The Eye
By the end of this module
you should know / be able to:
• Relate the structures of the eye to their functions. This
includes accommodation to focus on near or distant objects,
and adaptation to dim light.
• The eye is a sense organ containing receptors sensitive to
light intensity and colour.
• Identify the following structures on a diagram of the eye and
explain how their structure is related to their function: retina,
optic nerve, sclera, cornea, iris, ciliary muscles, suspensory
ligaments
• Accommodation is the process of changing the shape of the
lens to focus on near or distant objects.
• To focus on a near object: the ciliary muscles contract, the
suspensory ligaments loosen, the lens is then thicker and
refracts light rays strongly.
• To focus on a distant object: the ciliary muscles relax, the
suspensory ligaments are pulled tight, the lens is then pulled
thin and only slightly refracts light rays.
• Two common defects of the eyes are myopia (short
sightedness) and hyperopia (long sightedness) in which rays
of light do not focus on the retina.
• Generally these defects are treated with spectacle lenses
which refract the light rays so that they do focus on the retina.
• New technologies now include hard and soft contact lenses,
, Eye Structure
(complete the annotations and the table)
By the end of this module
you should know / be able to:
• Relate the structures of the eye to their functions. This
includes accommodation to focus on near or distant objects,
and adaptation to dim light.
• The eye is a sense organ containing receptors sensitive to
light intensity and colour.
• Identify the following structures on a diagram of the eye and
explain how their structure is related to their function: retina,
optic nerve, sclera, cornea, iris, ciliary muscles, suspensory
ligaments
• Accommodation is the process of changing the shape of the
lens to focus on near or distant objects.
• To focus on a near object: the ciliary muscles contract, the
suspensory ligaments loosen, the lens is then thicker and
refracts light rays strongly.
• To focus on a distant object: the ciliary muscles relax, the
suspensory ligaments are pulled tight, the lens is then pulled
thin and only slightly refracts light rays.
• Two common defects of the eyes are myopia (short
sightedness) and hyperopia (long sightedness) in which rays
of light do not focus on the retina.
• Generally these defects are treated with spectacle lenses
which refract the light rays so that they do focus on the retina.
• New technologies now include hard and soft contact lenses,
, Eye Structure
(complete the annotations and the table)
