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Optometry final Exam | Questions And Answers Latest {} A+ Graded | 100% Verified
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Optometry final Exam | Questions And Answers Latest {} A+ Graded | 100% Verified
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Optometry final Exam | Questions And Answers Latest {2024- 2025} A+ Graded | 100%Verified
emmetropia - optical state of the eye in which parallel light enters the eye and focuses on the retina
without the need for any corrective lenses or accommodation; this is the absence of refractive error and
the "normal" or ideal state of the eye
ametropia - refractive error, "abnormal" optical state of the eye in which parallel light rays enter the eye
and focus on an area other than the retina; this condition requires corrective lenses to produce clear
retinal images
astigmatism - optical error in which refractive power is not uniform in all meridians; light entering the
eye is focused at two distinct focal points where at least one focal point does not fall onto the retina
How can corneal astigmatism be measured? - keratometry
What are components of sphere-cylinder lens RX? - 1. Power (magnitude in D) of sphere component
2. Power (magnitude of D) of cylinder component
3. Axis (orientation) of the cylinder
i.e. +2.00 -3.00 X 145
i.e. -5.00 -2.00 X 060
If one meridian is at 60 degrees, where is the other - 150 degrees because 60+90=150
What are the possible values for magnitude of axis? - 1 degree-180 degrees
How can one determine the powers of the 2 principal meridians? - Principal meridian 1=power of more
(+) meridian
Principal meridian 2=sum of sphere and cylinder componenets
,Find primary and secondary meridians for this Rx.
+1.00 -2.00 X 110 - Principal meridian 1=+1.00D
Principal meridian 2=+1.00D + -2.00D= -1.00D
Find the primary and secondary meridians for the Rx.
-3.00 -4.50 X 010 - Principal meridian 1= -3.00D
Principal meridian 2= -3.00D + -4.50D= -7.50D
Find the primary and secondary meridians for this Rx.
+4.00 -6.50 X 175 - Principal meridian 1= +4.00D
Principal meridian 2= +4.00D - 6.50D= -2.50D
What are the 8 different types of refractive error? - 7 distance refractive errors which assume that
accommodation is at rest and that the eye is looking at a distant target (optical infinity)
1 near refractive error that involves a target closer than optical infinity and may involve accommodation
Define diopter - unit of measurement of the refractive power of the lens, and is equal to the reciprocal
of the focal length as measured in meters
What is the focal point of a +2.00D lens? - 0.5 m or 50 cm
What is the dioptric power of a lens that has a focal point of 20 cm? - +5.00 D
Define spherical refractive error - Refractive error is uniform in all meridians. No matter where cross-
section is taken, the refractive error is the same magnitude throughout
Define hyperopia - parallel light entering the eye is focused behind the retina and requires a plus lens to
converge the light to properly focus it on the retina; eye has too much minus power
, Define myopia - parallel light entering the eye is focused in front of the retina and requires a minus lens
to diverg the light to properly focus it on the retina; eye has too much plus power
What kind of lens is necessary to correct for astigmatism? - the two focal lengths need a lens with 2
different powers to bring the light to one single focal point on the retina; a sphere-o-cylinder lens
(compound lens or sphere-cylinder lens) has one power in one meridian and a different power in the
other meridian located 90 degrees away
Define principal meridians - two primary refractive cross sections of astigmatic refractive error; each
principal meridian has a power and orientation from 1-180 degrees and are located 90 degrees away
from each other
How can one describe amount of astigmatism? - magnitude in diopters and orientations as measured by
axis
What does with-the-rule astigmatism refer to? - prescription with an axis closer to 180 degrees
What does against-the-rule astigmatism refer to? - prescription with an axis closer to 90 degrees
What does oblique astigmatism refer to? - prescription that has an axis closer to 45 degrees or 135
degrees
Describe simple hyperopia - one single focal point behind the retina
Describe simple myopia - one single focal point in front of the retina
Describe simple astigmatism - 2 focal points with one on the retina and the other either behind or in
front of the retina
Describe simple hyperopic astigmatism - 2 focal points with one on the retina and the other behind the
retina
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