Questions and Answers
a lens focal length may be altered by? - answer changing the curvature of one
surface
what controls the amount of light that enters the eye? - answer Iris
lights changing direction as it passes from one medium to another is called what? -
answer refraction
meniscus, equiconcave and flat concave are all, what? - answer minus lenses
what term is used to describe the eyes tendency to TURN from its normal position? -
answer phoria
refractive condition where light focuses directly ON the retina...? - answer
emmetriopia
one convex and one concave surface is known as... - answer a meniscus lens
best lens treatment to reduce water and road glare? - answer polarized
establishes commercial and industry standards.. - answer ANSI
hard resin used in plastic - answer cr39
multifocals are measured to the... - answer lower edge of lens not frame
corneas index of refraction - answer 1.37
lens characteristic that corrects astigmatism is called.... - answer cylinder power
progressive marks are ______ mm apart - answer 34 mm
what prism could help EXOtropia? - answer base in prism
what prism could help ESOtropia? - answer base out prism
what happens if you move a PLUS lens CLOSER to the eye? - answer loses
perceived power
what happens if you move a PLUS lens AWAY from the eye? - answer gains
perceived power
, what happens if you move a MINUS lens CLOSER to the eye? - answer gains
perceived power
what happens if you move a MINUS lens AWAY from the eye? - answer loses
perceived power
Vertical prism U&U and D&D cancel out, but U&D you ____ - answer ADD U and D
horizontal prism O&O add, I&I add, But I&O____ - answer Cancel ea other I&O
TP @ 90 first column is? - answer 0,30,45,60,90
light travels at.... - answer 186,000 mps
both sides of lens is minus? - answer biconcave
both sides of lens are plus? - answer biconvex
plus lens decentered out will make the lens.... - answer thicker temporally
minus lens decentered out will make the lens.... - answer thicker nasally
ANSI standard on pd? - answer 2.5mm
ANSI for vertical prism? - answer .33
ANSI for horizontal prism? - answer .67
ANSI for segs? - answer 1mm
ANSI for cyl axis .25-.50 - answer 7 degrees
ANSI for cyl axis 0-.25 - answer 14 degrees
ANSI for cyl axis .50-.75 - answer 5 degrees
ANSI for cyl axis .75-1.50 - answer 3 degrees
ANSI for cyl axis greater than 1.50 - answer 2 degrees
ANSI for Sphere pwr up to 6.50 - answer .13D
ANSI for Sphere pwr above 6.50 is - answer 2%
ANSI for Cyl power up to 2.00D - answer .13D