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Methods Block 2 > Kinzer > Flashcards

Kinzer Flashcards

1
Q

Refractive error at birth

A
  • normal bell curve distribution
  • skew towards hyperopia
  • Myopia:0-25% in newborns
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2
Q

As infant grows…

A
  • shift towards emmetropia
  • due to growth of eye
  • skew towards myopia
  • within first year of life
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3
Q

Emmetropization

A

-process in which refractive errors shift towards emmetropia

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4
Q

Ocular development between 5-15

A
  • development SLOWS
  • anterior chamber depth INCREASES (3D)
  • Vitreous chamber depth INCREASES(3D)
  • Axial length INCREASES(3D)
  • cornea is stable
  • Lens power DECREASES 1-2D
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5
Q

Prevalence of myopia percentages

A
  • 2% ages 7-8
  • 15% at age 15
  • total myopic prevalence: 25%
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6
Q

Juvenile-onset myopia

A
  • increase 0.5D per year in teens
  • reduced ability of lens to compensate for growth in axial length
  • slows 13-14 for Female and 15-16 in Males
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7
Q

Adult-onset myopia

A

-10% of population is moyopic after teens

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8
Q

Age

A
  • single most important determinant of distribution of refractive error
  • small portion of myopes at birth
  • infant myopia: premies
  • astigmatism in infants: most are under 1D cyl
  • ages 6-8-myopia first observed
  • Astigmatism decreases: ATR shift
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9
Q

High school

A

-refractive error stable

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10
Q

Beaver-dam study

A
  • decreases in prevalence of myopia in older age

- 40-80 see decrease

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11
Q

Gender

A

-trends in refractive error are inconclusive

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12
Q

Ethnicity

A
  • not enough data to determine id there is a trend in refractive error
  • other studies: asian>white>black
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13
Q

NHANES study

A
  • compared white to black

- whites were 2 times more prevalent

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14
Q

Orinda longitudinal study

A
  • kids 5-12

- different ocular components for groups with high prevalence and groups with low prevalence

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15
Q

Geography

A
  • results are messed with from other factors

- similar trends found in US ethnicity studies

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16
Q

Diet

A
  • results are unclear
  • cannot ethically take things out of a kids diet
  • Alaskan eskimos local food vs government= no conclusions
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17
Q

Time

A
  • inconclusive for studies that focus on different decades
  • different studies have different methods and differet characteristics of what determines “myopia”
  • over all, decrease prevalence in older age
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18
Q

Myopia personality

A
  • not strong data
  • introversion
  • no social leadership or activity
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19
Q

Hyperopia personality

A
  • not strong data
  • carefree
  • impulsive
  • hyperactive
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20
Q

Systemic/ocular conditions

A

-both effect development of the eye, so there will be an effect on refractive error

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21
Q

Hyperopic occular diseases

A
  • albinism(ocular form)
  • maculopathies
  • rod monochromacy
  • achromatopsia
  • nystagmus
  • microphthalmis(small eye)
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22
Q

Glaucoma Near work theory

A

prolonged reading=muscle contraction=increased eye pressure=elongate eye=myopia

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23
Q

Glaucoma Associated conditions theory

A
  • genetic link: high prevalence for positive steroid responce=glaucoma and myopia
  • risk of ocular hypertension is higher in myopes
  • risk of developing glaucoma is higher in myopes
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24
Q

Against the rule astigmatism

A
  • myopia
  • pellucid marginal degeneration
  • thins inferior cornea and flattens vertical corneal meridian
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25
Q

Factors that for sure have an effect on refractive error

A
  • age
  • ocular diseases
  • systemic diseases
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26
Q

Factors that are inconclusive

A
  • gender
  • ethnicity
  • geography
  • time
  • personality
  • diet
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27
Q

Name the 4 factors associated with refractive error

A
  • hereditary
  • Near work Theory
  • intelligence
  • socioeconomic status
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28
Q

Hereditary factor

A

Parent/child

  • axial length and corneal power
  • 1 parent=0-20% chance
  • 2 parents=30-40% chance

Twins

  • axial length, corneal power, refractive error
  • monozygotic twins are more similar
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29
Q

Near work theory factor

A
  • excessive reading in childhood
  • increase in myopia among educated eskimos
  • decrease in myopia in WWII in Japan
  • adult onset myopia in college

EXCESSIVE AXIAL LENGTH AND MYOPIA IS LINKED TO READING, SCHOOLING, STUDYING, AND NEAR WORK

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30
Q

Intelligence factor

A
  • myopes have higher scores on tests of intelligence
  • compared tests for same age group
  • hyperopes read worse and perceptual anomalies are more frequent
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31
Q

Socioeconomic factor

A
  • two large studies
  • myopes more frequent in HIGH socioeconomic levels
  • connection to intelligence and education
32
Q

First month of life refractive error distribution of refractive error

A

from -10D of myopia to +5D of hyperopia

  • Mean refracted error: -0.7D
  • shift toward emmetropia with age
  • decrease in ATR in first few years
  • higher degree of of myopia in premature babies
33
Q

Change in refraction in school aged years

A
  • see most refractive changes
  • linear change between 7 and 12 years old
  • children who are myopic at age 5 will become MORE myopic
  • children entering school with 0-+0.5D of hyperopia will become myopic
  • children entering school with +0.5-+1,24D will be emmetropic at age 13
  • children entering with +1.50D of hyperopia or more will still be hyperopic
34
Q

Changes in hyperopes Vs myopes in school aged kids

A
  • greatest changes in refractive error occur in myopes

- rate of progression is FASTER when a child crosses FROM hyperopia TO myopia`

35
Q

Four types of myopia

A
  1. congenital:birth
  2. Youth-onset:school aged
  3. Early adult onset (late teens- 40s)
  4. Late adult onset (40 and up)
36
Q

Youth-onset

A
  • most common myopia
  • 5-6 years prevalence: 2%
  • 15-16 year prevalence: 20-25%
  • onset for females is 2 years earlier than males
37
Q

Ocular optical component in progression of myopia in school aged kids

A
  • AXIAL ELONGATION continues into late teens

- increased vitreous chamber is more prevalent than increased anterior chamber depth

38
Q

Ocular optical component in progression of hyperopia in school aged kids

A
  • decrease in refractive power
  • decrease in corneal lens and crystalline lens
  • axial length stops at early teens
  • experience changes, but they are all proportional
39
Q

Myopic in comparison to emmetropes

A
  • greater vitreous depth
  • greater corneal power
  • greater posterior crystalline lens radius
40
Q

Females vs males

A
  • shorter eyes
  • steeper cornea
  • more powerful crystalline lens
41
Q

Factors that affect the rate of childhood myopia

A
  • earlier the onset of myopia occurs, the greater the progression and faster
  • more reading
  • better readers
  • more time inside
  • higher IOP
  • temporal crescents inside the eye
  • near work
42
Q

Why is a shorter reading distance associated with myopia?

A

-shorter distance=more accomodation=more axial length=more myopia

43
Q

Childhood myopia and astigmatism

A
  • children with ATR at 5-6 develop myopia more than kids with WTR
  • once myopic, ATR do not have a greater progression
44
Q

Myopic control

A
  • medication
  • rigid CL
  • biofcals glasses
  • progressive glasses
45
Q

Medication control of myopia

A

Atropine and pirenzepine

  • used in dilation
  • knocks off focusing muscles
  • affects development of retinal ganglion cells
  • complete cyclo
  • distortion from dilation
  • possible allergies
  • once you stop treatment, myopia ACCELERATES
46
Q

Rigid CL myopic control

A
  • flattens cornea(axial elongation continues)
  • increases hyperopia
  • Gas permeable CL are effective, but only when CL wearing is continued
47
Q

Bifocals and progressives

A
  • bifocals have line and progressives have intermediates
  • reading add=less strain=less elongation=less myopia
  • can also be used for vergence and accomodation problems
  • rates of myopic progression are less in bifocals than single vision
  • MOST EFFECTIVE FOR CHILDREN WITH ESOPHORIA AT NEAR. SHIFTS IS TO ORTHO/LOW EXO RANGE (changes postrure)
48
Q

Refractive changes in young adulthood

A
  • refractive errors stabilize
  • some may have an onset of myopia(college)
  • some have very small shift in hyperopic direction
49
Q

Mean annual change in refractive error in young adults

A
  • 20-34: -0.05D a year

- 35-53: +0.03D a year

50
Q

Early Adult onset Myopia

A
  • onset in 20-40 years
  • prevalence for myopia increases from 20% at 20 years old to 30% at 40 years old
  • progression rate is less in early adult than in youth-onset
51
Q

Difference in Youth-onset and Early adult onset

A
  • Youth-onset: before puberty

- Early-adult onset: after puberty

52
Q

3 possibilities of myopia

A
  • adult stabilization
  • adult continuation
  • adult acceleration
53
Q

Adult stabilization

A

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

54
Q

Adult continuation

A

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

55
Q

Adult acceleration

A

-refractive change in the myopic direction accelerates in young adulthood

56
Q

Myopia and corneal power

A
  • adults with increases in myopia tend to have increases in corneal power
  • still a decrease in crystalline lens power
57
Q

Myopia progression and college

A

less than 10% of emmetropes and low hyperopes will develop myopia before age 40 in populations where subjects are not in college

  • 20-40% of emmetropes and low hyperopes are likely to become myopic before age 40 when they go to college or are in the military
  • unlikely for high hyperopes to be myopic even after college
58
Q

overall trend in young adults

A

-emmetropes and low hyperopes shift towards myopia is LESS COMMON AND LESS IN AMOUNT than myopes

59
Q

age different low hyperopes and early adult onset myopia

A

-17-18 year old low hyperopes are more likely to become myopic in near work situations than older low hyperopes

60
Q

Astigmatism in young-adult

A

-overall shift to being WTR

61
Q

Refractive changes from age 40 and up

A
  • trend toward hyperopia
  • refractive error increases in plus from 40-60 then DECREASES from 60 up
  • +1.24D change over 24 years
  • mean yearly rate change: +0.5D
62
Q

Nuclear cataract

A
  • age related nuclear cataracts give a shift to myopia

- some old people will notice they can read better so thats why

63
Q

Astigmatism and Age 40 and up

A

-shift towards ATR

64
Q

Emmetropization considerations

A
  • peak of refractive error distributions occurs at emmetropia and low hyperopia
  • coordinated growth of the eye AND some form of vision-dependent feedback system
65
Q

Changes in ocular optical components

A

Separately: large changes in refractive error
Together: less changes in refractive error

66
Q

Vitreous depth

A

-in childhood: increases which means myopic

67
Q

Anterior chamber depth

A

-increases in children=myopia

68
Q

Crystalline lens

A

power and thickness decrease for hyperopia

-posterior surface mostly involved in emmetropization

69
Q

Vision dependent feeback system

A
  • axial length changes based on vision input
  • large refractive errors occur when eye does not have normal ocular imagery
  • treatment of spectacles aids in emmetropization process and reduces amblyopia
70
Q

High myopia eye things

A
  • lid hemangiomas
  • ptosis
  • neonatal eyelid closure
  • retinopathy of prematurity
71
Q

Theories of myopic development

A
  • etiology unknown
  • genetic inheritance(+some lifestyle and environmental)
  • near work
72
Q

Primary theory for myopia

A
  • near work theory

- accommodation increases IOP and leads to stretching of the posterior segment of the eye and axial longation

73
Q

Mechanical forces on the sclera

A

-tension from extraocular muscles and IOP increase axial elongation

74
Q

Retinal defocus

A
  • defocus itself alters axial length

- not a mechanism of accommodation

75
Q

Retinal biochemistry

A

-some molecules stop myopia and some induce it

76
Q

theories of astigmatism

A
  • eyelid tension steepens the vertical corneal meridian and causes WTR
  • corneal WTR decreases when the eyelid is lifted
  • increases when palpebral aperature is narrowed
  • shift towards ATR in over 40 because decreased lid tension

Methods Block 2 (7 decks)

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