Lensometry Flashcards
How do you calculate the near add power ?
Near FVP - Distance FVP
adds are spherical, thus using the same meridian is ok
True or false: prism bends light, the vergence doesn’t change
True
(light rays will come out parallel)
Where is light deviated towards in a prism
base
Where is the image displaced/ shifted in a prism ?
apex
define the optical center of lenses
the point where prism by decentration =zero
define dist. between centers
dist. between the optical centers of L and R lens
what is inter pupillary distance
distance b/w R and L pupils
What is distance PD
the distance between the pupils when viewing a dist. object
Near PD
the distance between pupils when viewing a near object
Near Centratrion Distance
distance between visual axes, measured in the spectacle plane when viewing a near object
what is the correct way to record pupil results ?
distance PD/ near CD
What is ground/ work prism ?
same magnitude of prism all over lens
What is prism by decentration
the amount of prism varies across the lens
What range is used to calculate near PD
object to pupil plane
What range is used to calculate near CD
object to spectacle plane
