Sonia Yoo, MD 1 Fernanda Piccoli, MD 1 Artur Schmitt, MD 1 Takeshi Ide, MD 1 Tsontcho Ianchulev, MD 2

Authors have no financial interest in this subject matter.

1- BASCOM PALMER EYE INSTITUTE 2- 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 Formulas Challenges

 Anatomic parameters: - axial length - keratometry  Pre-refractive surgery measurements and history  Theoretical non-optical formulas to derive optical estimate

Current biometric formulas for IOL power estimation after LASIK surgery – low prediction

Intraoperative Optical Refractive Biometry - ORB

 Intraoperative aphakic auto-refraction for IOL estimation . (Ianchulev et al, Cataract Refract Surg. 2005 Aug;31(8):1530-6)

ORB FORMULA



No Axial Length measurement needed!

No Keratometry needed!

No Pre-Op History needed!

Purpose

 To figure out a predictive factor for IOL power estimation using the ORB methodology.

Patients and Methods

 29 patients – 34 eyes  100% = myopic LASIK  INTRAOPERATIVE PROCEDURE  Phacoemulsification + cortex aspiration  Discovisc ® (Alcon, Forthworth, Texas) in the bag  APHAKIC 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

REGRESSION ANALYSIS

APHAKIC SHPERICAL EQUIVALENT

Results

 AXIAL LENGTH  Average: 24.440 mm (21.950mm – 30.670mm)  APHAKIC SPHERICAL EQUIVALENT  Average : +9.996 (+1.500 – +13.125)  POWER IOL IMPLANTED (conventio nal formulas)  Average: 20.909D (5.0D – 26.0D)

IOL

SN60WF Alcon®  MODEL IOL IMPLANTED SN60AT Alcon® LI61A0 Bausch & Lomb® OTHERS

%

58.82% 26.47% 5.88% 8.82%

Results

 Correlation between intraoperative aphakic spherical equivalent and IOL power adjusted for emmetropia. (R 2 = 0.831) 30,00 25,00

APHAKIC SE X IOL ADJUSTED FOR EMMETROPIA

y = 1,6928x + 4,1153 R² = 0,8316 20,00 15,00 10,00 5,00 Ряд1 Ряд2 Линейная (Ряд2) 0,00 0,00 5,00 10,00

APHAKIC SPHERICAL EQUIVALENT

15,00

Results

 Predictive factor derived (PF) = 2.104±0.393 (p = 0.0045)  .

ORB IOL = PF X APHAKIC SE

n = 34 Type Eyes ORB ESTIMATED IOL POWER CORRELATION WITH ADJUSTED EMMETROPIC IOL POWER

LASIK EYES R 2 = 0.889 p<0.0001

CONVENTIONAL ESTIMATED IOL POWER

R 2 = 0.778 p<0.0001

Conclusion

 ORB 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 Perspectives



Improve accuracy and usability through:

 Intraoperative ACD Measurement;  Intraoperative Wavefront Refractive Technology;  Microscope Embedded Refractive Systems (Flow-through Retinoscopy);  Optimized Tracking and Visual Axis Centration.