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Blindness: A Spectrum of Vision

Throughout the world, there are up to 43 million people who are living with blindness, and many more who have some type of visual impairment.  As someone with sight, I do not know what it is like to live with visual impairment, however, two of the most important people in my life live with blindness and visual impairment, making this a very important topic for me!  Before coming to better understand both my mother’s and my daughter’s visual impairments, I can say that I truly didn’t understand what the term “blind” meant.  In my mind, when someone said they were blind, I assumed they had no vision at all, which I have come to realize after working in this field, is the common misconception that many people have in the general public.  Now that I have become further educated, not only on blindness and visual impairment, but also on the entire eye in general, I am better able to understand the needs of those in my life with visual impairment, and I am better able to advocate for my daughter and her needs.  So, I thought this would be a great topic for today!  Let’s delve into the world of blindness and visual impairment, and hopefully together, we can learn how to better serve those living with blindness.

Visual Impairment, Low Vision, and Blindness: What’s the Difference?

Great question, let me help answer that for you!  First, it is important to understand, as the title of this article alludes to, that sight comes on a spectrum, meaning there is a large range of vision from person to person, from those who need no correction to see 20/20, to those who are unable to see any form of object, light, color, or otherwise.  When I first started to educate myself on what being blind truly means, I came to understand that there are many terms that are used to describe loss of sight, but some of the most common terms used are “Visually Impaired”, “Low Vision”, and “Legally Blind”.  It may seem like all of these terms mean the same thing, however, while they are related in some ways, they can actually refer to many different variations of sight in an individual.  Visual impairment is a broad term that can be used to refer to those whose vision cannot be corrected fully by contact lenses, glasses, or other medical devices, have been determined to have low vision, or blindness.  I know, that seems very vague, and while it is, it is a good term to use in the medical field when medical personnel are unsure of their patient’s cause of impairment at the time, and it is also a term that I use quite frequently when describing my daughter’s sight to people, as I find it best explains her situation.  The difference between Visual Impairment and Low Vision, is that the term “Low Vision” refers to someone whose vision cannot be corrected better than 20/70 (Meaning what other people can see at 70 feet away, someone with a visual impairment would have to be 20 feet away to see the object), even with corrective lenses.  While Visual Impairment can be used as a loose term to describe variations in sight, Low Vision is closer in relation to the term “Legally Blind”, which has a very narrow description and use, which I will get into further in a moment.  All of this to say, there are differences in these terms, but it is always important to respect the term used by a person with vision loss as the most appropriate term to be used in regards to that individual.  Time to get into the meat of visual impairment: Legal blindness.  

“Legally Blind”: What Does it Actually Mean?

Having worked in the fields of optometry and ophthalmology for the past five years, I have heard the term “legally blind” many times, and to be honest, many times I have found it to be used incorrectly, or at least in a way that illustrates that there needs to be more education provided to the general public about what being legally blind actually means.  Now, before we get into the details of legal blindness, I want to state that sight is a very personal experience, and although two people may have the same condition, they may experience the world very differently, and they may feel vastly different about their circumstances.  Therefore, it is imperative that sighted people do not stereotype or categorize blindness into what they perceive it to be, but rather, rely on those living with visual impairment or blindness to relate their experience and how to best advocate for them.  As always, it is important to treat everyone with dignity and respect and not project our own ideas of what another person may be experiencing onto them.  So, let’s get into what legal blindness truly is.  

“Legally blind”, not surprisingly, is a legal term that refers to individuals with an array of visual impairment, ranging on a spectrum from those who still have some sight, and those who do not.  Legal blindness is determined by several factors that have been laid out by the Social Security Administration, and they are as follows:

  • The person’s better-seeing eye can not see better than 20/200, even with full correction by contact lenses or glasses (Meaning what other people can see at 200 feet away, people who see 20/200 will have to be at 20 feet away to see the object, person, etc.)
  • The person has a visual field of 20 degrees or less (Meaning their field of view is constricted, and commonly referred to as “tunnel-vision”.)

Okay, I know that seems very simple, and while it is in some aspects, these requirements do not really tell us anything about the individuals within these requirements, what their conditions are, and what they truly experience with their sight.  Defining legal blindness is helpful for individuals when they are seeking to receive services to help them better navigate their lives, whether that be through services that help them learn how to use a white cane, gain access to a guide dog, receive disability assistance, or any other government provided services or accommodation.  Before I go on to further explain the requirements for being legally blind, I want to say that not all people who have visual impairment, or any other health condition, will consider themselves disabled.  I will discuss this further at the end of the article, however, I wanted to say that although there are many visually impaired people who identify as disabled, and receive disability services through the government or other agencies, that does not mean all people identify this way.  But we will get into that a little later!  

Reflecting upon the requirements to be considered legally blind, it can be seen that although there will be a small percentage of people that have no vision (Around 15 percent of the visually impaired and blind community), which we commonly refer to as “No Light Perception” in the world of optometry and ophthalmology, there will be a large percentage of people that do have some sight to varying degrees.  I believe this is very important for the public to understand, as I have seen first hand, through being around both my mother and my daughter, that many people struggle to understand when someone states they are blind, yet they move around the world still using visual cues.  For example, while my mother does not use a white cane at this time to navigate the world outside of familiar places, that does not mean that she is able to see a majority of what other people see, which can sometimes lead people to believe that she is either exaggerating her condition.  While I won’t go into great detail about her experiences, as they are her own, I will say that it is disheartening, discouraging, and confounding when I see people treat her with anything less than respect.  Because of this, I believe it is now important to give you some information on eye conditions that may cause visual impairment, some of which lead to full loss of sight, and some of which do not.

Eye Conditions: What Causes Visual Impairment or Blindness?

There are many health conditions that can cause visual impairment and blindness, some of which are conditions that affect the entire body, called systemic conditions or disease, and some of which only affect the eye as an organ.  I think it is imperative that everyone understands that the actual eyeball itself does not see! (Weird, right?) I really like the way our doctors at Carrot explain this to patients, so in their terms, here is their explanation; “The eye does not actually see, in fact, it is the brain that sees.  Its best to think of the eye as an apparatus that sends signals to the brain, which then alerts us to what we are seeing.  So, if there is something wrong with the apparatus, being the eye, then the brain will not perceive its surroundings properly, and vision can be impaired.”.  Now, I have to say they have a much better way with words than I do when it comes to explaining the connection between the eye and the brain, but I hope that can help you better understand that sight is a joint effort between the eye and the brain.  There are many conditions, such as strokes and brain tumors, that can cause damage to the brain, which in turn damage a person’s sight, and in turn there are conditions that happen within the eye itself that inhibit signals from being sent to the brain, in turn also damaging sight.  Before we get into more conditions that affect sight, it is important that if you believe you have any of the following conditions, or if you are having trouble with your vision, that you see your eyecare professional as soon as possible.  This post is not intended to diagnose or help treat any conditions, so please contact your provider if you have any concerns! Let’s get into a few more of these conditions:

  • Diabetes: This is a systemic condition that creates several issues within the body, including damage to small blood vessels, the inability for the body to create insulin, high blood sugar, and many other complications.  This condition can be inherited, as seen in Type 1 Diabetes, or those with a rarer form of the condition called MODY Diabetes, or it can be acquired through lifestyle choices, as seen in Type 2 Diabetes.  Diabetes of any kind can cause Diabetic Retinopathy (DR), a condition in which the blood vessels in the retina (the tissue in the back of the eye) become weakened, and start to leak, causing many eye complications, and can even lead to severe vision loss.  There are ways to prevent and treat DR, so if you have diabetes, please ensure to see your eyecare professional at least once a year, if not every six months.
  • Age-Related Macular Degeneration (AMD or ARMD): As the name of this condition indicates, this is an issue that presents itself later in a person’s life, and it affects the most sensitive part of the eye, the macula.  The macula is what helps contribute to about 90 percent of a person’s vision, and in the case of AMD, small calcifications, called drusen, start to form within the layers of the retina, which can sometimes lead to fluid leaks within the retina itself, causing vision impairment and vision loss.  Like diabetes, this is a condition that can be treated when caught early, and while it can become serious, most people will develop minor AMD in their lifetime.  As our Dr. Herion says, “AMD means, congratulations, you’ve had birthdays!”.  
  • Glaucoma: This is a condition that can damage the optic nerve, the nerve that connects the eye to the brain, and helps send signals to the brain.  High intraocular pressure, or high IOPs, can cause pressure to be put on the optic nerve, which over long periods of time damages the nerve, and leads to peripheral vision loss. While there are many causes of Glaucoma, there are very universal treatments for this condition, including the use of daily eye drops.  However, when this condition goes unchecked and undiagnosed, the vision loss a person sustains from the condition is permanent and the damage cannot be reversed.
  • Cataracts: This is the leading cause of blindness in the world, and while this condition can be corrected by removing the cataract and placing an Intraocular Lens (IOL) into the eye, they can become harder to remove the longer they progress.  While there are cases of babies being born with cataracts, people developing them after an eye injury, or in some other instances, the average age of cataract removal in the United States is around the age of 70.  

The conditions listed above are some of the most common causes of visual impairment and blindness, however, I think it is very important that we discuss some of the uncommon reasons as to why someone may be losing their vision, as those uncommon reasons affect me and my family very personally.  Here are a few of those conditions:

  • Retinitis Pigmentosa (RP): RP is a rare, inherited retinal disorder that affects the retina, the tissue in the back of the eye, leading to severe damage and vision loss. Due to this being an inherited condition in most cases, it can be inherited in different ways, such as in an autosomal recessive, autosomal dominant, or x-linked recessive pattern.  To put it in a more simplified manner, there are differing forms of RP, which can be inherited if only one parent has the gene, if both parents have the gene, or by a variant on the X chromosome.  Depending on how the gene is inherited, will determine the severity of the form of RP, however, all forms of RP will cause some form of low vision or blindness.  Some people with RP will lose the majority of their vision by their teenage years, while a small majority will start to lose their vision later in life, sometimes not until their 20’s or 30’s.  Signs and symptoms of RP include decreased night vision, sensitivity when going from light to dark, changes in color vision, and loss of peripheral vision.  The majority of people with RP will still have light perception, however, many will require the used of white canes, guide dogs, or other accessibility devices to help them navigate their surroundings.
  • Usher Syndrome: This is a condition that not only affects a person’s vision, but a person’s hearing as well, and while this is a rare condition, it is the most common condition that affects vision and hearing loss.  Like RP, this is also an inherited condition, and many parents with the condition will have children with the condition as well.  The most common symptoms of this condition will be seen at birth or in early childhood, and include total or partial hearing loss, and vision loss that can start with loss of night vision and peripheral vision.  
  • Oculocutaneous Albinism (OCA or Albinism) : Albinism is another inherited condition that affects most of the person’s body, as the body produces very little or no melanin, a pigment that helps determine the color of your skin, and your eyes.  This condition also greatly affects the eyes, as melanin contributes greatly to the development of the eye, including the retina and the iris, the colored part of the eye.  While many know the signs of albinism to include very little colored eyes, skin, and hair, other symptoms include Nystagmus (uncontrollable eye movements, usually when the eye moves side-to-side), photophobia (extreme sensitivity to light), strabismus (lazy eye), poor depth perception, and problems with optic nerve.  Sight can vary greatly for those with Albinism, as they are different forms of the condition, however, visual impairment is a hallmark of the condition.
  • Achromatopsia: Color blindness, while not an uncommon condition, becomes extremely rare in the case of Achromatopsia, as this condition causes total lack of color vision, meaning the person only sees in black, white, and shades of gray.  This is a condition that affects the retina, specifically the rods and cones in the retina, with cones being responsible for color vision, and rods being responsible for night vision, or vision in low light.  Some symptoms of Achromatopsia include nystagmus, poor night vision, photophobia, high degrees of hyperopia (farsightedness), scotomas (blind spots in the field of vision), and of course, partial or total absence of color vision.
  • Aicardi Syndrome: While this is a very rare genetic condition that typically only affects girls, with only about 4,00 girls worldwide thought to have the condition, this is one that greatly affects my life, as my daughter has Aicardi Syndrome.  This is a non-hereditary, meaning not passed down through families, which has three hallmark signs, which are infantile spasms (seizures in childhood), absence of the corpus callosum (no connective tissue between the two halves of the brain), and retinal lacunae (thin spots in the retina).  Along with these three signs, other issues such as optic nerve hypoplasia (thinning optic nerves), strabismus, and anophthalmia and microphthalmia (being born with the absence of one or both eyes), severe scoliosis, gastrointestinal problems, hip dysplasia, and respiratory issues can, and most often do, occur with thirst syndrome.  My daughter was born with both eyes, but does have strabismus, a high degree of hyperopia, optic nerve hypoplasia, and due to the fact that she is non-verbal, we are not sure exactly what she sees, although we do know she has some vision.

There are countless other rare syndromes and conditions that I could list that contribute to visual impairment and blindness, and while I would love to do just that, I will leave further research up to you, although I hope I have shed some light on the many conditions that can cause vision issues.  With all of the conditions listed above, despite some of them having similar symptoms and issues, as I stated earlier, every individual with those conditions will not only have varying degrees of sight, but varying degrees of need for assistance and advocacy.  So before I end this post, let’s talk a little bit about what sighted people can do to be there for those living with blindness.

How Can You Help?

Piggybacking off what I said earlier, it is really important for those of us not living with visual impairment or blindness to understand that while we can be there for those people in our life that are living with those issues, we will never fully understand their experiences, and it is imperative that we listen to what they need, rather than making assumptions.  I have found that the best way to ensure that I am not taking anyone’s autonomy away from them, is by first always asking if someone, like my mother, needs assistance.  Although this is something that I do not always succeed at, I always try my best to only step in for help when she asks for it, as I know she is completely capable of doing things on her own, and that if she needs help, she will ask.  I believe this is a form of respect we should show to any person, regardless if they are blind or otherwise.  I also need to say that it is never appropriate to try and guide a blind person without their permission, and you should never touch a person without their consent.  Unless you feel as if someone is in danger, or truly struggling, you should always ask before helping someone and do not assume that they cannot handle a situation on their own.  

Another important thing I feel like I should not have to say, but find it is something I face with my daughter all of the time; Do not stare at people who you believe to be visually impaired.  While I do believe that many people are just curious, especially when it comes to people like my daughter as she is in a wheelchair, and while I always openly welcome any questions people may have about her, people who appear to be different than others are not a spectacle to behold.  Regardless if someone is aware that they are being stared at or not, it is inappropriate to intentionally make someone feel ostracized for appearing different.  It is also not appropriate to walk up to a complete stranger who appears to be blind and ask questions such as, “What happened to you?”, and “What’s wrong with your eyes?”.  In doing this, you are asking a stranger an extremely personal question about their private information, and in no circumstance is it okay to ask these things, unless the person gives you the permission to ask.  Please remember to be kind to those who are living a life different to yours, and know that while you may not feel as if you could live as they do, that does not mean there is anything “wrong” with them.  Which leads me to say that while there are visually impaired and blind people who identify as disabled, and being disabled is in no way a bad or shameful, there are those who do not identify this way, and it is important to know that.  Being disabled is far from shameful, and as a mother to a disabled child, I find great pride in who my daughter is, and her disability does not define who she is.  However, it is important to know that being disabled, and identifying as disabled person is a very personal thing, just as vision is, so please be attentive to what people are saying; Do they identify as blind? Visually impaired? Disabled?  Whatever term the blind person uses, is the appropriate term for a sighted person to use as well.

Where do we go from here?

Okay, wow, I know that was a lot of information!  The topic of blindness can be an overwhelming one, especially to those who do not have personal experience working with, caring for, or living with a blind or visually impaired person.  I think the most important thing for a sighted person to understand, is that the best thing you can do for any person in your life that is blind, is to listen to their needs, and treat them as you would anyone else.  I know, I know, that sounds like something that most people should know and have been told since childhood, but it is imperative that we seek to truly live this out in our daily lives.  Losing one’s sight is monumental, and while I cannot fully understand at this time what that is like, I hope that I am able to continue to learn how to advocate for those in my life living with blindness, and to spread some of what I have learned.  Please, if you or someone you love is experiencing vision loss, call our office and set up an appointment with Dr. Hammond or Dr. Herion to have a thorough eye exam.  At Carrot, we always strive to not only have the most up-to-date diagnostic equipment, but also the most caring, educated, and compassionate staff you could hope for in a medical office.  Our passion for patient care is what fuels our days, and we hope that we can be a part of your vision journey!

Resources for the Blind and Visually Impaired:

Foundation Fighting Blindness

Arizona Center for the Blind and Visually Impaired

View Finder (Low Vision Resource Center)

Foundation for Blind Children