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        How the Eyes Work

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 Binocular Vision

  Category: How the Eyes Work

 

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.

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 Eye Anatomy 101

  Category: How the Eyes Work

 

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,

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 Technology and Vision

  Category: How the Eyes Work

 

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.

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Binocular Vision

Created in All About Eyes

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 overlaps 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.

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Eye Anatomy 101

Created in All About Eyes

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

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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.

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Technology and Vision

Created in All About Eyes

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 a 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

  • 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.

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