ADVANCED IOL POWER CALCULATIONS Jack T ... - ascrs 2012

Jack T. Holladay, M.D., M.S.E.E., F.A.C.S.ADVANCED IOL POWER CALCULATIONSJack T. Holladay, MD, MSEE, FACSI. Formulas and MeasurementsA. Variables Used to Predict ACD1. Binkhorst 2 - 1981 - AL2. Holladay 1 - 1988 - AL, K3. SRK/T - 1990 - AL, K4. Hoffer Q - 1993 - AL, K5. Olsen - 1995 - AL, K, ACD6. Clarke- 1996 - AL, K1, K2 ACD, LT7. Holladay 2 - 1996 - AL, K, HWTW, REF, ACD, LT, AGEB. Normal Values for required Measurements1. Axial Length: mean = 23.5 mm, SD = 1.25 mm2. Keratometry: mean = 43.81 D, SD = 1.6 D3. Horizontal White-to-White (Corneal diameter): mean = 11.7 mm, SD = 0.46 mm4. Preoperative Refraction: mean = plano5. Anterior Chamber Depth (ultrasonic): mean = 3.1 mm, SD = 0.30 mm6. Crystalline Lens Thickness (ultrasonic): mean = 4.7 mm, SD = 0.41 mm7. Age: mean = 72, SD = 12 yearsII. Axial length Measurements in Aphakic and Pseudophakic eyesA. Aphakia - 1532 M/secB. Pseudophakia1. PMMA - 2718 M/sec2. Silicone - 980 M/sec3. Acrylic- 2120 M/secIII. Determination of corneal power following Keratorefrative Sx (PRK, LASIK, RK)A. Manual KeratometryB. Automated KeratometryC. Corneal TopographyD. Calculation from pre- keratorefractive surgery K’sE. Determination from hard contact lens trialIV. Data Screening Techniques on Preoperative MeasurementsA. Probability of unusual measurements (one eye only)B. Probability of asymmetrical measurements (both eyes)V. IOL Calculations requiring Axial Length MeasurementsA. Standard Cataract Removal with IOL1. Piggy-Back IOL’s: Use 34 D IOL posterior in bag2. Multifocal IOL’s: Target distance plano, near for -3.00 D.3. Toric IOL’s: IOL Toricity must always be less than corneal astigmatismB. Cataract Removal with IOL and Silicone in Vitreous: use convexplano ~ 3 D more, forbiconvex ~ from 5 - 6 D more in IOL.VI. IOL Calculations not requiring Axial LengthA. Secondary Implant for Aphakia: in sulcus or anterior chamber angleB. AC IOL in phakic patient: High myopia ( - IOL) & High hyperopia ( + IOL)Page 1 of 2

Jack T. Holladay, M.D., M.S.E.E., F.A.C.S.C. Secondary Piggy-Back IOL for high hyperopia (or myopia within 1 year)VII. Pediatric IOL calculationsA. Ideal Postoperative Target Refraction: plano to -1.00 D.B. Expected Myopic Shift with age: 4 D from age 2 to age 21.VIII. Minimizing Prediction ErrorA. Personalizing Formula Constants (A-const, ACD or Surgeon Factor)B. Prediction Error vs. IOL PowerC. Creating personalized constants for subgroups1. Axial Length (< 22 mm or > 26 mm)2. Keratometry (< 40 D or > 48 D)3. Preoperative Refraction (< -4 D or > +4 D)IX. Calculating SIRC (Surgically induced refractive change)A. From pre and post operative keratometryB. From pre and post operative refractionX. Outcomes AnalysisA. Prediction Error Analysis: Mean absolute prediction error should be < 0.50 D.B. Formula Comparisons: more predictors, better results in unusual eyesC. SIRC Results: Astigmatic AnalysisD. Visual Acuity Results1. Best corrected2. UncorrectedXI. Back-calculationsA. For determining source of error with refractive surpriseB. Comparison of back-calculated lens constant and actual lens constantPage 2 of 2

ADVANCED IOL CALCULATIONS 2012AdvancedIOL Power CalculationsJack T. Holladay, MD, MSEE, FACSClinical Professor of OphthalmologyBaylor College of MedicineHouston, Texas, USAFinancial Disclosure• I have the following financial interests orrelationships to disclose:• Acufocus ® –Consultant• Allergan® – Consultant• AMO ® –Consultant• NIDEK ® –Consultant• Oculus ® –Consultant• Wavetec ® –Consultant• Zeiss ® –ConsultantJack T. Holladay, MD, MSEE, FACSwww.docholladay.comClinical Professor of OphthalmologyBaylor College of MedicineHouston, TexasFax: 713 668 7336www.docholladay.com7Vergence Formulawww.docholladay.com7• Theoretical Formula has notchanged in 100 years• Physiologic Assumptionsmay be slightly different• Retinal thickness• Corneal Index of RefractionJACK T. HOLLADAY, MD, MSEE, FACS Page 1 of 19

ADVANCED IOL CALCULATIONS 2012Vergence Formula1336 1336IOLALELP1336ELP1000K1000DPostRx VE L PEffective Lens Position• Distance from cornealvertex to principal plane ofthin IOL (no thickness)• Same as ACD, but avoidsconfusion with anatomyPrediction of E L P 26 mm35 eyes = normalJACK T. HOLLADAY, MD, MSEE, FACS Page 2 of 19

ADVANCED IOL CALCULATIONS 2012Measurements taken forPredictors of ELP Axial Length Average K Horizontal WTW ACD LT Pre-opRefraction AgeHWTW GaugeHorizontal Corneal DiameterASICO # AE ASICO # AE Normal EyesShort Eyes ( < 21 mm)100080# of Ca ases8006004002000N = 82496%2% 2%Small Normal LargeAnterior Segment Size# of Ca ases604020080%N = 9320%0%Small Normal LargeAnterior Segment SizeJACK T. HOLLADAY, MD, MSEE, FACS Page 3 of 19

ADVANCED IOL CALCULATIONS 2012Long Eyes ( > 27 mm)Normal Physiologic Values# of Ca ases806040200N = 16290%0%10%Small Normal LargeAnterior Segment Size• Al: 23.5 mm+ 1.25 mm• K: 43.81 D +1.6 D• Hwtw: 11.7 mm+ 0.46 mm• Ref: -0.60 D + 2.00 DNormal Physiologic Values• ACD: 3.1 mm• LT: 4.7 mm• Age: 72 years+ 0.30 mm+ 0.41 mm+ 12.0 yearsCritical Data• Corneal Power• “Optical” Axial Length• Horizontal “White White-toto-WhiteWhite”(11 (11.7)• AC angle = WTW + 1.0 (12.7)• Sulcus = WTW + 1.5 (13.2)• Bag = WTW – 1.0 (10.7)CONCLUSIONEye Model must includeNINEtypes of eyes not onlyTHREEment SizeAnterior SegLargeCONCLUSION: 9 EYESMegalocornea+ axial MegalocorneahyperopiaLarge EyeBuphthalmosMegalocornea+ axial myopia(10%)axial a myopia yopa(90%)(0%)(2%)Normalaxial a hyperopia opa normal axial a myopia yopa(80%) (96%) (90%)SmallSmall eyeNanophthalmia Microcornea(20%) (2%)Short NormalLongAxial LengthMicrocornea+ axial opia(0%)JACK T. HOLLADAY, MD, MSEE, FACS Page 4 of 19

ADVANCED IOL CALCULATIONS 2012Relative Importance ofPredictors for ELP Axial Length 100 Average K 76 Horizontal WTW 24 Refraction 18 ACD 8 LT 7 Age 1THE HOLLADAY 2 FORMULAMore MeasurementsMore AccuracyFORMULA PERFORMANCECONCLUSIONSMean AbsoluteError (D)654N = 997321015 20 25 30Axial Length (mm)Holladay 1Hoffer QSRK/THolladay 2• Prediction Errors in Short Eyes:significantly improved by moremeasurements• Prediction Errors in Long Eyes:due to bad Axial Lengths, B-ScanMyopic StaphylomaJACK T. HOLLADAY, MD, MSEE, FACS Page 5 of 19

ADVANCED IOL CALCULATIONS 2012Zeiss-Humphrey IOL MasterSubtractfrom AscanmeasuredAilL Axial Length~ 0.8 mmZaldivar-Holladay JCRS May 2000Zeiss-IOL Master - 2000Difficult CasesAsteroid Hyalosis (vit. debris)Extreme Length (26.5 mm)Extreme Short (< 21 mm)Pseudophakic EyesSilicone in VitreousCataract Surgery …IOL Power CalculationsFollowing RefractiveSurgeryPreoperative Assessment• Endothelial Cell Count• Pachymetry• Direct Ophthalmoscope @ 16”• Corneal Topography• Determining Corneal Power• IOL CalculationJACK T. HOLLADAY, MD, MSEE, FACS Page 6 of 19

ADVANCED IOL CALCULATIONS 2012Corneal Power afterLASIK, PRK, RK Ideally, Calculation from bothsurfaces … Calculation from Prior Data Trial Hard Contact Lens Corneal Topography Automated Keratometry Manual KeratometryPachymetry andPosteriorCorneal SurfaceNew patentedlaser cross formeasurement ofposterior cornealsurface and opticalpachymentry4 mm OZ with 6 cuts ~~ - 4.00 DJACK T. HOLLADAY, MD, MSEE, FACS Page 7 of 19

ADVANCED IOL CALCULATIONS 20123 mm pinholeRigid Contact LensTrial Frame1. Calculation from Prior Data(Pre K & Δ MR known)Pre KR Mean K= 44.00 DChange in SEQ Ref = -4.50 DCalc Mean K = 39.50 DJACK T. HOLLADAY, MD, MSEE, FACS Page 8 of 19

ADVANCED IOL CALCULATIONS 20122. Calculation from Prior Data(Post Std. K’s & Δ MR only)Post Mean K= 40.58 DChange in SEQ Ref = -4.50 450DSTD K’s: -0.24* SEQ = -1.083. Calculation from Prior Data(Post Ctr Top Power & Δ MR only)Post Mean K= 40.27 DChange in SEQ Ref = -4.50 450DCtr Top: -0.15* SEQ = -0.77Calc Mean K = 39.50 DCalc Mean K= 39.50 D4. Trial Hard Contact Lens(Rigid Contact lens only)Plano HCL Base CurveSEQ Ref without CLSEQ Ref with CL= 41.50 D= +0.50 D= -1.00 DFront K = 41.50 - 1.50 = 40.00 D40.00 D – 10% (4.50) = 39.50 DMean K= 39.50 DPost-operative• Initial Hyperopic Shift• Long Term Hyperopic Drift• ATR Astigmatism DriftJACK T. HOLLADAY, MD, MSEE, FACS Page 9 of 19

ADVANCED IOL CALCULATIONS 2012Accuracy of EKRPriorSxLASIKSTD 4.5(D)0.56LASIK 0.56RK 0.94Holladay JT, Hill WE, Steinmueller A. Corneal PowerMeasurements Using Scheimpfl ug Imaging in Eyes With PriorCorneal Refractive Surgery. J Refractive Surgery 2009:25:862-868. (October 2009 Issue of J Refr Surgery)JACK T. HOLLADAY, MD, MSEE, FACS Page 10 of 19

ADVANCED IOL CALCULATIONS 2012Holladay ReportEquivalent Keratometric PowerJACK T. HOLLADAY, MD, MSEE, FACS Page 11 of 19

ADVANCED IOL CALCULATIONS 2012Normal LASIK RK41 to 44 D3 D Range36 to 41 D5 D Range32 to 45 D13 D RangeSummary• Optimal Zone• LASIK: 4.5 mm• RK: 5.0 mm• Customize for small/large pupilspils• Accuracy• LASIK: ± 0.56 D• RK: ± 0.94 D• Error on MYOPIC sideIOL Calcs Using Axial LengthAxial Length Measurements• Cataract or Clear Lens Removal• Primary Piggy-Back IOL’s• Multifocal IOL’s• Toric IOL’s• Silicone in Vitreous Compartment• Phakia• Aphakia• Pseudophakia• PMMA• Silicone• AcrylicAL 1555ALAL 1532AL 1532 + 0.4AL 1532 - 0.6AL 1532 + 0.2Primary Piggy-Back IOL’sPrimary PIGGY-BACKINTRAOCULAR LENSES• Current Formulas are veryinaccurate• ELP underestimated due to AL• Back lens displaced posteriorly• Severe hyperopic errors (+5 D)JACK T. HOLLADAY, MD, MSEE, FACS Page 12 of 19

ADVANCED IOL CALCULATIONS 2012PolypseudophakiaUp to 4 IOL’sPIGGY-BACKINTRAOCULAR LENSESJ.T. HolladayJane LeidleinJames P. GillsMyra Cherchio“Achieving Emmetropia In Extremely ShortEyes With Two Piggy-Back PosteriorChamber Intraocular Lenses.”Ophthalmology Journal. Vol. 103.July 1996 Blue Journal”Primary PIGGY-BACKINTRAOCULAR LENSES• Loop haptic IOL’s• Always align haptics• Haptics Horizontal (3 & 9)• Plate haptic IOL’s• Perpendicular• Axis @ 45º & 135ºPrimary Piggy-BackComplicationsAcrylicInterlenticular membrane3 to 5 D hyperopic shift @ 3 yrSiliconeInterlenticular membraneFlat SpotJACK T. HOLLADAY, MD, MSEE, FACS Page 13 of 19

ADVANCED IOL CALCULATIONS 2012Complications• Induced Astigmatism forLens Tilt of 20 D IOL• 10º 0.5 D• 20º 2.0 D• 30º 5.0 D• Lens Decentration 0.5 mm• Axial Misplacement 0.5 mmComplications• Axial Misplacement of 1.0 mm• 10 D 1.0 D• 20 D 2.0 D• 40 D 4.0 D• 60 D 6.0 DMinimizing Prediction Error• Holladay 2 Formula• Personalize Constant• Prediction Error vs. IOL power• Constants for Sub-groups• Axial Length, K’s and RefractionMultifocal IOL’s• Calculate required IOL forboth distance (plano) andnear (-3.00)• Difference in IOL powers isthe add required on IOL( See Array Calc 05)JACK T. HOLLADAY, MD, MSEE, FACS Page 14 of 19

ADVANCED IOL CALCULATIONS 2012Multifocal IOL’sIOL for distance = 22.31 DIOL for near = 26.75 DIOL Add = 4.44 DChoose nearest available Add(22.5 D with 4.5 D Add)Multifocal IOL Target• Plano to slightly hyperopic (+0.1to +0.3)• Rarely myopic unless specializenear requirement for near work• Ask patient for near distancepreference and look at presentbifocals or trifocalsArray Multifocal IOLAdd• 2.6 D @ SpectaclePlane• 3.8 D @ IOL PlaneToric IOL’s• Current Formulas do notwork because calculatedifferent ELP for steep andflat meridian• Predicted ELP must be thesame for each meridian --only one IOL positionToric IOL’s• Correcting Astigmatismwith IOL• IOL Astig = 1.41 * Corneal Astig• Ex. Cornea = 1 D of astigIOL = 1.41 D of astig tocorrectRatio = 1.41 for 22 D IOL, A=118{1.20 to 1.75 ( IOL or A)}Toric IOL’s• Calculate IOL power forsteep and flat meridianusing same ELP• Difference in IOL powers isthe toricity necessary tocompletely correct cornealastigmatismJACK T. HOLLADAY, MD, MSEE, FACS Page 15 of 19

ADVANCED IOL CALCULATIONS 2012Toric IOL’s• Always choose toricity toundercorrect cornealastigmatism• Eg: Steep calc yields 24.0 DFlat calc yields27.0 D• Ideal Toricity is 3.0 D(Use 24.0 D with < 3.0 D of toricity)OptimizerMean Dev = -0.72 DJACK T. HOLLADAY, MD, MSEE, FACS Page 16 of 19

ADVANCED IOL CALCULATIONS 2012Silicone in Vitreous Cavity• Use Convexo-PlanoIOL tominimize effect of Silicone(add 3 D to calculated IOL)• If Biconvex IOL(add 6 D to calculated IOL)• When Silicone removed -- 2to 5 D of induced myopiaIOL Calculationsusing aRefractive Formula(ignore axial length)IOL Calculation without ALREFRACTION FORMULA• Secondary AC or PC IOL forAphakia• Secondary Piggy-Back AC orPC IOL for Pseudophakia• Primary AC IOL in PhakiaIOL13361336ELP1000 K1000PreRx V13361336ELP1000 K1000DPostRx VSecondary Piggy-Back IOL’sIndicationsIntolerable PseudophakicRefractive ErrorRefractive Surprises Previous RK, PRK, LASIK Bad axial length - short/long Mislabeled IOL Axially displaced Misc.JACK T. HOLLADAY, MD, MSEE, FACS Page 17 of 19

ADVANCED IOL CALCULATIONS 2012Secondary Piggy-Back CalcAdvantages over Exchange Mislabeled IOL irrelevant Less risk to capsule or zonules Mismeasured AL irrelevant No AP shift of existing IOL Fewer unknown variablesPhakic IOL Calculations• Angle supported IOL• Calculations accurate• Iris supported IOL• Calculations accurate• ICL’sPediatric IOL Calculations• Ideal Refraction: plano to -1 D• Expect average of 4 D myopicshift from age 2 to 20• Much easier to correct myopiaat age 20 than amblyopiaMinimizing Prediction Error• Holladay 2 Formula• Personalize Constant• Prediction Error vs. IOL power• Constants for Sub-groups• Axial Length, K’s and RefractionJACK T. HOLLADAY, MD, MSEE, FACS Page 18 of 19

ADVANCED IOL CALCULATIONS 2012Surgically InducedRefractive ChangeSIRC• From Keratometry• Cataract & Clear Lensectomy• Keratorefractive Sx.• From Refraction• Keratorefractive Sx.Outcome Analysis• Prediction Error (50% < 0.50 D)• Formula Comparisons• Induced Astigmastism (SIRC)• Visual Acuity• Best Corrected• UncorrectedBack-CalculationsThank you !• Helpful in determining causeof refractive surprise• Back-calculated calculated K, AL and IOLpower compared to pre-op & topost-op op remeasured values• Back-calculated calculated ELP comparedto preoperative prediction byformulaSydney• • • • The International Society of Refractive Surgery • • • •April 23,2002JACK T. HOLLADAY, MD, MSEE, FACS Page 19 of 19