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IOL Power Calculations

Cataract Surgery Arizona

Latkany Method.1

The Latkany Method of myopic post-LASIK corneal power estimation is a postoperative regression method developed by Robert Latkany, et al and published in the Journal of Cataract and Refractive Surgery1. The advantage of this method is that it only requires that the surgeon know the refraction prior to LASIK. This is often helpful if the pre-LASIK refraction can be located from one source (such as an old pair of glasses), but there are no records from the keratorefractive procedure available.

This technique applies a regression formula to correct the IOL power calculated using the flattest K and the SRK/T formula.

The calculated IOL power is then adjusted by the formula:

-(0.47 [Pre-refractive surgery SEq] + 0.85)

The final IOL power is rounded to the nearest 0.50 D.

-(0.47 [SEq] + 0.85] = Post LASIK IOL power adjustment Cataract Surgery ArizonaWhere...

 SEq = The pre-LASIK spherical equivalent in diopters.

The Latkany Method for the right eye following myopic LASIK would be carried out as follows:

 

If the SRK/T calculated IOL power using the flattest K is +15.21 D for a plano result, and...

The pre-LASIK spherical equivalent was -5.63 D, then...

  -(0.47 [SEq]   +   0.85)   =   Post LASIK IOL power adjustment
           
  -(0.47 [-5.63 D]   +   0.85)   =   1.80 D = IOL power adjustment
           
  +1.80 D   +   15.21 D   =   17.01 D
           
  17.01 D rounded to nearest
0.50 D		   =   17.00 D =    Final adjusted IOL power.

The Latkany Method for the left eye following myopic LASIK would be carried out as follows:

 

If the SRK/T calculated IOL power using the flattest K is +15.66 D for a plano result, and...

The pre-LASIK spherical equivalent was -5.12 D, then...

  -(0.47 [SEq]   +   0.85)   =   Post LASIK IOL power adjustment
           
  -(0.47 [-5.12 D]   +   0.85)   =   1.56 D = IOL power adjustment
           
  +1.44 D   +   15.66 D   =   17.10 D
           
  17.10 D rounded to nearest
0.50 D		   =   17.00 D =    Final adjusted IOL power.

References

1. Latkany RA, Chokshi AR, Speaker MG, Abramson J, Soloway BD and Yu G, IOL Calculatins After Refractive Surgery. Journal of Cataract and Refractive Surgery 2005; 31(3):562-570