Navigating through a world woven together by sight can be a daunting task for those who bear the weight of the term ‘legally blind.’ What is legally blind? It’s a clinical term that goes beyond the simplistic perception of complete darkness, holding complex layers of vision impairment.
In this article, we unravel these layers, delving into the definition, causes, and impact of legal blindness, providing insight into the world of those living with this condition.
The Definition of Legal Blindness: What Prescription is Legally Blind?
Legal blindness is not simply a lack of sight but is, in fact, a legal term that defines a specific level of visual impairment. Two key metrics, visual acuity and field of vision, are crucial to understanding this definition.
Visual Acuity
Visual acuity refers to the sharpness or clarity of an individual’s central vision. It’s often measured using a Snellen chart, the familiar eye chart with large letters at the top that progressively get smaller towards the bottom. The results are presented as a fraction, such as 20/20 or 20/200.
The first number represents the distance (in feet) at which the test was performed, usually 20 feet, while the second number signifies the distance at which a person with “normal” vision could read the same line.
In terms of legal blindness, if someone’s visual acuity is 20/200 or worse in their better eye after corrective measures like glasses or contact lenses, they are considered legally blind. This means that what a legally blind person can see at 20 feet, a person with normal vision can see at 200 feet.
Field of Vision
The field of vision, on the other hand, refers to the total area an individual can see when their eyes are fixed straight ahead. Imagine it as the broad vista you can view without moving your eyes side to side or up and down. A healthy field of vision spans nearly 180 degrees.
In the context of legal blindness, if an individual’s field of vision is narrowed to 20 degrees or less, they’re classified as legally blind. This condition is also known as ‘tunnel vision’ as the person can only see objects directly in front, similar to looking through a narrow tube or tunnel.
Understanding these metrics and how they interact allows us to more accurately comprehend the term “legally blind.” Legal blindness doesn’t necessarily mean complete lack of sight but signifies a specific degree of vision loss as defined by these parameters. It’s crucial to remember that the experiences of those who are legally blind can vary greatly, with some retaining a significant amount of usable vision while others may see almost nothing.
Causes of Legal Blindness
A variety of medical conditions and diseases can lead to legal blindness, each impacting different parts of the eye. Here are some of the most common causes:
1. Age-Related Macular Degeneration (AMD)
AMD is the leading cause of legal blindness in people over the age of 60. It primarily affects the macula, the part of the retina responsible for sharp, central vision. There are two types: wet AMD, characterized by abnormal blood vessels leaking fluid or blood in the macula, and dry AMD, where the macula thins over time, leading to blurred vision or a blind spot.
2. Cataracts
Cataracts are a common cause of vision loss, especially in older individuals. They occur when the lens of the eye becomes clouded, preventing light from properly reaching the retina. This results in blurry vision, faded colors, and difficulty with light glare. While cataracts can be surgically removed to restore vision, untreated or severe cases can lead to legal blindness.
3. Glaucoma
Glaucoma is a group of eye conditions characterized by damage to the optic nerve, often caused by abnormally high pressure in the eye. The most common form, open-angle glaucoma, progresses slowly and can gradually lead to legal blindness by affecting peripheral vision first, then central vision.
4. Diabetic Retinopathy
This condition is a complication of diabetes, where high blood sugar levels damage the blood vessels in the retina. Over time, these blood vessels can bleed or leak fluid, distorting vision. In its advanced stage, new abnormal blood vessels proliferate on the retina’s surface, leading to scarring and cell loss, potentially resulting in legal blindness.
5. Retinitis Pigmentosa (RP)
RP is a genetic disorder that involves a breakdown and loss of cells in the retina. It often begins with night blindness in childhood and progressively leads to loss of peripheral and, eventually, central vision. While its progression varies, RP can result in legal blindness.
In addition to these conditions, genetic factors and birth defects can also cause legal blindness. However, the diseases mentioned above are the most common causes in the general population.
The Impact of Legal Blindness
The implications of legal blindness are far-reaching, influencing numerous aspects of an individual’s life. Here we examine the specific areas it can affect:
1. Lifestyle and Independence
One of the most immediate impacts of legal blindness is the significant change it brings to an individual’s day-to-day life. Tasks like reading, cooking, or navigating public transportation can become difficult or even impossible without assistance.
A legally blind person might struggle with recognizing faces, reading signs, or avoiding obstacles while walking, making even familiar environments challenging to navigate. Driving is usually out of the question, further limiting mobility and independence.
2. Emotional and Psychological Effects
The onset of legal blindness can be a traumatic experience, triggering a range of emotional responses. It’s not uncommon for individuals to grapple with feelings of loss, grief, frustration, or fear as they adjust to their new reality.
Anxiety and depression are also common among people experiencing significant vision loss. The lack of vision can lead to feelings of isolation or helplessness, which can further exacerbate these mental health issues.
3. Societal Perception and Stigma
Living with legal blindness also means facing societal misconceptions and the stigma attached to visual impairment. Individuals may encounter discriminatory attitudes or behaviors that stem from ignorance or misunderstanding about their condition.
This can result in exclusion from social activities, barriers in education or employment, and an overall lack of accessibility in various aspects of life. The societal stigma can add another layer of emotional burden, making the overall experience of living with legal blindness more challenging.
The impact of legal blindness is multi-dimensional, extending beyond physical limitations to mental health and societal interaction. The specific experiences of individuals can vary widely, influenced by factors such as their level of vision, the support they receive, and their personal resilience. However, understanding the potential challenges can pave the way for better support, empathy, and inclusion for those living with legal blindness.
Conclusion
To understand ‘what is legally blind’ is to recognize the struggles and resilience of those living with significant visual impairment. Legal blindness is not a complete darkness but a complex spectrum of visual limitations, affected by various medical conditions.
It profoundly impacts individuals’ lives, both physically and emotionally. By broadening our understanding, we can challenge societal misconceptions, fostering empathy and respect for individuals living with this condition.
