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Optics Block 7 > Accommodation And Presbyopia II > Flashcards

Accommodation And Presbyopia II Flashcards

1
Q

A -2.00D myope is overminued. She wears a -4.00D spec correction. If she has an 8D Amp of accommodation, what is the location of her near point when wearing her glasses?

A

16cm in front of her eyes

She is a +2.00D with her glasses. Take that away from the 6D amp of accommodation and you get 6. Inverse that and you get 16cm in front of her eyes

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2
Q

You measure the Rx. Of a 5 year old in an autorefractor. Your ret showed +1.ooD. The autorefractor show -3.00D. Which form of accommodation might account for the different results

A

Proximal accommodation

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3
Q

Your 45 year old patient says he has no problems with either reading or distance. You measure the spec Rx as:
OD: -1.00 -0.25 +180. +1.00
OS: +0.25 -0.50x170. +1.00

A

Objective presbyopia

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4
Q

Which is the most correct theory of the method for accommodation

A

Ciliary muscle contraction cause relaxation of the lens zonules

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5
Q

What does accommodation do

A

Causes zonules to relax. The lens balls up, increases space between ciliary body and lens

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6
Q

Lens capsule with age

A

Becomes less pliant

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7
Q

What does the lens capsule becoming less compliant have to do with accommodation

A

Causes progressive decrease in accommodative capacity

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8
Q

What could defeat efforts to produce an accommodative IOL placed inside the lens capsule

A

The lens capsule becoming more pliant with age

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9
Q

Shrinkage. Fibrotic tissue condenses and shrinks together and forms small hole

A

Phimosis

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10
Q

Primary factors leading to presbyopia

A
  1. The modulus of the elasticity of th elens capsule decreases with age
  2. The modulus of the elasticity of the lens substance increases slightly
  3. The lens size/volume increases progressively with age
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11
Q

Why does the modulus od the elasticity of the lens capsule decrease with age

A

It becomes progressively less stiff and mroe compliant

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12
Q

Why does the modulus of the elasticity of the lens substance increase slightly with age

A
  • the lens substance becomes stiffer, more plastic, and more sclerotic-like with age
  • thus the energy required to deform the lens substance itself increases with age, with this energy being proportional to the modulus of elasticity
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13
Q

What factor contributes to 44% of the loss of accommodation

A

The modulus of the elasticity of the lens substance increases slightly

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14
Q

The lens size/volume increases progressively with age and presbyopia

A
  • this makes the lens capsule function less effectively
  • it is more difficult to deform a larger body than to deform a smaller body, especially with a concomitant change in shape
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15
Q

What factor contributes to 55% of the loss of accommodation

A

The lens size/volume increases progressively with age

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16
Q

What are the two main factors that cause presbyopia

A

The size increases and becomes stiffer (lens)

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17
Q

What is presbyopia not caused by

A

Zonular elasticity
Ciliary muscle power
Control pathways and structures

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18
Q

Zonular elasticity and age

A

Remains constant

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19
Q

Ciliary muscle power and age

A

Increases from youth to 45

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20
Q

Control pathways and structures of the eye throughout presbyopia

A

Remain constant

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21
Q

What two structures change and cause presbyopia

A

Lens and lens capsule

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22
Q

When does amp of accommodation start dropping

A

About 50

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23
Q

When is amp amp accommodation about 0

A

75

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24
Q

Mean amp of accommodation

A

18.5-(0.30*age)

25
Q

Minimum amp of accommodation

A

15-(0.25*age)

26
Q

Max amp of accommodation

A

25-(0.40*age)

27
Q

What might be a common add given to a 50 year old patient

A

+1.50D

28
Q

Minimum expected amp for 40-44 years

A

5.00 to 4.00

29
Q

Range of near adds for 40-44

A

+0.75 to +1.00

30
Q

Minimum expected amp for 45-49

A

3.75 to 2.75

31
Q

Range of ad powers for 45-49

A

+1.00 to +1.50

32
Q

Minimum amp of accommodation for 50-54

A

2.50 to 1.50

33
Q

Range of adds powers for 50-54

A

+1.50-+2.00

34
Q

Minimum amp for 55-59

A

1.25 to 0.25

35
Q

Range of add for 55-59

A

+2-+2.50

36
Q

Minimum amp for 60 and over

A

0

37
Q

Range of adds for 60 and over

A

+2.25 to +2.50

38
Q

Disparity between retinal defocus and accommodative mechanism

A

Lag/lead accommodation

39
Q

How can lag/lead accommodation be measured

A

Ret

40
Q

What can lag/lead accommodation reveal problems with

A

Accommodation

41
Q

Lead accommodation

A

Looking in front of the ret

42
Q

Lag accommodation

A

Looking behind the ret

43
Q

What are some accommodation problems that will cause lead/lag accommodation

A

Presbyopia, accommodative insufficiency

Accommodative spasm

44
Q

Focusing so much on something in front of you that when you look up at something in the distance, it looks blurry

A

Accommodative spasm

45
Q

What are some things that could cause accommodative spasm

A

Latent hyperopia

Pseudomyopia

46
Q

When refracting someone with accommodative spasm, what is something you might have to do

A

Fogging repeatedly, cyclo, or sudden unfogging (-/+2.00Ds trial lens

47
Q

How fast someone can look between a -2.00 and a +2.00 at a neat object and tell you that is it “clear”

A

Accommodative facility

48
Q

Number of complete cycles in 60 seconds of going between -2 and +2

A

Accommodative facility

49
Q

What is a normal accommodative facility in adults

A

12cpm

50
Q

Is acommodative facility better monocularly or binocularly

A

Monocular

51
Q

What is a persons accommodation when there is a -2.00 40cm in front of them

A

-4.50

52
Q

What is a persons accommodation when there’s s a +2.00 40cm in front of them

A

0.5D

53
Q

Accommodation of an emmetropes is approximately equal to

A

The stimulus to accommodate

If something is 40cm away, it will take 2.5D to accommodate

54
Q

What can reduce stimulus in emmetrope accommodation

A

Depth of field

55
Q

What could provide stimulus to over and under accommodate in emmetropes

A

Aberrations

56
Q

______ need to accommodate less

A

Myope

57
Q

_______ need to accommodate more

A

Hyperope

58
Q

Accommodation with CL

A

Same as emmetropic

59
Q

Accommodation with glasses

A

Use vertex distance of glasses to calculate accommodative demand at the cornea

Optics Block 7 (6 decks)

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