Flashcards in Visual Development (M1) Deck (17)
What are differences in the photoreceptors of newborn infants in the fovea?
1. cones are flat
2. outer segments are short
3. no fibers of Henle
4. Ganglion cells bodies in one layer
5. No foveal pit
What are the Muller cell glia located between bipolar and amacrine cell bodies in the infant fovea called?
Transient layer of Chievitz
What is different about the inner nuclear layer at the fovea in infants compared to adults?
there is no inner nuclear layer at the fovea for adults but there is for infants
What percentage of ganglion cells that a person is born with eventually die?
Where is the optical aperture of adult cones? 1. Newborn cones? 2
1. inner segment'
2. not sure but not in inner segment
What is the idea that light entering a cone directly is more likely to be absorbed and looks brighter then a light entering a cone at an angle? 1. What is this due to?
1. Stiles-Crawford Effect
2. waveguiding by the cone inner segment
Why does much of the light that enter the cones of a newborn not reach the cone outer segments?
little or no waveguiding so no Stiles-Crawford effect
What is the type of Albanism where the lack of pigment is not absolute and visual signs and symptoms are less severe? 1. What is the more severe one? 2
What is the gold standard for infant acuity?
Teller acuity cards
Are the Teller Acuity cards a forced-choice preferential looking method or a yes/no method?
What is the rule for a normal acuity of a baby during development?
acuity in cycles per degree is about as good as their age in months
What is the pattern of a baby's increment threshold?
same pattern as adult but shifted up x50 for intensity for the baby
How does a baby's and adults threshold evaluating power of the background compare? 1. What does this info indicate? 2
2. baby rods are just about as sensitive to change as ours (obey Weber's law)
By what age can normal color vision be demonstrated?
What type of color vision come in later than the other types?
S-cone (tritan) comes in later than L and M cone discrimination
When does the visual acuity plateau to be the same as an adult?
3 years old