Biometry for Premium IOLs 2016

Jack T. Holladay MD MSEE FACS Page 1 of 6

4/10/2016 JTH 1

Improvement Strategies: Biometry,

Topography, Power Calcs to

Ref Surprises

Jack T. Holladay, MD, MSEE, FACSClinical Professor of Ophthalmology

Baylor College of MedicineHouston, Tx 4/10/2016 JTH 2

The Promise of No Glasses

or Contact Lenses !

4/10/2016 JTH 7

Requirements

Accurate Biometry – Optical

(IOL Master or LenStar)

Accurate K’s- Repeatable

4th Generation Formula (WTW)

Personalized Lens Constant

Eliminate Corneal Astigmatism4/10/2016 JTH 8

4/10/2016 JTH 9

Subtractfrom Ascanmeasured

Axial Length~ 0.8 mm

Zeiss - IOL Master - 2000Zaldivar-Holladay JCRS May 2000

4/10/2016 JTH 10

J Cataract Refract Surg 2011; 37:2018–2027

Biometry for Premium IOLs 2016

Jack T. Holladay MD MSEE FACS Page 2 of 6

4/10/2016 JTH 11

Linear Regression to compensate for AVERAGE Index of Refraction in Long Eyes

Measured 36 34 mm

4/10/2016 JTH 12

Requirements

Accurate Biometry – IOL Master

Accurate K’s- Repeatable

4th Generation Formula (WTW)

Personalized Lens Constant

Eliminate Corneal Astigmatism

4/10/2016 JTH 13

IOL Power Calculations Pentacam can measure FRONT &

BACK SURFACE POWER

Can Calculate: Equivalent K-Reading (EKR)

65% Mean, Peak & Average

NET POWER4/10/2016 JTH 14

EKR Reports Keratometry value but adjusts

for Back Surface Power from Normal (Current IOL Formulas)

If corneal front surface is 7.5 mm (45 D), but if back surface -0.3 D > normal:

EKR = 45.0 – 0.3 = 44.7 D

Note: Net Power = 43.3 D

4/10/2016 JTH 15Holladay Report Equivalent K-Reading

EKR

4/10/2016 JTH 16

Biometry for Premium IOLs 2016

Jack T. Holladay MD MSEE FACS Page 3 of 6

4/10/2016 JTH 23

IOL Calcs – Abnormal Cornea(Use 65% MEAN EKR) Post Refractive Surgery

Post PKP

Keratoconus

Corneal Scar

Any Irregular Astigmatism4/10/2016 JTH 24

Use 65% Mean EKR( @ 4.5, 4 & 3 mm zones)

4/10/2016 JTH 25

Normal LASIK RK41 to 44 D3 D Range

36 to 41 D5 D Range

32 to 45 D13 D Range

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POST LASIK

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Post LASIK CALC Kmean = 39.8 D

Used 39.8 D => SEQ = +1.12 D

(+1.00 + 0.25 X 155 = 20/20)

65% mean = 38.8 D => +0.12 D

Use 65% mean K4/10/2016 JTH 30

Conclusions EKR – Use 65% Mean for all

IOL Calcs

Look @ smaller zones than 4.5 mm if pupil very small

(< 3.0 mm in dim light)

Biometry for Premium IOLs 2016

Jack T. Holladay MD MSEE FACS Page 4 of 6

4/10/2016 JTH 31

Requirements

Accurate Biometry – IOL Master

Accurate K’s- Repeatable

4th Generation Formula (WTW)

Personalized Lens Constant

Eliminate Corneal Astigmatism4/10/2016 JTH 32

Vergence Formula

IOLAL ELP

DPostRxV

K(Post R)ELP

1336 13361336

10001000

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CONCLUSION: 9 EYESA

nter

ior

Seg

men

t Siz

e

Axial LengthShort Normal Long

Large

Normal

Small

Megalocornea Large Eye

+ axial Megalocornea Buphthalmos

hyperopia Megalocornea

+ axial myopia

axial hyperopia normal axial myopia

Small eye Microcornea

Nanophthalmia Microcornea + axial mopia

(20%)

(10%)(2%)

(2%)

(80%) (96%) (90%)

(0%)

(0%)

4/10/2016 JTH 35

Measurements taken forPredictors of ELP

Axial Length

Average K (Pre Ref)

Horizontal WTW

ACD

LT

Pre-opRefraction

Age4/10/2016 JTH 36

FORMULA PERFORMANCE

15 20 25 300

12

34

56

Axial Length (mm)Mea

n A

bsol

ute

Err

or (

D)

Holladay 1Hoffer QSRK/THolladay 2

N = 997

Biometry for Premium IOLs 2016

Jack T. Holladay MD MSEE FACS Page 5 of 6

4/10/2016 JTH 37

Requirements

Accurate Biometry – IOL Master

Accurate K’s- Repeatable

4th Generation Formula (WTW)

Personalized Lens Constant

Eliminate Corneal Astigmatism4/10/2016 JTH 38

Personalized Lens Constant Never use Manufacturer’s Constant

except to start 20 to 40 cases and continue Factors IOL Style Lens placement Post op medications Biometer, keratometer, …

4/10/2016 JTH 62

Requirements

Accurate Biometry – IOL Master

Accurate K’s- Repeatable

4th Generation Formula (WTW)

Personalized Lens Constant

Eliminate Corneal Astigmatism

TORIC IOL Calculations Commercial Calculators use a constant ratio (1.46) for

the corneal cylinder to the IOL cylinder Exact Calculation depends on IOL SEQ Power and ELP

… to correct 2D of corneal astigmatism 10 D IOL => 3.5 D Cylinder 22 D IOL => 2.9 D Cylinder 34 D IOL => 2.4 D Cylinder

A 1.1 D difference from 10 D to 34 D!

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Toric Optimization

Biometry for Premium IOLs 2016

Jack T. Holladay MD MSEE FACS Page 6 of 6

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PREOP 6 D Toric IOLLEF

4/10/2016 JTH 69

PREOP 6 D Toric IOL -- ODLEF

4/10/2016 JTH 70

PREOP 6 D Toric IOL -- OSLEF

4/10/2016 JTH 71

!Thank You!