Incidence And Distribution Of Refractive Anomalies

Question 1

At birth, what type of refractive error is most common?

Answer 1

Hyperopia

Question 2

What percentage of newborns are myopic?

Answer 2

Less than 25%, most at hyperopic.

Question 3

As an infant grows, they shift towards:

Answer 3

Emmetropia

Question 4

Why do infants become more Emmetropic as they become older?

Answer 4

Because as they grow taller, their eyes grow as well. Therefore, they become more myopic.

Within first year of life

Question 5

What is emmetopization?

Answer 5

The process in which refractive error shifts towards emmetropia as the child ages

Question 6

What happens between ages 5-15?

Answer 6

Ocular development slows

Anterior chamber depth increases

Vitreous chamber depth increases

Axial length increases

Cornea is stable

Lens power decreases

(Hyperopia decreases)

Question 7

On average, by how much do the eyes change between ages 5-15?

Answer 7

3 D

2 D from lens power

1 D from length of eye

Question 8

Between the ages 5-15, myopia increase by..

Answer 8

Over 7x to 15%

Question 9

Juvenile-onset myopia

Answer 9

Increase about -0.50 D per year during early teen years

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

Question 10

Myopia progression stops around what age?

Answer 10

14. 6-15.3 years old for females

15. 0-16.7 years old for males

Question 11

When does the eye stop growing?

Answer 11

Beyond ages 13-14

Question 12

Adult-onset myopia

Answer 12

10% of population is myopic after teen years

Question 13

Total myopic prevalence in adult population is about

Answer 13

25%

Question 14

Factors that affect refractive error distribution

Answer 14

Age
Gender
Ethnicity
Geography
Diet
Time
Personality
Systemic Conditions
Ocular Diseases

Question 15

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

Answer 15

Age

Question 16

Neonatal myopia

Answer 16

Associated with prematurity

Question 17

Astigmatism from birth to ages 6-8

Answer 17

Have greater than 1 D cyl, but then decreases ages 6-8

Question 18

When will refractive error become stable?

Answer 18

High school ages

Question 19

Refractive error in Gender

Answer 19

Inconclusive.

No significant differences between males and females.

Question 20

Ethnicities and Refractive Errors

Answer 20

Not enough data.

Caucasians have 2x prevalence of myopia than African Americans

Asians are more prevalent than Caucasians

Asians > Caucasians > African Americans

Question 21

Geography and Refractive Error

Answer 21

More so based on ethnicity.

Studies showed that other factors such as diet and education base geography

Alaskans > Austrailians/Europeans > US/Native Americans/Jewish > Nigerian/Black

Question 22

Diet and Refractive Error

Answer 22

Unclear. Difficult to alter nutritional needs of children.

Question 23

Time and Refractive Error

Answer 23

Inconclusive.

Studies done in different decades are difficult to compare with each other.

Overall trend: decrease in prevalence of myopia with increasing age in elderly range

Question 24

Personality and Refractive Error

Answer 24

Myopia is associated with:

• introversion
• inhibited disposition
• disinclination for motor activity and social leadership

Hyperopia is associated with:

• carefree
• impulsive
• hyperactive
• socially positive

NO STRONG DATA

Question 25

Systemic Conditions and Refractive Error

Answer 25

Effects the development of the eye

Albinism (inability to produce melanin)
-associated with myopia and high astigmatism

Down’s Syndrome
-myopic in 1/3 of population

Connective Tissue and Skeletal Disorders are associated with myopia

Homocystinuria
-lens dislocation, myopia, light iridies, hypotony, retinal elevation, cataract

Diabetes
-higher prevalence of myopia

Question 26

Ocular Diseases and Refractive Error

Answer 26

Majority of conditions are associated with myopia

Involves peripheral visual impairment

Conditions associated with hyperopia:
-albinism, maculopathies, Rod monochromacy

Question 27

Glaucoma is connected with..

Answer 27

Myopia

Question 28

Near-Work Theory of Myopia

Answer 28

Prolonged reading increases IOP, driving the expansion of the eye by mechanical force.

Directly related to Glaucoma

Question 29

Against the rule astigmatism

Answer 29

Pellucid Marginal Degeneration

Thins the inferior cornea and flattens the vertical corneal meridian

Question 30

Factors with a known affect on refractive error distribution

Answer 30

Age, Systemic Conditions, and Ocular Diseases

Question 31

With 1 myopic parent,

Answer 31

20-25% chance the child will be myopic

Question 32

With 2 myopic parents,

Answer 32

30-35% chance child will be myopic

Question 33

Inheritance and Refractive Error

Answer 33

Axial length and corneal power seem to be hereditary.

High heritabilities seem prevalent in axial length, corneal power, and refractive power.

Question 34

Near Work Theory and school aged children

Answer 34

Excessive reading causes abnormal eye growth, therefore leading to myopia

Question 35

Studies supporting Near Work Theory:

Answer 35

Increase in myopia prevalence in first school-educated Eskimos.

Decrease in myopia during WW2 in Japan

Adult onset myopia in college populations

Question 36

Intelligence and Refractive Error

Answer 36

Myopes tend to have higher scores on tests of intelligence and cognitive ability

Hyperopes tend to show poorer reading skills

Question 37

Socioeconomic Status and Refractive Error

Answer 37

Myopia tend to be over represented among the higher socioeconomic strata.
-and underrepresented on low income levels.

Possible link between myopia, intelligence, and education.