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Primary Eye Care > Chapter 1 > Flashcards

Chapter 1 Flashcards

1
Q

Is defined as the process by which the crystalline lens varies its focal length in response to changes in the vergence of incident light.

A

Accommodation

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2
Q

Image formed by the optical system of the eye.

A

Optical image

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3
Q

Image formed on the retina, which may be either sharply focused or blurred.

A

Retinal image

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4
Q

Which part of the eye contributes more than two thirds of the refraction of the eye?

A

Cornea

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5
Q

What part of the eye accounts for about 1/3 of the refraction of the eye?

A

Crystalline lens

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6
Q

What part of the eye is responsible for the changing the power of the lens during accommodation?

A

Ciliary muscle

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7
Q

What are the three types of fibers in ciliary muscle?

A
  1. Longitudinal fibers
  2. Radial fibers
  3. Circular fibers
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8
Q

Light travels from which direction?

A

Left to right

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9
Q

Divergent rays of light are considered?

A

Negative

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10
Q

Convergent rays of light are considered?

A

Positive

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11
Q

The extent to which the image may be located in front of or behind the retina and still appear to be clear is referred to as?

A

Depth of focus

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12
Q

The extent to which the visual acuity chart may be moved toward or away from the patient is referred to as?

A

Depth of field

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13
Q

Defined as the resolving power of the eye, or the ability to see two separate objects as separate.

A

Visual acuity

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14
Q

In _______ eye with accommodation relaxed, parallel rays of light converge to a sharp focus on the retina.

A

Emmetropia / emmetropic

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15
Q

Condition in which the accommodation relaxed, parallel rays of light converge to a focus in front of the retina.

A

Myopia

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16
Q

The far point of accommodation for myopic eye is defined as the farthest object for which an image point is focused on the retina, is always located at a _____ distance in _____ of the retina.

A

Finite; front

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17
Q

The near point of accommodation of the a myopic eye is defined as the nearest object point in which an image is focused on the _____ and is always located in ____ of the eye.

A

Retina; front

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18
Q

Myopia can occur in two extreme forms.

A
  • Axial length of the eye can be normal & focal length of the optical system is longer than normal.
  • Axial length of the eye can be longer than normal & the focal length of the optical system is normal.
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19
Q

Myopia cmay be corrected with _____ lens.

A

Diverging / negative

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20
Q

Once an individual begins to become myopic (typically occurs during childhood) the amount of myopia tends to increase gradually with time. What kind of myopia is this?

A

Progressive myopia

21
Q

This is a result of prolonged accommodation in which the ciliary muscle is thought to increase in tonicity to the point where it fails to fully relax when distance vision is attempted.

A

Ciliary spasm

22
Q

In the beginning stages of myopia, the individual may complain that distance vision blurs following prolonged near work but it clears after a few minutes.

A

Pseudomyopia

23
Q

The amount of myopia that is reversible (pseudomyopia) is probably no more than ____ D.

A

1.00 D

24
Q

Having difficulty seeing at night especially when the person is driving.

A

Night myopia

25
Q

The amount of night myopia is usually no more than ____ to ____ D.

A

0.50 D to 1.00 D

26
Q

It is a condition in which rays of light converge to a focus behind the retina.

A

Hyperope

27
Q

What are the two extreme forms of hyperope?

A
  • Axial length of the eye can be normal & the focal length of the optical system longer than normal.
  • Axial length of the eye can be shorter than normal & the focal length of the optical system is normal.
28
Q

The far point of accommodation for an uncorrected hyperopic eye is an imaginary point located ____ the retina.

A

Behind

29
Q

The near point of accommodation for a hyperopic eye may be either a ____ object point located in _____ of the eye or an imaginary point located ____ the eye.

A

Real; front; behind

30
Q

Hyperopia is corrected by means of _____ lens

A

Converging / Convergent / Positive

31
Q

Hyperopia is compensated by the tonicity of the ciliary muscle is called?

A

Latent hyperopia

32
Q

Type of hyperopia that cannot be compensated for by accommodation?

A

Absolute hyperopia

33
Q

Type of hyperopia that can be overcome or compensated for by accommodation?

A

Facultative hyperopia

34
Q

A refractive condition in which the eye’s optical system is incapable of forming point image for a point object.

A

Astigmatism

35
Q

Most corneas are more steeply curved in the vertical meridian than in the horizontal meridian, causing the vergence of light to be greater in the vertical than in horizontal meridian.

A

With the rule astigmatism

36
Q

When the vergence of light is greater in horizontal meridian than in vertical meridian is called?

A

Against the rule astigmatism

37
Q

A refracting surface having the same radius of curvature in different meridians is called

A

Spherical surface

38
Q

A refracting surface having different radii of curvature in different meridians is called

A

Toric surface

39
Q

With accommodation relaxed, if one focal line is located on the retina and the other is either in front of the retina or behind the retina, what type of astigmatism?

A

Simple astigmatism

40
Q

With accommodation relaxed, if both focal lines are either in front or back of the retina, the condition is called?

A

Compound astigmatism

41
Q

With accommodation relaxed, one focal line is located in front of the retina and other behind the retina is called?

A

Mixed astigmatism

42
Q

What type of lens you must give to a simple astigmatic patient?

A

Cylindrical lens

43
Q

What type of lens you must give to a compound astigmatic patient?

A

Toric lens

44
Q

This occurs when the near point of accommodation has receded to the point that is difficult or impossible to accommodate sufficiently for reading or other close work.

A

Presbyopia

45
Q

There is a significant difference in the spherical refractive errors for two eyes of 1.00 D and more

A

Anisometropia

46
Q

The refractive error of both eyes has same amount.

A

Isometropia

47
Q

A person is myopic in one eye and hyperopic in the other

A

Antimetropia

48
Q

It is a condition in which lowered visual acuity exists even with best corrective lenses

A

Amblyopia

Primary Eye Care (1 decks)

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