Everything You Need to Know about Visual Impairment

Visual impairment greatly limits those who suffer from it. Although it’s a very common problem around the world, nowadays, there are many technological aids.
Everything You Need to Know about Visual Impairment

Last update: 15 December, 2020

According to data from the World Health Organization (WHO), blindness and visual impairment affect at least 2.2 billion people around the world. Of those, 1 billion have a preventable vision impairment or one that has yet to be addressed.

The organization also points out that this condition more commonly affects people in low- and middle-income countries, women, older adults, and ethnic minorities. This corroborates the link between this problem and the difficulty or impossibility of accessing an adequate approach in time.

What’s visual impairment?

There’s no absolute consensus on the concept of visual impairment. This is because there are differences regarding the limit that separates the impairment from the disability as such. Nevertheless, one of the most popular definitions is the one we’ll share with you below.

We must note that the term “visual impairment” should be used generically for both people who are totally blind and those who have significant impairment. Thus, it’s a concept that covers any type of serious visual problem, regardless of what causes it.

In this regard, the concept is complemented by noting that said problem must generate limitations to perform certain activities, such as reading, writing and orientation, and mobility. In turn, blindness is any form of serious visual impairment, without implying a total absence of vision.

A blind person walking with a cane.
Blindness is a condition that makes daily life difficult. However, nowadays, people who are afflicted by it have more help.

What are its causes?

The main causes of visual impairment and blindness are cataracts, ametropia, trachoma, onchocerciasis or river blindness, glaucoma, diabetic retinopathy, and age-related macular degeneration. Below, we explain them in detail:

  • Cataracts. They’re considered the main cause of blindness in the world. Experts estimate that this condition accounts for 43% of cases and it’s due to a loss of transparency of the lens.
  • Diabetic retinopathy. It’s the main cause of vision loss in developed countries. It’s common in those who don’t control their blood sugar levels. It leads to progressive blindness due to small bleeds in the eye.
  • Age-related macular degeneration (AMD). The second cause of visual impairment in developed countries. It initially causes blurry central vision. But if it progresses, it can turn into blindness.
  • Glaucoma. It accounts for approximately 15% of the cases of visual impairment in the world. It leads to peripheral vision loss due to increased pressure inside the eye.
  • Trachoma. An infection that affects both eyes. It’s the leading cause of infectious blindness. It’s more common in developing countries.
  • Ametropia. Its forms include myopia, hyperopia, and astigmatism. It’s the eye’s inability to correctly focus the images of objects on the retina due to a disproportion between the length of the eye and the power of the eye.
  • Retinitis pigmentosa. This condition affects peripheral vision and the ability to see in the dark. It includes several chronic genetic eye disorders.

Detection, degrees, and types of visual impairment

Vision problems are detected in a checkup with an optometrist or ophthalmologist. Likewise, you should go see a professional if you have difficulty reading, seeing up close or far away, or seeing images clearly or if you have conjunctivitis or eye discharge.

There are four degrees of visual impairment, based on the acuity of the person’s eyeballs:

  • Mild: Less than 50% visual acuity
  • Moderate: Less than 33% visual acuity
  • Severe: Less than 10% visual acuity
  • Blindness: When the values recorded in the eye exam are less than 1%

On the other hand, from a functional and often legal standpoint, the classification is as follows:

  • Partial: When one eye is severely affected or both eyes are partially affected.
  • Total: Even with vision loss in both eyes, visual acuity of 0.1% or more is achieved.
  • Absolute: If visual acuity doesn’t exceed 0.1%.
A blind person reading with Braille.
The Braille system is invaluable for blind people.

The needs of a person with visual impairment

Fortunately, a person with visual impairment can use different aids to better cope with their condition. For orientation and mobility outside their house, they can resort to white canes, guide dogs, and, currently, technological tools such as GPS with apps for those who have vision problems.

To visualize objects and, depending on the degree of visual impairment, it’s a good idea for these patients to help themselves with greater lighting or with devices that have enlarged fonts, magnifying glasses, and high-power glasses. If a person is blind, Braille is a very effective method of reading.

For obvious reasons, the person must adapt their home to their visual conditions. Likewise, today, there are increasingly effective aids, such as augmented reality viewers and smart glasses for the blind.

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  • Gómez-Ulla, F., & Monés, J. (Eds.). (2005). Degeneración macular asociada a la edad. Prous Science.
  • Vinores, S. A., Küchle, M., Derevjanik, N. L., Henderer, J. D., Mahlow, J., Green, W. R., & Campochiaro, P. A. (1995). Blood-retina1 barrier breakdown in retinitis pigmentosa: light and electron microscopic immunolocalization. Histology and histopathology.
  • Escudero, J. C. S. (2011). Discapacidad visual y ceguera en el adulto: revisión de tema. Medicina UPB, 30(2), 170-180.
  • Cedeño, María Leonila García, Inger Solange Maitta Rosado, and Karina Gissela Rivera Loor. “Characterization of the Visual Disability and Its Relation with the Resilience.” International research journal of management, IT and social sciences 5.2 (2018): 32-40.
  • Sarabia, César Pineda, Xóchitl Josefina Zarco Vite, and María Luisa Ruiz Morales. “Retinopatía diabética, una complicación descuidada.” Atención Familiar 25.2 (2018): 83-85.
  • Weinreb, Robert N., et al. “Primary open-angle glaucoma.” Nature Reviews Disease Primers 2.1 (2016): 1-19.
  • Silva, J. N., et al. “TRACOMA: FASES CLÍNICAS E FORMAS DE DIAGNÓSTICOS.” International Journal of Parasitic Diseases 1 (2018).
  • Osorio Illas, Lisis, et al. “Prevalencia de baja visión y ceguera en un área de salud.” Revista Cubana de Medicina General Integral 19.5 (2003): 0-0.
  • Arroyo, Nicole, et al. “El Modelo dual de reconocimiento de la palabra en el Sistema Braille.” CienciAmérica 8.1 (2019): 90-104.