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Methods > Accommodation > Flashcards

Accommodation Flashcards

1
Q

Accommodation

A

process to make and maintain a focused retinal image

changes lens power and lens curvature

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2
Q

What causes the lens changes in accommodation?

A

Ciliary Muscle

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3
Q

Ciliary Muscle

A

parasympathetic innervation

contracts to cause lens changes and releases resting tension of zonules

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4
Q

Edinger-Westphal Nucleus

A

where parasympathetic pathway starts

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5
Q

3 physiological changes in accommodation

Triad or Near Reflex

A

eye accommodation
pupil constriction
eyes converge

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6
Q

Change in pupil size

A

controls light
modifies depth of focus
varies any optical aberration

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7
Q

Reflex Accommodation

A

auto adjustment to maintain focused retinal image
response to blur
important for scanning eye movements

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8
Q

Vergence Accommodation

A

induced during fusional vergences

leads to convergence accommodation/ convergence ratio (CA/C)

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9
Q

Proximal Accommodation

A

refocusing from perceived nearness of target

stimulated by targets w/in 3 m of person

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10
Q

Tonic Accommodation

A

“Lead of Accommodation”
resting level of accommodation (0.5 - 1.5D)
due to baseline stable parasympathetic innervation
reduces with age

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11
Q

Factors that affect Accommodation

A

blur, convergence, proximal issues, pharmacology, minus lens, disease

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12
Q

Retinal image factors that affect Accommodation

A

contrast, spatial frequency, retinal image motion

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13
Q

Non-retinal factors that affect Accommodation

A

mood, voluntary effort, target luminance, training

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14
Q

Optical Cues that affect Accommodation

A

offer info about directionality, astigmatism, aberrations

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15
Q

Non-optical cues that affect Accommodation

A

size, proximity, apparent distance, depth cues

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16
Q

Aberrations

A

occur when peripheral rays do not coincide with the central and on axis rays

17
Q

Depth of Focus

A

variation in image distance that is tolerable without defocus

18
Q

Muscarinic blockers

A

inhibit accommodation by preventing acetylcholine from binding
Tropicamide and Cyclopentolate

19
Q

Presbyopia

A

age related loss of accommodative amplitude
40-45 yrs
complete loss of accommodation by 50-55
2.5D loss per yr

20
Q

Factors that lead to loss of Accommodation

A

lens thickness and size increase, springiness of capsule decreases (thickens), anterior surface curvature increases
zonule # decreases

21
Q

What remains the same when a person starts to lose accommodation?

A

Ciliary muscle function
zonule elasticity
motor neuron pathway

22
Q

Accommodation Excess

A

treated with distance correction and VT

23
Q

Accommodation Infacility

A

correction and VT

24
Q

Accommodation Insufficiency

A

correction and plus lenses

Methods (6 decks)

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