DGH TECHNOLOGY SCANMATE FLEX - Post Refractive Formulas

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7. Once calculated, results will automacally be imported into the IOL Calculator Screen
and used for IOL Power Calculaons. Selecng the [OK] buon without calculang will
close the calculator and save the values entered, but will not import a Kcorr to the IOL
Calculator.
8. Use the “K Correcon Method” drop-down box on the IOL Calculator Screen to see the
corrected corneal power (Kcorr) predicted by the other Post Refracve Formulas. If the
new method selected requires informaon that has not been entered, the Post Refracve
Calculator will open automacally. Once the desired Post Refracve Formula has been
selected, proceed with the IOL Power Calculaon.
POST REFRACTIVE FORMULAS
It has been well established that the corneal power for paents that have undergone corneal
refracve eye surgery cannot be accurately measured using current keratometry or topography
methods. The Post Refracve Calculator included with the Scanmate soware helps predict the
true corneal power for paents that have undergone corneal refracve surgery. The Scanmate
soware is equipped to calculate the corrected corneal power (Kcorr) using History Derived,
Clinically Derived, Refracon Derived, Contact Lens Over-Correcon and Double K methods.
These methods have been implemented as described by Shammas, H. John. Intraocular lens
power calculaons. Slack Incorporated, 2004
HISTORY DERIVED
The History Derived method is considered to be one of the most accurate methods for
determining the true post-surgical corneal power. Unfortunately, it also requires the most
informaon about the paent – some of which may not be available. This History Derived
method calculates the amount of correcon that was achieved through refracve surgery and
adds it to the pre-surgical corneal power. This method can be used with 3rd generaon formulas
(SRK/T, Hoer Q or Holladay 1).
Required Inputs: Pre Refracve Surgery K measurements
Pre Refracve Surgery Spectacle Refracon (S.E.)
Post Refracve Surgery Spectacle Refracon (S.E.)
CLINICALLY DERIVED
The advantage of this formula is that no informaon prior to the refracve surgery is needed.
The only input required for this method is the average (post-surgical) manual keratometry
measurement of corneal power. The disadvantage is that since the amount of correcon
achieved through refracve surgery is unknown, it is not factored into the calculaon. This
method can be used with 3rd generaon formulas (SRK/T, Hoer Q or Holladay 1).
Required Inputs: Post Refracve Surgery K measurements
( ) ( )
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−
−
−=
pre
pre
post
post
avecorr
S.E.1
S.E.
S.E.1
S.E.
K-preK
( )
1
avecorr
6.8mK-post x 1.14K
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−=