Material 100% Solved
Optical center Correct Ans-area of the lens that has no prismatic effect (light isn't bent) on
principal meridians
Peripapillary area Correct Ans-surrounding retina just outside disc -- can have various
changes
posterior segment evaluations Correct Ans-optic nerve head, peripapillary area (adjacent to
nerve), fundus/vasculature, macula (darker, temporal)
prevalence of color blindness Correct Ans-roughly 8% in males, 0.5% in females; far greater
likelihood of red-green deficiency (protan/deutan) than blue-yellow (triatn). Extremely rare for
monochromatism
Principal meridians Correct Ans-axial areas in which the greatest and least dioptric powers
are found
Progressive Addition Lenses (PALs) Correct Ans-"no line bifocals"; Add power read directly
off lens under right lighting conditions
Pros to global stereopsis Correct Ans-constant tropia unable to appreciate global stereo of 660
arc seconds or finer; no monocular cues; eliminates guessing
,Pros to local stereopsis Correct Ans-very visible targets, easier to see by all patients; less
cognitive process
Protanomalous trichromats Correct Ans-those who are "red-weak" require more red stimulus
to appear the same as normal trichromat; confuse red-green stimulus
protanope Correct Ans-deficient in erythrolabe (or, malfunctioning L cone)
pseudoisochromatic plates Correct Ans-figures, images, numbers produced by dots varying in
color and brightness; creates images that can not be differentiated from background unless color
normal
pseudopallor Correct Ans-post cataract surgery -- yellow lens removed, making ONH appear
far whiter in appearance
Random Dot E Correct Ans-mostly with young kids, purely global stereopsis; three cards
(blank, embossed E, RDS E); tested at 50, 100, 150cm (= 500", 250", 168")
Random Dot E procedure Correct Ans-show Model E & ask if they see; shuffle blank and
model E - display at 50cm - they are to point at E (repeat until 4/4 or 4/5); repeat with stereo E
and blank card. Continue to 100cm and 150cm if they get it right
Random Dot E recording Correct Ans-sc/cc, correct/trials, distance, stereo test used (RDE)
, Random Dot E set up Correct Ans-polarized glasses, best near correction, proper illumination
Random Dot Stereograms (RDS) Correct Ans-two sets of 4 boxes, each w/ specific amount of
disparity with hidden forms; measures global stereopsis (no monocular clues); more sensitive
randot stereo book Correct Ans-tests both local (Wirt circles) and global stereopsis (random
dot stereograms)
Randot stereo book procedure Correct Ans-start with RDS forms - 500" and 250". (+) if at
least 1 correct. If unable, probably a constant strab. Check local stereopsis next if they passed
global
Randot stereo book set-up Correct Ans-full illumination, near correction, polarization and at
40cm -- "testing depth perception". Cannot shake book or head
RDS if strabismic Correct Ans-Constant strabismic likely unable to identify any forms on
RDS (dont need to check local); but can ID Wirt circles up to 70" b/c of monocular clues
Recording RDS Correct Ans-cc/sc; level of stereo with Wirt circles; level of global stereo;
suppression; stereo test used
Red Reflex Correct Ans-reflection off of the retina; stand ~2ft from pt with no power in O-
scope; move side-to-side and up/down; opacities are shadows