Haigis-L Formula - Post Hyperopic LASIK.
The Haigis-L Formula1.
Using an IOLMaster corneal radius measured in mm, the hyperopic
version of the Haigis-L algorithm generates a corrected corneal radius,
which is then used by the regular Haigis formula to calculate the IOL
power.
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Prior Hyperopic LASIK
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This corrected, average corneal power in keratometric diopters is then
used with the regular Haigis formula to calculate the power of the intraocular
lens.
In essence, what the hyperopic version of the Haigis-L formula does is begin
with a small intermediate area and then correct it based on a regression-derived
algorithm. If this corrected central corneal power is then entered into the
regular Haigis formula, it will do a good job with the calculation. This is
due to the fact that the Haigis formula does not tie the effective lens
position estimation to the central corneal power. This dependence on the central
corneal power for the effective lens position calculation is one of the drawbacks
of older, 2-variable, 3rd generation IOL power calculation formulas, such as
SRK/T, Holladay 1 and Hoffer Q, which require an Aramberri double-K method
correction to remove the artifact generated by a falsely flat central cornea.
For the IOL power determination, the hyperopic version of Haigis-L and
the Haigis formula are actually the same. The only difference between the
two is that the hyperopic version of Haigis-L first calculates a new corneal
radius based on the myopic Haigis-L algorithm.
The hyperopic version of the Haigis-L formula is now available on the most
recent IOLMaster software and also at the ASCRS on-line
post-keratorefractive IOL power calculator at iol.ascrs.org
References
1. Haigis W, Lege BAM, Neuhann TF: Bestimmung wirksamer Hornhautradien nach hyperoper LASIK. Fortschritte der Ophthalmochirurgie
(A.Scharrer, A.Reuscher, Th..Neuhann (Hrsg), 18.Kongress der Deutschen Ophthalmochirurgen. Diomed-Verlag, Ebelsbach, p.95, 2005.
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