blood pressure, according to the study authors. In addition, the American Heart Association recently released a report, Driving Health Equity in the Workplace, that aims to address drivers of health inequities in the workplace.

Encouraging greater awareness of implicit bias may be one way to help reduce discrimination in the workplace. Implicit bias refers to the unconscious assumptions and prejudgments people have about groups of people that may underlie some discriminatory behaviors. You can explore implicit biases with these tests, which were developed at Harvard and other universities.

On an individual level, stress management training can reduce blood pressure. A range of stress-relieving strategies may offer similar benefits. Regularly practicing relaxation techniques or brief mindfulness reflections, learning ways to cope with negative thoughts, and getting sufficient exercise can help.

About the Author

Julie Corliss, Executive Editor, Harvard Heart Letter

Julie Corliss is the executive editor of the Harvard Heart Letter. Before working at Harvard, she was a medical writer and editor at HealthNews, a consumer newsletter affiliated with The New England Journal of Medicine. She … See Full Bio View all posts by Julie Corliss

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

How well do you score on brain health?

Need another jolt of motivation to shore up a resolution to shed weight, sleep more soundly, boost nutrition or exercise levels, or cut back on alcohol? Then you'll be pleased to learn that any (and all) of these efforts can also add up to better brain health.

An international study led by researchers at the McCance Center for Brain Health at Massachusetts General Hospital devised and validated a Brain Care Score (BCS) card that makes it easy to total up what you're doing well and where you might do better. The prize is a healthier brain — specifically a lower risk for dementia and strokes.

Designed to predict how current habits might impact future brain health, the user-friendly scorecard is apparently the first of its kind, says Dr. Andrew Budson, a lecturer in neurology at Harvard Medical School.

"It's a real service that the researchers have developed a scale like this and completed the first study to determine if scoring worse on this scale raises your risk for dementia and stroke," says Dr. Budson, who wasn't involved in the analysis. "On one hand, no one's done something quite like this before. On the other, however, it's really wrapping together health factors everyone has known for a number of years in new packaging."

What's included on the scorecard?

Called the McCance Brain Care Score, the card tallies points from 12 physical, lifestyle, and social-emotional domains.

Physical components relate to

• blood pressure
• blood sugar
• cholesterol
• body mass index (BMI).

Lifestyle components include

• nutrition
• alcohol intake
• smoking
• aerobic activities
• sleep.

Social-emotional factors inquire about

• stress management
• social relationships
• meaning in life.

Each response is given a score of 0, 1, or 2, with the highest possible score totaling 21. Higher scores suggest better brain care.

"All these physical and lifestyle factors can contribute to the risk of dementia to some extent through strokes," Dr. Budson says. "Those that aren't a risk through strokes are usually related to the fact that a healthy brain is a brain that's using all of its parts. Engaging in healthy relationships and meaningful activities helps us maintain good brain structure and function."

What did the analysis involve?

The study was published online in Frontiers of Neurology in December 2023. It involved nearly 399,000 adults ages 40 through 69 (average age 57; 54% women) who contributed personal health information to the UK Biobank.

During an average follow-up period of 12.5 years, participants recorded 5,354 new cases of dementia and 7,259 strokes. Researchers found that participants with higher Brain Care Scores at the study's start had lower risks of developing dementia or strokes over time.

These threats to health and independence take a stunning — and growing — toll on people in the US. Dementia affects one in seven Americans, a rate expected to triple by 2050. Meanwhile, more than 795,000 people in the United States suffer a stroke each year, according to the CDC.

What did the study find?

Each five-point step higher in the BCS rating assigned when the study began was linked to significantly lower risks of dementia and stroke, with those odds varying by age group:

• Participants younger than 50 at the study's start were 59% less likely to develop dementia and 48% less likely to have a stroke with each five-point higher score on BCS.
• Participants 50 through 59 at the study's start were 32% less likely to develop dementia and 52% less likely to have a stroke with each five-point higher score on BCS.

But those brain disease benefits appeared to diminish for those older than 59 at the study's start. This group experienced only 8% lower odds of dementia and a 33% lower risk of stroke with each five-point higher score on BCS. Study authors theorized that some of these participants may have already been experiencing early dementia, which is difficult to detect until it progresses.

"I feel very comfortable that the study's conclusions are entirely correct, because all the factors that go into its BCS are well-known things people can do to reduce their risk of stroke and dementia," Dr. Budson says.

What are the study's limitations?

However, Dr. Budson notes that the study did have a couple of limitations,. The UK Biobank fell just short of collecting all the components of the BCS in its dataset, lacking meaning-of-life questions. So its scores ranged from 0 to 19, not up to 21. "It's a practical limitation, but it should be acknowledged that so far, there have been no studies to validate the actual 21-point scale they're recommending we use," he says.

The analysis also evaluated participants' scores at just one point in time instead of several, Dr. Budson says. Future research should determine whether people can lower their stroke and dementia risk by improving their BCS over time with behavior and lifestyle changes.

How can you play this game at home?

While better brain health may be the clear prize of a higher score, it's far from the only benefit. That's because improving any health component of the BCS also benefits our overall well-being.

"By improving these factors, not only will people help their brain, but they'll also help their heart and reduce their risk of cancer," Dr. Budson adds. "These factors will absolutely also improve your psychological health, which is certainly an important part of brain health."

The scale's simple breakdown of health factors also makes it easy to focus on tweaking one or two without getting overwhelmed.

"Let's say someone's nutrition isn't perfect — and they know it — but they're not willing to change their diet. Fine. They can then decide to do more aerobic exercise, for example, or to stop drinking, or to get the sleep their body needs," he says.

What one change could put you on a path to better brain health?

If he had to choose just one factor to improve brain health, Dr. Budson would focus on meaning of life, "which means you generally feel your life has meaning or purpose," he says. To do that, he suggests giving deep, quiet thought to what you wish your life's purpose to be, whether you expect to live a long time or just a few years.

"Once you have a purpose, then you have a reason to follow through with assessing all the other items on the BCS scale and seeing what you can do so you'll be around longer, and be competent and capable longer, to help fulfill the meaning and purpose of your life," he says.

About the Author

Maureen Salamon, Executive Editor, Harvard Women's Health Watch

Maureen Salamon is executive editor of Harvard Women’s Health Watch. She began her career as a newspaper reporter and later covered health and medicine for a wide variety of websites, magazines, and hospitals. Her work has … See Full Bio View all posts by Maureen Salamon

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD