The Eye and Retina

What is the stimulus for vision

Light

Electromagnetic spectrum

• Energy is described by WHAT

Electromagnetic spectrum

• Energy is described by WAVELENGTH

Electromagnetic spectrum

• Spectrum ranges from WHAT wavelength WHAT rays to WHAT wavelength WHAT waves.

Electromagnetic spectrum

• Spectrum ranges from SHORT wavelength GAMMA rays to LONG wavelength RADIO waves.

Electromagnetic spectrum

• Visible spectrum for a human ranges from WHAT to WHAT
  nanometers.

Electromagnetic spectrum

• Visible spectrum for a human ranges from 400 to 700
  nanometers.

Electromagnetic spectrum

• Most perceived light is WHAT light

Electromagnetic spectrum

• Most perceived light is REFLECTED light

The eye contains WHAT for vision

The eye contains RECEPTORS for vision

Light enters the eye through the WHAT and is focused by the WHAT and WHAT to a sharp image on the WHAT

Light enters the eye through the PUPIL and is focused by the CORNEA and LENS to a sharp image on the RETINA

WHAT and WHAT are the visual receptors in the retina that contain visual WHAT

RODS and CONES are the visual receptors in the retina that contain visual PIGMENT

the WHAT carriers information from the retina toward the brain

the OPTIC NERVE carriers information from the retina toward the brain

What are the three differences between rods and cones

• WHAT

• WHAT

• WHAT

What are the three differences between rods and cones

• Shape

• Distribution on retina

• Number

Shape

• Rods = WHAT and WHAT

• Cones = WHAT and WHAT

Shape

• Rods = LARGE and CYLINDRICAL

• Cones = SMALL and TAPERED

Distribution on the retina

• Fovea consists solely of WHAT

• Peripheral retina has WHAT and WHAT

• More WHAT than WHAT in the periphery

Distribution on the retina

• Fovea consists solely of CONES

• Peripheral retina has RODS and CONES

• More RODS than CONES in the periphery

There about WHAT million rods and WHAT million cones

There about 120 million rods and 6 million cones

Blind spot

Place where optic nerve leaves the eye

We can’t see the blind spot because

• One eye covers the WHAT of the other

• It is located at the edge of the WHAT

• The brain "WHAT” in the spot

We can’t see the blind spot because

• One eye covers the BLIND SPOT of the other

• It is located at the edge of the VISUAL FIELD

• The brain "FILLS IN” in the spot

What are the two types of retina degeneration

• WHAT

• WHAT

What are the two types of retina degeneration

• Macular degeneration

• Retinitis pigmentosa

Macular degeneration

Degeneration of the fovea and its surrounding area.

The affect individuals can’t see what they look at directly

Retinitis pigmentosa

The peripheral retina initially degenerates, and the degeneration may extend and eventually affects the fovea also

The cornea, which is fixed, accounts for about WHAT% of focusing

The cornea, which is fixed, accounts for about 80% of focusing

The lens, which adjusts its WHAT based on object distance, accounts for the other WHAT%

The lens, which adjusts its SHAPE based on object distance, accounts for the other 20%

Accommodation (change in the WHAT shape) results when WHAT are tightened, which causes the lens to WHAT

Accommodation (change in the LENS’S shape) results when CILIARY MUSCLES are tightened, which causes the lens to THICKEN

The thickened lens focus WHAT objects on the retina

The thickened lens focus NEAR objects on the retina

What are the two types of vision problems

• WHAT

• WHAT

What are the two types of vision problems

• Myopia (nearsightedness)

• Hyperopia/presbyopia (farsightedness)

Myopia (or Nearsightedness)

• Inability to see WHAT objects clearly.

Myopia (or Nearsightedness)

• Inability to see DISTANT objects clearly.

Myopia (or Nearsightedness)

• Image is focused WHAT of retina.

Myopia (or Nearsightedness)

• Image is focused IN FRONT of retina.

Myopia (or Nearsightedness) - Caused by:

• WHAT myopia

• Constant WHAT (the muscles fail to relax).

• WHAT myopia

Myopia (or Nearsightedness) - Caused by:

• REFRACTIVE myopia

• Constant ACCOMMODATION (the muscles fail to relax).

• AXIAL myopia

Refractive myopia

cornea or lens bends TOO MUCH light.

Axial myopia

Eyeball is too LONG.

Myopia (or Nearsightedness)

• Corrective (WHAT) lenses are needed for seeing WHAT objects.

Myopia (or Nearsightedness)

• Corrective (CONCAVE) lenses are needed for seeing DISTANT objects.

Hyperopia/presbyopia (or Farsightedness)

• Inability to see WHAT objects clearly.

Hyperopia/presbyopia (or Farsightedness)

• Inability to see CLOSE objects clearly.

Hyperopia/presbyopia (or Farsightedness)

• Image is focused WHAT the retina.

Hyperopia/presbyopia (or Farsightedness)

• Image is focused BEHIND the retina.

Hyperopia/presbyopia (or Farsightedness) - Caused by:

• Eyeball being too WHAT.

• Hardening of the WHAT and weakening of the WHAT (muscles fail to contract).

Hyperopia/presbyopia (or Farsightedness) - Caused by:

• Eyeball being too SHORT.

• Hardening of the LENS and weakening of the CILIARY MUSCLES (muscles fail to contract).

Hyperopia/presbyopia (or Farsightedness)

• Corrective (WHAT) lenses are needed for WHAT activities, such as reading.

Hyperopia/presbyopia (or Farsightedness)

• Corrective (CONVEX) lenses are needed for CLOSE activities, such as reading.

Hyperopia

• Is not a consequence of WHAT

• Can occur from WHAT or WHAT

• Cause is unusual shaped WHAT, WHAT or WHAT

Hyperopia

• Is not a consequence of AGING

• Can occur from CHILDHOOD or BIRTH

• Cause is unusual shaped EYEBALL, LENS or CORNEA

Presbyopia

• Is a consequence of WHAT

• Usually first occurs from the age of WHAT on

• Caused by WHAT of the lens and weakening of WHAT over time

Presbyopia

• Is a consequence of AGING

• Usually first occurs from the age of 40 on

• Caused by HARDENING of the lens and weakening of CILIARY MUSCLES over time