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methods BLOCK 2 > Incidence and distribution of refractive anomolies > Flashcards

Incidence and distribution of refractive anomolies Flashcards

1
Q

refractive error at birth

A

-skews towards hyperopia

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2
Q

What is the percentage of newborsn with myopia?

A

0-25%

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3
Q

why do infants shift towards emmetropia as they grow?

A
  • due to eye growth
  • skew towards myopia
  • mostly within 1st year of life
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4
Q

emmetropization

A

the process in which refractive error shifts towards emmetropia

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5
Q

When does ocular development slow?

A

Ages 5-15

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6
Q

How much does the anterior chamber depth increase by?

A

0.10 to 0.20mm, slows by Aggies 5-15

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7
Q

How much does the vitreous chamber depth increase by?

A
  • 1mm
  • about 3D change for every 1mm
  • slows by ages 5-15
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8
Q

How much does the axial length increase by?

A
  • 1mm
  • about 3D change
  • slows by ages 5 to 15
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9
Q

What happens to the cornea throughout growth

A

Pretty much stable

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10
Q

What does the lens power do throughout growth?

A
  • decreases by 2D
  • lens thins but still grows new fibers
  • slows by ages 5 to 15
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11
Q

What does hyperopia do with ocular growth?

A
  • decrease about 1D

- slows by ages 5-15

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12
Q

When does emmetropization occur?

A

Age 5-15

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13
Q

Prevalence of myopia increases by how much during emmetropization

A

Increases by over 7 times to 15%

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14
Q

Juvenile-onset myopia increase

A
  • About -0.50D per year during early teens

- from reduced ability of lens to compensate for the growth in axial length

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15
Q

When does myopia progression stop?

A

Around 14.6-15.3 years for females
Around 15-16.7 for males
-from eye not growing beyond age 13-14

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16
Q

Adult onset myopia

A

10% of population is myopic after teen years

-total myopic prevalence in adult population is about 25%

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17
Q

Both hyperopia and axial length increase…

A

Slow down at 5

Stops at 13-14

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18
Q

Factors that affect refractive error distribution

A
  • age
  • gender
  • ethnicity
  • geography
  • diet
  • time
  • personality
  • systemic conditions
  • ocular diseases
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19
Q

What is the single most important determinant of distribution of refractive error in a given group?

A

Age

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20
Q

infants with myopia at birth

A

Very small portion

  • neonatal myopia associated with prematurity
  • astigmatism 1.00D cyl
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21
Q

When is low to moderate myopia first observed and progresses?

A
  • age 6-8

- astigmatism decreases, ATR shift (from decrease in WTR corneal toricity> ATR lenticular toricity

22
Q

Juvenile-onset myopia progression and cessation

A
  • progression is 0.40D
  • Cessation at age 14-15 females and 15-16 males
  • lens can’t compensate for growing eye
23
Q

About when does refractive error become stable?

A

High school

24
Q

Adult onset of myopia and progression of pre-existing myopia

A
  • prevalence is 25%

- decrease in prevalence of myopia in older age

25
Gender
-inconclusive
26
Ethnicity
- not enough data - prevalence of myopia in Caucasian group twice as much as African American group - across all groups: myopia develops primarily from excessive axial length - different ocular component profiles for groups with low prevalence of myopia vs groups with high prevalence of myopia
27
Geography
- study results are confounded by other factors (diet, education) - similar trends found in US ethnicity studies
28
Diet
- unclear - ethical dilemma to alter nutritional needs of children - Eskimos showed no difference in eating a regional diet vs 1 American meal per day
29
Time
- inconclusive | - overall trend: decrease in prevalence of myopia with increasing age in elderly range
30
Personality
-no strong data
31
What is myopia associated with (personality-wise)
- introversion - inhibited disposition - disinclination for motor activity and social leadership
32
What is hyperopia associated with (personality-wise)
- carefree - impulsive - hyperactive - socially passive
33
Systemic conditions
- homocystinuria | - diabetes
34
Homocystinuria and refractive error distributions
- metabolism issue with the excretion of homocysteine in the urine and excesses of homocysteine and methionine in the blood - fair hair and skin - mental retardation - Lens dislocation - myopia - light iridies - hypotony (not enough eye pressure) - retinal elevation - cataract
35
Diabetes and refractive error distributions
-higher prevalence of myopia | -
36
Ocular diseases and refractive error distributions
- majority are associated with myopia - clear visual input needed for normal emmetropization to occur and some diseases obscure clear vision - congenital cataracts - posterior polar and nuclear cataracts - congenital ptosis ( astir increases after surgical correction) - retrolental fibroplasia - corneal opacification - vitreous hemorrhage - hemangioma (astir and myopia) - Phylctenular keratitis (alters corneal curvature)
37
Ocular diseases associated with hyperopia
- involves fovea like development - albinism (OCULAR!, systemic is myopic) - maculopathies - rod monochromacy (color defect)
38
Hereditary conditions associated with myopia
- achromatopsia - nystagmus - microcornea - keratoconus - Fabry's disease (corneal and lenticular accumulation of glycosphingolipid) - microphakia - ectopia lentis - coloboma - choroideremia - Gyrate atrophy - fundus flavimaculatus - retinitis pigmentosa - progressive bifocal chorioretinal atrophy - extensive myelination of the nerve fibers - Wagner's disease (membranous vitreous, arteriolar sheathing, choroidal sclerosis, cataract) - vitreoretinopathy - familial external ophthalmoplegia
39
Hereditary conditions associated with hyperopia
- Achromatopsia - Nystagmus - microphthalmia
40
Glaucoma and refractive error
-connected with myopia
41
Near-work theory of myopia
- prolonged reading (accommodation) increases IOP, driving the expansion of the eye by mechanical force - related to glaucoma
42
Associated conditions with glaucoma and myopia
- genetics link- high prevalence of positive steroid response among myopia and glaucoma patients - risk of OHTN appears to be higher in myopia than in emmetropes - risk of open angle glaucoma and conversions of OHTN to glaucoma is higher in myopes than in emmetropes
43
ATR astigmatism and refractive error distribution
- pellucid marginal degeneration | - thins the inferior cornea and flattens the vertical corneal meridians
44
Based on consistent study results, these factors have a known affect on refractive error distributions
- age - systemic conditions - ocular diseases
45
These factors are found to be inconclusive on having a known refractive error association
- gender - ethnicity - geography - diet - time - personality
46
Heredity and refractive error
- modes of inheritance: vary by study | - higher hertibilites in axial length and corneal power
47
Studies of twins show high heritability in:
- axial length - corneal power - refractive error
48
Near Work Theory
- Excessive reading during childhood causes abnormal eye growth , leading to myopia - increase in myopia prevalence in first school-educated Eskimos - decrease in myopia prevalence during WWII in Japan - adult onset myopia in college populations - excessive axial elongation and myopia is linked to schooling, studying, reading, and other near work
49
Intelligence
- myopes trend to have higher scores on tests of intelligence and cognitive ability and get better grades than other refractive error groups (even after factoring age trends) - hyperopes tend to show poorer reading skills and other perceptual anomalies more frequently
50
Socioeconomic status
- myopes tend to be over represented among the higher socioeconomic strata and underrepresented among the lower income levels - possibly due to connection between myopia, intelligence and education
51
What percentage of adults are myopic?
25%
52
Factors associated with refractive error
- hereditary - near work - intelligence - socioeconomic

methods BLOCK 2 (8 decks)

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