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Ophthalmic Optics Final Exam: Questions & A+ Solutions (Expert Answered)
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Ophthalmic Optics Final Exam: Questions & A+ Solutions (Expert Answered)
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Ophthalmic Optics Final Exam: Questions & A+Solutions (Expert Answered)
Where is the best vision in the progressive lens? Right Ans - corridor (even
though there's some distortion in periphery)
Which of the following is NOT true:
a) prism bends light
b) prism changes the vergence
c) prism doesn't change the clarity of the image
d) prism has prismatic power Right Ans - b) because prism does NOT
change the vergence
Light moves towards the _______ and image moves towards the __________
a) base; apex
b) base; base
c) apex; base Right Ans - a) base; apex
Do we prescribe prism relative to the base or the apex? Right Ans - base
(base in or base out etc)
What is a prism diopter? Right Ans - The amount of prism needed to divert
a ray of light 1 cm from its original path measured 1 m distance
What is the location that the prism is prescribed in single vision lenses?
a) fitting cross
b) distance reference point
c) prism reference point Right Ans - c) prism reference point (PRP/MRP)
What is prentice's rule? Right Ans - prism diopters= decentration (cm)*
lens power
(the power used in this equation is the power in the meridian that the patient
is looking in)
Reasons to prescribe prism
a)strabismus
b) phoria/tropia
c) both a and b Right Ans - c) both
,When does unwanted prism occur? Right Ans - when the lab de-centers
incorrectly and the patient is no longer looking through the OC
Decentering the lens occurs when moving the ______ to where the _____ is
a) frame to where the eye is
b) eye to where the frame is Right Ans - a) you have to move the frame you
can't move the eye (move frame to align OC with PD)
What is the equation for PD? Right Ans - frame PD= (A+DBL)/2
What happens if both eyes are not pointed at the same target at the same
time? Right Ans - diplopia (prism can correct double vision)
Which of these prism prescriptions is not paired correctly with the tropia it
corrects:
a)BI-exo
b)BO-eso
c)BD-hyper
d)BU-hyper Right Ans - d) because BU should be used to correct hypo
How do you line up the PRP with PD? Right Ans - first decenter the lens so
that the OC is aligned with PD, then after finding the prism reference point
with prentice's rule, decenter the frames again so that PRP is lined up with PD
Horizontal prism in the same direction ______ and different direction______
when combining prism across both eyes
a) add; add
b) add; cancel
c)cancel; add Right Ans - b) add; cancel
Vertical prism in the same direction ______ and different direction______ when
combing prism across both eyes
a) add; add
b) add; cancel
c)cancel; add Right Ans - c) cancel; add
When combining prism across the same eye: opposing directions will ______
and same direction will______ Right Ans - cancel; add
, What can we do to improve lens appearance for high amounts of prism?
Right Ans - split the prism between both eyes
Which prism corrects temporary conditions and allows for correction in plano
power?
a) Fresnel
b) Resultant
c) Grinding
d) Clip on Right Ans - d) clip on
Which prism grinds the difference between edge thickness along the base-
apex line at the meridian of prismatic effect?
a) Fresnel
b) Resultant
c) Grinding
d) Clip on Right Ans - c) grinding
Which prism is a series of short prisms that a stick on thin plastic sheet that
you cut to the size of the lens?
a) Fresnel
b) Resultant
c) Grinding
d) Clip on Right Ans - a) fresnel
What is the most common use of fresnel prism? Right Ans - patients with
VF defect post-stroke
Which prism is used when the patient needs both vertical and horizontal
prism?
a) Fresnel
b) Resultant
c) Grinding
d) Clip on Right Ans - b) resultant
What is presbyopia? Right Ans - progressive loss of focusing ability at near
(accommodation); initial loss at 40 and complete loss by 65
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