What Are the Types of Visual Impairments?
Vision loss can happen for a variety of reasons, causing the types of visual impairments to cover a wide spectrum. As a rule, visual impairment cannot be fixed simply by glasses or contact lenses. There are stages of vision loss. What we call blindness is when a visual impairment results in total or near-total vision loss.
Over the last several decades, vision loss has decreased in the United States, but a large number of people still experience visual impairments, especially in developing countries. A vision diagnosis affects everyone differently. Use of vision is different for every person, and the diagnosis may change year to year.
Common signs of visual impairment include eyes that don’t move together when following an object, crossed eyes, different sized pupils, squinting, eye-rubbing, excessive clumsiness, sitting too close to screens, or avoiding activities that require good vision.
Many types of visual impairments exist: loss of central vision or peripheral vision, blurred vision, and extreme sensitivity to light to name a few. Visual impairments can occur due to cataracts or the effects of rare diseases, or they may result from damaged or missing eye structure. While the list of visual impairments is extensive, we’ll cover a few of the most notable types of poor vision.
Also called “lazy eye,” this functional problem often causes decreased vision in one or both eyes, but it doesn’t include any detectable damage to the retina. The brain tends to shut down vision in one eye to favor the good vision in the other eye. Depending on the situation, the treatment may be something as simple as wearing a patch on the good eye so the weaker eye can strengthen.
Aniridia is the incomplete formation of the iris. It is usually a congenital anomaly, but it can also result from an injury where an object penetrates the eye. This condition often causes poor vision and sensitivity to light. Sometimes corrective and tinted lenses can help resolve the problem.
Achromatopsia can develop due to malformation or partial/total absence of cones in the eye, which makes it difficult to distinguish colors. It’s important to note that this is different from color blindness. This hereditary condition often includes some vision loss in bright light. The severity of achromatopsia differs across patients, with the most severe cases unable to see any colors at all.
When the eye is unable to focus completely at any distance, it usually results from a spoon-like shape of the normally spherical cornea. This shape bends light rays unequally, which prevents vision focus. Most people have some degree of astigmatism and slight astigmatism may not be a problem, but more severe cases require special glasses or surgery.
Cloudiness of vision often signifies the appearance of cataract, which prevents clear vision because of the cataract’s clouding of the lens. For the most part, cataracts occur due to age, trauma, or disease. The most common cure is a simple surgery usually done as an outpatient procedure.
What we call “color blindness” is not blindness at all, but a deficiency in how certain people perceive color. There are different types of color blindness, with red-green and yellow-blue types the most common forms. For the most part, males are more likely to be color blind than females. To deal with color blindness, the individual must learn other ways to recognize important information, such as recognizing the state of traffic lights by the positioning of the light rather than by the coloring.
Glaucoma is a condition caused by damage to the optic nerve and retinal nerve fibers by increased pressure in the eye. Glaucoma is preventable if caught early enough. Prescription drugs or surgery can correct the condition and prevent further vision loss.
This vision loss occurs when an individual can clearly see objects that are far away but not focus on objects nearby. Basically, light rays from a distant object strike the retina before the eye can focus. This is a common visual disorder and glasses or contact lenses are usually used to correct this problem.
The deterioration of the macula causes loss of focused central vision, which challenges acuity and color discrimination. This vision loss can affect all ages, but is most common in older people; in fact, it is the most common form of vision loss in people aged 50 or over. The most common form of the macular degeneration is Stargardt’s Disease.
The opposite of hyperopia, people with myopia can see objects that are near but cannot see objects that are in the distance. In this case, the light rays enter the eye and come to a focus before reaching the retina. A simple solution to this vision loss is glasses or contacts, however, some may be eligible for surgery to correct the vision.
Optic Nerve Atrophy
When the optic nerve atrophies, this dysfunction results from the optic nerve not being able to send electrical impulses to the brain. The most common cause of the atrophy of the optic nerve is poor blood flow, but the condition may result from trauma, toxins, or radiation as well. The lack of communication between brain and optic nerve results in vision loss, which may include blind spots.
A condition caused by the separation of the retina from the pigmented cell layer that maintains the retina, retinal detachment can cause severe myopia. Usually caused by a slight retinal tear that begins to experience fluid passing from the vitreous into the sub-retinal space, the tear disrupts the eye structure. This condition tends to require surgery to restore normal sight.
Visual impairments can be caused by many different types of situations including infections and trauma. Whether the infection occurs before birth or during life at some point, vision loss can be the result of localized infection. Head injuries can also cause vision impairments.
With so many different types of visual impairments, it’s important that society creates a world that is accessible to everyone. At StrongGo, we work towards greater accessibility every day with our detectable dome tiles that help signify to people with low vision an intersection or mass transit platform.