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.
16
Q
Infant Saccades
- Direct relation b/w what?
- In adults what is shown preceding a Saccade?
- At 6 Months, is a Potential shown?
- What about at 12 months?
- Velocity is similar/different to adults?
a. What does this suggest?
A
- b/w Cortical development and execution of saccades
- A Cortical Spike is shown in adults…Its a Potential preceding saccade
- No potential is shown
- Have a potential, but smaller, and similar timing to adults
- Similar
a. Brainstem is mature at birth as it regulates motor behavior.
17
Q
Infant Saccades
- Able to perform at birth but immature. (What 3 things will we see)?
- Does the head and eyes move together?
- Velocity-Amplitude relationship: Similar or different to adults?
- Saccades are Adult like at what age?
A
- a. Hypometric Saccades
b. Succession of saccades (1-5), but same size and amplitude
c. Longer latency of initial movement and acquisition times - Yes.
- Similar to adults
- at Age 1.
18
Q
Pursuits
- Define
A
- Ability to track a moving target at low to moderate velocity
19
Q
Pursuit Mechanism
- Visual Signal to Cortex: What happens here?
- Cortex to Brainstem: What happens here?
- Brainstem to muscle: What happens?
A
- Perception of Location; Attention; Decision Making
- Pulse Generator –> Neural Integrator
- Motor Output
20
Q
Pursuit Basics
- Primary Stimulus?
- Latency?
- Cortex: What happens here?
- Brainstem: What happens here?
A
- VELOCITY (Only happens w/a MOVING OBJECT)!
- 100 ms (Shorter than a saccade latency)
- Perception of target velocity, attention to target, initiation of movement and maintenance of pursuit (Step of neural activity)
- Eye position signal produced (Ramp of Neural Activity)
21
Q
Infant Pursuits
- At what age can infants start making a pursuit movement?
- What 4 things do we note on pursuits?
- Why are they inaccurate?
A
- 1-4 wks.
- a. Increased Latency
b. Low Gain (Can’t quite stay on the target when following the pursuit)
c. Low Velocity
d. Short duration - Visual Cortical mechanisms for target velocity are not fully developed
22
Q
Pursuits (2)
- Depends on what 2 things?
- What type of object is MORE LIKELY to ELICIT a SMOOTH PURSUIT?
- Significant improvement by what month?
A
- Size of the target and its velocity
- LARGER, Highly stimulating, Slow moving target.
- By 4 Months
23
Q
Oculomotor Skills: Age of development: Recap
- Pursuits
- OKN
- Saccades
A
- 1-4 Weeks
- Asymmetric at Birth
- Birth
24
Q
Accommodation
- Newborns:
a. Depth of focus?
b. Do Large changes in Target distance elicit blur? Why or why not? - Accommodation is variable for what months after birth?
- Have more adult like levels of accuracy when?
- Why does an infant have to accommodate so early?
A
- a. LARGE DOF
b. No. Secondary to Poor VA and Attention; So there’s no stimulus to accommodate BUT they do have the ability! - for the first 1-3 months
- at 3-4 months
- Most are Hyperopic at birth, resulting in POOR DVA, viewing distances are very close, so infant must accommodate to have reasonable NVA!
25
Q
Binocular Vision
- What is it?
- 3 Levels of Binocular Function: What are they?
A
- 2 eyes see a common portion of visual space
- a. Bifoveal Fixation
b. Fusion
c. Stereopsis
26
Q
Binocular Fixation and Convergence
- At birth, Binocular Fixation on what?
- Adult like at what age?
- Fusional Vergence at what age?
- DO NOT WORRY about eye turns PRIOR to what age?
A
- on the FACE
- 3-4 months
- 6 Months
- prior to 6 months!
27
Q
Stereopsis
- Present at birth?
- Sudden onset at what age?
- Rapid maturation and complete at what age?
- Disparity (Random Dot) Detection at what age?
- Amblyopia Factors during this period will do what?
A
- ABSENT
- at 3-5 Months
- at 4-6 Months
- at 3-4 Months
- Will DECREASE STEREOPSIS, Hampering development
28
Q
Color Vision
- First Discriminate what at Birth?
- At what Age will they start seeing BLUE and GREEN?
- At what age will they get functional vision of all three cones, with an adult like spectra?
- Thresholds are LOW due to what?
a. They reach ADULT LEVELS after how many years?
A
- First discriminate Red at Birth
- About 1 Month
- About 3-4 months
- Due to Contrast, cognition, etc.
a. After several years (one study said it took 20 years to hit adult levels)
29
Q
Emmetropization
- What is it?
- Eyes become less what over time?
- What if the baby is a Myope?
A
- Process that human eyes undergo allowing them to grow in a coordinated manner
- Less Hyperopic
- Once a Myope, ALWAYS a MYOPE!
30
Q
Refractive Error
- Newborn: Shift towards what?
- 1st Birthday?
- Ultimate Goal?
- Hyperope?
- Myope?
A
- Towards Hyperopia (2-3 D)
- (+0.50 - +1.00 D)
- Maintain emmetropia while the visual system grows and develops
- May become less Hyperopic over time
- Once a Myope, Always a Myope
31
Q
Astigmatism
- Anything over how much cyl is normal in a newborn?
- % of newborns with >0.75 D Cyl?
- Adults w/>0.75D cyl?
- What will decrease?
- Astigmatism is STABLE at what age?
- Oblique Cyl is more/less stable?
a. Should be monitored closely for what? - If you see astigmatism under the age of 1, what will you Rx?
A
- Over >0.75 D cyl
- 65%
- 8%
- ATR will decrease
- at 4 years
- More stable
a. for Strab/Amblyopia - NOTHING.