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methods BLOCK 2 > Development Of The Ametropias > Flashcards

Development Of The Ametropias Flashcards

1
Q

First month of life refractive error distribution range

A

-10D to +5D

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2
Q

Mean refractive error in the first month of life

A

-0.70D

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3
Q

ATR in the first few years of life

A

Decrease

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4
Q

What are premature infants more likely to have?

A

Higher degrees of myopia

-especially with very low birth weights

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5
Q

What kind of refractive error change between ages 6/7 to 11/12?

A

Linear

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6
Q

How much hyperopia will a 5/6 y/o have to still be hyperopia at age 13/14?

A

+1.50D

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7
Q

Majority of 5/6 year olds with refractive error of _______ to _______ will be emmetropic at age 13/14.

A

+1.50D

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8
Q

Most children entering school with refractive errors of _____ to ____ will be myopic at age 13/14

A

0 to +0.49D

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9
Q

Children who are myopic at age 5/6 will become…

A

More myopic

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10
Q

Among school aged children, what refractive error had the greatest change?

A

Myopes

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11
Q

When is refractive change fastest for school aged children?

A

When a child crosses from hyperopia into myopia

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12
Q

What are the 4 types of myopia?

A
  • congenital
  • youth onset
  • early adult onset
  • late adult onset
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13
Q

What is the most common type of myopia?

A

Youth onset

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14
Q

Youth onset myopia

A
  • school age years
  • most common type of myopia
  • prevalence at 5 or 6 years of age: 2%
  • prevalence at 15 or 16 years of age: 20-25%
  • onset for females about 2 years earlier than males
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15
Q

Mean age of cessation of childhood myopia?

A
  • 15.21 for females

- 16.66 for males

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16
Q

Once myopia appears in childhood, it increases until

A

Middle to late teens

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17
Q

What is responsible for myopia progression in childhood myopia?

A

Axial elongation

Refractive power decrease

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18
Q

Refractive power decrease in childhood myopia from…

A

Decrease in crystalline lens power and decrease in corneal power (hyperopia)

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19
Q

Axial length increases in childhood

A

Associated with normal growth of the eye in emetropic and hyperopic children, stops in early teens

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20
Q

Emmetropic children between 6 and 14 years old show:

A
  • increase in axial length
  • decrease in crystalline lens thickness
  • decrease in crystalline power
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21
Q

Myopic vs emmetropic young adults

A
  • greater vitreous depth
  • greater corneal power
  • greater posterior crystalline lens radius
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22
Q

School aged and young adult females vs males

A
  • shorter eyes
  • store corneas
  • more powerful crystalline lens
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23
Q

The earlier in life the onset of myopia occurs

A

The greater the amount of myopia developed by late teens to early adulthood

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24
Q

Higher rate of childhood myopia progression is associated with

A

Earlier onset of myopia

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25
Q

Myopes vs nonmyopes

A
  • spend more time reading and doing other forms of near work
  • have occupations that require near work
  • have better reading abilities
  • have more years of education
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26
Q

Shorter reading distance associated with

A
  • greater myopia progression

- the closer they read, the more myopia

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27
Q

Children with ATR at 5/6y develop myopia by age

A

13/14y vs those without astigmatism or WTR

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28
Q

Once myopic, ATR astigmats…

A

Do not have greater rates of childhood myopia progression

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29
Q

Associated with higher rates of childhood myopia progression

A
  • earlier onset age and/or higher initial amount of myopia
  • near-point esophoria
  • temporal crescents and other myopic fundus changes
  • higher IOP
  • greater amount of time spent reading and doing near work
  • less time spent on outdoor activities
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30
Q

Slowing of myopia with pharmaceuticals: Atropine

A
  • daily
  • effects the development of retinal ganglion cells
  • unpopular bc
    • completel cycloplegia
    • photophobia from dilation
    • possible allergic reaction
  • myopia progression accelerates upon stopping treatment
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31
Q

Myopia control with pharmaceuticals: Pirenzepine

A

-similar to atropine

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32
Q

Myopia control with rigid lenses

A
  • flattens cornea (while axial elongation continues)

- eye becomes more hyperopic

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33
Q

Myopes

A

+0.03D

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34
Q

Myopes

A

-0.42D

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35
Q

Effectiveness of RGP CLs

A

Effective in myopia control but only while CLs wear continued

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36
Q

Myopia control with bifocal lenses

A
  • these lenses provide different refractive correction for distance and near
  • can also be used for certain accommodation and vergence disorders
  • rate of myopia progression lower than in single vision lens
  • most effective in lower myopia progresssion rates for children with esophoria at near
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37
Q

What do bifocals best correct for children

A

Most effective in lowering myopia progression rates in children with esophoria at near
-want a near addition power to shift near phoria orthodox/low exo range

38
Q

Myopia control with PALs

A
  • same trend found as in bifocal specs

- rates of myopia progression about 0.2D less per year with PALs than with single vision lenses in esophoria

39
Q

During school age years, astigmatism tends to…

A

Increase a small amount

40
Q

In school age children, what kind of changes do you see in astigmatism?

A

Changes towards ATR more common than WTR

41
Q

5/6 year olds more likely to become myopic with what type of astigmatism?

A

ATR

42
Q

General trends for young adult hood

A
  • refractive error stabilizes
  • some onset of myopia
  • some progression of myopia
  • some have small shift in the hyperopic direction
43
Q

Mean annual changes for 20-34 year olds

A

-0.05D/year

44
Q

Mean annual changes in 35-43 year olds

A

+0.03D per year

45
Q

Earaly adult onset myopia

A

20-40 years old

  • based on physical maturity
  • prevalence of myopia > 0.50D increased from about 20% at 20 years old to 30% at 40 years old
46
Q

What can progress in young adulthood?

A

Youth onset myopia and early adult-onset myopia

-rate of early adult onset myopia progression

47
Q

Adult stabilization

A

Childhood myopia progression is followed by stabilization of refractive error in young adulthood

48
Q

Adult continuation

A

Childhood myopia progression followed by a general slower progression of myopia in young adulthood

49
Q

Adult acceleration

A

Refractive change in the myopic direction accelerates in young adulthood

50
Q

What is the percentage of emmetropes that will develop myopia before age 40 in populations where subjects are not in college?

A

10%

51
Q

What percentage of emmetropes and low hyperopes are likely to become myopic before age 40 in populations where they go to college/military?

A

20-40%

52
Q

In young adults, shift towards myopia by emmetropes and low hyperopes vs myopes

A
  • less common

- lower in amount

53
Q

College student with >+1.00D after 4 years of school?

A

Unlikely in either principal meridian to be myopic after 4 years
-if hyperopic, shift not so much in myopic progression

54
Q

17/18y old low hyperopes vs older low hyperopes

A

More likely to become myopic in heavy near work situations

55
Q

What kind of astigmatism is there a shift towards in young adulthood?

A

WTR

56
Q

When does increase in plume occur to, and when does decrease

A

Increases in plus from 40 to mid 60, then decreases

57
Q

Mean refractive error at 40 years old

A

+0.73D

58
Q

Mean refractive error at 64 years old

A

+1.97D

59
Q

Mean yearly rate change for ages 40 on

A

+.50D per year

60
Q

Mean refractive error at 65 years old

A

+1.72D

61
Q

Mean refractive error at 74 years old

A

+1.21 D

62
Q

After age 45

A
  • shift in hyperopic directions
  • some myopes increase in myopia
  • age related nuclear cataract causes shift towards myopia
63
Q

Age related nuclear cataract

A
  • after age 45
  • shift towards myopia
  • May be able to read better at first when they first start
64
Q

Astigmatism trend in age 40 and on

A
  • shift towards ATR

- mean change is 0.25DC per decade

65
Q

Shift towards ATR ages 40-44

A

+0.27DC

66
Q

Shift towards ATR over 80

A

-0.81DC

67
Q

Prevalence of >0.25DC WTR 40-44

A

29%

68
Q

Prevalence of > 0.25 WTR over 80

A

6.8%

69
Q

Prevalence of > 0.25 DC ATR 40-44

A

9.5%

70
Q

Prevalence of >0.25 DC ATR over 80

A

65.1%

71
Q

Emmetropization

A
  • the process to explain why there are more people with emmetropia and near emmetropia
  • peak of refractive error distributions occurs at emmetropia and low hyperopia
  • accounts for coordinated eye growth and some form of vision-dependent feedback system for ocular refractive development
72
Q

If changes in ocular components occurred separately

A

Large changes in refractive error

73
Q

If changes in ocular optical components occurred together

A

Less changes in refractive error

74
Q

Emmetropization during childhood

A
  • vitreous depth increases – myopia
  • crystalline lens power and thickness decreases (hyperopia; posterior surface mostly involved with emmetropization)
  • anterior chamber depth increases
75
Q

Vision dependent feedback system

A

-axial length changes based on visual input

76
Q

Axial length change based on visual input

A

Large refractive error occur when the eye does not have a normal ocular imagery

77
Q

Axial length greater in

A
  • neonatal eyelid closure
  • juvenile corneal opacification
  • congenital cataracts
78
Q

High myopia can be caused by

A
  • lid hemangiomas
  • ptosis
  • neonatal eyelid closure
  • retrolental fibroplasia associated with retinopathy of prematurity
  • vitreous hemorrhage in infants and children
79
Q

What aids in emmetropization process and reduces amblyopia?

A

Treatment of spectacle correction

80
Q

Amblyopia

A

Brain does not allow eye to see 20/40

81
Q

Etiology

A

Unknown

82
Q

Genetic inheritance

A
  • some studies show that genetic inheritance and lifestyle and environment contribute to myopia
  • other studies show that genetic inheritance is not a factor
83
Q

Near work

A

-sustained accommodation increases IOP which leads to stretching of the posterior segment of the eye which leads to axial elongation

84
Q

Mechanical forces on the sclera

A

Tension from extrocular muscles and IOP cause axial elongation

85
Q

Retinal refocus

A

Defocus itself alters axial length (not the mechanism of accommodation)

86
Q

Retinal biochemstry

A
  • biochemical agents affect the function of retinal synapses

- some studies show that this stops myopia, others show that these molecules induce myopia

87
Q

Etiology of astigmatism

A
  • unknown
  • eyelid tension theory
  • high prevalence
88
Q

Etiology of astigmatism eyelid tension

A

Eyelid tension steepens the vertical cornea meridian and causes WTR

89
Q

What happens when the eyelids are lifted from the eye?

A

Corneal WTR astigmatism decreases

90
Q

What happens when palpebral aperture is narrowed?

A

Corneal WTR astigmatism increases

91
Q

What is the shift towards ATR in over 40 years of age due to?

A

Decreased lid tension

methods BLOCK 2 (8 decks)

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