Pediatric Optometry: L3: Vision Development Part 2

Question 1

Development of Visual System

1. Complete at Birth?
2. Maturation of Visual System is influenced by several Factors. Name 4.

Answer 1

1. Incomplete at birth.

2. Light Deprivation; Maturing Visual Cortex; Post-Natal Nutrition; Visual Stimulation

Question 2

Factors Affecting Development

1. Internal Factors
   a. What’s a big one?
   b. What does Maturation refer to?
2. External Factors
   a. What a big one?
   b. Learning: What does this refer to?
3. Interaction: What does this refer to?

Answer 2

1. a. Hereditary or genetic makeup
   b. basically to genetically predetermined patterns of growth and how they come about.
2. a. Environmental Factors (like nutrition)
   b. Basically, what is going on in the environment that helps the child pick up and learn specific skills
3. Relationship b/w Internal and External

Question 3

Development

1. Is it a LINEAR FUNCTION?
2. MRI Study of Fetuses and children aged 0-13 years shows what?

Answer 3

1. NO!

2. A Rapid Eyeball Growth Curve IN UTERO and from birth to 18 months.

Question 4

Visual Acuity

1. Does VA develop the same with everyone?
2. VA development is rapid in the first how many months?
3. Months: 0-6, what 2 things develop at the SAME RATE?
4. Months 6-11: Which is superior: Binocular Acuity or Monocular Acuity?
5. What does taking an accurate VA depend on with the child?

Answer 4

1. NO! There’s a large individual variation.
2. First 6 Months
3. Monocular and Binocular develop at the same rate.
4. Binocular Acuity is superior to Monocular Acuity
5. Attention levels, motor and sensory skills

Question 5

VAs

1. OKN:
   a. Newborn
   b. 2 Months
   c. 6 Months
   d. 12 Months
2. Preferential Looking
   a. Newborn
   b. 2 Months
   c. 6 Months
   d. 12 Months
   e. 18 Months
3. VEP
   a. Newborn
   b. 2 Months
   c. 6 Months
   d. 12 Months
4. Which test is the ONLY TEST at 6 Months that will GIVE a VA of 20/20?

Answer 5

1. a. 20/400
   b. 20/400
   c. 20/100
   d. 20/60
2. 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
3. a. 20/100
   b. 20/80
   c. 20/20-20/50
   d. 20/20
4. VEP!

Question 6

Contrast Sensitivity

1. What is it?
2. With age, our ability to detect Lower Contrast Levels Increases or Decreases?
3. Studies show that Contrast Sensitivity is NOT Adult like still at what ages?

Answer 6

1. Minimum Contrast needed to detect SINE WAVE GRATING of VARYING SPATIAL FREQUENCIES
2. INCREASES
3. 7-9 yrs

Question 7

Oculomotor

1. Do normal eye movements develop in a visually impaired infant?
2. First Symptom of Significant visual impairment?
3. All eye movements are dependent on what?
   a. Ex?

Answer 7

1. No.
2. Abnormal Eye Movements
3. on Infants interest and Attention level.
   a. Shown same object multiple times…they lose interest…change target to attract attention.

Question 8

Fixations

1. Good or bad before 2-3 months?
2. At 3 Months?

Answer 8

1. BAD

2. Should be fixating new objects

Question 9

Saccades

1. What are they?
2. Latency?

Answer 9

1. High Velocity Eye Movement that shifts direction of gaze from 1 spatial location to another
2. About 200 ms (more concerned about Voluntary Saccades when looking at the child)

Question 10

Utilization of Saccades

1. Voluntary: Purpose?
2. Reflexive: Purpose?
3. Saccadic Scan Path: Purpose?

Answer 10

1. Look at Object of Interest
2. Direction of event occurs suddenly w/o warning
3. Enter room, engaged in social situation, u get a panoramic scene. Lets u get a large amt of info.

Question 11

Saccade Basics

1. Large Magnitude: Purpose?
   a. Amt of Degrees?
2. Small Amplitude
   a. Use?
3. Latency?
   a. Why this latency?

Answer 11

1. Everyday circumstances
   a. 2-40 degrees
2. a. Reading, Maintaining Fixation
3. 200 ms
   a. Time for passage of visual signal to cortex –> Processing –> Flow of Oculomotor Signals to EOMs.

Question 12

1. What is the Fastest of Human Behaviors?

Answer 12

1. Saccades

Question 13

Saccade Basics

1. It’s a Ballistic System: What does this refer to?
2. Purpose of the Cortex?
3. Brainstem does that?

Answer 13

1. Once activated, it will run until the task is completed (Once u initiate it, you can’t stop it)
2. When and where the saccade will be executed.
3. Produce shape and motor signals that go to the EOMs

Question 14

Saccadic Mechanism

1. Visual Signal goes to Cortex where what happens?
2. Cortex sends info to the Brainstem where what happens?
3. Brainstem then does what?

Answer 14

1. Perception of location. Decision making. Attention
2. Pulse Generator –> Neural Integrator
3. Motor Output

Question 15

Infant Saccades

1. 3 Major features?
2. Why do these Features occur?

Answer 15

1. 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)
2. 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.

Question 16

Infant Saccades

1. Direct relation b/w what?
2. In adults what is shown preceding a Saccade?
3. At 6 Months, is a Potential shown?
4. What about at 12 months?
5. Velocity is similar/different to adults?
   a. What does this suggest?

Answer 16

1. b/w Cortical development and execution of saccades
2. A Cortical Spike is shown in adults…Its a Potential preceding saccade
3. No potential is shown
4. Have a potential, but smaller, and similar timing to adults
5. Similar
   a. Brainstem is mature at birth as it regulates motor behavior.

Question 17

Infant Saccades

1. Able to perform at birth but immature. (What 3 things will we see)?
2. Does the head and eyes move together?
3. Velocity-Amplitude relationship: Similar or different to adults?
4. Saccades are Adult like at what age?

Answer 17

1. a. Hypometric Saccades
   b. Succession of saccades (1-5), but same size and amplitude
   c. Longer latency of initial movement and acquisition times
2. Yes.
3. Similar to adults
4. at Age 1.

Question 18

Pursuits

1. Define

Answer 18

1. Ability to track a moving target at low to moderate velocity

Question 19

Pursuit Mechanism

1. Visual Signal to Cortex: What happens here?
2. Cortex to Brainstem: What happens here?
3. Brainstem to muscle: What happens?

Answer 19

1. Perception of Location; Attention; Decision Making
2. Pulse Generator –> Neural Integrator
3. Motor Output

Question 20

Pursuit Basics

1. Primary Stimulus?
2. Latency?
3. Cortex: What happens here?
4. Brainstem: What happens here?

Answer 20

1. VELOCITY (Only happens w/a MOVING OBJECT)!
2. 100 ms (Shorter than a saccade latency)
3. Perception of target velocity, attention to target, initiation of movement and maintenance of pursuit (Step of neural activity)
4. Eye position signal produced (Ramp of Neural Activity)

Question 21

Infant Pursuits

1. At what age can infants start making a pursuit movement?
2. What 4 things do we note on pursuits?
3. Why are they inaccurate?

Answer 21

1. 1-4 wks.
2. a. Increased Latency
   b. Low Gain (Can’t quite stay on the target when following the pursuit)
   c. Low Velocity
   d. Short duration
3. Visual Cortical mechanisms for target velocity are not fully developed

Question 22

Pursuits (2)

1. Depends on what 2 things?
2. What type of object is MORE LIKELY to ELICIT a SMOOTH PURSUIT?
3. Significant improvement by what month?

Answer 22

1. Size of the target and its velocity
2. LARGER, Highly stimulating, Slow moving target.
3. By 4 Months

Question 23

Oculomotor Skills: Age of development: Recap

1. Pursuits
2. OKN
3. Saccades

Answer 23

1. 1-4 Weeks
2. Asymmetric at Birth
3. Birth

Question 24

Accommodation

1. Newborns:
   a. Depth of focus?
   b. Do Large changes in Target distance elicit blur? Why or why not?
2. Accommodation is variable for what months after birth?
3. Have more adult like levels of accuracy when?
4. Why does an infant have to accommodate so early?

Answer 24

1. a. LARGE DOF
   b. No. Secondary to Poor VA and Attention; So there’s no stimulus to accommodate BUT they do have the ability!
2. for the first 1-3 months
3. at 3-4 months
4. Most are Hyperopic at birth, resulting in POOR DVA, viewing distances are very close, so infant must accommodate to have reasonable NVA!

Question 25

Binocular Vision 1. What is it? 2. 3 Levels of Binocular Function: What are they?

Answer 25

1. 2 eyes see a common portion of visual space 2. a. Bifoveal Fixation b. Fusion c. Stereopsis

Question 26

Binocular Fixation and Convergence 1. At birth, Binocular Fixation on what? 2. Adult like at what age? 3. Fusional Vergence at what age? 4. DO NOT WORRY about eye turns PRIOR to what age?

Answer 26

1. on the FACE 2. 3-4 months 3. 6 Months 4. prior to 6 months!

Question 27

Stereopsis 1. Present at birth? 2. Sudden onset at what age? 3. Rapid maturation and complete at what age? 4. Disparity (Random Dot) Detection at what age? 5. Amblyopia Factors during this period will do what?

Answer 27

1. ABSENT 2. at 3-5 Months 3. at 4-6 Months 4. at 3-4 Months 5. Will DECREASE STEREOPSIS, Hampering development

Question 28

Color Vision 1. First Discriminate what at Birth? 2. At what Age will they start seeing BLUE and GREEN? 3. At what age will they get functional vision of all three cones, with an adult like spectra? 4. Thresholds are LOW due to what? a. They reach ADULT LEVELS after how many years?

Answer 28

1. First discriminate Red at Birth 2. About 1 Month 3. About 3-4 months 4. Due to Contrast, cognition, etc. a. After several years (one study said it took 20 years to hit adult levels)

Question 29

Emmetropization 1. What is it? 2. Eyes become less what over time? 3. What if the baby is a Myope?

Answer 29

1. Process that human eyes undergo allowing them to grow in a coordinated manner 2. Less Hyperopic 3. Once a Myope, ALWAYS a MYOPE!

Question 30

Refractive Error 1. Newborn: Shift towards what? 2. 1st Birthday? 3. Ultimate Goal? 4. Hyperope? 5. Myope?

Answer 30

1. Towards Hyperopia (2-3 D) 2. (+0.50 - +1.00 D) 3. Maintain emmetropia while the visual system grows and develops 4. May become less Hyperopic over time 5. Once a Myope, Always a Myope

Question 31

Astigmatism 1. Anything over how much cyl is normal in a newborn? 2. % of newborns with >0.75 D Cyl? 3. Adults w/>0.75D cyl? 4. What will decrease? 5. Astigmatism is STABLE at what age? 6. Oblique Cyl is more/less stable? a. Should be monitored closely for what? 7. If you see astigmatism under the age of 1, what will you Rx?

Answer 31

1. Over >0.75 D cyl 2. 65% 3. 8% 4. ATR will decrease 5. at 4 years 6. More stable a. for Strab/Amblyopia 7. NOTHING.