Questions and Correct
Answers | New Update
Prentice Rule - ANSWER ✔✔(Power x distance in mm) /10
Cornea index of refraction - ANSWER ✔✔1.37
Tear Film, Vitreous index of refraction - ANSWER ✔✔1.33
Crystalline lens index of refraction - ANSWER ✔✔1.42
Optical Standard index of refraction - ANSWER ✔✔1.53
Crown Glass index of refraction - ANSWER ✔✔1.523
,High index of refraction - ANSWER ✔✔1.74
CR-39 index of refraction - ANSWER ✔✔1.49/1.50
Poly index of refraction - ANSWER ✔✔1.586
Air - ANSWER ✔✔1.00
How fast does light travel through air - ANSWER ✔✔186,000 mi/sec
MBS formula - ANSWER ✔✔ED+2 (decentration)+2
Focal length formula - ANSWER ✔✔1/Dioptic Power power
Dioptic Power formula - ANSWER ✔✔1/Focal Length
Antimetropia - ANSWER ✔✔Rx with unlike signs in both eyes
Anisometropia - ANSWER ✔✔Difference of 2 diopters btwn OD & OS
Anisiekonia - ANSWER ✔✔When images from right and left eye are
so different the brain can not achieve fusion
What is the Radius of a 1 diopter curve? - ANSWER ✔✔530mm
Radius formula - ANSWER ✔✔530/Power = Radius
Power formula - ANSWER ✔✔530/Radius = Power
Vertical Decentration formula - ANSWER ✔✔Seg.ht. - B/2
, How much HORIZONTAL prism tolerance is allowed? - ANSWER
✔✔2/3 of a diopter
-or-
0.667
How much VERTICAL prism tolerance is allowed? - ANSWER ✔✔1/3
of a diopter
-or-
0.333
Base Curve tolerance - ANSWER ✔✔+/-0.75
Sphere Tolerance up to 6.50 - ANSWER ✔✔+/- 0.13
Sphere Tolerance above 6.50 - ANSWER ✔✔+/- 2%
Cylinder Tolerance >1.50 - ANSWER ✔✔+/-2°
Cylinder Tolerance >0.50 / less than or equal to 1.50 - ANSWER
✔✔+/-3°
Cylinder Tolerance >0.25 / less than or equal to 0.50 - ANSWER
✔✔+/-7°
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