NBEO - Ophthalmic optics || 100% Verified Solutions.
the image produced by any lens meridian will be oriented
a) in the same orientation as the meridian that produced it
b) 90 degrees away from the meridian that produced it correct answers 90 degrees away from the
meridian that produced it
interval of Sturm correct answers distance between 2 line images from spherocylindrical lens
circle of least confusion correct answers dioptric (NOT LINEAR) midpoint of the interval of
Sturm
T or F. The spherical equivalent puts the circle of least confusion on the retina correct answers
true
difference in glasses with plus cyl vs minus cyl correct answers minus cyl = front surface is
spherical, back surface has cyl
plus cyl = front surface has cyl, back surface is spherical
how to measure base curve on minus cyl vs plus cyl glasses correct answers minus cyl = front
surface with lens clock
plus cyl = least plus power on front surface with lens clock
axis is designated to which meridian for plus cyl glasses?
(most plus vs most minus meridian) correct answers most minus meridian
always write the axis with the sphere power meridian
how to write in cross-cylinder form correct answers axis and power are always 90 degrees away
from each other
A patient has uncorrected WTR astigmatism.
Does horizontal or vertical line image focus in front of the other? correct answers horizontal line
focuses in front
cornea is steeper in vertical meridian (more power focuses in front)
image focuses 90 degrees away
, difference between simple vs compound vs mixed astigmatism correct answers simple = one
meridian focuses at plano
compound = both meridians focus on same side of plano (either both myopic or both hyperopic)
mixed = each meridian focuses on different sides of plano (one myopic, one hyperopic)
which axis corresponds with WTR vs ATR astigmatism for plus cyl notation? correct answers
for plus cyl:
WTR = 90
ATR = 180
A uncorrected patient sees vertical lines more clearly.
What type of astigmatism is this?
a) WTR myopia
b) ATR myopia
c) WTR hyperopia
d) ATR hyperopia correct answers horizontal corneal meridian is closer to plano than vertical
corneal meridian
either WTR myope
or ATR hyperope
type of cylinder induced by pantoscopic tilt vs face form correct answers panto induces cylinder
along axis 180 = 90th meridian (lens is tilted along horizontal meridian)
face form induces cyl along axis 90 = 180th meridian
(lens is tilted along vertical meridian)
when should you use face form to compensate for lens tilt? correct answers when the major
reference point (MRP) is decentered inward
if the MRP is decentered out, do not use negative face form (that would just look weird)
T or F. Prisms change the vergence of light correct answers false
they do not have dioptric power, they have prismatic power
they bend light, but do not change the vergence
definition of prism diopter correct answers 1 cm of horizontal/vertical deviation at 1m test
distance
the image produced by any lens meridian will be oriented
a) in the same orientation as the meridian that produced it
b) 90 degrees away from the meridian that produced it correct answers 90 degrees away from the
meridian that produced it
interval of Sturm correct answers distance between 2 line images from spherocylindrical lens
circle of least confusion correct answers dioptric (NOT LINEAR) midpoint of the interval of
Sturm
T or F. The spherical equivalent puts the circle of least confusion on the retina correct answers
true
difference in glasses with plus cyl vs minus cyl correct answers minus cyl = front surface is
spherical, back surface has cyl
plus cyl = front surface has cyl, back surface is spherical
how to measure base curve on minus cyl vs plus cyl glasses correct answers minus cyl = front
surface with lens clock
plus cyl = least plus power on front surface with lens clock
axis is designated to which meridian for plus cyl glasses?
(most plus vs most minus meridian) correct answers most minus meridian
always write the axis with the sphere power meridian
how to write in cross-cylinder form correct answers axis and power are always 90 degrees away
from each other
A patient has uncorrected WTR astigmatism.
Does horizontal or vertical line image focus in front of the other? correct answers horizontal line
focuses in front
cornea is steeper in vertical meridian (more power focuses in front)
image focuses 90 degrees away
, difference between simple vs compound vs mixed astigmatism correct answers simple = one
meridian focuses at plano
compound = both meridians focus on same side of plano (either both myopic or both hyperopic)
mixed = each meridian focuses on different sides of plano (one myopic, one hyperopic)
which axis corresponds with WTR vs ATR astigmatism for plus cyl notation? correct answers
for plus cyl:
WTR = 90
ATR = 180
A uncorrected patient sees vertical lines more clearly.
What type of astigmatism is this?
a) WTR myopia
b) ATR myopia
c) WTR hyperopia
d) ATR hyperopia correct answers horizontal corneal meridian is closer to plano than vertical
corneal meridian
either WTR myope
or ATR hyperope
type of cylinder induced by pantoscopic tilt vs face form correct answers panto induces cylinder
along axis 180 = 90th meridian (lens is tilted along horizontal meridian)
face form induces cyl along axis 90 = 180th meridian
(lens is tilted along vertical meridian)
when should you use face form to compensate for lens tilt? correct answers when the major
reference point (MRP) is decentered inward
if the MRP is decentered out, do not use negative face form (that would just look weird)
T or F. Prisms change the vergence of light correct answers false
they do not have dioptric power, they have prismatic power
they bend light, but do not change the vergence
definition of prism diopter correct answers 1 cm of horizontal/vertical deviation at 1m test
distance
