3.1.1 Vision and Physiological Optics Flashcards Preview

Brain and Behavior > 3.1.1 Vision and Physiological Optics > Flashcards

Flashcards in 3.1.1 Vision and Physiological Optics Deck (20)
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1
Q

What is accomidation and how can it change with age?

A

Lens changes curvature to adapt to changes

Ciliary muscle contract - leading to increased curvature of the lens

Accomidation will decrease with age. Causes presbyopia

2
Q

What is the difference between concave and convex lens in regards to focal points?

A

Convex lens focuses light at a point behind the lens (away from light source)

Concave lense focuses light at a point in front of the lens

3
Q

What is a hyperopic eye?

A

This is considered farsighted.

Parallel rays are focused in an area posterior to the retina

4
Q

What are the covered parts?

A

Left - angle of incidence

Right - Angle of refraction

5
Q

What is the numerator and demoinator in the snellen acuity notation?

A

Example - You sat 20 feet in front of a chart

The gaps and strokes of the smallest letters you could read would subtend 1 min arc at 360ft

(Essentially someone with normal acuity could read letters correctly at 360 ft.

6
Q

What is the index of refraction?

A

n=C/V

Meaning that this is how a new medium will change the speed of light

7
Q

What is the power of the cornea and lens?

A

Cornea (42D)

Lens (20D)

8
Q

What is the difference between convex and concave lenses?

A
9
Q

What are the characteristics of an emmetropic eye?

A

The cornea and lens work to focus light on the retina in a correct fashion

10
Q
A
11
Q

How does focal length compare to lense curvature in a convex lens?

A

Larger radius (think the earth) has flatter lens

Flatter lens will bend the light less, so it has to travel further before meeting

12
Q

What is the definition of legal blindness?

A

20/200 or visual field of less than 20 degrees

13
Q

What would you use to correct myopia?

A

Bi concave lens would create diverging rays

14
Q

Explain the differences in the 2 mediums in figures A, B and C?

A

If index of refraction (n2) is larger, then light bends towards the normal

In Example A, n2 >n1, like light going from air through glass

In Example B, n2>>n1, so more refraction, greater angle of refraction

In Example C, n1=n2 (eg: light going from 2 pieces of glass held against each other)

15
Q

What is the physiological limit of visual acuity?

A

It is limited by the space between rods and cones from each other in the retina

16
Q

How does the power of a strong lens compare to a weak lens?

A

Power is the inverse of focal length in meters.

Meaning a stronger lense will have a focal length with a smaller value.

17
Q

What is astigmatism?

A

Vertical axis curvture and horizontal axis curvature on the cornea are different

18
Q
A
19
Q

What are the characteristics of a myopic eye?

A

Parallel rays are focused anterior to retina

20
Q

Would could you use to correct hyperopia?

A

Convex lense would cause the focal length to become shorter

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