Accommodation And Presbyopia Flashcards

1
Q

You have a -2.oo D myopic patient that has an accommodative amplitude of 8 D. What is their near point?

A

2+8=10
1/10=0.1m
10cm

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2
Q

Your emmetropic patient wants to read their computer monitor at 0.8m. What us the minimum accommodation necessary to see the monitor clearly. Assume +-0.25D depth of focus

A

4/5=5/4=1.25D

1.25-0.25=1.00D

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3
Q

You have a +2.00D uncorrected hyperope with an accommodative amplitude of 6D. What is a comfortable close distance for them for long periods of time (1/2 their AA)

A

+2.00 hyperopia
6D AA (3 for comfort)
3-2=1D left
1m

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4
Q

Normal aging process of the eye

A

Presbyopia

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5
Q

The age related continuous but gradual loss of accommodation

A

Presbyopia

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6
Q

The function whereby the converging power of the optical. System of the eye is increaes so that light diverging from a near source may be brought to a focus upon the retina

A

Accommodation

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7
Q

A process whereby the young eye is able to change the point of focus from a distance object to a near object

A

Accommodation

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8
Q

Other terms for presbyopia

A
  • normal decreasing elasticity of the crystalline lens that leads to loss of accommodation
  • accommodation insufficiency
  • accommodative insufficiency
  • presbyopia
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9
Q

Who is at risk for presbyopia

A

Anyone over the age of 35

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10
Q

Signs and symptoms of presbyopia

A
  • hard time reading small print
  • having to hold things at arms distance
  • problems seeing objects that are close to you
  • headaches
  • eye strain
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11
Q

Needing optical correcting to the best distance correction to achieve an acceptable near VA (add on top of distance vision)

A

Objective hyperopia

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12
Q

Needing optical correction to the presenting distance correction to achieve acceptable near VA

A

Functional presbyopia

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13
Q

How many people world wide have presbyopia

A

1 billion

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14
Q

How many people lack adequate presbyopia correction

A

Half

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15
Q

What is the projected number of presbyopes in 2020

A

1.37 bil;lion

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16
Q

Symptom of presbyopia

A
  • ocular discomfort with sustained near work
  • drowsiness during near work
  • holding stuff further away
  • asthenopia related to excessive accommodative efforts
  • transient diplopia or esophoria
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17
Q

What is the most recent theory of accommodation that says that the ciliary muscle relaxes and zonular fibers at ‘resting’ tension cause lens to contract and increase dioptric power?

A

Herman von helmholtz

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18
Q

What are some debunked theories of accommodation

A
  • accommodation causes increase in zonular tension
  • no need for active focusing because if the interval of sturm
  • pupil size changes result in accommodation
  • corneal curvature changes
  • shift in lens position
  • change in axial length of the eye
19
Q

What state are the zonules relaxed in

A

Accommodation

20
Q

What state are the zonules tense

A

Relaxed

21
Q

When is there always tension on the zonules

A

When relaxed

22
Q

In what state is the lens under tension at the equator from the ciliary body?

A

Relaxed

23
Q

What does the tension on the lens in the relaxed state do

A

Keeps the surfaces flat so that for an emmetropic eye distant objects focus on the retina

24
Q

In what state is the ciliary muscle constricted and the tension on the equator of the lens is relaxed?

A

Accommodated

25
Q

Surface curvature of the lens in accommodation

A

Increases

26
Q

Power of the lens in accommodation

A

Increases

27
Q

What are the different types of accommodation

A

Reflex
Vergence
Proximal
Tonic

28
Q

What are the two major types of accommodation

A

Reflex and vergence

29
Q

Automatic adjustment of refractive state to obtain and maintain a sharply defined and focused retinal image in response to a blur input.

A

Reflex accommodation

30
Q

How much dioptric power is reflex accommodation

A

Up to 2.00D blur

31
Q

What assists in reflex accommodation

A

Small scanning eye movements, or microsaccades, assist in the process

32
Q

What is the largest and most important component of accommodation under both monocular and binocular viewing conditions

A

Reflex accommodation

33
Q

Induced by the innate neurological linking and action of disparity (fusional) vergence

A

Vergence accommodation

34
Q

What gives rise to the convergence accommodation/convergence (CA/C) ratio?

A

Vergence accommodation

35
Q

What is the second major component of accommodation

A

Vergence accommodation

36
Q

Due to the influence of knowledge of apparent nearness of an object

A

Proximal accommodation

37
Q

Stimulated by targets within 3m of the individual

A

Proximal accommodation

38
Q

When does proximal accommodation become quite large?

A

With near viewing, providing up to 80% of the total near response without other cues

39
Q

What is proximal accommodation stimulated by

A

Perceptual cues

40
Q

Why is it sometimes hard to measure wavefront abberations for LASIK sometimes

A

Because of proximal accommodation

41
Q

Reveled in the absence of blur, disparity, and proximal inputs

A

Tonic accommodation

42
Q

How is tonic accommodation measured

A

By removal of the other three inputs (large dark room)

43
Q

What is the mean tonic accommodative level in young adults

A

About 1D with a range from nearly 0 to 2.00D

44
Q

What kind of accommodation reduces with age

A

Tonic accommodation.