Accommodation Flashcards
A dynamic change in the power of the eye
And a change in the focus from distance to near
—is describing what?
accomodation
In accomodation the optical power of the lens(increase/decreases)
increases
accomodation is measured in ____ a measure of the ____ of light
Diopters
vergence
Accomodation is mediated through:
(contraction/relaxation) of the ciliary muscle
release of zonular (tension/relaxation) of the equator
(rounding/flattening) up of the lens (force exerted by capsule)
contraction
tension
rounding
The increased opitcal poewr of accomodation is achieved through (increase/decrease) anterior and posterior lens sruface curvatures and (increased/decrease) thickness of the lens
increased
increased
T/F in accommodation the lens decreases in size
T
In a unaccommodated eye the image of the distant object is (not in /in) focus retina
in
In a unaccommodating eye the image of near object is (in/out) of focus on retina
out
In a accommodated eye image of near object (in/out) focus on retina
in
Myopes can focus clearly on objects (closer/farther) than optical infinity without accommodation
closer
Hyperopes can focus clearly on objects at optical infinity only through an accommodative (increase/decrease)or with (positively/negatively) powered lenses
increase
positively
Because the cornea is made up of largely fluid and proteins it has a (higher/lower) refractive index then air which is 1.00
higher
What is the refractive index f the cornea?
1.376
The optical power of the cornea is attributable to a combination of the (positive/negative) radius of curvature and the (higher/lower) refractive index than the surrounding air.
positive
higher
T/F
The refractive index of aqueous humor and cornea is very different therefore the posterior cornea and aquieous interface is relatively large.
F
The refractive index of aqueous humor and cornea is very SIMILAR therefore the posterior cornea and aquieous interface is relatively SMALL
T/F The vitreous humor and aqueous humor have different refractive index
F. both have 1.336
T/F the surfaces of the lens has a different refractive index then the center of the lens
T. surface is 1.386
center 1.406
The optical power of the cornea comes from the change in____ ____ and the (positive/negative) radius of curvature
Additionallly, the (center/anterior/posteror/lateral) surfaces of the lens also add the optical power of the eye.–pick two
refractive index
positive
anterior , posterior
It was found that in the past it was thought that the (posterior/anterior) lens surface did not move with accomoation and the posterior lens surface curvature did not chage
—However—-
It stands corrected that the (posterior/anterior) lens surface increases in curvature and moves (upward/backward) with accommodation
posterior
posterior
backward
The range over which a target can be moved toward or away from the eye wihtout a perceptible change in the blur or focus of the image describes what —(depth of field/depth of focus)
depth of field
The focusing error that can be tolerated without an appreciable decrease in acuity or change in blur or focus of the image on the retina–which one does this describe
(depth of field/depth of focus)
depth of focus
T/F For any given accommodative state, there is a range of distances over which an object is perceived to be in focus.
T
Depth of focus is dependent on __(sclera/cornea/pupil)___ size
pupil
Large/Small pupil = Larger depth of focus
Small
Large/Small pupil = Small depth of focus
Larger
With accomodation the pupil size (increases/decreases) , increases the depth of focus
decreases
T/F Nothing happens to the pupil size as you age with accomodation
F. as you age pupil size decreases
Senile miosis –(increases/decreases) pupil size
decreases
In senile miosis , (increased/decreased) need for add in presbyopic correction which (increases/decreases) depth of focus
decrease
increases
Why would senile miosis help pt. who are aging? (what activity would it help with)
reading
In accomodation at rest, the eye is focused for (near/distance) and the zonules apply an (inward/outward) tension on the lens
distance
outward
The lens is held in a relatively flattened and (accomodatied/unaccomodated) state
unaccomodated
At rest, the eyes have some residual or resting level of accommodation amounting to approximately __ diopters. This is called ____ accommodation.
A) 2.5
B)1.5
C)3.5
D)4.5
1.5
tonic
Pupil (constrict/dilate)
eyes (converge/diverge)
Eyes (accomodate/unaccomodate)
–this describes the accomodative _____
constrict
converge
accomodate
triad
Accommodative stimulus presented monocularly results in a (monocular/binocular) accommodation and convergence response.
Similarly, a convergence stimulus in one eye resutls in pupil (dilation/constriction), convergence , accomodation in both eyes
binocular
constriction
What is another name for the accommodative triade?
near reflex
Inducing accommodation is done with a _(-/+)__ lens in front of an eye, the eyes accommodates to overcome the defocus
(-)
If the vergence of the eyes is increased, for instance by placing (base-out/base-in) prisms in front of the eyes, pupil (constriction/dilates), convergence, and accommodation occur.
base-out
constriction
accomodation is ___driven
blur
Topical application of muscarinic cholinergic agonist (pilocarpine) to the eye results in stimulation of the (ciliary muscle/iris/cornea)
ciliary muscle
Pupil constriction occurs with pharmacologic stimulation, but (convergence/divergence) does not.
Convergence
T/F accommodation can also be induced through pharmacologic stimulation
T
Accommodative __(exotropia/esotropia)___ often occurs in uncorrected hyperopes as a consequence of needing to accommodate to even see distant objects in focus
esotropia
T/F accommodative esotripa only occurs in uncorrected myopes as a consequence of needing to focus a distant object
F. hyperopes
Atropin, cylopentolate, troicamide– all three of these__(activate/block)____ accomodation
block
Atropin cyclopentolate and tropicamide block accommodation by acting like (agonist/antagonist) to the muscarinic receptors, they (do not/do) activate receptor
agonists
do not
blocking accomodation is called?
cycloplegia
Using a minus lens in front of the eyes or eye can (maximize/minimize) the letter size
minimize
T/F you can measure accomodativeamplitude by putting plus lenses on a patients eye
F. MINUS LENSES
T/F Accurate objective measurement requires static or dynamic refractometers
T
The age related loss in accomodative abiliy, results in nearly complete loss in accommodative ability by about __yrs of age
A) 60
B)50
C)35
D)45
50
Per decade there is a ____D linear decline in objective measurement of accommodation
A) 2.3
B)1.3
C)3.3
D)4.5
2.3
2/3 of accommodative amplitude is lost between ages __to__
A) 10-20
B)15-25
C)15-35
D)10-35
15-35
Which age group is of most interest in understanding the progression to presbyopia ? A) 10-20 B)15-25 C)15-35 D)10-35 Why is this age group of most interest?
15-35, becasue they lose 2/3 of accomodative amplitude
Corneal refractive surger
cataract surgery
accomodative IOLs
–these are all surgical options for persons with ____(hyperopia/myopia/presbyopia)___
presbyopia
Controversial surgical interventions claim to actually restore ___(the cornea/accomodation_____
accomodation
T/F future surgical prospect may include a deformable polymer
T
What is an example of a controversial surgical intervention that claims to restore natural accommodation?
scleral expansion surgery
