3. Normal Development of Binocular VIsion

Question 1

at 1 months, infants appear to have what kind of eye position? why?

Answer 1

slight intermittent exotropic or ortho

due to a large angle kappa (8 to 10 deg)

Question 2

at what age do infants have a shift to ortho?

Answer 2

around 3 months

Question 3

at what age does convergence become accurate and consistent in infants?

Answer 3

3-4 months

Question 4

at 1 month of age, how developed is convergence in infants?

Answer 4

convergence is absent or partial/intermittent but accommodative convergence is present

Question 5

What does Held propose that accurate convergence is due to?

Answer 5

due to the development of ocular dominance columns and cortical disparity control mechanisms

Question 6

at what age do kittens develop adult levels of depth perception and steropsis

Answer 6

6 weeks

Question 7

in human infants, what is the age of onset of stereopsis

Answer 7

3 months

Question 8

when does the switch occur for infants to prefer a fusible stimuli over a non-fusible pattern

Answer 8

3 months and 1 week

Question 9

where does Held propose that stereo and binocular fusion dvelop?

Answer 9

both develop due to ocular dominance columns and binocularity mechanisms in the visual cortex

Question 10

how does monocular visual resolution acuity develop in infants? binocular?

Answer 10

monocular: acuity levels off around 6 months of age then begins to improve agian
binocular: tends to just go straight up so that at alittle after 3 months, binocular acuity is better than monocular

Question 11

when does binocular pupil summation occur in infants?

Answer 11

6 months of age, the response goes up to adult levels

Question 12

what allows for binocular summation of constriction?

Answer 12

binocular fibers from the cortex develop connections in the pretectum, adding cortical input to the system

Question 13

pupil constriction is largely….

a. cortical
b. subcortical ?

Answer 13

b. subcortical

Question 14

when is the onset of symmetric monocular optokinetic nystagmus?

Answer 14

around 3 months of age

Question 15

how do children w/ an unilateral esotropia vs alternate esotropia develop amblyopia?

Answer 15

unilateral=steady increase in the development of amblyopia

alternators=no amblopyia

Question 16

what is Vernier acuity aka hyperacuity?

Answer 16

the ability to align things in space (positional sense)

Question 17

How do Vernier acuity and VA compare at 11 weeks, 14 weeks, and 22 weeks?

Answer 17

11 weeks: vernier acuity much lower than VA
14 weeks: equal
22 weeks: vernier acuity much better than VA

Question 18

when does the second phase of development occur for vernier acuity to improve again? when does it stop?

Answer 18

4 or 5 yrs old until 10-12 years when vernier is 5x better than grating acuity

Question 19

what is the last change in visual development

Answer 19

crowding