The Eye

• What is a sclera?

  The tough, supporting wall of the eyes
• What is a cornea?

  The transparent outer layer found at the front of the eyes. It refracts light into the eye
• Waht is the iris?

  It contains muscles that allow it to control the diameter of the pupil and how much light enters the eye
• What is a lens?

  It focuses the light onto the retina (which contains receptor cells sensitive to light intensity and colour)
• How is the shape of the lens controlled?

  By ciliary muscles and suspensory ligaments
• What does optic nerve do?

  It carries impulses from the receptors on the retina to the brain
• What happens to the eye when it detects a bright light?

  The circular musles in the iris contract and the radial muscles relax. This reduces the amount of light that can enter the eye
• What happens to the eye when it detects dim light?

  Radial muscles contract and the circular muscles relax,which makes the pupil wider
• What are the names of the two types of receptor cells in the retina? 

  • rod cells
  • cone cells
• Which light-sensitive cells in the retina enable you to see in colour?

  Cone cells
• The eye is a sense organ. Which two stimuli are the receptor cells of the eye sensitive to?

  • light intensity
  • colour
• Which light sensitive cells in the retina enable you to see in the dark?

  Rod cells
• The point where light focuses on the retina is called the

  Fovea. This region contains the highest concentration of cone cells and gives the sharpest image. 
• What is the purpose of the iris reflex?

  To ensure the optimum amount of light enters the eye
• When the pupil is very large, do we describe it as 'constricted' or 'dilated'?

  Dilated
• Which two muscles make up the iris? 

  circular and radial muscles
• When the eye is exposed to bright light, will the pupil constrict or dilate?

  Constrict
• What happens to the circular and radial muscles when the pupil constricts?

  circular muscles contract and radial muscles relax
• What is the tough white layer surrounding the eye called?

  Sclera
• What role does the cornea play in vision?

  It refracts light as it enters the eye
• What is the gap in the iris called?

  Pupil
• How does the iris affect light entering the eye?

  It determines the size of the pupil
• What happens to light after it passes through the pupil?

  It is further refracted by the lens
• What does the retina contain?

  Light receptors
• What is the function of the light receptors in the retina?

  They detect light and send impulses to the CNS
• What do ciliary muscles and suspensory ligaments do?

  Change the shape of the lens
• What is the process called that helps the eye focus on objects at different distances?

  Accommodation
• What happens to the lens when looking at a near object?

  The lens becomes thicker
• What occurs to the ciliary muscles when focusing on a distant object?

  They relax
• What is hyperopia?

  Difficulty seeing close objects
• How do glasses with convex lenses help long-sighted people?

  They refract light onto the retina
• What is myopia?

  Difficulty seeing distant objects
• How do glasses with concave lenses help short-sighted people?

  They refract light onto the retina
• What are the alternatives to wearing glasses for vision correction?

  • Contact lenses: lightweight, invisible, two types (soft and hard)
  • Laser eye surgery: changes cornea shape, risks involved
  • Lens replacement surgery: replaces faulty lens with artificial lens, higher risks
• What are the two types of contact lenses?

  Soft and hard lenses
• What does laser eye surgery do for short-sighted people?

  It slims down the cornea
• What is a risk associated with lens replacement surgery?

  Damage to the retina
• What could happen if complications occur during lens replacement surgery?

  The patient could lose their sight