Sensory experiences get worse as we get older. No other age related loss is as universal as
All systems detect energy from the environment, which is picked up by special receptors
located in an organ. This energy is converted into a signal.
-Sensory Nerves: acoustic nerves= hearing, optic nerves= vision
-Normal age related changes can also occur due to disuse, abusse
-- impairment in sensory systems limits our interaction with the world
-Without these senses, we feel disoriented, degraded input for vision and hearing
affects how we code information and respond to information.
-There are 3 main layers: sclerotic coat, choroid, retina
-Lense divides the insde of the eye: the inner part is called the Aqueous humor and
the outside is called the Vitreous humor
-the eye is a spherical shape
-Sclerotic coat- is a hard tissue, helps the eye preserve its shape bevcause fluids
existing in the eye create a pressure, therefore a hard coating is needed to withstand
-Choroid: made by a network of blood vessels which carry oxygen and nutrients
-It has structures that make fluids. The centre of the eye is the iris- pigmentiation
represents the colour of the eye
-- it is responsible for dilating th size of pupils to avoid allowing too much light to
enter. If luminense decreases, the pupil increases by 4 times to let more light in.
-the size of the pupil is affected by emotional factors
-Retina: is like a small fishernet, it is made by cells, is the screen onto which an
image of the world is projected. It contains rods and cones- particles of light.
-Axis of ganglion cells make up the optic nerve.
-Anterior (aqueous humor)- is like a water chamber- it carries nutrients to various
structures and removes waste that is created by activities occuring in the eye. In a
normal eye, this input and output is a perfect balance. (in terms of how much liquid
is mae and released)
-Lens- is connected to the muscles that change the shape of the lens- can make an
image blurry or clear. It also projects an image onto the retina.
-If the image falls behind the retina, then the lens will increase its curvature.
-Refractory power: bending rays to allow the image to fall on to the retina.
-However there is a limit, when an object gets too close, one is unable to see the
-As one ages: the vitreous humor becomes opaque (less transparent) which limits the
light that is able to reach the receptors at the back of the eye.
-Also, the role of the pupil is to get bigger or smaller to control how much light
enters, but as one ages, the maximum opening is reduced, therefore less light enters
the eye. This begins at an early age but occurs slowly.
As a result, with a shrinking pupil and a less transparent jelly (vitreous humor)- the eye
only recieves 75% of the light that others receive.
This can become a problem at night where there is low illumination- individuals will be
unable to see
Also the rate at which the pupil size changes (gets bigger and smaller) slows down, because
muscles get weaker
-This is a problem for people driving at night because they have to transition from a
dark area to light immediately, if a car passes by
Lens: is made up from layers of cells, and new layers are constantly being added. Therefore,
the lens gets thicker (more hard) and bigger in size and the old cells begin to shrink. As we
age, this process reduces the transparency of the lens therefore less light passes through.
Also, the lens becomes a yellow colour, therefore blue, green, violet range are hard to see.
-The eye becomes more sensitive to glare because the lens has become thick and less
- The lens becomes less flexible, it is harder for it to change its shape to focus at short
-Occurs around age 40, women develop presbyopia 5 years earlier than men. This
condition can be noticed when people have to hold a newspaper far away in order to
-Near point is receding, lens gets thicker, the muscles get weaker therefore muscles
can’t bend lens as much, in order to bring the image onto the retina, therefore near
point gets far, and past the near point, one sees a blurry image.
-Presbyopia can be improved by wearing convex lens.
-Accomodation speed slows down: needed to adjust to change in distances.
-Visual acuity: the ability to tell apart small details of an image. Details can be
viewed better with a greater visual acuity.
-Visual acuity declines slowly, at 40 years, steepness of the slope increases therefore
acuity declines faster.
-At 80 years, one can see at an average of 20 feet, whereas an average 20 year old can
see at 200 feet.
Problems can occur in the optic nerve, or other organs.
-A lot of variability exists in terms of visual acuity among people- therefore a
question is asked: can practice with tasks that involve acuity, reduce the effects of
aging on acuity? Ex. shooting a basket ball
-It was found that there is a genetic predisposition to good visual acuity, however
training and practise can improve it. (both factors influence it)
Reduced Dynamic Visual Acuity: examines how one processes information in moving time.
Ex. reading signs on a bus as it moves.
Visual Field: if we keep our head still, and our eyes don’t move, everything we can see is
our visual field. After age 50, the size of the visual field reduces faster.
Depth perception: ex. look at a distance between things- researchers say that this occurs
due to a loss of binocular cells, which process information from the right and left eye
Processing of visual information: it takes longer to extract information form a source, and it
takes longer to do things.
As one gets older, one becomes more vulnerable to pathology.
Glaucoma: Leading cause of blindness: it is a steady increase in pressure in the interior
chamber: aqueous humor, which is responsible for bathing structures (is a part of the
Sensory experiences get worse as we get older. No other age related loss is as universal as sensory loss. All systems detect energy from the environment, which is picked up by special receptors located in an organ. Sensory nerves: acoustic nerves= hearing, optic nerves= vision. Normal age related changes can also occur due to disuse, abusse. Impairment in sensory systems limits our interaction with the world. Without these senses, we feel disoriented, degraded input for vision and hearing affects how we code information and respond to information. There are 3 main layers: sclerotic coat, choroid, retina. Lense divides the insde of the eye: the inner part is called the aqueous humor and the outside is called the vitreous humor the eye is a spherical shape. Sclerotic coat- is a hard tissue, helps the eye preserve its shape bevcause fluids existing in the eye create a pressure, therefore a hard coating is needed to withstand this pressure.