Pediatric Optometry: L3: Vision Development Part 2 Flashcards
1
Q
Development of Visual System
- Complete at Birth?
- Maturation of Visual System is influenced by several Factors. Name 4.
A
- Incomplete at birth.
2. Light Deprivation; Maturing Visual Cortex; Post-Natal Nutrition; Visual Stimulation
2
Q
Factors Affecting Development
- Internal Factors
a. What’s a big one?
b. What does Maturation refer to? - External Factors
a. What a big one?
b. Learning: What does this refer to? - Interaction: What does this refer to?
A
- a. Hereditary or genetic makeup
b. basically to genetically predetermined patterns of growth and how they come about. - a. Environmental Factors (like nutrition)
b. Basically, what is going on in the environment that helps the child pick up and learn specific skills - Relationship b/w Internal and External
3
Q
Development
- Is it a LINEAR FUNCTION?
- MRI Study of Fetuses and children aged 0-13 years shows what?
A
- NO!
2. A Rapid Eyeball Growth Curve IN UTERO and from birth to 18 months.
4
Q
Visual Acuity
- Does VA develop the same with everyone?
- VA development is rapid in the first how many months?
- Months: 0-6, what 2 things develop at the SAME RATE?
- Months 6-11: Which is superior: Binocular Acuity or Monocular Acuity?
- What does taking an accurate VA depend on with the child?
A
- NO! There’s a large individual variation.
- First 6 Months
- Monocular and Binocular develop at the same rate.
- Binocular Acuity is superior to Monocular Acuity
- Attention levels, motor and sensory skills
5
Q
VAs
- OKN:
a. Newborn
b. 2 Months
c. 6 Months
d. 12 Months - Preferential Looking
a. Newborn
b. 2 Months
c. 6 Months
d. 12 Months
e. 18 Months - VEP
a. Newborn
b. 2 Months
c. 6 Months
d. 12 Months - Which test is the ONLY TEST at 6 Months that will GIVE a VA of 20/20?
A
- a. 20/400
b. 20/400
c. 20/100
d. 20/60 - a. 20/400-20/1200
b. 20/150-20/600
c. 20/25-/20/200
d. 20/50-/20/100 (why the variability? The 12 Month old has figured out the test)
e. 20/40/20/100 - a. 20/100
b. 20/80
c. 20/20-20/50
d. 20/20 - VEP!
6
Q
Contrast Sensitivity
- What is it?
- With age, our ability to detect Lower Contrast Levels Increases or Decreases?
- Studies show that Contrast Sensitivity is NOT Adult like still at what ages?
A
- Minimum Contrast needed to detect SINE WAVE GRATING of VARYING SPATIAL FREQUENCIES
- INCREASES
- 7-9 yrs
7
Q
Oculomotor
- Do normal eye movements develop in a visually impaired infant?
- First Symptom of Significant visual impairment?
- All eye movements are dependent on what?
a. Ex?
A
- No.
- Abnormal Eye Movements
- on Infants interest and Attention level.
a. Shown same object multiple times…they lose interest…change target to attract attention.
8
Q
Fixations
- Good or bad before 2-3 months?
- At 3 Months?
A
- BAD
2. Should be fixating new objects
9
Q
Saccades
- What are they?
- Latency?
A
- High Velocity Eye Movement that shifts direction of gaze from 1 spatial location to another
- About 200 ms (more concerned about Voluntary Saccades when looking at the child)
10
Q
Utilization of Saccades
- Voluntary: Purpose?
- Reflexive: Purpose?
- Saccadic Scan Path: Purpose?
A
- Look at Object of Interest
- Direction of event occurs suddenly w/o warning
- Enter room, engaged in social situation, u get a panoramic scene. Lets u get a large amt of info.
11
Q
Saccade Basics
- Large Magnitude: Purpose?
a. Amt of Degrees? - Small Amplitude
a. Use? - Latency?
a. Why this latency?
A
- Everyday circumstances
a. 2-40 degrees - a. Reading, Maintaining Fixation
- 200 ms
a. Time for passage of visual signal to cortex –> Processing –> Flow of Oculomotor Signals to EOMs.
12
Q
- What is the Fastest of Human Behaviors?
A
- Saccades
13
Q
Saccade Basics
- It’s a Ballistic System: What does this refer to?
- Purpose of the Cortex?
- Brainstem does that?
A
- Once activated, it will run until the task is completed (Once u initiate it, you can’t stop it)
- When and where the saccade will be executed.
- Produce shape and motor signals that go to the EOMs
14
Q
Saccadic Mechanism
- Visual Signal goes to Cortex where what happens?
- Cortex sends info to the Brainstem where what happens?
- Brainstem then does what?
A
- Perception of location. Decision making. Attention
- Pulse Generator –> Neural Integrator
- Motor Output
15
Q
Infant Saccades
- 3 Major features?
- Why do these Features occur?
A
- Increased Latency; Initial Saccade performed in the wrong direction (infant is still learning them); Succession of Saccades (may do 3-4 as they are first learning)
- Underdeveloped attention; Visual mechanism for perception; Spatial Localization
* Saccades are usually HYPOMETRIC at first.
* HYPERMETRIC is VERY RARE…Should be CONCERNED if u see that!
* Visual attention is probably the biggest factor.