sonia yoo, md 1 fernanda piccoli, md 1 artur schmitt, md 1 takeshi ide, md 1 tsontcho ianchulev, md...

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.