Focusing Images on the Retina
80% Cornea, ﬁxed
20% Lens, variable
The process by which the lens adjusts shape
to focus light from objects on the retina.
In a relaxed eye, parallel
rays from a distant object
fall into focus on the retina.
Diverging rays from a
nearer object will fall into
focus behind the retina.
In this case, muscles in
the eye change the shape of
the lens to maintain focus
on the retina.
(I play a part of video which reinforces how the structure
of the eye supports the function of the eye)
Why do the eyes move?
Lots of reasons ...
Eye movements maintain the center of attention
on the most acute part of the eye, the fovea.
Since the eyes are a short distance apart in the head,
they have to make vergence movements to maintain
Useful in depth perception
The structure of the eye supports the
function of the eye.
Eye movements serve to maintain high
resolution and binocular ﬁxation.