Mandell-Moore Guide for Empirical Bitoric Design

Click here for a blank guide, which you can print for your office.

Mandell-Moore Bitoric Lens Guide – Per Eye

1. Keratometry @ @
2. Spectacle Rx (Minus Cyl Form) x
Flattest K Sphere
Power
Steepest K Sph+Cyl
Power
3. Enter K
4. Enter Spectacle Power
5. Vertex Adjust Line 4
6. Insert Fit Factor (-) (+) (-) (+)
Add Lines (3&6) (5&6) (3&6) (5&6)
7. Final CL Rx
Base Curve Power Base Curve Power

Bitoric Lens Fit Factor

Corneal CylFit Flat MeridianFit Steep Meridian

2.0 Diopters On K (0 D) 0.50D Flatter
2.5 Diopters 0.25D Flatter 0.50D Flatter
3.0 Diopters 0.25D Flatter 0.75D Flatter
3.5 Diopters 0.25D Flatter 0.75D Flatter
4.0 Diopters 0.25D Flatter 0.75D Flatter
5.0 Diopters 0.25D Flatter 0.75D Flatter

Instructions

  • On line 1 and 2 enter the patient Keratometry readings and Spectacle Rx respectively.
  • On line 3 enter the flattest K in the box on the left side and the steepest K in the box on the right.
  • On line 4 enter the sphere power in the box on the left and the sphere power plus the cylinder power in the box on the right.
  • If the powers noted in line 4 are greater than or equal to +/- 4.00 D an adjustment for vertex distance is entered in line 5. Vertex adjusted powers are used to complete the remaining calculations.
  • Use the Fit Factor Chart above for the values needed to be entered into line 6. The amount of corneal cyl will determine the Fit Factor for the flat and steep meridians. “On K” has a 0 Fit Factor.
  • Add/Subtract the lines as noted and enter the results in line 7. These are the actual numbers that you will give the lab to manufacture your bitoric lens. They are referred to as drum value.

Example of How to Fill in the Guide

1. Keratometry 42.50 @ 180 46.00 @ 90
2. Spectacle Rx (Minus Cyl Form) -4.00 -4.00 x 180
Flattest K Sphere
Power
Steepest K Sph+Cyl
Power
3. Enter K 42.50 46.00
4. Enter Spectacle Power -4.00 -8.00
5. Vertex Adjust Line 4 -3.75 -7.25
6. Insert Fit Factor (-) 0.25 (+) 0.25 (-) 0.75 (+) 0.75
Add Lines (3&6) (5&6) (3&6) (5&6)
7. Final CL Rx 42.25 -3.50 45.25 -6.50
Base Curve Power Base Curve Power

Click here for a blank guide, which you can print for your office.