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Flashcards in Wong's shit Deck (22)
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1
Q

5 criteria for desinging specs?

A
Functionality
aesthetics
safety
comfort
precision
2
Q

what does ansi stand for

A

american national standards institute

3
Q

what is Z80.1

what is Z87

A

Z80.1 is the code for dress eyewear

Z87 is the code for occupational sfetey

4
Q

where is the greatest power meridian

A

solve all tolerance questions using the greatest power as the “sphere” power

5
Q

what is inadvertent prism power for horizontal and vertical

A

hori: 0.33, 033, 0.66 total or 2.5mm
vert: 0.33, 0.33, 0.33 total or 1mm

6
Q

what is the 3 part definition for a base curve

A
  1. beginning curve
  2. always the front curve
  3. if there are more than 2 curves on the front then it is the flattest
7
Q

what are the definitons that define the boxing system for measuring frames?
A, B, DBL, ED, GC, GCD, DBC, FPD, datum
what does A+DBL=?

A
A-longest horizontal
B-longest vertical
DBL-least distance btwn lenses
ED-twice the longest radius
GC-geometric centers
GCD-geometric center distance
DBC-dist btwn center
FPD-frame PD
datum-half of B 
A+DBL=GCD 
GCD=DBC=FPD
8
Q

what is prism by deviation
vertical imbalance
image jump

A
  • prism by deviation: deviation in relation to power of prism at distance of 1m
  • vertical imbalance: human tolerance to prism, esp with vertical aniso
    1. when pts eye above datum line and OC on datum line
    2. when pt becomes presby and eyes travel vertically towards the near add area of lens and get double vision
  • image jump: specific to segment itself, same formula F(add)*c(dist seg line to near OC) /10
9
Q

what is the CPSREI and their primary objective

A

CPSREI: coalition to prevent sports related eye injuries

  • to warn and eliminate the use of street eye wear when engaged in sports related activites.
  • most common sports related injury is “finger to the eye”
10
Q

what is ASTM rep and what do they oversee?

A

american society for testing matierals

-testing of sport protective eyewear (F803)

11
Q

what percentage of sports related injuries could have been prevented by wearing sports protective eyewar?

A

90%

12
Q

define photochromic

A

photochromic lenses change from clear indoors to an increasingly darker color as it is exposed to more and more UV radiation

13
Q

what are polarized lens

A

polarized lenses eliminate blinding glare from a horizontal refelctive surface
-not designed to eliminate reflection on lens surface itself but BLINDING GLARE pass through lens

14
Q

what is tint

how is a gray 80 diff from a gray 20

A

the numeric value associated w/ a tint represents the amount of light that is absorbed.
a gray of 80% absorbs 80% of light and transmits 20% (and is a very dark color lens)

15
Q

what is an antireflective coating

A

coating applied to lens surfaces to decrease reflection and allow more light to pass through the elsn and eye
-increases vision, esp at night

16
Q

what is the range of abbey values

which material are the purest

A

20-60

  • greatest number is purest
  • CR-39 and crown glass are purest
17
Q

what is the advantage to an aspheric lens

A

produce some power all around but use less weight

  • doesnt follow typical definition of base curve (3rd def of being flattest curve)
  • the flattest part of lens is towards the PERIPHERY, esp on a plus lens
18
Q

what is the index to CR39, polycarbonate, and crown class

A

cr39: 1. 498
crown glass: 1.523
poly: 1.586

19
Q

what is the index that lens is calibrated

A

1.530

20
Q

what is an Abbe value

A

the lens’ potential to cause chromatic aberration, as the # gets closer to 60, the lens is considered to be more optically pure and has lesser of a chance for the pt to experience the effects of CA

21
Q

what is specific gravity

A

sp graveity of a lens is its comparative weight in grams/cubic centimeter

22
Q

what is the sagitta of an ophthalmic lens

A

the perpendicular distance for the vertex of a surface to the plane of its knife-edge thickness