Vision

One of the most crucial tests performed during an eye exam is the visual acuity test. This helps your eye doctor determine if your vision has been compromised or not.

Your eye doctor can perform different visual acuity tests, such as the very common Snellen eye chart. That's the one with letters and numbers on it – which you'll pretty much see in almost any eye doctor's office!

However, if you've never had an eye check-up before and you don't know what a visual acuity test is, you might have a few questions. So, read on.

What is a visual acuity test?

The term visual acuity refers to the clarity or sharpness of vision measured at a certain distance. A visual acuity test is an eye examination that measures how clearly you can distinguish shapes and details from a distance.

It's worth noting that this test merely measures one aspect of your vision, as other factors determine how well you can see including depth perception, peripheral vision, and color vision.

Visual acuity tests are also divided into a few types, which we'll talk more about later on.

Depending on what type of test is conducted and where it can be performed by the following professionals:

• Optician
• Ophthalmic technician
• Nurse
• Optometrist
• Ophthalmologist

Additionally, other organizations such as driver's license offices also use the visual acuity test to determine how well you can see.

If you need some help differentiating between these eye doctors – check our guide on optometrists vs ophthalmologists.

What's the purpose of the visual acuity test?

If you've noticed changes in your vision, such as blurriness or difficulty seeing objects nearby or from afar clearly, then you need to take a visual acuity test.

The following is a list of vision issues that a visual acuity test can screen for:

• Nearsightedness (myopia)
• Farsightedness (hyperopia)
• Astigmatism
• Age-related farsightedness (presbyopia)
• Ophthalmologist

How often should you get your eyes tested?

Regular eye exams are key to improving and maintaining your eyes' health, as they can help your eye care specialist with the early detection of symptoms or conditions.

Here's a quick breakdown of how often you should get your eyes checked, depending on your age.

• Children aged between 6 and 12 months issues can arise in one's eyes from childhood, so getting them checked early on is integral to healthy development. The American Optometric Association (AOA) recommends getting children's eyes checked at least during this period.
• Children under 18 years they should get their eyes checked every one to two years.
• Adults between 18 and 40 years they should get their eyes checked at least once every two years.
• Adults between 55 and 64 years they should get their eyes checked every one to three years.
• Adults older than 65They should get their eyes checked once a year.

If you wear glasses, contacts, or any form of visual aid, it's best to get your eyes checked every 1 to 2 years to ensure your prescription is up to date.

The same frequency applies if you have any of the following conditions: diabetes, glaucoma, cataracts, or age-related macular degeneration (AMD).

When in doubt, always consult your eye doctor about how often you should check-in. Before your visit, here's a more detailed guide to eye exams for your reading pleasure.

What types of visual acuity tests are there?

Snellen eye chart

The Snellen eye chart is the most common way to test for visual acuity.

If you're somewhat familiar with what a visual acuity test is, this is probably the first thing that comes to mind.

The Snellen eye chart uses a chart with letters, numbers, and symbols, and you've likely seen one in your school's nurse's office or eye doctor's office. The characters come in different sizes which are arranged in rows and columns.

How it works is that your eye care specialist will get you to view the chart from 20 feet away to determine how well you can see from a distance. They'll ask you to cover one eye and read out the letter you can see with your uncovered eye. The same process will then be repeated with your other eye. The test ends when you can no longer accurately distinguish the letters you're reading.

Random E

The random E test is similar to the Snellen eye chart.

In the random E test, you must determine which direction the letter 'E' is facing. To do so, you need to point in the direction the letter is facing when you are looking at it on a chart or projection: up, down, left, or right.

Pinhole visual acuity test

The pinhole test is specifically used for diagnosing myopia. Source: Bond Eye Associates

This test is used specifically for diagnosing nearsightedness and farsightedness, otherwise known as myopia. You'll be asked by your eye doctor to cover one of your eyes with a paddle, just like the one you'd use for a standard Snellen eye chart test.

The main difference with the paddle used in the pinhole visual is that it has one or a few tiny holes in it. Instead of covering your eye to read a chart, you'll use the covered eye to look through the pinholes. Looking through the pinhole helps your eye care doctor determine whether your reduced vision is caused by a refractive error such as myopia or hyperopia.

Simplified test for children

Instead of letters and numbers, children are asked to look at animals and symbols. Source: Vision Direct

You can find a variety of simplified tests for children. Some eye care providers give flashcards with symbols or letters, which children then have to match on the chart. Some can also be given a Snellen eye chart that features animals and symbols instead of symbols and numbers.

These types of tests make it easier for children and keep them from being too overwhelmed.

How to interpret your visual acuity test results

Fractions are used to express visual acuity, which is why you may have seen the number 20/20 floating around. If you have 20/20 vision, it means you can see objects clearly from a distance of 20 feet, which is considered normal. If you have a vision of 20/60, you need to be 20 feet away to see an object that people can normally see from 60 feet away.

If your vision goes over 20/20, it may mean you may need corrective measures in the form of glasses, surgery, or contact lenses.

However, as mentioned earlier, having 20/20 vision doesn't mean you can see perfectly. Visual acuity is only one of the few factors that affect your vision. For instance, you can have 20/20 vision but not have excellent peripheral vision.

What to expect after a visual acuity test

Once you've finished your visual acuity test, your eye doctor will give you the necessary recommendations.

If it's your first time undergoing a visual acuity test, you may be recommended a variety of visual aids such as eyeglasses, contacts, or surgery. From there, your doctor will determine which option works best for you depending on your needs, lifestyle, and preferences.

If you're someone who is already wearing a form of vision correction, your eye care provider will update your prescription. In this case, you may need to get new glasses or contact lenses.

Glasses and contacts are available in a variety of lenses, so here are the types of lenses as well as the vision issues they cater to.

Now you know all about visual acuity tests!

The visual acuity test is a great, tried-and-tested way to measure how well you can see from a distance. However, it's important to remember that they don't measure your overall vision, so don't be disheartened if you don't have 20/20 vision.

Before we leave you, here's a reminder to get your eyes checked regularly, or as soon as possible if you see any changes in your vision or suspect something amiss. Prevention is better than cure may be a cliché, but it could save your life.

Binocular vision is super important in our everyday lives. It helps us judge depth and distance accurately, which is essential when you think about it—just imagine trying to park your car without it!

It also contributes significantly to our hand-eye coordination and overall world perception. Let's dive in and explore what binocular vision is all about, how it works, and why it's so crucial for our daily activities and overall well-being.

What the heck is binocular vision

Binocular vision creates a 3D view using two eyes facing the same direction. Source: Wikipedia

So, how can we see the world around us with both eyes? Well, that's because we have something called binocular vision. It means that our eyes work together to create one image. It's necessary since our eyes are at slightly different angles. Each eye sees a slightly different view of the world.

Our brain then combines these two slightly different images into a three-dimensional image with depth and dimension. The way binocular vision works in the brain is unique. Our brain receives information from each eye separately and then compares the differences between the two images.

Our two eyes must be pointed in the same direction and work together to create a cohesive view. The retina is crucial in sending information to the brain to create this view. It then uses this information to calculate the distance and depth of objects in our environment. That's the basics of how we can tell the distance of an object.

Seeing with only one eye limits your ability to perceive depth.

In comparison, monocular vision, which is the ability to see with only one eye, has some limitations. It lacks the depth perception and ability to accurately judge distance that binocular vision provides. For example, if you're looking at a flat image like a photograph with only one eye, it can be difficult to tell how far away objects in the photo are.
Binocular vision provides an advantage in activities like catching a ball or driving a car, where we must accurately judge the distance and speed of objects in our environment.

Binocular vision helps us in our everyday activities

Binocular vision is important in driving because it allows for accurate judgment of distance and speed.

Have you ever stopped to think about how we can navigate the world? Well, a big part of that is thanks to binocular vision. It helps us accurately judge the distances and locations of objects in our environment.

But it's not just everyday tasks that binocular vision is essential for—it's also critical for daily activities like driving. You must have a binocular vision to accurately judge distance and speed to avoid obstacles and other drivers. And in sports like baseball, tennis, and basketball, accurately judging the speed and distance of the ball or other players can make all the difference.

The implications can be significant for people with impaired binocular vision.. It can make daily activities more challenging and dangerous and limit their ability to participate in particular sports or other activities. But the good news is, there are treatment options available—things like vision therapy or corrective surgery—that can improve binocular vision and alleviate these limitations.

We aren't born with perfect binocular vision

Having your child's eyes checked early is crucial to help detect any binocular vision problems.

Binocular vision isn't something we're born with—it takes some time to develop. In infants, it develops around four months old and continues to improve until about three years old. During this time, the brain is learning to fuse the slightly different images from each eye into one cohesive picture.

Early detection and treatment of binocular vision problems in children cannot be overstated. If left untreated, binocular vision problems can lead to permanent vision impairment, difficulty with learning and development, and even behavioral issues.

It's possible to correct disorders in binocular vision

Eye patches can help lazy eyes by encouraging the weaker eye to work harder. Source: Family Doctor

Common binocular vision disorders in children include amblyopia (also known as lazy eye) and strabismus (where the eyes are misaligned).

Fortunately, these conditions can often be corrected or improved with early detection and treatment. Treatment options may include vision therapy, corrective lenses, or in some cases, surgery.

Strabismus is a condition where the eyes are misaligned, meaning they don't point in the same direction. This condition can lead to double vision, headaches, and difficulty with depth perception. Amblyopia (lazy eye) is a condition where one eye doesn't develop properly during childhood.

This can result in poor eye vision and cause depth perception problems. So, what causes these binocular vision disorders? Well, there are a few different factors that can contribute. Strabismus is a condition where the eyes are not correctly aligned, and it can happen because the muscles that control the eyes or the nerves that signal those muscles are not working correctly.

Amblyopia mainly stems from a misalignment or difference in refractive error between the two eyes during childhood development. There are several treatments available for these binocular vision disorders.

Treatments for both eye disorders include eye patches, corrective lenses, and surgery. The key is to catch these disorders early on and seek treatment as soon as possible.

Get checked regularly to maintain eye health

Eye exams go beyond checking if you need prescriptive eyewear or not.

Eye exams aren't just for people who already wear glasses or contacts — they're essential for everyone. That's because eye exams can detect a wide range of vision problems, including those related to binocular vision.

The eye doctor will check your eyes' alignment and how well they work together. They'll also test your depth perception and overall visual acuity. This can help catch potential problems early on before they become more severe and challenging to treat.

But the importance of regular eye exams goes beyond just detecting vision problems. Regular eye exams can also help maintain healthy vision over time. They are also essential to detect signs of eye diseases like glaucoma or macular degeneration.

There are some cost-effective options available. Many vision insurance plans cover routine eye exams, and some vision clinics offer affordable packages for people without insurance. You can also look into free vision screenings from community organizations or public health clinics.

Binocular vision supports our daily activities in many ways

Maintaining healthy binocular vision involves regular eye check-ups.

Binocular vision is critical to our everyday lives, helping us judge depth and distance accurately, improving our hand-eye coordination, and contributing significantly to our overall perception of the world.

But as we've seen, healthy binocular vision is only sometimes given. Disorders related to binocular vision, like strabismus and amblyopia, can cause severe problems if left untreated. That's why it's so important to prioritize your eye health and seek professional guidance regarding your vision needs.

So if you last had an eye exam a while ago, now's the time to schedule one. Your eye doctor can assess the alignment and function of your eyes, catch potential problems early on, and help you maintain healthy vision over time.

Don't let vision problems go undetected—prioritize your eye health today!

References

• 'Lazy eye (amblyopia)', Mayo Clinic.
• 'Strabismus', Medline Plus.
• 'Binocular Vision', See Vividly.

Picking a cup of coffee up from a counter without knocking everything else – seems like a simple enough task, right?

In reality, it's the result of good depth perception, which is a pretty sophisticated visual process involving the coordination of your eyes and hands.

Without depth perception, our lives would look quite different. For starters, you wouldn't be able to drive safely, and sports would be even more complex than they already are, among others. Let's dive into how depth perception works.

What is depth perception?

Depth perception helps us determine how far an object is.

The ability to see things in 3D and judge distances is depth perception in action. When we look around, light rays enter the pupil and land on the retina. There, these rays form two-dimensional images that are sent to the brain for processing. The brain then interprets these images as a three-dimensional representation of the world around us.

In addition to that, the brain uses different cues to understand how far away things are and how they are positioned in space. These clues are called binocular, monocular, and oculomotor cues.

What are binocular cues?

Binocular cues are visual cues that involve the use of both eyes to perceive depth and distance. These cues include retinal disparity, the difference in the images that each eye sees, and convergence, which is the inward movement of the eyes as they focus on an object at a close distance. These cues are important for depth perception and spatial awareness.

What are monocular cues?

Monocular cues rely on the use of one eye to perceive depth, or techniques to create depth, motion, and spatial relationships in an image. These include relative size, relative height, relative motion, linear perspective, and texture gradient.

Relative size represents objects' sizes in proportion to each other, while relative height represents objects' heights relative to each other. Relative motion creates a sense of movement in an image.

Linear perspective creates the illusion of depth and three-dimensionality by using objects' and viewers' relationships. A texture gradient creates a sense of depth by gradually changing the texture or surface quality in an image.

What are oculomotor cues?

Oculomotor cues, such as convergence and accommodation, are visual cues related to the movement of the eyes. The brain uses these cues, along with the change of size and motion as the eye moves, to determine the perception of depth.

How does poor depth perception affect us?

Having poor depth perception can affect a person's ability to judge distances and perceive the three-dimensional structure of objects. This can make driving, sports, and even walking difficult. It can also make judging the size and shape of objects challenging.

Depth perception issues for adults

Depth perception allows a driver to accurately judge distances and the position of objects in space.

For adults, poor depth perception can lead to difficulties with tasks requiring fine motor coordination such as threading a needle, or spatial tasks such as navigating unfamiliar spaces or driving.

It could also endanger those with jobs that require spatial awareness, such as pilots, crane operators, and architects.

Underlying conditions like crossed eyes or lazy eye can lead to poor depth perception. This may lead to double vision or difficulty seeing 3D objects, so do seek treatment if you have any of these conditions.

Depth perception issues for children

For children, depth perception is vital for cognitive development and physical coordination.

Children with poor depth perception may have trouble with tasks requiring fine motor coordination, like holding a pen for writing or drawing and judging distances. This can make climbing, playing on playground equipment, and even walking difficult for them. It can also affect their school abilities, as it can make reading and mathematical tasks more tricky.

In worse cases, poor depth perception in children presents a safety hazard as it increases the likelihood of accidents.

4 ways to test your depth perception

1. At-home method of testing

Several methods can be done at home to determine if an individual has a problem with depth perception. Credit to Research Gate:

• TappingTapping with one finger (left) and tapping with each finger while the remaining digits are weight-bearing (right).
• Pincer graspMaximum (left) and minimum pincer (right).
• Hand opening and closingMaximum opening (left) and closing (right).
• GraphomotricityDrawing an M (top-left), a 3 (top-right), an S (bottom-left), and a spiral (bottom-right).
• Oculo-manual coordination using the eyes to track and fingers to tap on the moving pink dots.

Hand-eye coordination and finger-thumb tests are commonly used to evaluate an individual's ability to judge distances and coordinate their eyes and hands.

Meanwhile, the hole-in-the-card test is used to determine if someone has difficulties perceiving depth in 2D images or judging distances.

2. Testing your depth perception at an eye exam

The Snellen chart is a standard method used in eye exams.

An eye doctor can use various tests to assess a person's depth perception, with the standard one being the Snellen chart. It's a test that involves reading smaller letters or symbols from a distance and converting the results to a fraction.

On that note, regular eye exams are essential to keep your eyes' health in check and update your prescription if you have one.

To assess the perception of 3D objects, the stereo test is utilized. This test measures an individual's ability to detect depth and spatial relationships in a three-dimensional environment.

3. Randot Stereotest

The Random Stereotest requires identifying the correct animal and geometric shapes. Source: Review of Optometry

The Random Stereotest gauges how well you can see the depth and 3D structure in an image. It does this by showing you two pictures with random dots, which you look at through a special viewer. How well you can make out the 3D image from the 2D dots will determine your result.

4. Contour Stereotest

With the Contour Stereotest, you look at a picture using glasses to see the 3-D figure.

The Contour Stereotest checks a person's depth perception and looks for problems with stereo vision or binocular function. It works by making one wear glasses that make lines on cards appear in 3D by gradually reducing the distance between the lines.

Are there vision issues that can affect depth perception?

Blurry vision

Blurry vision affects how well you can see the details of things and how far away they are. It makes it hard to focus on objects, so you can't tell how close or far away they are.

This can make it hard to do tasks that require spatial awareness, such as playing basketball.

Strabismus (crossed eyes and lazy eye)

Strabismus is a condition where one's eyes don't point in the same direction. This can lead to double vision, trouble tracking moving objects, and other issues.

Since the brain can 'rewire' itself during childhood, it's crucial to catch and treat this condition early. Early treatment may restore normal binocular vision and prevent more serious vision problems down the line.

Amblyopia

Amblyopia is a condition where one eye's vision does not develop properly in childhood and is caused by the brain receiving different messages from each eye. It can cause difficulty seeing things far away, more accidents, and a lack of depth perception.

Eye trauma

Eye trauma is any injury caused to the structure surrounding the eyes, such as the eyelids or the muscles controlling movement. Depending on the severity and location of the damage, it can result in blurred vision, double vision (diplopia), reduced vision, visual field loss, color vision loss, and affected depth perception.

Treatments & ways to improve depth perception

While some treatments and techniques require low levels of intervention and can be done at home, others require professional advice from an eye doctor.

Eye exercises

Doing regular eye exercises can help improve one's vision by strengthening eye muscles, which leads to more accurate information from the eyes to the brain. Examples of eye exercises include following a moving object with your eyes and alternating between looking at near and far objects.

Improved lighting

Lighting can help improve depth perception by providing additional visual cues to the brain, such as details on an object, shadows, and edges.

Glasses or contact lenses

Wearing eyeglasses can help correct depth perception issues.

Corrective lenses can help improve depth perception by correcting any underlying vision problems that caused it in the first place, like blurry vision.

Corrective lenses can be used in two forms: eyeglasses and contact lenses. Before you decide on one, understand first the benefits and drawbacks of each type. It's also best to consult an ophthalmologist or optometrist to determine which type of corrective lenses best suits your individual needs.

Vision therapy

Vision therapy, also known as visual training or eye therapy, uses specific exercises and activities to improve the brain's ability to process visual information. It is typically done under an optometrist or ophthalmologist's supervision.

Surgery

In some cases of more severely impaired depth perception, surgery may be required.

Strabismus surgery, also known as eye muscle surgery, corrects misaligned eyes. The procedure involves adjusting the muscles around the eye that control its movement by strengthening or weakening them. This helps to realign the eyes so that they point in the same direction, improving the patient's vision and depth perception.

People with age-related, traumatic, congenital, or secondary cataracts may need to have cataract surgery. This procedure removes a cataract (or cloudy lens) that is affecting vision. It's replaced with an artificial intraocular lens (IOL) that caters to the patient's visual needs.

Aside from the natural lens becoming cloudy over time, cataract surgery may also be required to fix an injury to the eye, congenital defects, or medical conditions such as diabetes.

Corneal refractive surgeries like LASIK, PRK, or SMILE can also improve depth perception by correcting refractive errors such as myopia (shortsightedness), hyperopia (farsightedness), and astigmatism.

The importance of depth perception in our lives

Depth perception is like a superpower for our eyes. It helps us understand how far away things are and where they are in space. It's vital for many daily activities, like throwing a ball, driving a car, and even walking around without bumping into things.

However, things can go wrong sometimes. If you're having trouble with depth perception, please schedule an appointment with a trusted optometrist or ophthalmologist as soon as possible.

Imagine all the amazing sights that fill our world – breathtaking sunsets, gorgeous flowers, and vibrant rainbows.

Have you ever thought about what makes these wonders visible to us? There's a name for it, and it's called the visible light. Here's what it's all about.

What does the visible spectrum have to do with sight?

Everything we can see on Earth comes down to the science of light and the visible spectrum.

The visible spectrum is a portion of the electromagnetic spectrum that we can see. This spectrum consists of:

• Radio waves
• Microwaves
• Infrared (IR)
• Visible light (ROYGBIV)
• Ultraviolet (UV)
• X-rays
• Gamma rays

The portion that we can see from the electromagnetic spectrum is also referred to as 'visible light', the visible light spectrum, or simply light.

Out of the many electromagnetic radiations within the electromagnetic spectrum, we are only able to see visible light because of the cone-shaped cells in our eyes that are specifically tuned to the wavelengths in this portion.

Colors we can see on the visible spectrum and their wavelengths

Notably, the human eye can only detect wavelengths from 380 to 700 nanometers. This means the spectrum of colors we can view ranges from violet, which has the shortest wavelength (380), to red, which has the longest (700).

The colors we can see on the visible spectrum and their wavelength ranges. Source: Color Meanings

As you can tell from this, each color has its unique wavelength, and this wavelength also determines what color we see on an object. For instance, a red apple reflects light in the red portion of the spectrum, which leads our eyes to perceive the apple as… red!

However, the range of wavelengths our eyes detect can also vary due to factors such as a person's eyesight and vision problems. With the rise of electronic devices, our eyes have been more exposed to blue light, which is on the shorter wavelength section of the visible spectrum, and this has been believed to cause more eyesight issues.

Lacking one or multiple cone photoreceptor types, which are the cone-shaped cells in the eye that detect the wavelengths, can also lead to color blindness.

Heat and temperature can also cause objects to change their wavelengths and by extension their color. It's for this reason that you can see a hot pan on a stove glow red, yellow, or blue, as the changing temperature affects its wavelength and color.

As objects heat up, their atoms and molecules start to move faster, causing a shift in the light they reflect.

What does the sun have to do with the visible spectrum?

The sun emits a broad spectrum of electromagnetic waves, although the human eye is only able to see a small portion of them. Source: Eyes of Howick

The waves emitted by the sun range from ultraviolet to our visible spectrum to infrared, although our eyes can only see the visible spectrum.

The phenomenon of temperature affecting color is evident in the color of the sun and other stars. The hotter something is, the shorter wavelengths it has, making its color go from the reddish side to the more violet side of the spectrum.

This is why a hotter star emits a bluish light and color, like Rigel which is about 12,000°C. On the other hand, a cooler sun will radiate a reddish light and color, such as the star Betelgeuse which is 3,000°C. The sun's surface temperature of 5,500°C puts its wavelength in the yellow region of the visible spectrum.

When all the visible colors go together, they create the appearance of 'white light.' During mid-day, the light is shining directly above our heads, making it appear white and bright. However, when something refracts the light, such as raindrops in the air during a sunny day, the other colors in the spectrum become visible, which leads us to…

Ever wondered how rainbows are formed?

Rainbows are what we see when the full spectrum of colors is scattered from the right angle.

Rainbows are a natural display of the visible spectrum. Source: Science News Explores

It needs the right conditions of light and moisture in the air, such as when the sun shines just after the rain. The water droplets that are still in the atmosphere act as a prism that splits the white light we normally see into separate light wavelengths. This is why we can also see rainbows in foggy conditions, above the sea, and in waterfalls.

When light meets a droplet, it is reflected inside the droplet and refracted out again into the air, creating the familiar arched shape of a rainbow.

The different colors of the rainbow are seen in a specific order because of the different angles at which the light exits the raindrop. As such, red always appears on the outermost edge of the rainbow and purple is the innermost.

Colors beyond the visible spectrum

Some flowers use UV light to attract pollinators like bees. Source: Chelifer

The sun is a giant ball of gas emitting a tremendous amount of energy, including light of various wavelengths like visible light, ultraviolet (UV), and infrared.

Out of these wavelengths, we can only see visible light. UV and infrared light have wavelengths that are beyond the limits of our biological capability, either due to their size or energy level.

Although our eyes can't see UV and infrared light (with exceptions), some animals can see colors beyond the visible spectrum that we can't even imagine.

While the lowest wavelength we can detect is 380nm, birds can see from 300–400 nm, which is within the UV range. Bees can also see UV light found in some flowers, allowing them to pollinate. Some nocturnal animals, such as snakes, mosquitoes, frogs, and some forms of fish, can even see infrared light.

See the world in full color with the visible spectrum

The visible spectrum directly impacts the way we experience and interpret the world around us. Every day, we rely on our eyes to take in the colors and light that make up the visible spectrum, and our brains use that information to create our perception of reality.

From a practical perspective, understanding the visible spectrum is important for many fields, such as photography, art, and science. Photographers use the visible spectrum to capture images with the right amount of light and color, and scientists use it to study the properties of light and color in their experiments.

If you're a lover of all things eye-related, be sure to bookmark Door2USA Prescription Glasses for more fun facts, tips, and guides!

Picture this. You're at the optometrist's office, squinting at the eye chart as the letters gradually get smaller and smaller. Suddenly, the optometrist tells you that you're legally blind.

What does that even mean? Is it possible that you could be legally blind and not even realize it? Don't worry. You're not alone in your confusion. Legal blindness is a term that can be difficult to understand, and it's important to know the prescription to be legally blind.

Let's discuss the definition of legal blindness and explore how visual acuity is measured. We'll also explore the impact and misconceptions of the term. So, let's clear up some confusion and shed some light on this important topic.

What is legal blindness?

Although legal blindness doesn't mean total blindness, it can significantly impact a person's ability to perform daily tasks.

Legal blindness is a term used to describe a level of vision loss that meets specific criteria set by a country or organization. This can impact a person's ability to perform daily activities and access certain services and benefits.

The retina, which is part of the eye that contains photoreceptor cells that help detect light and send signals to the brain, can be affected by various medical conditions or injuries that result in vision loss.

Being legally blind depends on various factors, including visual acuity and visual field. Visual acuity refers to the sharpness of your vision. On the other hand, the visual field refers to the total area in which objects can be seen when a person looks straight ahead.

This means that while a person with 20/20 vision can see letters on an eye chart at a distance of 20 feet, a person with legal blindness can only see from 200 feet away. In other words, someone with legal blindness sees at 20 feet, whereas someone with normal vision can see at 200 feet.

But if your prescription corrects your vision to 20/20, yet your visual field is limited to 20 degrees or less, you may still be legally blind. Those with a limited visual field may be unable to see objects off to the side or above or below their line of sight.

In some cases, being legally blind may require assistive technologies.

The impact of legal blindness on people's lives can be significant. It can affect a person's ability to read, work, and carry out daily activities independently. For example, a person with legal blindness may have difficulty reading street signs, recognizing faces, or performing tasks that require fine motor skills, such as cooking or using a computer.

Legal blindness can also affect a person's mental health and social well-being, as they may feel isolated or excluded from activities that others take for granted.

How is visual acuity measured?

Visual acuity is measured using an eye chart, with the results recorded as a fraction or decimal.

Visual acuity is typically measured using an eye chart or a standardized test determining how well a person can see at a specific distance. The most common type of eye chart is the Snellen chart, which consists of rows of letters in decreasing size.

During an eye exam, an eye chart is placed 20 feet away from the person being tested, and they are asked to read the letters from the top row down. The smallest row of letters that can be read accurately determines the person's visual acuity.

A LogMAR chart is a type of eye chart that uses a logarithmic scale to measure visual acuity. Source: ResearchGate

Another type of chart used to measure visual acuity is the LogMAR chart, which uses a series of letters of equal difficulty arranged in rows. The LogMAR chart is often used in research settings and is more precise than the Snellen chart.

The test results are recorded as a fraction or decimal, showing how far away a person can read the chart compared to someone with normal vision. For example, if a person has a visual acuity of 20/40, they can read the chart from 20 feet away, while a person with normal vision could read the same chart from 40 feet away.

Visual acuity can also be expressed as a decimal. For example, 20/20 vision, considered normal vision, is expressed as 1.0 in decimal form. A person with 20/40 vision, which is half as good as normal vision, would have a decimal visual acuity of 0.5.

What prescription is considered legally blind?

Prescription is not the sole factor in blindness.

Different countries and organizations have established specific criteria to determine legal blindness.

The World Health Organization (WHO) and the US Social Security Administration (SSA) both have definitions for legal blindness. According to the WHO, legal blindness is when a person has a visual acuity of less than 20/400, or a visual field of fewer than 10 degrees, even with corrective lenses.

The SSA, on the other hand, defines legal blindness as a visual acuity of 20/200 or less in the better eye with the use of corrective lenses or a visual field of 20 degrees or less in the better eye.

Other factors can also affect visual acuity, including age, disease, and injury. As people age, their vision may naturally decline, and they may need corrective lenses to maintain good vision. Diseases such as macular degeneration and glaucoma can also cause vision loss, and injuries to the eye can result in permanent vision impairment.

Some common misconceptions about legal blindness

Each person's legal blindness is unique, and as a result, their navigation needs may differ.

Misconceptions and myths often surround legal blindness. One of the most common misconceptions is that legal blindness means complete darkness or the inability to see anything.

In reality, legal blindness is a spectrum. People with different levels of vision loss may have different needs and abilities. Another misconception is that all people who are legally blind use guide dogs or white canes to navigate.

While some people with legal blindness use these tools, others may use magnifiers, special software, or other assistive devices to help them read, use a computer, or perform other tasks. Some people also believe that legal blindness is a permanent condition that cannot be improved. However, this is not always the case.

Legal blindness doesn't equate to total blindness.

Depending on the cause of the vision loss, some people may be able to improve their vision with corrective lenses, surgery, or other treatments.

Legal blindness is not a medical diagnosis but rather a term used to describe a specific level of vision loss that meets the criteria set by a country or organization. It is a legal term to determine eligibility for certain government benefits and services, such as disability payments or access to assistive technology.

Understanding legal blindness and supporting people with visual impairments

Understanding legal blindness creates empathy.

Legal blindness can profoundly impact a person's life, affecting their ability to carry out daily activities and participate fully in society. People with different levels of vision loss may have different needs and abilities and face different challenges depending on their circumstances. It's crucial to support and advocate for people with visual impairments and to raise awareness about legal blindness and the challenges faced by those who are legally blind.

Some ways to support and advocate for people with visual impairments include providing accommodations in the workplace or public spaces, promoting accessibility in digital media, and advocating for policies and laws that protect the rights of people with disabilities.

Raising awareness about legal blindness can also help to reduce the stigma and misconceptions surrounding vision loss. By increasing understanding and empathy, we can work towards creating a more inclusive and accessible society for all.

Humans cry for many reasons. It's a natural response to various emotions, not just sadness.

You might cry when you're overjoyed, frustrated, or physically hurt. Because of this complexity, the answer to 'Why do humans cry' can be a little complex.

And while it might seem odd to cry in situations that aren't necessarily sad, it turns out that there's a good reason for it.

Crying serves a critical function in our physiology and psychology.

While scientists are still trying to understand the role of tears fully, it's clear that they play an essential part in our lives.

Let's delve into the science and meaning behind why humans cry.

Our tears appear for different reasons

Tears are a natural lacrimal gland secretion above each eye's outer corner. While all tears contain water, salt, and various proteins, there are three distinct types of tears, each with its unique composition and purpose.

Basal tears

Basal tears are a constant shield from dirt and debris to lubricate our eyes.

Eye strain can also cause the tear glands to produce more basal tears as a protective mechanism.

They contain enzymes, antibodies, and other immune factors that help kill bacteria and prevent infection.

Reflex tears

We generate reflex tears as a reaction to irritants such as smoke, dust, or the fumes released from onions.

Compared to basal tears, they are produced in more significant amounts and may contain a higher concentration of antibodies to combat bacterial infections.

Emotional tears

This type is our body's response to strong emotions like happiness, sadness, or frustration.

Tears shed due to emotional states contain protein-based hormones that can assist in reducing emotional stress and act as signals of the specific emotional states to those around us.

What's the emotional function of tears?

While all tears serve a physiological function, emotional tears strongly connect to our emotional well-being. Some researchers believe that emotional tears are critical in helping us regulate our emotions and communicate our feelings to others.

Emotional release theory (catharsis hypothesis)

One theory behind the function of emotional tears is the release theory or catharsis hypothesis.

According to this, crying helps us release and process emotions healthily. When we cry, we release stress hormones and other chemicals that build up in response to emotional stress.

By shedding tears, we can 'let go' of these emotions and reduce our feelings of distress.

Research on crying and emotional regulation

Several studies have supported the emotional release theory of crying.

For example, research has shown that people who cry during emotional situations tend to feel better afterward and have lower levels of stress hormones than those who do not cry.

Additionally, studies have found that crying can improve mood, reduce tension, and increase feelings of emotional closeness with others.

What's the physiological function of tears?

While emotional tears have garnered much attention for their role in emotional regulation, tears serve a wide range of physiological functions. Tears are essential for maintaining healthy eyes and protecting them from damage and infection.

Lubrication theory

One of the primary functions of tears is to lubricate the eye's surface. Tears contain oils, water, and mucus that moisten the eye and prevent dryness.

This lubrication is vital for maintaining clear vision and avoiding damage to the cornea, which can occur if the eye becomes too dry.

Research on tears as a defense mechanism

Tears also defend against infection and foreign particles.

This defense is thanks to tears containing enzymes, antibodies, and other immune factors to help fight off bacteria and other pathogens that may enter the eye.

In addition to their immune function, tears also help protect the eye from foreign particles, such as dust and debris, that may enter the eye.

This protective function is critical for maintaining healthy vision and preventing injury to the eye.

What's the social function of tears?

In addition to their emotional and physiological functions, tears also serve an important social role.

Tears can be a powerful tool for connecting with others, eliciting empathy and support, and strengthening social bonds.

Social bonding theory

The social bonding theory of tears suggests that crying evolved to strengthen social bonds and elicit support from others.

When we cry, we signal to others that we are distressed and need help or comfort.

This can trigger empathy and compassion in others, leading them to offer support and assistance.

Cross-cultural differences in crying behavior

While tears serve a similar social function across cultures, there are differences in how crying is perceived and expressed.

For example, some cultures may view crying as a sign of weakness, while others may view it as a sign of emotional strength.

There may also be differences in how often people cry and the situations that trigger crying.

How can culture and gender affect our crying behavior?

Crying behavior can vary widely between genders and cultures. While there is no definitive answer to how much people of different genders or cultures cry, research has shown some broad patterns and differences.

Tears – men vs. women

On average, women cry more often than men. The variation in crying behavior between genders is partly attributed to biological factors such as hormone levels, but social and cultural norms also influence it.

Men are often socialized to suppress emotions, including crying, to demonstrate strength and emotional control.

Influence of cultural norms on crying behavior

Cultural norms also play a significant role in shaping crying behavior.

Some cultures view crying as a sign of weakness or vulnerability, while others view it as a natural and healthy expression of emotion.

In some cultures, crying is only acceptable in certain situations, such as during mourning or religious rituals.

Implications for mental health and well-being

These cultural and gender differences in crying behavior can have significant mental health and well-being implications.

Suppressing emotions and not allowing oneself to cry can lead to feelings of emotional numbness and detachment, as well as physical symptoms such as headaches and muscle tension.

Why we may cry too much

While crying is a natural and healthy expression of emotion, excessive crying can indicate an underlying medical condition. Conditions such as depression, anxiety, and grief can all lead to excessive crying, as can certain medical conditions such as hormonal imbalances or neurological disorders.

You may be depressed or suffer anxiety

Depression and anxiety are common medical conditions associated with excessive crying. They are symptoms of intense emotional distress triggered by minor stressors or events.

In severe cases, excessive crying may interfere with daily functioning and lead to feelings of hopelessness and despair.

Getting treatment may be necessary

If excessive crying interferes with daily life, seeking medical attention may be a good idea. Treatments for excessive crying may include therapy, medication, or a combination of both.

Cognitive-behavioral therapy can help individuals learn coping strategies for managing intense emotions and reduce the frequency and intensity of crying episodes.

Medications such as antidepressants may also help reduce excessive crying in some cases.

When to seek help for tears

It's essential to seek medical attention if excessive crying interferes with daily functioning or causes significant distress.

Not only can medical treatment help reduce excessive crying, but it can also address underlying medical conditions contributing to the problem.

Early intervention in seeking help can lead to better treatment outcomes and prevent additional emotional and physical distress.

Tears are essential but we need to know why

Tears serve many functions, from lubricating and protecting the eye to releasing emotional tension and strengthening social bonds.

Emotional tears, in particular, can help us regulate our emotions, elicit empathy and support from others, and communicate our feelings.

Understanding crying behavior is crucial because it can help us better understand ourselves and others.

By recognizing the different functions of tears, we can learn to express our emotions healthily and strengthen our social connections.

Additionally, understanding the medical conditions associated with excessive crying can help individuals seek appropriate medical attention and effective treatment.

The next time you shed a tear, remember that it's not just a personal or physiological experience–it's also a social and emotional one.

We can cultivate greater emotional awareness and connection by embracing and understanding our tears.

References

• ' Why we cry', American Psychological Association.
• ' Is crying good for you?', Harvard Health Publishing.
• 'Facts About Tears', American Academy of Ophthalmology.
• ' Is crying a self-soothing behavior?', National Center for Biotechnology Information.
• 'Biochemistry, Tear Film', National Library of Medicine.
• ' Why Crying Improves Our Well-being: An Attachment-Theory Perspective on the Functions of Adult Crying'. Research Gate.
• 'Why might a person cry for no reason?'. Medical News Today.

An eye roll is one of the most common gestures out there. With just one second of it, you can express your feelings without a word.

However, where did the interpretation of an eye roll come from? And why do we do it? Let's explore the answers to these questions as you scroll down.

What is an eye roll & have they always been the same?

Eye rolling back then was a flirtatious gesture.

When we roll our eyes, that's a common sign of annoyance. For some people, it's how they express their disbelief with a hint of sarcasm as if saying, 'Yeah, right.'

It's such a powerful form of non-verbal communication that many people don't like it. However, this eye-rolling wasn't seen as passive-aggressive before. It meant the opposite!

Back in Shakespeare's era, eye rolls were a flirtatious gesture. Yes, you read that right.

In one of his poems, he wrote that the villain was 'rolling his greedy eyeballs in his head' while looking at his object of desire.

Until the 1950s, you'd see books, music, and films using an eye-roll as a flirting gesture.

Sometimes, you'll see actors dramatically roll their eyes while they swoon, almost fainting at the sight of the leading man.

Of course, this romantic meaning flipped 180 degrees when the 1960s hit. Slowly but surely, eye-rolling was equal to feeling annoyed, exasperated, or frustrated.

By the 1980s, that negative connotation stuck until now.

But an eye roll means different things around the world

The Woodabe tribe has a traditional dance that involves eye-rolling. Source: Adventure.com

For some cultures, eye-rolling has a whole different meaning. In the West, it can refer to feeling irritated or in disbelief.

However, it's a different case for the Woodabe tribe in Africa. As per tradition, they would attend the Gerewol festival, a yearly beauty pageant–slash–matchmaking party.

In this special event, Woodabe men would don their intricate clothes and makeup. Then, they would dance for hours, rolling their eyes and gnashing their teeth to show their beauty.

All of these are in hopes of finding their perfect match. They use eye-rolling to find a romantic partner or to attract them.

The psychology behind an eye roll

Eye-rolling is a reaction connected to our emotions. Source: Pinterest

Since time immemorial, human beings have expressed their emotions through action.

When you're angry, you might clench your fists or jaw. The same goes for eye-rolling.

When someone rolls their eyes, that's their natural reaction to what's happening before them. It can signify disbelief, boredom, contempt, and more.

The gesture itself is like when you're brushing off something that might overwhelm you emotionally.

Or, it could be that you feel superior and dismiss someone else's ideas as unimportant or irrelevant to you.

For these reasons, you might see moody teenagers often use this gesture.

Some of your co-workers at a boring meeting might also do this, wanting to wrap it up ASAP.

In a 2018 study, researchers found that eye movement, such as an eye roll, can link to personality traits.

For instance, it relates to how agreeable you are or whether you're an extrovert.

Another study in 2021 also suggested that eye-rolling isn't a 100% negative gesture.

It can be a protest or a healthy disagreement, especially with 'someone going too far.'

How we use eye rolls in different contexts

Eye-rolling can mean different things based on the context. Source: NY Times

It's pretty fascinating how we can communicate with our eyes only. With a simple eye-roll, you can say so much and get a reaction from others too.

For instance, you might roll your eyes in the following situations.

• You're in an argument, and the other person frustrates you.
• Someone tells a bad joke, and you're not impressed at all.
• The lecture or meeting sounds boring.
• Your least favorite person butts in the conversation.
• Someone announces a false claim, and you don't believe it.
• You feel attacked or defensive during a conversation.
• You don't have the energy to deal with life right now.

However, it can also be a sign of feeling so much joy. Someone might roll their eyes while eating their favorite food or gushing about their crush.

It all depends on the context. If your friend or romantic partner rolls their eyes at you, even when you're being serious, that might be a red flag in your relationship.

On the other hand, rolling your eyes at someone might also offend them.

This is especially true if you're not super close friends, and they need more context to understand what you're trying to express.

Regarding these scenarios, the best way forward is, to be honest about your intentions.

Non-verbal talk can only do so much. It's still up to you how you can express yourself the best way you can.

Did you know eye rolls affect social interactions & relationships?

Eye-rolling can affect your relationship's way of communication.

Rolling your eyes at your significant other might seem harmless at first. But, if it happens way too often, it can signify something wrong in the relationship.

When you roll your eyes during a conversation, it's like you're shrugging the topic off or sighing with your eyes.

It's a pretty dismissive gesture. And, of course, your partner will probably get offended.

Too much eye-rolling can lead to an argument. Your partner might feel ignored and disrespected every time you dismiss them with your eyes. And the same goes for you if the scenario's reversed.

Rather than going for healthy communication, too much eye-rolling turns your relationship into a one-sided convo.

Over time, this can lead to bitter resentment and a lack of trust.

So, if there's too much dismissive eye-rolling, keep these simple relationship tips in mind.

• Be honest and emphaticAsk if there's something wrong, and talk about how the eye-rolling makes you feel.
  
• Set your boundaries if you want less non-verbal communication, you must say it aloud and set it as a rule. It also helps you and your partner respect each other better.
• If you're on the verge of an argument to take a break.
• If the eye-rolling is too much you should ask for professional help. Maybe it's a symptom of a vision problem or a sign of an underlying issue in your relationship.

Eye rolls in men and women

Women are more likely to roll their eyes. Source: Galore Mag

Frequently, you might see women rolling their eyes more than men. It's not just because they learn it at school.

Rolling their eyes is one of their evolutionary traits.

You see, researchers found out that women are more likely to express their aggression indirectly.

Instead of getting into fistfights, women might criticize, spread rumors, and roll their eyes at someone.

It can be their way of showing who's in charge without getting physical. You can interpret an eye-roll as them saying, 'Enough, stop wasting my time.'

As a result, eye-rolling is one of the non-verbal tactics that can trigger someone's fight-or-flight instinct.

It can also make other people anxious.

So really, this gesture isn't only a rebellious tantrum for teenagers. Eye-rolling is a survival tactic used since history was born.

For women, it can be one of their ways of dealing with society to tell the haters to be quiet without saying a word.

Let your eyes roll away, but not too much

Eye-rolling is one of the top-tier non-verbal forms of communication. It speaks volumes about your feelings, even if you don't say it aloud.

However, it's reasonably easy for others to misunderstand this gesture.

You should try to express yourself differently, especially if you don't want to be mistaken for a snob who rolls their eyes at everyone.