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Vision & The Eye

Anatomy, Physiology and How we see

Learning Objectives

  • Explain how the eye works to see the world around us
  • Describe the anatomy of the eye & Label Diagrams

Vision involves the eye and the brain.

Vision is your ability to see.

The eye gathers pictures and sends them to the brain.

The eye is made of the iris and the pupil.

The eye is one of your sense organs.

The Eye



The pupil becomes larger and smaller as it controls the light coming into the eye.

The black part of the eye is the pupil.

The colored part of the eye is the iris.

The Parts of the Eye

  • Smooth radial muscles
  • Circular muscles
  • These surround a hole – the pupil

Iris and Pupil

  • muscle in the iris contracts making the pupil smaller in bright light
  • different muscle in the iris contract to make the pupil larger in dim light

Changing the size of the pupils

  • Sclera
  • Retina
  • Cornea
  • Iris
  • Pupil
  • lens
  • Suspensory ligaments
  • Ciliary muscle
  • Refract
  • Focus

Key terms

  • Suspensory ligaments
  • Ciliary muscle
  • Refract
  • Focus
  • Lens
  • Sclera
  • Retina
  • Cornea
  • Iris
  • Pupil

Structure of the eye

Sensory neurone Blind spot (no rods and cones)

Surrounds the cornea, lubricated by watery tear fluid


Transparent part of the sclera, Allows light to enter the eye.

Light sensitive rod and cone cells

Tough and fibrous

Blood vessels

  • There are two lenses in your eye, the cornea and the eyelens.
  • The cornea, the front surface of the eye, does most of the focusing in your eye
  • The eyelens provides adjustable fine-tuning of the focus




Structure of the Eye: Cornea and Lens

  • Light is refracted when it enters the eye
  • Cornea
  • Front of Lens
  • Rear of Lens
  • Image forms on retina

Refract (bend)

Blind Spot

Lens held in place by suspensory ligamentsSuspensory ligaments are attached to ciliary ,muscle

  • Ciliary Muscles relax
  • Suspensory ligaments pulled taught
  • Lens pulled thin
  • Light rays enter at a less acute angle
  • less bending power, longer focal length

Looking at a distant object

  • Ciliary muscles contract
  • Suspensory ligaments loosen
  • Lens bulges
  • Light rays enter at a more acute angle
  • bending power Is more
  • Shorter focal length

Looking at a close object


long sighted (hyperopia)- the focal point is too long Distant image will be clear

Short sighted (myopia)- the focal point falls short. Near image will be clear

Short and long sighted


Optics of the Human Eye