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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
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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
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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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