DGH TECHNOLOGY SCANMATE FLEX, Руководство оператора

Страница: 41 / 64

41
REFRACTION DERIVED
This method is useful when the pre - operative K values are unknown, but the pre - operative
spectacle refraction is known.
Required Inputs: Pre Refractive Surgery Spectacle Refraction (S.E.)
Post Refractive Surgery K measurements
Post Refractive Surgery Spectacle Refraction (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
patient
’ s eye. If the refraction remains the same, the corneal curvature is equal to that of the
contact lens. If the over - refraction results in a higher myopic error, the difference in refraction is
added to the base curve value. This method can be used with 3rd generation formulas (SRK/T,
Hoffer Q or Holladay 1).
Required Inputs: Contact Lens Base Curve
Contact Lens Power
Contact Lens Over - Refraction (S.E.)
Post Refractive Surgery Spectacle Refraction (S.E.)
DOUBLE - K (SRK - T)
This method uses the pre - refractive corneal power to estimate the post - refractive anterior
chamber depth (also known as effective lens position). The post - refractive corneal power is
estimated using the History Derived Method. This method can be used with the SRK/T formula.
The Double K method modifies the SRK - T formula to use both pre - and post - refractive surgery K
values. The pre - refractive surgery K value is used to calculate the effective lens position, and the
post - refractive surgery K value is used for IOL power calculations. This method have been
implemented as described by Aramberri, J. “ Intraocular Len Power Calculation After Corneal
Refractive Surgery: Double - K Method. ” Journal of Cataract and Refractive Surgery 29:11 (Nov
2003): 2063 - 2068.
Required Inputs: Pre Refractive Surgery K measurements
Pre Refractive Surgery Spectacle Refraction (S.E.)
Post Refractive Surgery Spectacle Refraction (S.E.)
( ) ( )








−
−
−
− =
pre
pre
post
post
ave corr
S.E. 1
S.E.
S.E. 1
S.E.
x 0.23 K - post K
power
post
post
over
over
curve base corr
CL
S.E. 1
S.E.
CL x 0.012m 1
CL
CL K
+








−
−






−
+ =