How to Pick Correct Lap Tool?

[jeepj27]

Hi Everyone - I have perhaps a basic question....

Can you explain how to pick the proper Lap tool for a given prescription?

Is there a proper formula?

For Instance an Rx:

OD: -0.75 -1.00 x 072
OS: +1.50 -1.00 091

THanks in advance for any help....!

[Lab Insight]

Hi Everyone - I have perhaps a basic question....

Can you explain how to pick the proper Lap tool for a given prescription?

Is there a proper formula?

For Instance an Rx:

OD: -0.75 -1.00 x 072
OS: +1.50 -1.00 091

THanks in advance for any help....!

Simple math in theory using a lens clock to measure F1, F2, however without using software will require a sagittal depth meter to measure exact F1.

Assuming you are going to conventionally concave surface these lenses instead of stock using a 6 base curve:
OD: -0.75 -1.00, F1 = 6.00, F2 would equal -6.75/-7.75 which is the lap you would use and should fit F2 perfectly
OS: +1.50 -1.00, F1= 6.00, F2 would equal -4.50/-5.50 which is the lap you would use and should fit F2 perfectly

[lensmanmd]

Simple math in theory using a lens clock to measure F1, F2, however without using software will require a sagittal depth meter to measure exact F1.

Assuming you are going to conventionally concave surface these lenses instead of stock using a 6 base curve:
OD: -0.75 -1.00, F1 = 6.00, F2 would equal -6.75/-7.75 which is the lap you would use and should fit F2 perfectly
OS: +1.50 -1.00, F1= 6.00, F2 would equal -4.50/-5.50 which is the lap you would use and should fit F2 perfectly

Don't forget index of material and pad compensation. In CR39, the above would be -6.87/-8.00 lap.