(Activities)
THE EYE: Process of Normal Vision
Anatomy and Physiology of the Eye
How vision takes place
Blindness and Low Vision
Types and Causes of Problems of Vision
Special Adaptations, Aids and Technology for students who are blind and with low vision
The Education of Students with Visual Disability
What to do when a blind student is mainstreamed in class (for teachers)
Success stories of children and youth who are blind or with low vision
Spinning Wheel IllusionStare at one of the 5 wheels. Whichever one you stare at will appear to suddenly stop spinning. In reality -
none of the wheels are turning at all.
The eye is a complex part of the human body that no other organ can equal.
The sense of vision is a complex and intricate physiological system.
There are 3 elements necessary for good vision to take place. These are:A pair of healthy, intact and efficiently
functioning eyes with complete parts
A well lighted objects
A healthy brain
Five physiological/physical
systems in visions:
The Protective Structure
The Refractive Parts
The Muscles
The Retina and Optic Nerves
The Brain (where vision takes
place)
Surrounds the eye to protect it from harm.
These are:
Eye Socket – contains the eyeball; It protects the
sensitive mechanism for vision trauma together
with the bones in cheeks and forehead
Bones in the cheek and forehead
The Lacrimation System (tear ducts) – secretes
fluid/tears that clean and keep the eyes moist
Eyelids – moistens and clean the cornea through
blinking
Eyebrows and Eyelashes – catch foreign bodies that
might enter the eyes.
Bends or refract light rays so that the image of the
object focuses on the retina.
These are:
Cornea – Protects the sensitive parts of the eye; It starts
the process of vision by bending the light rays into
patterns or images
Aqueous Humour - A watery liquid that fills the front
chamber of the eye to keep the eyeball properly inflated
Pupil – It constricts or dilates to regulate the amount of
light entering the eye.
Iris
Lens – adjusts its thickness so that both near and far
objects can be brought to focus on the retina.
Vitreous Humour - a chamber filled with liquid; fills
most of the eyes interior
Functions to coordinate and balance the
movements of the eyes.
They turn, raise and lower the eyes in
response to cranial or brain nerve impulses
Retina – a multilayered sheet of nerve
tissues at the back of the eye.
Rods and Cones – light receptor cells
Rods – 130 Million for black and white vision;
responsible for night vision (or images under low
illumination)
Cones – 7 Million for color perception
Macula – most sensitive part of the eye; the
area that is vital to the exact discrimination
of the details of an image/object
Optic nerves – connected to the retina;
conducts visual images to the brain
LOCATION: at the back of the head
It is one of the four lobes of the brain that
are named for the major skull bones that
covers them
Others are: Parietal Lobe – processes body sensations
Temporal Lobe –auditory or hearing
Frontal Lobe – governs the highest functions
associated with conscious activities and intelligence
The basic function of the eye is to collect the visual stimuli
and information in the form of mechanical energy from the
environment through the psychological process –
SENSATION
The stimuli are converted to electrochemical form or nerve
impulses through the process of TRANSDUCTION.
The optic nerves conveys the nerve impulses to the occipital
lobe of the brain where PERCEPTION takes place.
3 Conditions for vision to take place:
The eyes are stimulated by light rays
The light rays are reflected from objects in the visual field
The mechanical energy is converted into nerve impulses
which the brain processes
BLINDNESS : (legal definition) it is based on measurement of
visual acuity, field of vision and peripheral vision.
Visual Acuity – the ability to clearly distinguish forms or discriminate details at a specific distance. Normal Visual Acuity is measured by reading letters, numbers and others symbols from a chart 20ft away.
The Snellen Chart is commonly used for this purpose.
Field of Vision – refers to the area that normal
eyes cover above, below and on both sides when
looking at an object or when gaziing straight
ahead. The field of normal vision covers
approximately a range of 180 degrees.
Central field of Vision – looking directly at an object
Peripheral Vision – the outer ranges of the field of vision
Tunnel Vision – results from an extremely restricted field
of vision.
Legal Blindedness – condition where visual acuity
is 20/200 in the better eye after the best possible
correction with glasses or contact lenses. The field
of vision for this person is about less than 180
degrees to an area of 20 degrees.
BLINDEDNESS - Educational Definition
Total blindness – the person is absolutely without
sight but may have light and movement perception
and travel vision.
The degree of blindness include:
Light perception (can differentiate light and
dark/day and night)
Movement perception (can detect if an object or a
person is in motion or in still position)
Travel vision (field of vision is enough to travel
safely in familliar area)
In SpEd, children who are blind are differentiated
from those who have low vision (ex. Children who
are blind are given Braille books but children with
low vision are given materials with large print)
Low vision – a level of vision that with standard
correction hinders an individual in the visual
planning and execution of tasks, but which
permits enhancements of the functional vision
through the use of optical or non-optical aids and
environmental modifications or techniques.(Corn’s
definition of Low Vision)
The inability of the eyes to function
efficiently may be traced to:
1. Errors of Refraction
2. Imbalance of the Eye Muscles
3. Diseases
4. Trauma or Accidents
After light rays enter cornea, acqueous humour and pupil and the lens fails to refract or bend the light rays to the central part of the retina.
Hyperopia (Farsightedness) – the lens fails to focus the light rays near objects on the retina. Convex lenses are used to converge the light rays on the retina.
Myopia (nearsightedness) – the eyes are abnormally long from front to back and the lens fails to refract the light rays from a distant objects on the retina. Concave lenses are used to correct myopia.
Astigmatism – the cornea which normally forms a portion of a spherical lens is deformed, the refraction of light becomes faulty and blurred vision results. Cylindrical lenses are used to correct the direction of the spherical lens.
When the muscles of both eyes do not work together in a coordinated way
Strabimus – different images are cast on each retina resulting to cross-eyedness or squinting.
Diplopia (double vision) – results when the brain cannot fuse the differences in the images cast on the retina into a single image. It can be corrected by prescription lenses, exercise, surgery.
Amblyopia – occurs when vision is suppressed in one eye and it becomes weak or useless.
Nystagmus – a condition in which there are rapid involuntary movements of the eyeball that cannot result to nausea and vomiting and dizziness. (in some cases, it is a sign of brain malfunction or inner ear problems)
Cataract – caused by the clouding of the lens which results to progressive blurring of vision and eventually blindness occurs.
It is associated with the aging process but it can occur early among persons with diabetes mellitus.
Children also can suffer from congenital cataract.
Diabetic retinopathy – occurs when diabetes mellitus interferes with the flow of blood to the retina causing it to degenerate
Corneal scar – called “pilak”, whitish substance caused by injuries and inffectionsdue to accidents and malnutrtion.
Diseases of the retina – can be congenital or present at birth.
Coloboma – a degenerative disease in which the central/peripheral areas of the retina are not completely formed resulting to impairment of the visual field, the central visual acuity and blindness.
Retinitis Pigmentosa – a hereditary condition that results in the degeneration of the retina. It can result to blindness.
Glaucoma – a condition in which there is excessive pressure in the eye.
This happen because of a certain
experience leading to injuries affecting
the eye.
Example :
Retinal Detachment
Eyes are hit or struck by a foreign objecy
Rubella – mild disease in most people. But pregnant woman who come in contact with someone with rubella(specially during the first 3 months) may have a risk of having a rubella baby.
A rubella baby can have serious problems such as permanent damage to the eyes and ears, including blindness and deafness, heart disease and brain damage.
It is responsible for 95% of deaf and blind babies.
Braille – primary means of literacy for a
blind person. It is a system of writing and
reading in which letters, words, numbers
and others are made from raised and
embossed dots.
It was invented 1830’s by Loiuse Braille, a
young blind man Frenchman who played organ
in church and use it to record church hymns
and music.
It is a complex system. It uses 6 dots that are
arranged two wide and three deep and
numbered
Blind students learned to read and write in braille by using a brailler which operates like a typewriter with 6 keys.
A portable laptop called VersaBraille II+ is also available for written work, taking notes and tests.
Braille Alphabet
Typewritter – they use it to communicate with
their teachers, classmates and friends.
Manipulative and Tactile Aids – are used in
learning mathematics, sciences and social
studies.
The Cisenaire rods – developed by Belcastro (1989);
enables the student to quickly identify by touch
The Cranner Abacus – used in teaching numerical
concepts and computing 4 basic operations
The Speech-Plus talking calculator – it talks by
voicing entries and talks aloud
Braille, Verbal or Taped instructions
Embossed relief maps and diagrams
3D models and Electronic Probes
Technological Aids
Optacon (optical to tactile converter) – small
electronic device that converts regular print into a
readable vibrating form for blind people.
The Kurzweil Personal Reader – a sophisticated
computer with an optical character recognition
(OCR) system that scans and reads via synthetic
voice typeset and other printed matter.
Assistive Technology –enables blind person to
access personal computers.
1960’s – integration of blind students in regular
classes. Blind boys and girls who have average
or better mental ability were enrolled in regular
classes at School Division Pasay City, Manila
and the Teacher Training Department of the
Philippine Normal College.
The SPED teachers teaches skills and concepts
that most children learn visually through the
remaining senses: audition, touch, olfaction,
gestation and other non-visual experiences.
Blind students learned to read and write in braille. Two brailled coded are learned:
(1) Filipino Brailled Code and (2)English Brailed Code American Edition.
The Philippine Printing House for the Blind at the Department of Education transcribes most of the materials in braille.
The Resources for the Blind Incorporated (RBI), a foreign funded NGO assist the DepEd through teacher training, preparation of instructional materials and other related projects.
Blind children receive instruction in orientation and mobility. Orientation – the ability to establish one’s position in
relation to environment through the use of the remaining senses.
Mobility – the ability to move safely and
efficiently from one point to another.
The Sped Teacher uses appropriate methods
and procedures to teach travel at home, the
school and the community.
The Sped Teacher uses manipulative and tactile
aids in teaching mathematics, science and the
other subjects in the curriculum.
Truly, an efficient Sped teacher “opens the door
to a world from which his/her student who are
blind or have low vision are more removed than
seeing children.” (Lowenfield,1973)
It’s okay to use words like “look” and “see”
when communicating with a blind person.
Introduce him/her to the other students and
encourage him/her to answer them.
Include him/her in all class activities
Extend the opportunity of being a leader to
the blind child
The same disciplinary rules that apply to the
rest of the class should apply as well to the
child with visual impairment.
Encourage him/her to move about the classroom to
get the materials or to do certain activities.
Give verbal instructions or oral cues
Provide space to accommodate his or her special
materials (ex. Braille books, tactual aids etc.)
Motivate the seeing classmates to become
interested in topics related to vision and visual
impairment
Your acceptance of the child will serve as a positive
example to their classmates
Always say who you are instead of asking him or
her to guess who you are.
The blind student may exhibit certain mannerisms
(rocking, flapping, or poking the fingers into the
eye). Consult the SPED teacher on how to deal
with such behaviors.
She has been blind since she was 4, but that didn’t stop her excelling in her academics. She has been a consistent honorstudent from 4th grade onwards. She also graduated as a Valedictorian when she was in High School. Though college may be a great risk for her, she did not made her condition as an excuse for learning. She took up Bachelors degree in English and determined to teach children who experiences the same situation as hers.
“My mission is to inspire other people, blind or sighted. I want to be of service to blind people by educating them. Hopefully that’s what God wants me to do.”
Born prematurely and after was exposed to too much oxygen caused him to be blind.
Today, he has been singing in conciertos all over the world and was also renowned in his singing skills from classical broadways to popular music.
He is also a linguist. He knew 6 languages (French, German, Italian, Spanish, Russian, and Japanese languages)