DGH TECHNOLOGY SCANMATE FLEX - Page 41

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REFRACTION DERIVED
This method is useful when the pre-operave K values are unknown, but the pre-operave
spectacle refracon is known.
Required Inputs: Pre Refracve Surgery Spectacle Refracon (S.E.)
Post Refracve Surgery K measurements
Post Refracve Surgery Spectacle Refracon (S.E.)
CONTACT LENS OVER-CORRECTION (CL Over-Corr)
This method requires the doctor to place a plano hard contact lens of a known curvature on the
paent’s eye. If the refracon remains the same, the corneal curvature is equal to that of the
contact lens. If the over-refracon results in a higher myopic error, the dierence in refracon is
added to the base curve value. This method can be used with 3rd generaon formulas (SRK/T,
Hoer Q or Holladay 1).
Required Inputs: Contact Lens Base Curve
Contact Lens Power
Contact Lens Over-Refracon (S.E.)
Post Refracve Surgery Spectacle Refracon (S.E.)
DOUBLE-K (SRK-T)
This method uses the pre-refracve corneal power to esmate the post-refracve anterior
chamber depth (also known as eecve lens posion). The post-refracve corneal power is
esmated using the History Derived Method. This method can be used with the SRK/T formula.
The Double K method modies the SRK-T formula to use both pre- and post-refracve surgery K
values. The pre-refracve surgery K value is used to calculate the eecve lens posion, and the
post-refracve surgery K value is used for IOL power calculaons. This method have been
implemented as described by Aramberri, J. “Intraocular Len Power Calculaon Aer Corneal
Refracve Surgery: Double-K Method.” Journal of Cataract and Refracve Surgery 29:11 (Nov
2003): 2063-2068.
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.)
( ) ( )








−
−
−
−=
pre
pre
post
post
avecorr
S.E.1
S.E.
S.E.1
S.E.
x 0.23K-postK
power
post
post
over
over
curve basecorr
CL
S.E.1
S.E.
CL x 0.012m1
CL
CLK +








−
−








−
+=