Legally blind people can be broken into two categories: those who
are totally blind, and
those who are vision impaired.
Many people think that blindness is seeing black. It is not. There
are varying degrees of
vision impairment. Most people we call legally blind have
some form of vision. Very few
are completely blind. Completely blind people cannot see
anything at all, and do not react to light. Sometimes, vision
impaired people may see shapes, but perhaps not in detail. Others
may have tunnel vision, while yet others have blurry overall
vision. Each person will be
different. If your eyesight is failing, you can be referred to your local Blind
Foundation directly, or through your local GP, optometrist or
opthalmologist. Please contact your local Blind Foundation for
information on their referral process.
Visual impairments and blindness can be hereditary, caused by environmental factors or even from accidents. They occur in
people of all ages, although a majority of people are generally
elderly - due to age related issues. Some examples of causes of
blindness and vision impairments may be: walking into objects that
may penetrate the eye, rubbing your eyes when there are chemicals
or other substances on your hands, losing sight through illnesses
such as meningitis, and so on.
person is different, and it is important to seek medical
advice, rather than try to self diagnose any potential issues.
Imagine how you would be affected if you had any of the
eyesight conditions mentioned below.Below are some of the more common vision impairments,
(along with a picture of normal vision to compare some of the
other eyesight conditions view of that same picture to); and a
brief description as
to how they may affect vision:
A person with normal vision might see the whole picture
Macular degeneration is predominent in people
aged 55 and over. Some people may have a loss of their central
vision (blurring, followed by distortion and eventually blind
spots), and may only see around the outsides. Central vision loss
from AMD occurs when photoreceptor cells in the macula degenerate.
In most cases, if one eye has it, the other will develop it as
A person with macular degeneration might see the outside of the
picture but not the middle.
People with glaucoma may have tunnel vision, and
may not see things to the outside, as well as reduced night
A person with glaucoma might see the middle of the picture but not
Cataracts leave a cloudiness over the lens of
the eye, causing blurred vision and sensitivity to glare. These
can occur in either eye.
A person with cataracts might see a cloudy picture.
Damaged blood vessels in the eyes cause patchy
vision, decreased night vision, and sensitivity to glare.
A person with diabetic retinopathy might see some colour, however
the picture may be quite patchy.
Pigmentosa (RP) refers to a group of inherited diseases that
cause the retina to degenerate. The retina (which lines
the back inside wall of the eye) is responsible for capturing
images. People with RP experience a gradual decline in their
vision because photoreceptor cells (rods and cones) die. Forms of
RP and related diseases include: X-linked
syndrome, Leberís congenital
amaurosis, Rod-Cone disease,
and Refsum disease,
among others. Symptoms depend on whether rods or cones are initially
involved. Rods generally, are affected first. The outer rods are triggered by dim
light, and their degeneration affects
peripheral (outside) vision and night vision. The more
centrally located cones
are responsible for colour and sharp central vision, and so affect colour perception and central
vision. Night blindness is one of the earliest and most
frequent symptoms. RP is generally diagnosed in teenagers and
young adults. It is a progressive disorder which varies from
person to person. Most people with RP are legally blind by 40,
with a central visual field of less than 20 degrees in diameter.
In families with X-linked
choroideraemia RP, males are more often affected, and
females can be the carriers. (For example, a mother with three
children may have two sons - one who is visually impaired and one
who is sighted, while the daughter may or may not be a carrier).
Choroideremia is a rare inherited disorder that causes progressive
loss of vision due to degeneration of the choroid and retina.
People with Usher Syndrome
experience both RP (vision loss) as well as hearing loss and a
loss of balance. Usher 1 is severe hearing loss and issues with
balance at birth, and vision loss appears in early adolescence;
Usher 2 is moderate to severe hearing loss at birth and vision
loss appears after adolescence with hearing loss remaining stable;
and Usher 3 is good or mild hearing impairment at birth, with
vision loss appearing around puberty and balance may or may not be
affected. People with Leber
Congenital Amaurosis generally have severe loss of vision
at birth. Other related issues may include roving eye
movements, deep-set eyes, and sensitivity to bright light.
Some patients with LCA also experience central nervous system
Dystrophy results from a primary loss of rod
photoreceptors, followed by loss of cones. An initial loss of
colour vision and of visual acuity is followed by night blindness
and loss of peripheral visual fields. Bardet-Biedl syndrome is a complex disorder that
affects many parts of the body including the retina. People with
this syndrome will have an eyesight condition similar to retinitis
pigmentosa (RP). They are born with extra toes and or fingers, and
can suffer from obesity and may also suffer from developmental
issues and kidney issues. People with Refsum disease generally have vision loss, the
absence of the sense of smell, and a variety of other signs and
symptoms. Some people with Refsum are born with bone abnormalities
of the hands and feet, while others develop degenerative issues
with other body parts.
Stargardt disease is the most common form of
inherited juvenile macular degeneration. Vision loss is
progressive and caused by the death of photoreceptor cells in the
central portion of the retina called the macula. Stargardt disease
typically develops during childhood and adolescence. People with
this may have decreased central vision, while still keeping their
side vision. They may also notice a decrease in colour perception.
This is because photoreceptor cells involved in color perception
are concentrated in the macula.
Other not so commonly heard
of eye conditions
Small round white spots appear in the areas of
the macula and optic disc, in early adult life. Progression to
form a mosaic pattern termed 'honeycomb' occurs thereafter.
Blue cone monochromatism is characterized by
poor central vision and colour discrimination, called partial
Juvenile retinoschisis is an inherited disease
diagnosed in childhood that causes progressive loss of central and
peripheral (side) vision due to degeneration of the retina.
Best disease, also known as vitelliform macular
dystrophy, is an inherited form of macular degeneration
characterized by a loss of central vision.
You only have one set of eyes and once they are damaged they
can't be fixed. While you are young please protect your
eyes. Simple actions that you can take are things like: wearing
your sunglasses, eating properly and not playing around with
sharp objects. While not all vision impairments can be
prevented, some certainly can, and some others can be minimised.