Methods for IOL calculations after prior LASIK

Uday Devgan MD,

The three main factors in IOL calculations are corneal power, axial length, and effective lens position. Prior LASIK makes this more challenging because it will affect the corneal power, making dioptric measurements more challenging. The prior LASIK may also affect the calculation of the effect lens position (ELP) since some formulae will use the keratometry value in determining ELP.

This printout (Nidek OPD scan) gives a tremendous amount of information. A full explanation is in the video below.
This combination tomography & topography uses dual-scheimpflug methods to image the cornea. A full explanation is in the video below.
This OCT of the cornea shows both pachymetry and epithelial mapping. A full explanation is in the video below.
The printout from the biometer gives a lot of important information, but you should not rely on the standard IOL calculations because they assume a virgin eye and this is not the case. A full explanation is in the video below.
This is the online calculator from the ASCRS. The goal is to enter as much data as you have. A full explanation is in the video below.
This is the calculation page from the ASCRS website. Which IOL power do we choose from this? A full explanation is in the video below.

IOL calculations are, in fact, estimations and this is particularly true in eyes with prior kerato-refractive surgery such as LASIK. We can get reasonably close to achieving our post-op goal of plano for this patient, but the spread of the results bell curve is wider than for virgin eyes.

Click below for the video to understand the process of IOL calcs after LASIK:

Published by Uday Devgan MD

Professor Uday Devgan MD is a Los Angeles Cataract Surgeon who authors CataractCoach.com to teach the best techniques of Cataract Surgery to Eye Surgeons from around the world.

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