Binocular Vision

The human visual system is a complex network including the eye, ocular nerves, and key brain areas that process visual information. Under most circumstances, we use information from both eyes to create a single visual image. This ability to converge information from both eyes is called binocular vision. In some cases, the eyes fail to seamlessly meld visual information into a coherent image. An eye care provider can assess vision to determine if there are problems with binocular vision that require further care.

How Does Binocular Vision Work?

Unlike some other animals, humans’ eyes are both set on the front of the face, permitting binocular vision. Each eye has a field of view, which is the area that you can see when you close one eye. The center of the eyes’ fields of view overlap with one another, although visual information in the periphery can only be detected by one eye. This information is transmitted to an area of the brain in the back of the head, which synthesizes the overlapping visual information to make a single coordinated image.

Binocular Vision and Depth Perception

One of the reasons that binocular vision is so important is that it allows us to perceive depth and relationships between objects. Each eye sees slightly different spatial information and transmits these differences to the brain. The brain then uses the discrepancies between the two eyes to judge distance and depth. The result is the ability to see a 3-D image and distinguish the relationships between objects. Depth perception is technically called stereopsis or stereoscopic vision.

Causes of Binocular Vision Problems

If the eyes can no longer maintain their correct position or focus on the same object, the result is problems with binocular vision. In cases of strabismus, or cross-eye, the eyes are not properly aligned, with one is drifting from its normal position. Strabismus causes the brain to have difficulty synthesizing visual images from each eye, resulting in impaired binocular vision and depth perception. Amblyopia, or lazy eye, is another condition that causes binocular vision problems. Amblyopia occurs when the brain ignores input from one eye, affecting depth perception and other visual abilities.

Fortunately, most problems with binocular vision are easily treated through eyeglasses, vision therapy, or surgery. Receiving a thorough annual optometry exam — especially during childhood when the visual system continues to develop — is essential to detect these eye problems. Your eye care provider can recommend treatment options that correct or manage problems with binocular vision.

Glare and Halos

Glare and halos are both eye symptoms that some people experience around bright lights. Halos show up as bright circles around a light source. Glare is light that interferes with your vision, making it difficult to see or sometimes making your eyes water.

These symptoms can show up at any time of the day. Halos often appear at night when the area around the lights is dim or dark, such as while driving at night.

Several conditions can cause glare and halos, such as aging or certain types of eye surgery. Treatment may involve taking care of the underlying cause. Other times, you may need to avoid driving at night if the glare and halos interfere with your driving.

Causes of Glare and Halos

Several things can cause glare and halos, including:

  • Cataracts
  • Refractive surgery, such as LASIK
  • Aging
  • Common eye problems such as nearsightedness, farsightedness or astigmatism
  • Pupil dilation during an eye exam
  • Artificial lens implants used to treat cataracts (intraocular lenses, or IOLs)

When your eyes are heavily dilated during an eye exam, the light passes through the outer edge of the lens. This allows the light to bend (refract) differently as it passes through. This can cause glare.

If you have had LASIK or another kind of refractive surgery, you may experience glare or halos around light for several months after the procedure.

Treatment for Glare and Halos

Before deciding on a treatment, your eye doctor will perform an eye exam to determine what’s causing the glare and halos. Possible treatments include:

  • Watching and waiting to see if the glare and halos clear up on their own, such as after LASIK surgery
  • Medicated eye drops
  • Treatment for cataracts
  • Wearing sunglasses during the day to reduce glare
  • Using the visor on your car to keep direct sunlight out of your eyes
  • Correcting your vision with glasses or contact lenses

If you notice pesky glare or halos, contact our office today. We can diagnose your condition and suggest appropriate treatment options.

Eye Anatomy 101

The eye has many parts that work together to create vision. The eyes themselves are only part of “seeing.” The brain is also involved. The eyes, though, begin the complex process of vision by gathering, focusing and passing on visual information to the brain.

To help you learn how the eye works, here is a quick overview of the anatomy of the eye. This information is also useful in understanding which parts of the eye are affected by different health problems of the eye.

Cornea. Light first enters the eye through this transparent, dome-shaped surface that covers the front of the eye. The cornea bends — or refracts — the light onto the eye’s lens.

Pupil. This is the round hole at the front of the eye that appears black. It is located behind the middle of the cornea and is surrounded by the iris.

Iris. The iris, or the colored part of the eye surrounding the pupil, controls how much light enters the eye. The iris can make the pupil bigger or smaller by opening or closing.

Lens. Behind the pupil and the iris is a transparent structure that looks similar in shape to the lens of a magnifying glass. Unlike glass lenses, though, this part of the eye can change shape. This enables it to bend the rays of light even more, so they land in the right place on the retina, at the back of the eye.

Vitreous body, or gel. The eye is filled with a gel that helps it keep its round shape. Light entering the eye first passes through the cornea then the lens and then the vitreous body before reaching the retina.

Retina. At the back of the eye is the retina, or a thin layer of light-sensitive nerve cells. The retina contains different types of photoreceptors — called rods and cones — which respond to light that lands on them.

Cones. These light-sensitive nerve cells are located in the macula, which is located at the center of the retina. Cones are necessary for focused central vision. Cones also enable you to see colors in bright-light conditions.

Rods. These light-sensitive nerve cells surround the macula and extend to the edge of the retina. The rods provide you with your side, or peripheral, vision. They also help you see at night and in dim light.

Optic nerve. The cells of the retina turn light into electrical impulses. These electrical signals are collected by the optic nerve — a bundle of about 1 million nerve fibers — and transmitted to the brain. The brain puts all this information together to produce the image that you see.

To learn more about eye anatomy or to have your eye health examined, please contact our practice.

Technology and Vision

The primary sufferers of technology-related eyestrain used to be adults whose work involved computers. Now, however, people of all ages use computers, smartphones, tablets and gaming devices, which can take their toll on the eyes. As people’s reliance on technology grows, so does the incidence of eyestrain. Keep reading to learn more about digital eyestrain and how you can protect your eyes in the digital age.

How Much Screen Time Is Too Much?

After two hours of screen time, the eyes typically begin to get tired and suffer from digital eyestrain. Additional contributing factors to developing eyestrain include small print, devices held at non-ergonomic angles too far from eyes and the blue light emitted from digital screens. People who wear glasses or contacts are even likelier to strain their eyes, as their prescriptions might not be ideal for mid-range viewing of electronics.

Screens and Blinking

When going about their day, the average person blinks approximately 18 times per minute. However, staring at a screen slows the blink rate. This can lead to itchy, dry and burning eyes. Office workers with computer-related jobs may even undergo physiological changes to their eyes that are similar to those experienced by people who suffer from dry eye disorder.

Age-Related Trends

People of different ages tend to use technology differently. The Vision Council, which represents optical industry suppliers and manufacturers, analyzed these differences in its 2015 report on digital eyestrain. The council determined that Millennials (individuals born between 1981 and 1996) and members of Generation X (individuals born between 1965 and 1980) are the most likely to strain their eyes due to screen overuse. Sixty percent of Millennials and nearly one-third of Gen Xers spent nine or more hours per day looking at a screen. Only 26 percent of Baby Boomers (individuals born between 1946 and1964) are as glued to digital technology as the aforementioned generations. About 63 percent of Gen Xers and 68 percent of Millennials reported symptoms of digital eyestrain.

Protect Your Eyes

Despite the rise of digital eyestrain, most people are not about to give up their smartphones and tablets. So how do you protect yourself? Here are a few ways:

  • Tweak your lighting. Turn down your ambient lighting when looking at screens, and avoid fluorescent tube lighting. Windows should be to the side of your computer, rather than directly in front or behind it.
  • Pick the right display. Liquid crystal displays (LCDs) with flat panels are better than cathode ray tube (CRT) monitors. If you are still using a flickering CRT display, it is time to upgrade. Go for a larger screen with high resolution.
  • Adjust your computer’s display settings. Brightness should be about the same as that of your surrounding area. Use the “view” menu to zoom in and make text bigger without changing the font size. Reduce the color temperature to reduce blue light. Microsoft Windows users will find display settings in the control panel. Apple users should look in systems preferences.
  • Take breaks. Blink. Look off into the distance. Better yet, get up and walk around.
  • Get regular eye exams. Your eye doctor is your ally in avoiding digital eyestrain. Discuss your computer use, how far you sit from the screen and what other devices, such as tablets and smartphones, you typically use.

Call us today. We’ll set up your next comprehensive eye exam to help determine ways you can protect your eyes against digital eyestrain and other factors that may affect your eye health.

How the Eyes Work

Every morning, we open our eyes and become immersed in a wealth of visual information. The eyes and related brain structures are a complex system that allows us to experience visual information from the surrounding world. It is easy to take clear vision for granted, but even subtle changes in the structure or functioning of the eyes can disrupt our sight. An eye care provider conducts a thorough eye exam to ensure that these components are functioning together well.

Basic Eye Anatomy

The eyeball is not a single, spherical structure as is commonly thought. It consists of a smaller, curved portion called the cornea that attaches to a larger, roughly spherical structure called the sclera (the white of the eye). The eyeball is filled with a jelly-like substance called the vitreous fluid.

Toward the front of the eye are three essential structures: the iris, pupil, and lens. The iris is the colored part of your eye. It can open and close to determine how much light to let in through the pupil, the black hole in the center of your eye. Finally, the lens is a flexible, convex structure that changes shape to direct light rays in different directions within the eye.

At the back of the eyeball is a layer of tissue called the retina. The retina consists of millions of photosensitive cells that react to certain types of light. Cone cells are clustered toward the center of the retina, and react to colors and details in bright light. Rod cells, which are spread toward the periphery of the retina, react to dim lighting conditions.

How the Eyes Facilitate Vision

When light enters the eye through the pupil, it passes through the lens, which changes shape to ensure that the light rays hit the retina. When the light rays reach the back of the eye, it stimulates the rod and cone cells to fire. Cone cells detect fine details and color in the center of your visual field. Rod cells detect edges in peripheral vision and allow us to perceive shapes in dim light.

The rods and cones in your retina convert light energy into electrical signals, which exit the eye through the optic nerve, located just below the center of the retina. The optic nerve carries visual information to the occipital cortex in the very back of your brain, where it is processed to result in a rich visual experience.

If any part of this complex arrangement functions improperly, vision is impaired. Thus, it is essential to receive regular optometry exams to have your eye structures and visual abilities checked.

Lifestyle Practices for Eye Health

Protecting your eyesight is an important part of staying healthy overall. Maintaining sound eye health will also help you preserve your quality of life as you age. To keep your eyes as healthy as possible, follow these simple lifestyle practices.

Get regular eye exams. Some eye problems — including age-related macular degeneration, diabetic eye disease and glaucoma — may not show any warning signs until they have progressed into their advanced stages, limiting the treatment options. However, by undergoing regular eye exams, your eye doctor can help detect eye problems in their early stages and suggest appropriate treatment options sooner.

Learn your family eye health history. If other members of your family have been diagnosed with eye conditions, you may be more at risk of developing them. If you have a family history of eye disease, alert your eye doctor, so he or she can monitor your eye health.

Eat a healthy diet. It’s not just carrots that are good for your eyes. A diet rich in fresh fruits and vegetables can help keep your eyes healthy. This includes dark, leafy greens, such as collard greens, kale and spinach. Fish high in omega-3 fatty acids may also help protect your eye health; these include halibut, salmon and tuna, among others.

Maintain a healthy weight. Being overweight or obese can increase your risk of certain eye conditions, such as diabetic eye disease and glaucoma. Eating a healthy diet and exercising regularly can help you lose weight and keep the weight off. If you still have trouble, talk to your doctor.

Give up smoking. Smoking tobacco increases your risk of several eye conditions, including age-related macular degeneration, cataracts and damage to the optic nerve. If left untreated, these eye conditions can lead to blindness.

Wear sunglasses. The ultraviolet rays in sunlight can damage, not only your skin, but also your eyes. To keep your eyes safe, wear sunglasses whenever you are outside. Make sure the glasses are certified to block 99 to 100 percent of both UV-A and UV-B radiation.

Let your eyes rest regularly. If you read, use a computer or do close-up work for long periods, give your eyes frequent breaks using the 20-20-20 rule. Every 20 minutes, look at an object about 20 feet away for 20 seconds.

Keep your contact lenses clean. If you wear contact lenses, be sure to follow their cleaning instructions closely. In addition, wash your hands thoroughly before you take out or put in your contact lenses. This will reduce your risk of developing an eye infection.

Be eye safe at work. If your workplace requires protective eyewear, be sure to wear them at all times. In addition, know what to do if you, or one of your coworkers, has an eye injury or is splashed in the eyes with harsh chemicals.

Nutrition for Eye Health

Eating right is essential for keeping your body healthy. This is as true for your eyes as it is for your heart. A diet that is rich in fresh fruits, vegetables and whole grains, and is low in saturated fat, can reduce your risk of heart disease. This will also keep your arteries healthy, so they can continue to supply your eyes with oxygen-rich blood.

In addition to eating an overall healthy diet, though, some foods in particular are excellent for your eye health.

Green, leafy vegetables. Kale, spinach, collards and other leafy greens are all high in lutein and zeaxanthin. These nutrients may reduce the risk of chronic eye diseases such as age-related macular degeneration (AMD) and cataracts. These nutrients are also found in broccoli, corn, eggs and peas.

Cold-water fish. Salmon, halibut and tuna are all rich in omega-3 fatty acids, a healthy fat that may reduce your risk of developing AMD. If you are vegetarian, walnuts and ground flax seeds will provide some types of omega-3 fatty acids, but you may need to take microalgae supplements to obtain DHA omega-3s.

Citrus fruit. Oranges, grapefruit, tangerines and lemons are all high in vitamin C. This antioxidant is essential for healthy eyes and may slow down the formation of cataracts and onset of AMD. You can also obtain vitamin C from other foods, including peaches, red peppers, strawberries and tomatoes.

Legumes. Black-eyed peas, lima beans, kidney beans and peanuts are all rich in zinc. This mineral, which is found in the eye in high concentration, may help prevent your eyes from being damaged by light. Zinc is also found in lean red meat, poultry, milk and whole grains.

Nuts. Almonds, pecans and other nuts are rich in vitamin E, a nutrient that may slow the progression of AMD and may prevent the formation of cataracts. You can also find vitamin E in avocados, spinach, sunflower seeds and whole grains.

Carrots. Rich in beta-carotene, carrots keep your night vision working properly. This nutrient is also found in other orange-colored fruits and vegetables, such as apricots, cantaloupe and sweet potatoes.

To learn more about protecting your eye health, contact us today.

Protecting Your Eyes

Of our five senses, humans rely on vision most strongly. Our everyday experience of the world is colored by our ability to see, our memory draws heavily upon visual information, and many activities of daily living are challenging without sight. As a result, it is essential to protect your eyes from damage. Regular visits to an eye care provider allow you to receive a professional eye exam that checks for damage due to inadequate eye protection.

Eye Strain

Americans are spending more time than ever in front of screens. From checking email on smartphones to staring at a computer screen in your office to watching TV in the evenings, too much screen use can cause eye strain. Experts recommend taking at least five minutes per hour to relax your eyes and alleviate strain. Go for a brief walk or focus on distant objects to reduce eye strain before returning to the task at hand.

Dust, Wind, and other Environmental Stressors

It is easy for eyes to become damaged by windy conditions, blowing dust, air pollutants, and other small particles in the air. When facing dusty or windy conditions, eye drops or safety glasses can protect your eyes from damage. Contact wearers should opt for glasses to prevent particles from irritating the surface of your eyes. Whenever possible, stay indoors on very windy or dusty days to prevent eye damage. If your eyes become very irritated, visit the eye doctor for a thorough optometry exam and treatment recommendations.

Sun Protection

Everyone knows that UV rays cause sunburns, but did you know that UV exposure damages your eye tissue as well? Lengthy, intense exposure to UV rays may increase your risk of macular degeneration, cataracts, and other eye conditions that affect your vision. To stay safe, find a pair of sunglasses that block 100% of UVA and UVB rays. Darker lenses or more expensive styles do not always translate to better UV protection. When possible, choose wrap-around styles that do not let light in from the side. Sunglasses are not just for summertime or bright days — UV damage can occur year-round and can be especially bad during the wintertime when sunlight reflects off of ice and snow.

In general, the best policy is to avoid taking chances with your eye health. Wear proper protection when heading outside, playing sports, and working with dangerous tools or chemicals. Your eyes are designed to last a lifetime; treat them well, and you can avoid major vision problems that affect everyday life.