Visual Impairment and Blindness Nakhleh E. Abu-Yaghi, M.B.B.S Department of Ophthalmology

The scope of the problem Blindness knows no borders 45 million people in the world suffer from profound vision impairment This is highest in developing nations A high proportion of blindness is preventable through public health measures Many other cases are treatable

Legal blindness & Low Vision Legal Blindness is defined as visual acuity of < 3/60, or corresponding visual field loss to <10° in the better eye with best possible correction Low vision is defined as visual acuity of less than 6/18, but equal to or better than 3/60 or visual field loss to < 20 degrees, in the better eye with best possible correction

Impairment of the visual system Loss of one eye equals 25% impairment of the visual system and 24% impairment of the whole person Total loss of vision in both eyes is considered to be 100% visual impairment and 85% impairment of the whole person

Impairment Vs Disability Vs Handicap Impairment a health problem exists  medical intervention leads to cure  Equal opportunity if the medical problem persists  “permanent” (dysfunctional) condition  Disability (functional problem)  rehabilitation  Equal opportunity

Handicap is a permanent social/community problem  social participation/ integration Institutional/ community-based rehabilitation, special education and training

Global estimate of visual impairment by WHO region

Vision impairment is most common >60yrs across all regions Poorer communities: children > adults Developing countries: cataracts and water- borne parasites, both of which can be treated effectively North America and Western Europe: age- related macular degeneration and diabetic retinopathy

Visual impairment : causes Cataracts Glaucoma Retinal degeneration Muscular problems that result in visual disturbances Corneal disorders Diabetic retinopathy Congenital disorders Albinism Infection

According to WHO estimates in 2002, the most common causes of blindness around the world are: Cataracts (47.8%), Glaucoma (12.3%), Age-related macular degeneration (AMD) (8.7%), Trachoma (3.6%), Corneal opacity (5.1%), and Diabetic retinopathy (4.8%),

Pediatric blindness Developed countries Retinopathy of prematurity Genetic diseases (cataract & retinal dystrophies) CNS problems Congenital malformations (optic nerve hypolplasia)

Developing countries Infections leading to corneal scarring (trachoma) Malnutrition (Vitamin A deficiency) Ophthalmia neonatorum Congenital cataract and glaucoma

Protocol – interacting with blind or visually impaired people Remember people with vision impairments are people just like you. They don’t want pity or condescending treatment Their sense of smell, touch, or hearing did not improve when they lost their vision. They simply rely on them more and may get more information through those senses than you do.

Protocol – interacting with blind or visually impaired people When you meet or come in contact with an individual who is blind or visually impaired, don't be ill at ease It isn’t necessary to raise your voice or address them in a child like manner Don't ask their spouse or companion what they may want

Interacting with blind or visually impaired people Always introduce yourself by name Please speak when you enter and exit a room If you have someone visually impaired as a houseguest, it is important to orient him or her to their surroundings

Approach and management There are a number of techniques that allow the visually impaired person to complete daily activities using their remaining senses.

Improving the sense of touch Adaptations of banknotes so that the value can be determined by touch In some currencies, such as the euro and pound sterling, the size of a note increases with its value. europound sterling

Improving the sense of touch Many banknotes from around the world have a tactile feature to indicate denomination in the upper right corner. This tactile feature is a series of raised dots, but it is not standard Braille

Improving the sense of touch Labeling and tagging clothing and other personal items Placing different types of food at different positions on a dinner plate Marking oven, dishwasher, and dryer dials for ease of use

Mobility Many people with serious visual impairments can travel independently using a white cane, the international symbol of blindness. A long cane is used to extend the user's range of touch sensation, swung in a low sweeping motion across the intended path of travel to detect obstacles

Basics of learning to walk with a White cane When the left foot is forward the cane sweeps over to the rightside of the person. When the right foot is forward the cane sweeps over to the leftside. When walking up or down stairs the cane makes contact at all times with the ground to judge the height and width of the steps. The person then proceeds forward always with one step ahead of the other. When catching public transport the cane is used to shoreline along the vehicle to locate the doorway.

White cane Canes are painted white for maximum visibility, and to denote visual impairment on the part of the user

Guide Dogs Trained to lead blind individuals around obstacles on the ground and overhead. Visually impaired people who employ these animals must already be competent travelers, and must use auditory (and, for those with some vision) and/or visual cues to determine when to begin crossing a street

Guide Dogs The dogs learn when to stop and when to go at street corners based on commands from their owners They do not read traffic signs or lights in part because dogs are color blind The owner listens to traffic sounds and tells the dog to go when it sounds as if traffic has stopped The dog is trained not to go if there is danger

Reading and magnification Most visually impaired people read print, either of a regular size or enlarged through the use of magnification devices Magnifying glasses can be handheld or rest on desktops

Reading aids Totally blind patients use Braille and Moon type or rely on talking books and readers

Computer equipment Special hardware such as scanners

Large Print Computer Keyboard Labels

Color Video Magnifier

Computers with refreshable Braille Modern web browsers, which can increase the size of text on some web pages through browser controls or through user- controlled style sheets

Others Enlarged or marked oven dials Talking thermometers Talking watches, clocks Talking scales Talking calculators Talking compasses …etc.

Braille Devised in 1821 by Louis Braille To read and write. Based on a method of communication originally developed by Charles Barbier in response to Napoleon's demand for a code that soldiers could use to communicate silently and without light at night called night writing

Braille Each braille character or "cell" is made up of six dot positions, arranged in a rectangle containing two columns of three dots each rectangle

Braille

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