Guide for the Blind

 

Index

- Overview
- Epidemiology 
- Different Types of Blindness

- Causes of Blindness

- Adaptive Strategies and Management
- Additional Resources

 

Overview

Blindness refers to the inability to see, but is officially defined as when a person has less than 20/200 vision in their best eye of a visual field of less than 10 degrees. Visual impairment or blindness can happen for a number of reasons; most often it is a result of medical condition or trauma, which was left untreated for extended periods of time. Visual impairment or partial blindness refers to someone who has limited vision but is not necessarily blind. Blindness cannot be treated through the use of contact lenses, though in some cases it can be helped through surgical treatments.

 

Epidemiology 

The World Health Organization (WHO) estimates that about 285 million people suffer from visual impairment worldwide. 39 million are considered to be blind. Of those cases the major causes were cataracts and uncorrected refractive errors. Refractive errors are the leading cause of visual impairment throughout the world, however in low to middle income countries the leading contributor to vision impairment is cataracts. An estimated 90% of the world's visually impaired occur in developing countries. In 1995, 1.3 million Americans reported legal blindness. 3.5% of seniors who are at the age of 65 and over are legally blind. The federal government spends an estimated $4 billion annually on people who are blind. Women are at a higher risk of becoming blind, and the risk increases for people who are over the age of 65.

Blindness Statistics and Facts - http://www.who.int/mediacentre/factsheets/fs282/en/index.html

Blindness Stats - https://nfb.org/blindness-statistics

 

Vision Impairment and Blindness Stats - http://www.nei.nih.gov/eyedata/pbd_tables.asp

 

 

Different Types of Blindness

 

Blindness occurs when an insufficient mount of light comes in contact with the retina or the information cannot be sent to the brain correctly. There are four levels of vision function; normal vision, moderate visual impairment, severe visual impairment and blindness. When someone uses the term low vision they are describing the combination of moderate and severe vision impairment.

 

When speaking about blindness specifically it can be divided into three types; complete blindness, color blindness and vision blindness.

 

Complete blindness
- Complete blindness is categorized as a complete loss of vision or inability to see. Legally, blindness is described as having worse than 20/200 vision capability. 

Color Blindness
 - Color blindness (also referred to as
dyschromatopsia) is the inability to distinguish between certain colors. The most common forms of color blindness limit the ability to decipher different shades of red and green. A large majority of color blindness cases are present at birth.


Night Blindness
 - Night Blindness refers to the difficulty people have seeing at night or in low level lights.

 

Types of Blindness - http://www.livestrong.com/article/121214-different-types-blindness/



Causes of Blindness

Blindness can be caused by a number of things. Cataracts, glaucoma, macular degeneration and diabetic retinopathy have all been known to result in blindness. Globally the leading cause of blindness is uncorrected refractive errors. In fact 43% of blind cases are largely due to refractive errors.  The second leading contributor to blindness is a cataract. A clouding in the lenses of the eyes causes cataracts. It is related to 33% of global cases of blindness and effects 22 million Americans.

There are many more causes that can result in blindness. For example trauma to the eye has been known to cause loss of vision. This is more common among young patients under the age of 30. The injury causes damage to the functional nerves, which send signals to the brain.

Other causes of blindness include:

Glaucoma
Macular degeneration
Corneal Opacity
Diabetic Retinopathy
Childhood blindness
Trachoma
Onchocerciasis

 

Leading Causes of Blindness - http://www.nlm.nih.gov/medlineplus/magazine/issues/summer08/articles/summer08pg14-15.html

Common Causes of Vision Impairment - http://www.umm.edu/ency/article/003040.htm

Why Do People Become Blind? - http://www.masseyeandear.org/for-patients/patient-guide/patient-education/diseases-and-conditions/why-do-people-become-blind/

 

Adaptive Strategies and Management

People who are blind or visually impaired can travel, read and manage independently, usually through the use of an aid or tool for assistance. Due to the advancements in technology and assisted technology, there are many tools available to help the visually impaired.

For mobility many people use a white can with a red tip to help them get around. The cane is designed to extend the person's range of touch sensation. Others prefer the use of a guide dog. Guide dogs have been trained to navigate around and indicate to the owner when steps or obstacles are in the way. Another method for mobility assistance is GPS navigation for the visually impaired, designed to help with orientation and navigation.

For reading, people who are completely blind can learn to read Braille or listen to audio books which convert text to speech. In cases where the person is visually impaired but not completely blind, there are books with large print offered as well as specially designed magnifying glasses for assistance.

 

Blind Adaptive Strategies - http://en.wikipedia.org/wiki/Blindness

 

Additional Resources:

Action for Blind People - http://www.actionforblindpeople.org.uk/

America Foundation for the Blind - http://www.afb.org/default.aspx

America Printing House for the Blind - http://www.aph.org/

Assistive Media - http://www.assistivemedia.org/Assistive_Media/Welcome.html

Better Vision for Children Foundation - http://www.consumernet.org/lazyeye

Blind in Business - http://www.blindinbusiness.co.uk/

Blindness Data and Maps - http://www.who.int/blindness/data_maps/en/index.html

Braille Institute of America - http://www.brailleinstitute.org/library

Braille Without Borders - http://www.braillewithoutborders.org/ENGLISH/index.html

Lighthouse International - http://www.lighthouse.org/

National Braille Association - http://www.nationalbraille.org/

National Braille Press - http://www.nbp.org/

The Central Library for the Blind, Visually Impaired and Handicapped - http://www.clfb.org.il/en/

The New York Institute for Special Education -
http://www.nyise.org/

 

 

 

 

My Other Resource Pages:

A Guide to the Spanish Language-    https://files.nyu.edu/am4457/public/Spanish-language-Resource-Center.htm

Latin Language and Literature Resources-   https://files.nyu.edu/am4457/public/Latin-Language-Literature-Resources.htm

Dental Resources-   https://files.nyu.edu/am4457/public/Dental-Resources.htm

Home Security Tips- http://blsciblogs.baruch.cuny.edu/security/