Adi Levy

The clinical process

Adi Levy

Premium Center Manager, Ein-Tal Eye Center

Tel-Aviv , ISRAEL

Biometry & IOL Calculation Training

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Modern cataract surgery =

Cataract extraction

+

Refractive surgery

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Achieving spectacle independence is a challenge

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Accurate Measurements

Precise Formulas

How to improve the accuracy of the IOL power

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Accurate Measurements

Precise Formulas

How to improve the accuracy of the IOL power

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How to achieve reliable measurements

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1. Biometry

Immersion US

OA-2000

Lenstar

IOL Master

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IOL Master

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Strict validation criteria – by W.Hill

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• Axial Length

Signal-to-noise ratio (SNR) > 10

• Keratometry

• Contact Lenses

IOL MASTER

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LENSTAR

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When optical biometry is not possible

Measurement consistency

Lacking the artifact of variable corneal compression

Always do the measurement on both eyes

Immersion US

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2. Ocular surface

A. Ocular surface problems (dry eye) influence the reliability of

the measurements.

B. Consider treatment.

C. Repeat measurements.

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1. History of amblyopia

2. History of anisometropia

3. Check glasses

4. Macular pathology

5. Repeat measurements

3. Unequal Measurements?

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Personalized Lens Constant is critical for minimizing

systematic variations that are present in all of our

instruments and surgical techniques

(the placement of the IOL, the location & design of the incision…)

4. Personalized Lens Constant (PLC)

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Personalized Lens Constant (PLC)

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IOL-Master

Holladay HIC software

ULIB (http://www.ocusoft.de/ulib/c1.htm)

Personalized Lens Constant (PLC)

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Accurate Measurements

Precise Formulas

How to improve the accuracy of the IOL power

Adi Levy

Accurate Measurements

Precise Formulas

How to improve the accuracy of the IOL power

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How to use the precise formula

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Multi-formulas

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Multi-formulas

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A. Inaccurate AL measurement:

◦ Staphyloma

◦ Fixation

B. IOL power calculation formulas

High myopia

Causes of mistakes:

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Adjustment of lens constants (Ulib)

Adjustment of AL (Koch & Wang)

Barrett’s universal formula

Aim for moderate myopia

Solutions

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Multifocal IOL

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Remember!

1. The main purpose is:

reducing dependence on glasses

2. Any multifocal IOL will somewhat compromise

contrast-sensitivity in exchange for multifocality

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How to succeed with multifocal IOL

Step #1 Patient selection

Step #2 Preoperative exams

Step #3 IOL calculation

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How to succeed with multifocal IOL

Step #1 Patient selection

Step #2 Preoperative exams

Step #3 IOL calculation

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: Patient selection includes

Personality

Lifestyle

Ocular pathology

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Personality

Perfectionist

Non-compromiser

Hypercritical

Unrealistic expectations

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Lifestyle

♦ Occupation

♦ Engineer

♦ Graphic designer

♦ Professional driver

♦ Hobbies

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AMD

Diabetic retinopathy

Retinal dystrophies

Glaucoma

Amblyopia, only eye

Ocular Pathology

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How to succeed with multifocal IOL

Step #1 Patient selection

Step #2 Preoperative exams

Step #3 IOL calculation

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1. Biometry

2. Topography / Tomography

3. Macular OCT

Preoperative exams

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1. Biometry

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2. Topography / Tomography

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High order aberrations?

Inform the patient about the risk of side effects

(halos, glare…)

Consider the option of monofocal IOL, mono-vision,

extended range of vision …

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Contraindication to multifocal IOLs is any abnormality

of the macula and the optic nerve that restricts:

Potential visual acuity

Contrast sensitivity

Field of vision

3. OCT

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How to succeed with multifocal IOL

Step #1 Patient selection

Step #2 Preoperative exams

Step #3 IOL calculation

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IOL CALCULAION

1. Multi-formula

2. Aim for emmetropia

3. Astigmatism?

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Who is the best patient?

1. Mild hyperopia

2. Easy going personality

3. No astigmatism

4. Reliable biometry

5. Realistic expectations

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Toric IOL

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20-30% of the candidates for cataract surgery have

preoperative astigmatism of 1.50D or greater

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What are we looking for?

Regular astigmatism

Reliable measurements

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What are we looking for?

Regular astigmatism

Reliable measurements

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Corneal topography :

Confirm regular, symmetrical astigmatism

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astigmatism irregularLook out for

POST PKP

POST RK

Corneal scar

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... Keratoconus

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Advanced keratoconus with regular central astigmatism

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What are we looking for?

Regular astigmatism

Reliable measurements

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What are we looking for?

Regular astigmatism

Reliable measurements

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4.29 @ 65 IOL MASTER 4.22 @ 115 4.44 @ 64 LENSTAR 4.20 @ 113 4.75 @ 59 GLASSES 5.25 @ 123 4.24 @ 71 ATLAS 4.38 @ 117 4.12 @ 61 ANTERIOR AST. (PENTACAM) 4.20 @ 124 0.60 @ 80 POSTRIOR AST. (PENTACAM) 0.50 @ 116

Summary table of astigmatism

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IOL MASTER 2.46 @ 169

LENSTAR 1.71 @ 7

GLASSES 1.50 @ 178

ANTERIOR AST. (PENTACAM) 2.00 @ 7

POSTRIOR AST. (PENTACAM) 0.20 @ 85

But….

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IOL MASTER 2.46 @ 169

LENSTAR 1.71 @ 7

GLASSES 1.50 @ 178

ANTERIOR AST. (PENTACAM) 2.00 @ 7

POSTRIOR AST. (PENTACAM) 0.20 @ 85

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ATLAS 1.82 @ 6

LENSTAR 1.71 @ 7

IOL-MASTER 2.46 @ 169

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Posterior corneal steep meridian is mostly vertical

Overcorrection WTR

Undercorrection ATR

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Solutions:

Baylor toric IOL nomogram

Barrett toric calculator

Vector analysis

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Baylor Toric IOL Nomogram (Douglas D. Koch)

WTR

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Baylor Toric IOL Nomogram (Douglas D. Koch)

ATR

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:Recommendations

1. Confirm no corneal-pathology / ocular surface

2. Look at the topographic map - r/o irregular astigmatism

3. Verify reliable measurements

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:how to improve our results –In summary

Accurate Measurements

Precise Formulas

Finding the right lens for each patient

Learning from experience

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