Aetiology of Amblyopia

Question 1

what is the critical period for visual development

Answer 1

7-8 yrs

Question 2

what is the sensitive period

Answer 2

time of deprivation to teen age years

Question 3

why is the brain vulnerable

Answer 3

neural plasticity

Question 4

when is amblyopia thought to start

Answer 4

when baby is binocular (2-4 months)

Question 5

does the age of the px affect the response to treatment

Answer 5

yes - the younger the px the more rapid the improvement

Question 6

why does the age matter in relation to response of treatment

Answer 6

due to the neural plasticity

Question 7

what is the exception of treatment beyond age 8

Answer 7

anisometropic amblyopia or those with no previous treatment

Question 8

what else can amblyopia affect

Question 9

What are the two mechanisms for amblyopia

Answer 9

deprivation of form vision - passive element and abnormal binocular interaction or competition - active/dynamic element

Question 10

what did Hubel and Wiesel (1965) do to test effects of strabismus

Answer 10

on cats - surgically induced or lid suturing to prevent BSV - have an abnormally high proportion of monocular cells at the visual cortex where there should be binocular cells

Question 11

when are children most sensitive to amblyopia

Answer 11

0-3 yrs old

Question 12

when does the sensitivity to amblyopia decrease

Answer 12

until 7yrs old

Question 13

what do the X and Y cells do

Answer 13

send responses to the brain

Question 14

where is our best vision in the eye

Answer 14

fovea

Question 15

what do X cells do

Answer 15

respond to sustained stimulation (stable images, well focused images)

Question 16

where are X cells most dense

Answer 16

fovea

Question 17

what are X cells poor at

Answer 17

spatial resolution and detecting contrast

Question 18

How many layers in the LGB

Answer 18

6 layers

Question 19

does deficit in the LGN have an effect on amblyopia

Answer 19

yes makes it more dense

Question 20

what are ocular dominance columms

Answer 20

columnar arrangement of the cells in the striate cortex

Question 21

how much does 1D affect the response in cells

Answer 21

reduced affect in one cell

Question 22

how many D is a risk factor for child aged 1

Answer 22

3D - would mean they are likely to have this for the rest of their life.

Question 23

is amblyopia a genetic condition?

Answer 23

No but the amblyogenic factors are genetic

Question 24

what is the definition of amblyopia

Answer 24

a reduction in visual acuity secondary to neurological deficits in visual output but abnormal brain stimulation during critical periods of visual development.

Question 25

what is the prevalence of amblyopia

Answer 25

1-5%

Question 26

what is the most common cause of vision loss in infants and young children

Answer 26

amblyopia

Question 27

true of false the prevalence of amblyopia is higher in lower socioeconomic classes

Answer 27

true

Question 28

what are the 7 functional types of amblyopia

Answer 28

stimulus deprivation, strabismic, anisometropic, ametropic, meridional, idiopathic, hysterical/psychogenic

Question 29

what is the type of organic amblyopia

Answer 29

toxic

Question 30

can improvement be expected from functional amblyopia treatment

Answer 30

yes

Question 31

what is organic (toxic) amblyopia

Answer 31

no lesion detectable, can be reversible or irreversible, consider if no response to treatment.