As people get older, the lens in their eyes becomes less elastic and loses its ability to quickly change shape to focus on objects at different distances, leading to difficulty refocusing. If too much light falls on the photoreceptors in the eye, they would not recover quickly enough to allow for clear vision. The iris helps control the amount of light entering the eye by contracting or expanding.

1.  Receptors (photoreceptors: rods and cones)
 Other tissues that allows the receptor cells to
work effieciently.
 Its own bloody supply and physical protection.

2. An image is formed when rays of light are
focused onto the retina.

3.  Lens have the ability to produce an image of
objects at different distances. (accomodation)

4.  As people get older lens become less elastic
and loses its ability to change shape. This
makes harder to refocus quickly on objects at
different distances.
What happens to people when they become older?

5.  If too much light fell on the photoreceptors
they would not recover in time to allow clear
vision.
What happens if too much light fell on the photoreceptors?

6.  The Iris contracts or expands to control the
amount of light that enters the eye.

7.  Choose a visual problem: myopia, cataracts, lazy eye,
astigmatism, hyperopia, blindness or color blindness.
What is/are the cause/s?
What are the symptoms?
Do they have a treatment?
Design a presentation to expose this visual problem for
the rest of the class.