Quality of vision is referred to in terms of what?
- acuity and field
What does the 20/20 method measure?
- visual acuity of eye
What is field of vision?
- area within which objects can be seen when eyes are fixed straight ahead
What is visual impairment/vision loss?
- refers to a range of visual ability - legal blindness,
partially sighted, totally blind
What is legal blindness?
- 20/200 in the better eye even with the best
correction - 200 FOV
What does it mean to be partially sighted?
- can make out shapes and object
What is the average age for someone with a visual impairment?
- 40
What percentage of Canadians will experience vision loss after the age of 65?
- 1/9
What percentage of Canadians will experience vision loss after the age of 80?
- 1/4
What are some common causes of vision loss in children?
- congenital cataracts, optic nerve disease, retinopathy of prematurity
What are some common causes of vision loss in adults?
- cataracts, macular degeneration, diabetes
What is the retina?
- inner lining of eyeball
- expansion of optic nerve
- sensory receptors for light
- tissue which lines the inside of the eye and sends visual images to the brain
What are three conditions of the retina to be aware of?
- detachment, pigmentosa & glaucoma
What is retinal detachment?
- retina separates from back of the eye and detaches causing blurry or blind spot in field of vision
- as cells die vision is lost
Why does the retina detach?
- detaches because of small tares or holes
- fluid may seep through the small tares and flow between back wall of eye and the retina
- eye diseases,
complications of diabetes and or tumours - avoid activities that will jar the head
What is retinal pigmentosa?
- inherited
- slow but progressive degeneration of retinal cells causing loss of vision (light sensing cells)
- restricts vision field, causes tunnel vision and
night blindness - avoid low light activities
What is glaucoma?
- increased pressure inside of the eyeball damages optic nerve
- affects peripheral vision and with time can affect central vision and can result in complete loss of vision
- avoid activities that include increased eye pressure (swimming)
What is retinopathy of prematurity?
- abnormal growth of blood vessels within the retina and vitreous that occurs in some premature infants
- nutrients are not delivered to the retina properly
- blood vessels are fragile and prone to leak
What can later stages of retinopathy of prematurity lead to?
- can lead to the formation of scar tissue on the retina, vitreous hemorrhage, and retinal detachment
How can ROP damage the brain?
- oxygen is poorly circulated/regulated in the incubator and too much oxygen damages the retina, may cause mild damage to the brain
What is cataracts?
- clouding of the lens of the eye
- may affect just a small part of the lens, or it may cloud the entire lens
What does the lens of the eye do?
- located near the front of the eye
- focuses light on the retina, to form the images we see
What can cause changes in the medical makeup of the lens?
- aging, certain medications (e.g. steroids), genetics, eye injuries, or certain diseases can cause cataracts
Can children get cataracts?
- yes, congenital cataracts
- inherited, or cause by an eye infection before birth?
What are some causes of cataracts?
- caused by a change in the chemical makeup of the lens
- eye injuries, such as a hard blow, puncture, cut, intense heat, or chemical burn can damage the lens, diabetes
What is diabetic retinopathy?
- change in blood vessels that feed retina
- vessels can either dry up and prevent nutrients from reaching retina or they can leak and ‘flood’ the area
How many diabetics get diabetic retinopathy?
- 1/4
What is proliferative diabetic retinopathy?
- as the disease advances, blood vessels become blocked or closed and parts of retina die
- new blood vessels grow, abnormally, and tend to bleed into eyes, blocking vision
- scar tissue forms, retina tears, and retina can detach itself from the back of the eye
How can retinopathy be treated?
- lasers seal leaky vessels, stop growth of new ones
What is macular degeneration?
- most common cause of severe vision loss in Canada, esp. among elderly
- blurred central vision
- macula can become distorted or thin, or abnormal blood vessels develop and leak fluid and blood under macula, into retina
How can vision impairment affect development?
- motor development and performance is often delayed in infants who have a visual impairment
- lack of play and social skills
How can visual impairment affect physical activity?
- can be difficult to teach movement patterns
- lowered fitness than sighted peers
- mechanical inefficiency in gait in unfamiliar areas
What are some considerations for physical activity opportunities?
- brightly coloured & auditory equipment
- make distinction between surfaces to indicate out of bounds
- braille on swimming pool walls
- guidewires
- difficulty with spatial awareness and body image
What are some considerations for movement?
- walking in a straight line; making turns
- facing sounds, people
- find starting point after a short walk
- relate direction to sunshine
What are some considerations for sound usage?
- bouncing objects
- catch bouncing object
- follow a voice
- jump rope
What are some considerations for orientation and mobility training?
- demonstrate/talk about how to play
- pump legs while swinging
- jungle gym
- teeter-totter with friends
What are some considerations for safety?
- orientation (landmarks, anchor points)
- consistent, clutter–free area
What are some considerations for communication?
- descriptive language
- brailling or hand-body manipulation
- augmented sensory information (beeper balls,
bright colour strip on badminton net etc.) - ‘buddies’
- use residual vision – large print, contrasting colours
How can you guide and describe?
- person with VI holds the back of your arm above elbow
- walk side by side
- verbal indications of steps (up or down)
- change in surface (incline, decline, hole)
- doors (push or pull open)
