Lecture Three

Question 1

Describe the eye movements that an infant can make.

Answer 1

Can show optokinetic nystagmus within 5 days
Bring an object into the fovea at 2 weeks
Begin to make pursuit eye movements at 8-10 weeks
Make saccades to where the lights going to be at 3 months

Question 2

What is an infants visual acuity like.

Answer 2

Snellen acuity is 20/800 at birth
Fixed focus at 20cm
Acuity improves rapidily over the first few months.

Question 3

How good is an infants contrast sensitivity?

And how is poor visual acuity shown?

Answer 3

Performance rapidly improves over the first 3 months and poor visual acuity is shown by high frequency cut off.

Question 4

What color can infants discriminate at one week of age?

Answer 4

Can discriminate red and green.

Question 5

At what age do infants prefer to look at facial features?

Answer 5

2 months

Question 6

At what age can infants discriminate their mothers face?

Answer 6

1 month

Question 7

At what age do infants notice changes in hairline?

Answer 7

10-12 weeks.

Question 8

What did Fantz show that newborns and 4 months like to look at?

Answer 8

newborns didnt show normal face preference.

Infants looked longer at normal looking face.

Question 9

Some kittens were raised in drums.
How long does exposure have to last to bias the receptive fields?
At what age does deprivation have no effect
And what does reverse switching show?

Answer 9

Exposure for merely an hour was sufficient to bias the receptive fields.
In a cat deprivation has no effect after 6 months of age but longer in monkeys and humans.
Reverse switching shows that the cells switch preference and do not just show atrophy.

Question 10

What is Amblyopia?

Answer 10

‘lazy eye’
reduced visual acuity in an otherwise normal eye
onset is before age 6
associated with history of abnormal binocular visual experience.

Question 11

What is amblyopia generally accompanied by?

Answer 11

• Starabismus
• Anisometropia
• Astigmatism
• Form deprivation

Question 12

What is astigmatic amblyopia?

Answer 12

Asymmetrical optics leads to some orientations being blurred.
If optical asitgmatism is uncorrected in childhood then astigmatic amblyopia results.
Amblyopia is a non-correctable visual loss.

Question 13

What does strabisumus refer to ?

Answer 13

refers to an eye turn. 
Results in loss of binocularity 
one eye is often surpressed 
corrected by surgery
affects about 3% of adults.

Question 14

What is Anisometropic Amblyopia?

What is it usually seen with?

Answer 14

Its where one is in focus (emmetropic) but the other is out of focus (hyperopic)
Usually seen with hyperopic anisometropia

Question 15

What are the different treatments for the various problems?

Answer 15

Corrective surgergy for squint
Surgery for cataract
Optical correction for astigmatism
Occlusion therapy for anisometropia

Question 16

What is the oblique effect?

Answer 16

We are less sensitive to oblique lines than verticals and horizontals