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IOL Power Calculations

Cataract Surgery Arizona

Wang - Koch - Maloney Method.1

The Modified Maloney Method of post-LASIK corneal power estimation was originally described by the well-known refractive surgeon Robert Maloney and subsequently modified by Doug Koch and Li Wang.

The advantage of this method is that it requires no historical data and has been reported to have a low variance when used with either the Holliday 2 formula or a 2-variable formula combined with an Aramberri double K method correction nomogram published by Koch and Wang.1

Using this technique, the central corneal power is estimated by placing the cursor at the exact center of the Axial Map of the Zeiss Humphrey Atlas topographer. This value is then converted back to the anterior corneal power by multiplying the Axial Map central topographic corneal power by 376.0/337.5, which is the same as 1.114. An assumed posterior corneal power of 6.1 D is then subtracted from this product.

(CCP x 1.114) - 6.1 = Post-LASIK adjusted corneal power Cataract Surgery ArizonaWhere...

 CCP = the corneal power with the cursor in the center of the Axial Map Cataract Surgery Arizona of the Zeiss Humphrey Atlas topographer.

The Modified Maloney method for the right eye following LASIK is carried out as follows:

 

If the Axial Map central corneal power is 40.91 D, then...

  (CCP x 1.114)   -   6.1   =   Post-LASIK adjusted corneal power
           
  (40.91 D x 1.114)   -   6.1   =   39.47 D

 

The Modified Maloney method for the left eye following LASIK is carried out as follows:

 

If the Axial Map central corneal power is 41.36 D, then...

  (CCP x 1.114)   -   6.1   =   Post-LASIK adjusted corneal power
           
  (41.36 D x 1.114)   -   6.1   =   39.98 D

References

1. Wang L, Booth MA, Koch DD. Comparison of intraocular lens power calculations methods in eyes that have undergone LASIK. Ophthalmology 2004 111(10) 1825-1831.