Development Of The Ametropias Flashcards
First month of life refractive error distribution range
-10D to +5D
Mean refractive error in the first month of life
-0.70D
ATR in the first few years of life
Decrease
What are premature infants more likely to have?
Higher degrees of myopia
-especially with very low birth weights
What kind of refractive error change between ages 6/7 to 11/12?
Linear
How much hyperopia will a 5/6 y/o have to still be hyperopia at age 13/14?
+1.50D
Majority of 5/6 year olds with refractive error of _______ to _______ will be emmetropic at age 13/14.
+1.50D
Most children entering school with refractive errors of _____ to ____ will be myopic at age 13/14
0 to +0.49D
Children who are myopic at age 5/6 will become…
More myopic
Among school aged children, what refractive error had the greatest change?
Myopes
When is refractive change fastest for school aged children?
When a child crosses from hyperopia into myopia
What are the 4 types of myopia?
- congenital
- youth onset
- early adult onset
- late adult onset
What is the most common type of myopia?
Youth onset
Youth onset myopia
- 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
Mean age of cessation of childhood myopia?
- 15.21 for females
- 16.66 for males
Once myopia appears in childhood, it increases until
Middle to late teens
What is responsible for myopia progression in childhood myopia?
Axial elongation
Refractive power decrease
Refractive power decrease in childhood myopia from…
Decrease in crystalline lens power and decrease in corneal power (hyperopia)
Axial length increases in childhood
Associated with normal growth of the eye in emetropic and hyperopic children, stops in early teens
Emmetropic children between 6 and 14 years old show:
- increase in axial length
- decrease in crystalline lens thickness
- decrease in crystalline power
Myopic vs emmetropic young adults
- greater vitreous depth
- greater corneal power
- greater posterior crystalline lens radius
School aged and young adult females vs males
- shorter eyes
- store corneas
- more powerful crystalline lens
The earlier in life the onset of myopia occurs
The greater the amount of myopia developed by late teens to early adulthood
Higher rate of childhood myopia progression is associated with
Earlier onset of myopia