sonia yoo, md 1 fernanda piccoli, md 1 artur schmitt, md 1 takeshi ide, md 1 tsontcho ianchulev, md...
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Sonia Yoo, MD1
Fernanda Piccoli, MD1
Artur Schmitt, MD1
Takeshi Ide, MD1
Tsontcho Ianchulev, MD2
Authors have no financial interest in this subject matter.
1- BASCOM PALMER EYE INSTITUTE2- SAN FRANCISCO, CALIFORNIA
New Paradigm
More than 1.000.000 refractive surgery cases per year;
Ageing of “Baby Boomers”;
Higher expectations regarding refractive cataract surgery outcomes.
Current Biometric FormulasChallengesAnatomic parameters:
- axial length- keratometry
Pre-refractive surgery measurements and historyTheoretical non-optical formulas to derive optical estimate
Current biometric formulas for IOL power estimation after LASIK surgery – low prediction
Intraoperative Optical Refractive Biometry - ORBIntraoperative aphakic auto-refraction for IOL
estimation. (Ianchulev et al, Cataract Refract Surg. 2005 Aug;31(8):1530-6)
No Axial Length measurement needed!No Keratometry needed!No Pre-Op History needed!
ORB FORMULA
Purpose
To figure out a predictive factor for IOL power estimation using the ORB methodology.
Patients and Methods29 patients – 34 eyes100% = myopic LASIK
INTRAOPERATIVE PROCEDUREPhacoemulsification + cortex aspirationDiscovisc ® (Alcon, Forthworth, Texas) in the bagAPHAKIC AUTO-REFRACTION (Retinomax ®– Nikon, Tokyo, Japan)
IOL IMPLANT – according to SRK/T and Holladay Formulas (IOLMaster®, Carl Zeiss Meditec, Jena, Germany)
Patients and Methods
POST –OP MANIFEST SPHERICAL EQUIVALENT (1 month post-op)
ADUSTED EMMETROPIC IOL POWER
APHAKIC SHPERICAL EQUIVALENT
REGRESSIONANALYSIS
ResultsAXIAL LENGTH
Average: 24.440 mm (21.950mm – 30.670mm)
APHAKIC SPHERICAL EQUIVALENTAverage : +9.996 (+1.500 – +13.125)
POWER IOL IMPLANTED (conventional formulas)Average: 20.909D (5.0D – 26.0D)
MODEL IOL IMPLANTED
IOL %
SN60WF Alcon® 58.82%
SN60AT Alcon® 26.47%
LI61A0 Bausch & Lomb® 5.88%
OTHERS 8.82%
ResultsCorrelation between intraoperative aphakic spherical
equivalent and IOL power adjusted for emmetropia. (R2 = 0.831)
IOL
ADJU
STED
FO
R EM
MET
ROPI
A
ResultsPredictive factor derived (PF) = 2.104±0.393 (p = 0.0045).
n = 34n = 34
Type EyesType Eyes ORB ESTIMATED ORB ESTIMATED IOL POWERIOL POWER
CONVENTIONAL CONVENTIONAL ESTIMATED IOL ESTIMATED IOL
POWERPOWER
CORRELATION CORRELATION WITH WITH
ADJUSTED ADJUSTED EMMETROPIC EMMETROPIC
IOL POWERIOL POWER
LASIK EYESLASIK EYES RR22= 0.889 = 0.889 p<0.0001p<0.0001
RR22 = 0.778 = 0.778 p<0.0001p<0.0001
ORB IOL = PF X APHAKIC SE
ConclusionORB Clinical Utility
• A purely refractive methodology was derived to predict IOL power after refractive surgery (LASIK);
• The ORB method showed close correlation with conventional formulas;
• The ORB method showed close correlation with emmetropia;
• The ORB method appears to be sustainable over a large axial length range: 21.950mm – 30.670mm.
New PerspectivesImprove accuracy and usability through:
Intraoperative ACD Measurement;Intraoperative Wavefront Refractive Technology;Microscope Embedded Refractive Systems (Flow-through
Retinoscopy);Optimized Tracking and Visual Axis Centration.