MT 1 Flashcards
When seeing with motion during ret:
“Down with the ship,” add + (turn knob down)
When seeing against motion during ret:
“Up against the wall.” add - (turn knob up)
Torsional eye movements
intorstion: top of eye rotates toward nose
extorstion: top of eye rotates away from nose
Disconjugate vergence
convergence: toward nose
divergence: away from nose
What is goal of versions?
Move eyes in 6 cardinal directions, or determine muscle restriction
Cranial nerves related to EOMs
III- oculomotor (all others)
IV- trochlear (SO)
VI- abducens (LR)
Hering’s law
TWO eyes, contralateral synergists are equally innervated
Sherrington’s law
ONE eye, contraction accompanied by proportional relaxation of antagonist
Recording abnormal EOM’s
“limitation of gaze”
NPC
distance where convergence breaks down
NPC Pd calculation
(IPD x 10) / (NPC break in cm + 2.7)
ex. IPD 60, NPC 5 cm
Pd = 78
T/F: HBRx worn during NPC
True (near Rx required)
Pinhole accomplishes:
increased depth of field/focus, reduced blur
***reduced brightness
Snellen notation:
Numerator: testing Dx
Denominator: letter size (Dx letter subtends 5’ arc)
Progression after big E:
CF > HM > LP with projection > LP > NLP
Which is better VA?
A. 0.40/2.0M
B. 0.40/1.0M
B
Which is better VA?
A. 0.40/0.8M
B. 0.20/0.8M
A
Which is better VA?
A. 0.40/1.2M
B. 0.30/0.8M
B
reciprocal of fraction is MAR number, lower MAR is better
How much less is NPD on average than DPD?
~3 mm
Myopia
Eye: too much + (long eyeball)
Image pt in front of retina, far pt closer than infinity
Hyperopia
Eye: too much - (short eyeball)
Image pt behind retina, far pt beyond infinity
Simple myopic astigmatism
One at retina, one in front of retina
Simple hyperopic astig
One at retina, one behind retina
Compound myopic astig
Both in front of retina
Compound hyperopic astig
Both behind retina
Mixed astig
One in front of retina, one behind
Calculate height of letter (Optotype)
tan(5/60) = x/20 ft (20 ft x 304.8 mm)
in mm
