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Med310A > VISION A > Flashcards

VISION A Flashcards

1
Q

________
= formation by cornea and lens of a real, reduced, up-side-down image on back of eye
= transmission of visual information to the visual cortex

A

Seeing

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2
Q

The ______ controls balance, the ________ keeps vision steady as head moves

A

Vestibular apparatus
Vestibular ocular reflex

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3
Q

What is the pathway of rays through the eye to reach the photoreceptors?

A

Cornea, anterior camber, pupil, lens, vitreous, inner retinal layers

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4
Q

Visual-based neural signals pass through what structures of the eye to visual cortex ?

A

Photoreceptors, intermediate retinal neurons, retinal ganglion cells to Lateral Geniculate Nuclei

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5
Q

Axons from the retina exit via the ____

A

Optic nerve

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6
Q

The choroid layer contains ____

A

Blood vessels

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7
Q

Pigment epithelium of retina absorbs excess ____

A

Light

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8
Q

Light rays must be focused on the ____ , a maximally focused image initiates resolution of the finest detail

A

Fovea

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9
Q

Light strikes the photoreceptors in the fovea directly because overlying ____ are pushed aside

A

Neurons

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10
Q

During the __________ the lens becomes more powerful to converge divergent rays coming from close objects onto the fovea

A

Accommodation reflex

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11
Q

Far objects (>20 ft) : parallel/diverging rays? Lens or no lens accommodation ?

A

Parallel
No lens accommodation

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12
Q

Near objects (<20 ft) : parallel/diverging rays? Lens/no lens accommodation ?

A

Diverging
Lens accommodation

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13
Q

_____ objects :Parallel Rays, No Lens Accommodation

A

Far

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14
Q

_______ objects :Diverging Rays, Lens Accommodation

A

Near

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15
Q

A physiological reflex that permits focusing on near and far objects by changing the curvature of the lens

A

Accommodation

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16
Q

_______: Relaxation of ciliary body muscles: Tightens
zonule ligaments, stretches lens, is sympathetically controlled.

A

Far focus

17
Q

________: Contraction of ciliary body muscles moves ciliary body inward : Loosens zonule ligaments, lens gets fatter (more convex), is parasympathetically controlled.

A

Near focus

18
Q

“Normal” eye: “__________”
-Far focused as default
-Near needs lens accomm.
(Lens gets fatter to converge
and move light rays forward onto fovea)

A

Emmetropic

19
Q

Eyeball too long: “_______”
-Near focused as default
-Far focused front of retina -Correct w/CONCAVE lenses (To diverge rays and
MOVE IMAGE BACKWARD to fovea)

A

Myopic

20
Q

Eyeball too short: “________”
-Far focused by lens accomm.(lens gets fatter)
-Near focused behind retina
-Correct w/CONVEX lenses (To converge rays and MOVE IMAGE FORWARD TO FOVEA)

A

Hyperopic

21
Q

Optic nerve afferents driven from each eye lead to _______ controlling both eyes

A

Binocular efferents

22
Q

_______ conditions:
Iris dilator pupilae muscles contract
Radial fibres shorten
Pupil diameter increases
Allows more rays to enter eye

A

Low light

23
Q

__________ conditions:
Iris constrictor pupilae muscles contract
Concentric fibres shorten
Pupil diameter decreased
Blocks some rays from entering eye

A

High light

24
Q

Low light conditions = pupil _____
High light conditions = pupil _____

A

Dilates
Constricts

25
Q

________= spatial resolving capacity of the visual system
Ability of eye to see fine detail
Limited by diffraction , aberrations and photoreceptor density in eye
Target recognition tasks, which are most commonly used in clinical visual acuity measurements, require recognition or naming of a target , such as with snellen letters

A

Visual acuity

26
Q

List 3 factors that affect visual acuities :

A

Eye movement
Pupil size
Refractive error
Illumination
Exposure time of target
Area of retina stimulated
State of adaptation of eye

27
Q

In the ____ fraction 20/20, the 1st number represents test distance, 20 ft
2nd number represents distance that normal eye can see the same letter on eye chart

A

Snellen

28
Q

_______- distance away from object a normal subject can be to clearly see detail

A

Visual acuity

Med310A (29 decks)

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