Kinzer Flashcards
Refractive error at birth
- normal bell curve distribution
- skew towards hyperopia
- Myopia:0-25% in newborns
As infant grows…
- shift towards emmetropia
- due to growth of eye
- skew towards myopia
- within first year of life
Emmetropization
-process in which refractive errors shift towards emmetropia
Ocular development between 5-15
- development SLOWS
- anterior chamber depth INCREASES (3D)
- Vitreous chamber depth INCREASES(3D)
- Axial length INCREASES(3D)
- cornea is stable
- Lens power DECREASES 1-2D
Prevalence of myopia percentages
- 2% ages 7-8
- 15% at age 15
- total myopic prevalence: 25%
Juvenile-onset myopia
- 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
Adult-onset myopia
-10% of population is moyopic after teens
Age
- 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
High school
-refractive error stable
Beaver-dam study
- decreases in prevalence of myopia in older age
- 40-80 see decrease
Gender
-trends in refractive error are inconclusive
Ethnicity
- not enough data to determine id there is a trend in refractive error
- other studies: asian>white>black
NHANES study
- compared white to black
- whites were 2 times more prevalent
Orinda longitudinal study
- kids 5-12
- different ocular components for groups with high prevalence and groups with low prevalence
Geography
- results are messed with from other factors
- similar trends found in US ethnicity studies
Diet
- results are unclear
- cannot ethically take things out of a kids diet
- Alaskan eskimos local food vs government= no conclusions
Time
- 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
Myopia personality
- not strong data
- introversion
- no social leadership or activity
Hyperopia personality
- not strong data
- carefree
- impulsive
- hyperactive
Systemic/ocular conditions
-both effect development of the eye, so there will be an effect on refractive error
Hyperopic occular diseases
- albinism(ocular form)
- maculopathies
- rod monochromacy
- achromatopsia
- nystagmus
- microphthalmis(small eye)
Glaucoma Near work theory
prolonged reading=muscle contraction=increased eye pressure=elongate eye=myopia
Glaucoma Associated conditions theory
- 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
Against the rule astigmatism
- myopia
- pellucid marginal degeneration
- thins inferior cornea and flattens vertical corneal meridian
Factors that for sure have an effect on refractive error
- age
- ocular diseases
- systemic diseases
Factors that are inconclusive
- gender
- ethnicity
- geography
- time
- personality
- diet
Name the 4 factors associated with refractive error
- hereditary
- Near work Theory
- intelligence
- socioeconomic status
Hereditary factor
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
Near work theory factor
- 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
Intelligence factor
- myopes have higher scores on tests of intelligence
- compared tests for same age group
- hyperopes read worse and perceptual anomalies are more frequent