The eye

• What is the primary function of the human eye?

  To detect light and allow vision
• How do light-sensitive cells in the retina function?

  They generate electrical impulses sent to the brain
• What are the main structures of the eye and their functions?

  • Cornea: Refracts light towards the retina
  • Iris: Regulates pupil diameter
  • Pupil: Allows light to enter
  • Lens: Focuses light onto the retina
  • Ciliary Muscles: Adjust lens shape
  • Suspensory Ligaments: Connect lens to ciliary muscles
  • Retina: Contains light-sensitive receptor cells
  • Optic Nerve: Carries impulses to the brain
  • Sclera: Protects the eye
  • Choroid: Supplies oxygen and nutrients
  • Fovea: Responsible for sharp vision
• What is the process called when the eye adjusts the lens shape?

  Accommodation
• What happens during accommodation for near objects?

  • Ciliary muscles contract
  • Suspensory ligaments loosen
  • Lens becomes thicker
  • Light is refracted more strongly
• What happens during accommodation for distant objects?

  • Ciliary muscles relax
  • Suspensory ligaments tighten
  • Lens becomes thinner
  • Light is refracted less
• What is the pupil reflex and its purpose?

  • Adjusts pupil size based on light levels
  • Protects retina from bright light
  • Allows more light in dim conditions
• What occurs in bright light during the pupil reflex?

  • Circular muscles contract
  • Radial muscles relax
  • Pupil constricts
• What occurs in dim light during the pupil reflex?

  • Circular muscles relax
  • Radial muscles contract
  • Pupil dilates
• What is myopia also known as?

  Short-sightedness
• What causes myopia?

  Eyeball is too long or cornea too curved
• Where does light focus in myopia?

  In front of the retina
• How is myopia corrected?

  With concave lenses
• What is hyperopia also known as?

  Long-sightedness
• What causes hyperopia?

  Eyeball is too short or lens too thin
• Where does light focus in hyperopia?

  Behind the retina
• How is hyperopia corrected?

  With convex lenses
• What are the treatments for vision defects?

  1. Contact Lenses

  • Sit directly on the cornea
  • Soft lenses: Comfortable, frequent replacement
  • Hard lenses: Durable, less comfortable

  1. Laser Eye Surgery

  • Reshapes cornea for light refraction
  • Permanent but surgical risks

  1. Replacement Lenses

  • Artificial lenses implanted in the eye
  • Risk of infection or retinal damage