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 Cyl

Fit Flat Meridian

Fit 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.