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Adi Levy
The clinical process
Adi Levy
Premium Center Manager, Ein-Tal Eye Center
Tel-Aviv , ISRAEL
Biometry & IOL Calculation Training
Adi Levy
Modern cataract surgery =
Cataract extraction
+
Refractive surgery
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Achieving spectacle independence is a challenge
Adi Levy
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
Adi Levy
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)
Adi Levy
IOL-Master
Holladay HIC software
ULIB (http://www.ocusoft.de/ulib/c1.htm)
Personalized Lens Constant (PLC)
Adi Levy
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
Adi Levy
How to use the precise formula
Adi Levy
Adi Levy
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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Adi Levy
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
Adi Levy
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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Adi Levy
ATLAS 1.82 @ 6
LENSTAR 1.71 @ 7
IOL-MASTER 2.46 @ 169
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Adi Levy
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
Adi Levy
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