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
- 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?
What percentage of Canadians will experience vision loss after the age of 65?
What percentage of Canadians will experience vision loss after the age of 80?
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?
- slow but progressive degeneration of retinal cells causing loss of vision (light sensing cells)
- restricts vision field, causes tunnel vision and
- 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?
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
- 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.)
- 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)