Hyperopia Myopia and how the eye focuses

• The cornea of the eye is a fixed focus
• The lens of the eye allows us to focus on distant or near objects
• Accommodation is the change in the shape of the lens to focus on objects
• The ciliary muscle surrounds the lens
• The ciliary muscle contracts or relaxes to change the thickness of the lens
• When the ciliary muscle contracts, the lens becomes thicker and refracts light rays more strongly
• When the ciliary muscle relaxes, the lens becomes thinner and only slightly refracts light rays
• To focus on distant objects, the ciliary muscle relaxes and the suspensory ligaments are pulled tight, making the lens thin
• To focus on near objects, the ciliary muscle contracts and the suspensory ligaments loosen, making the lens thicker
• Long sightedness is called hyperopia
• People with hyperopia cannot focus on nearby objects
• In hyperopia, the eyeball is too short, causing light to focus behind the retina
• The elderly may experience hyperopia due to the lens becoming less elastic
• Hyperopia can be treated with glasses with convex lenses
• Short sightedness is called Myopia
• People with myopia cannot focus on distant objects
• Myopia can be caused when the lens is too thick, causing light to focus in-front of the retina
• Myopia can be treated with glasses with concave lenses
• Laser surgery can be used to change the shape of the cornea for greater or lesser light refraction
• Artificial lenses can be used to replace the natural lenses inside the eye
• Name all parts of this diagram:

  • Convex lens
  • Cornea
  • Pupil
  • Iris
  • Ciliary muscle
  • Suspensory ligaments
  • Retina

  
• Name all parts of this diagram:

  • Concave lens
  • Cornea
  • Pupil
  • Iris
  • Ciliary muscle
  • Suspensory ligaments
  • Retina