Ophthalmologist Andrew Iwach said some take better care of cars than their eyes.

If you’re over 40, here’s what you need to know about protecting and prolonging your eye health.

Two East Bay women in their late 50s have been best friends since middle school. Their health is fine, and they have similar lifestyle attitudes, tending toward mellow and balanced, and they’re definitely not Type As. Their incomes teeter on the lower end of middle class. One eats meat while one doesn’t. Both color their gray, at home. Dedicated moms of young adults, they are lifelong lovers of reading, especially fiction. They also adore movies, streaming or in theatres, and they like writing, too.

But after about age 40, these gal pals noticed one major difference between them. Marta, from El Cerrito (not her real name), pours over her computer for work and pleasure, curls up in bed with a book, relaxes to her nightly TV. She’s eye naked: no glasses, no contacts. But she’s just starting to squint, a little.

Ellen, of Berkeley (not her real name), however, is totally dependent on reading glasses — magnifiers — for many things. And as she gets older, she needs stronger and stronger lenses and strives not to miss a “readers” sale at Walgreens, Target, or CVS.

Neither woman has ever worn prescription glasses.

Welcome to eyes and aging, unique for each person and hard to predict. But for everyone, eyes change with age. Eyes are an inescapable reality of lifespan.

“A change in vision is often the first undeniable sign of aging,” said the Merck Manual, a health education publication.

How the eyes change, when, and to what degree is highly individual. But some change is inevitable. And as with the rest of the body, practicing good eye health can help your blinkers function well longer and slow serious conditions.

So what is good eye health for aging? It centers on knowing you eyes well medically, from the inside out.

“As we age, the eyes get a little more wobbly, so more things can happen,” said Melanie Hom, an Oakland ophthalmologist. “At middle age, it’s a good idea to get a baseline eye exam. Like with anything, early diagnosis gives you a better chance of getting treatment and better outcomes.”

There’s a tendency for people to separate their eyes from the rest of their bodies and take their optical health for granted. This makes sense, because for most people, eyes don’t take that much fuss, beyond glasses or contacts. Eyes may be itchy and runny during allergy season. Many eye diseases don’t have noticeable early symptoms, making them easy to miss. Eyes commonly get lost among the other woes and maladies of the older years — increased cholesterol, weight gain, arthritis, and hearing loss. As a consequence, eye conditions often aren’t diagnosed until they’re serious, making treatment much trickier.

“The earlier we can detect things across the board, the more options we generally have to save vision,” said Andrew Iwach, a San Francisco ophthalmologist. “Timing is everything.”

He added:  “I see people taking better care of their cars than their eyes. For most of us, the eyes are amazingly low maintenance. But even though everything seems fine, you can still have underlying issues. If we detect them early, we can tweak things, and you’re back on the road again. Prevention is best.”

By age 40, everyone should get a baseline eye exam by an ophthalmologist, a medical doctor who specializes in eyes, recommends the American Academy of Ophthalmology. “That’s an important inflection point as we get older,” Iwach said.

Confused by the three Os of eye care? You’re not alone. An ophthalmologist is a medical doctor of the eyes; an optician makes and fits glasses or contacts; an optometrist tests vision and prescribes corrective lenses.

Some optometrists, depending on their equipment and training, can detect and treat less serious eye conditions. But ophthalmologists are medical specialists of the eye, best trained to provide comprehensive health care.

Hom pointed out that many ophthalmologists team with optometrists, even sharing the same practice.

At a baseline eye exam, your doctor will advise you on follow-up care, based on your eyes as well as the rest of your health. Diabetes, high blood pressure, smoking, and family history are known risk factors for serious eye conditions.

So, what’s inevitable, or at least common, to aging eyes?

Presbyopia or loss of near vision. Yes, this is what Ellen is experiencing, and it sounds like it’s starting for Marta, both over 40. Everyone should expect fuzzy near vision starting around middle age. As people age, the lenses of their eyes get stiffer, affecting one’s ability to focus close up. Flexible and normally transparent, the eye lens, which sits behind the pupil, refracts incoming light as it reaches the retina, helping with focus. Light enters through the pupil and through the lens to the retina at the back of the eyes, which translates it into electric pulses that result in images in the brain. Like muscles, lenses change shape to change focus, and also like muscles, they tend to get stiffer in older age. A result is blurry close vision.

In most cases, reading glasses from the drug store solve the problem. But people who are also nearsighted or need glasses to see far away will need to get bifocal or multifocal glasses to help compensate for both vision issues. Symptoms of eyestrain, uncomfortable, red, fatigued eyes are common in today’s screen-addicted culture.

Other lens conditions. The lens can become denser with age, which makes it harder to see at dusk or in dim light. Lenses can also yellow, affecting color perception, especially of blues, greens, and violets. Colors may not be as bright or distinct.

Cataracts. The same process that causes lenses to yellow can result in cataracts, a film over the lens causing cloudy vision. Cataracts start slowly and may not be noticed until vision is impaired. They’re “a normal aging change,” Iswach said. “If someone lives long enough, they generally get cataracts.”

In early stages, glasses or good lighting can help people with cataracts see. But as the cataracts get worse, surgery is the best treatment for most people, and cataract surgery is safe and effective.

Pupils shrink. Pupils, working with the surrounding iris, open and close to control the amount of light entering the eye. With aging, pupils tend to shrink and become less efficient at controlling light, making it harder to see clearly in dim light and also harder to adjust to super bright light or glare.

“The pupil becomes smaller and less responsive to changes in light. That’s why people in their 60s need three-times more light for comfortable reading than those in their 20s. Smaller pupils make it more difficult to see at night,” said the National Institutes of Health. Bright light at home or in the workplace can help older eyes see clearly. When these aren’t enough, ask a doctor.

Dry-eye. Tear glands produce fewer tears as people get older, which can result in dry, scratchy, red eyes, and blurry vision. Over-the-counter drops such as artificial tears can help. Unfortunately, screen time, whether gazing at a phone or large computer screen, exacerbates dry eyes, because it affects one’s natural blink rate. When looking at bright screens, viewers blink less, and blinking protects natural eye moisture and helps eyes clean themselves. “You overlie the baseline blink rate and that can lead to irritation and dryness of the eyes. It doesn’t cause permanent damage, but functionally people are very much affected by it, because the eyes are uncomfortable,” Iwach said. Heavy screen users should be aware of this, he said. “It’s a trade off.”

In today’s screen-addicted culture, general eyestrain is common, marked by uncomfortable, red, tired eyes and often blurred vision. In this case, prescription reading glasses or eye moisturizer may bring more relief than over-the-counter options, Hom said.

Floaters. It’s scary to look across the table at your friend and see a field of dark spots floating across your eyes. But in most cases, floaters, as these specks are called, aren’t a serious problem, but a normal symptom of age-related changes in the jelly-like substance inside the eye, called vitreous. As we get older, the protein fibers of the vitreous tend to clump together casting shadows across the retina. These shadows are floaters, dots or specks or lines. The condition is called vitreous collapse.

See an eye doctor as soon as you can when you experience floaters to make sure it isn’t a sign of something more serious such as retinal detachment.

“In 99.9 percent of the time, we just watch these,” Hom said. Floaters don’t go away, but most people learn to live with them. “You kind of learn to ignore the floaters. They become less bothersome. Over time your brain gets used to them,” Hom said.

Age-related macular degeneration, or AMD. AMD is damage to the macula, which is in the center of the retina. There are two types of AMD, dry, which is most common; and wet, which is rare. In dry macular degeneration, the macula gets thinner or covered with clumps of proteins causing central vision blindness. Peripheral vision can stay intact. In wet AMD, abnormal leaking blood vessels grow under the retina. Symptoms might not be noticeable until the condition is quite serious.

There is no cure for macular degeneration, but new medications may slow its progress, which is why early diagnosis is key. Smoking is a significant risk factor for AMD. Iswach said he has patients who tried to quit smoking many times and couldn’t, until diagnosed with AMD. “Blindness is a powerful message.”

Other risk factors, according to the American Academy of Ophthalmology, include: being over age 50, diets high in saturated fat, a family history of AMD, being Caucasian, and having heat disease or high cholesterol.

Glaucoma. After middle age, fluid pressure inside the eye can gradually increase, damaging “the optic nerve. This condition, called glaucoma, starts by affecting side or peripheral vision. It

“can worsen to blindness. Because it progresses slowly, many people may have glaucoma and

not know it. Early treatment can make a big difference in slowing the progression of glaucoma, another important reason to get an eye exam.

Diabetic retinopathy. People with diabetes are at risk for retinal damage caused by swelling and leaking blood vessels linked to high blood sugar levels, a condition called diabetic retinopathy. Sometimes the condition causes blood vessels to close, or the growth of abnormal vessels. This condition, which tends to worsen over time, results in blindness. Good diabetes management and control is the best way to prevent or slow diabetic retinopathy. If you have diabetes, makes sure to get your eyes checked.

Detached or torn retina. Though not super common, age increases the risk of having a retina detach or tear. Untreated, this condition causes blindness. Other risk factors include being extremely nearsighted or having a family history of retinal detachment. Symptoms include sudden floaters or tiny specks across your vision, flashes of light, a shadow, or partial vision blockage. These are urgent or emergency conditions, needing immediate medical attention. Retinal tears or detachments are usually treated by surgery, and the sooner the problem is caught, the better the chance of success.

With aging eyes and the certainty of change, ophthalmologist Iwach leans toward philosophy and optimism. “Even if you do everything right in life, sometimes things go wrong. But if you extend your efforts, the odds are you’ll improve outcomes,” he said.