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METODOLOGIE DI CALCOLO

Giacomo Savini

Studio Oculistico d’Azeglio – Bologna

ICCRS Fondazione GB Bietti – Roma

METODOLOGIE DI CALCOLO

Condizioni necessarie per un calcolo accurato

1) Strumentazione (biometria) aggiornata

2) Formule aggiornate

3) Costanti ottimizzate

Giacomo Savini

BIOMETRIA

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ULTRASUONI

OTTICA

BIOMETRI AD ULTRASUONI

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Tecnica ad immersione

Ottimizzazione costanti

Stessa accuratezza della biometria ottica


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Confronto Immersione - Tomey - Topcon

Campione = occhi con SN60WF

Criteri di esclusione

Stafiloma

Mancanza di misurazioni con 1 dei 3

metodi

CDVA postop <5/10


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Totale = 217 occhi (Aprile 2011-Giugno 2018)

107 occhi con misurazioni disponibili per tutti

i 3 metodi

Immersione Aladdin OA-2000

Lunghezza 24.13 +/-1.52 24.20 +/-1.56 24.21 +/-1.56

< 22 2 (1.9%)

22-24.5 73 (68.2%)

24.5-26 22 (20.6%)

>26 10 (9.3%)


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Median Absolute Error = differenza fra refrazione

predetta e refrazione postoperatoria (D)

Friedman’s test

(nonparametric

ANOVA)

p = 0.6036

Friedman’s test

(nonparametric

ANOVA)

p = 0.7680

Friedman’s test

(nonparametric

ANOVA)

p = 0.8044

Friedman’s test

(nonparametric

ANOVA)

p = 0.5578


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Percentuale di occhi con

errore di predizione ≤0.5 D


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Conclusioni:

No differenze significative fra biometria

ad immersione e biometria ottica

Vantaggi biometria ottica

maggiore velocità, minore invasività

formule di Barrett e Olsen

Vantaggi biometria ad immersione

Sum-of-segments


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BIOMETRI OTTICI

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Haag-Streit

LenStar

Haag-Streit

EyeStar 900

Movu

Argos

Nidek

AL-Scan

Oculus

Pentacam AXL

Heidelberg

Anterion

Zeiss

IOLMaster 700

Ziemer

Galilei G6

Tomey

OA-2000

Topcon

Aladdin

BIOMETRI OTTICI

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Non esistono prove che un biometro sia più

( o meno) accurate degli altri

Uniformità misurazioni (K, ACD, AL) per

poter usufruire delle costanti ULIB

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BIOMETRI OTTICI

Aladdin OA-2000 Galilei G6

Giacomo Savini

Haigis Hoffer Q Holladay SRK/T Barrett

Tomey OA-2000 85.9% 87.9% 91.9% 87.9% -

Topcon Aladdin 85.0% (86.7%)

82.6% (84.8%)

82.6% (84.8%)

86.8% (86.1%)

- (89.4%)

Ziemer

Galilei G6 83.8% 83.8% 80.1% 82.3% 85.3%

Prediction Error ≤0.50 D

BIOMETRI OTTICI

Red = published data

Blue = larger (n=151), updated, unpublished data

CALCOLO IOL PER CHIRURGIA

REFRATTIVA DELLA CATARATTA

Giacomo Savini

Avvisare sempre i pazienti che nel 5-10%

dei casi può essere necessario un ritocco

laser per migliorare la refrazione.

LA SCELTA DELLA FORMULA

Olsen Holladay 1

Hoffer H5

SRK/T

SRK II

Haigis

Holladay 2

EVO

Hoffer Q

?

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Barrett UII

Hill-RBF Panacea

CHOOSING THE FORMULA

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FORMULE TEORETICHE L’approssimazione “Thin-lens”

La cornea ed il

cristallino sono

infinitamente sottili

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Vergenza dei

raggi dalla IOL

alla retina

Vergenza dei

raggi dalla

cornea alla IOL


Le formule “thin-lens” differiscono

principalmente per il metodo con cui predicono

la posizione della IOL

Hoffer Q < K, AL

Holladay 1 < K, AL

SRK/T < K, AL

Haigis < ACD, AL

Holladay 2 < K, AL, ACD, LT, WTW

Giacomo Savini


Giacomo Savini

Lunghezza assiale

<22 mm Hoffer Q

22-24,5 mm Media 3 formule

24,5-26 mm Holladay 1

>26 mm SRK/T

Haigis: valida in tutti i gruppi

Holladay II: valida ma superflua

SRK e SRKII: mai!

Linee guida Hoffer


Confronto Haigis-Hoffer Q negli occhi corti

Attenzione all’ACD

ACD >2.40 mm: no differenza fra Haigis e Hoffer Q

ACD <2.40 mm: Haigis più accurata di Hoffer Q

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Evitare la SRK/T negli occhi con K o piatto

Melles et al Ophthalmol 2018

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Attenzione a ACD e LT

Melles et al Ophthalmol 2018

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Nuove formule

Barrett Universal II

Olsen

Hill-RBF

EVO

Panacea

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Barrett Universal II

Formula «thin-lens» (non pubblicata)

Gratis su www.apacrs.org

ELP predetto da AL, K, ACD

LT e WTW = optionals

http://www.apacrs.org/


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Olsen (C-constant)

Basata sul ray-tracing

Posizione IOL predetta da LT e

ACD


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Hill-RBF 2.0 (Radial Basal Function)

www.rbfcalculator.org

Basata su intelligenza artificiale, no formule ottiche

Database aumentato da 3.445 a 12.419 occhi

Potere fino a -5 D

Target Rx diversa da zero

http://www.rbfcalculator.org/


Giacomo Savini

EVO (Emmetropia Verifying Optical) Formula

www.evoiolcalculator.com

Thick-lens formula (non pubblicata) sviluppata in Singapore da

T.K. Yeo, MD

Basata su K, AL e ACD (no LT)

http://www.evoiolcalculator.com


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Panacea

Thin-lens formula (non pubblicata), basata sulla formula di

vergenza standard, sviluppata da D. Flikier in Costarica

www.panaceaiolandtoriccalculator.com

Predizione ELP da K, AL, ACD, LT

Il potere corneale include informazioni sul rapporto A/P e Q-

value

Disponibile gratuitamente come app

http://www.panaceaiolandtoriccalculator.com


Giacomo Savini

Intraocular lenspower formulaaccuracy:

Comparison of 7formulas

Jack X. Kane, MBBS, Anton Van Heerden, MBChB, FRANZCO, Alp Atik, MBBS,

ConstantinosPetsoglou, MBBS, MMed(Clin.Epi), FRANZCO

PURPOSE: Toassesstheaccuracyof 7intraocular lens(IOL) power formulas(Barrett Universal II,

Haigis, Hoffer Q, Holladay1, Holladay2, SRK/T, andT2) usingIOLMaster biometryandoptimized

lensconstants.

SETTING: Public hospital ophthalmologydepartment.

DESIGN: Retrospectivecaseseries.

METHODS: Data from patients having uneventful cataract surgery with Acrysof IQSN60WFIOL

implantationover 5yearswereobtainedfromthebiometryandpatient charts. Optimizedlenscon-

stantswerecalculatedfor eachformulaandusedtodeterminethepredictedrefractiveoutcomefor

each patient. This was compared with theactual refractive outcometo givetheprediction error.

Eyeswereseparatedintosubgroupsbasedonaxial length(AL) asfollows:short (%22.0mm),me-

dium(>22.0 to<24.5mm), mediumlong(R 24.5 to<26.0mm), and long(R 26.0mm).

RESULTS: Thestudy included3241patients. TheBarrett Universal II formulahad thelowest mean

absolutepredictionerror over theentireALrange(P<.001, all formulas) aswell as in themedium

(P<.001, all formulas), medium-long(P<.001, except Holladay1andT2), andlongAL(P<.001,

except T2) subgroups. Nostatisticallysignificant differencewasseenbetweenformulas in theshort

AL subgroup. Overall, the Barrett Universal II formula resulted in the highest percentage of eyes

withpredictionerrorsbetweenG0.25diopter D, G0.50D, andG1.00D.

CONCLUSION: IneyeswithanALlonger than22.0mm, theBarrett Universal II formulawasamore

accuratepredictor of actual postoperativerefraction than theother formulas.

Financial Disclosure: Noneof theauthorshasafinancial or proprietary interest inanymaterial or

methodmentioned.

JCataract Refract Surg2016; 42:1490–1500Q 2016ASCRSandESCRS

Ongoing advances mean that cataract surgery is

now arefractiveoperation and not simply an extrac-

tion procedure. Changes in surgical technique have

resulted in amorepredictablepostoperativeintraoc-

ular lens(IOL) position,1 and partial coherenceinter-

ferometry (PCI) has increased the precision of

preoperative measurements, leading to improved

postoperativerefractiveresults.2New IOL power for-

mulas have attempted to improve the accuracy of

their refractive outcome predictions, predominantly

by increasing the number of variables they assess.

Thenumber of variablesassessed rangesfrom2(Hol-

laday 1,3 Hoffer Q,4,5 SRK/ T,6T27) up to7(Holladay

2A). Theoretically, increasing thenumber of relevant

variables assessed should increase the accuracy in

predicting postoperative refraction, but many of

these newer formulas have not been adequately

assessed.

Few studieshaveevaluated asubstantial number of

eyesacross theentireaxial length (AL) range. Aristo-

demou et al.8 tested the Hoffer Q, Holladay 1, and

SRK/ T formulas in 8108 eyes (the largest IOL power

formula study) and found that theHoffer Q was the

most accurate formula for ALs below 21.0 mm (in 1

of the2IOLsstudied), theHolladay 1trended toward

thehighest accuracy ineyesfrom23.5mmto26.0mm,

and in longeyes(O26.0mm) theSRK/ Twasthemost

accurateformula. Narvaez et al.9 studied 643eyesus-

ing theHolladay 2, Hoffer Q, Holladay 1, and SRK/ T

formulasand found no significant differencebetween

any of them. In 2043eyes, Olsen et al.10 found no dif-

ference between the Haigis, Hoffer Q, Holladay 1,

Q 2016 ASCRSand ESCRS

Published by Elsevier Inc.

1490 http://dx.doi.org/10.1016/j.jcrs.2016.07.021

0886-3350

ARTICLE

Comparison of 9 intraocular lenspower

calculation formulas

David L. Cooke, MD, Timothy L. Cooke, BA

PURPOSE:Toevaluatetheaccuracyof 9intraocular lens(IOL) calculationformulasusing2optical

biometers.

SETTING: Privatepractice, Saint Joseph, Michigan, USA.

DESIGN: Retrospectiveconsecutivecaseseries.

METHODS: NineIOL power formulapredictions with observed refractions after cataract surgery

werecomparedusing1 IOLplatform. Theperformanceof each formulawas ranked for accuracy

bymachineandbyaxial length(AL). TheOlsenwasfurther dividedbyapreinstalledversion(Olse-

nOLCR)andapurchasedversion(OlsenStandalone).TheHolladay2wasdividedbywhetherarefraction

wasentered(Holladay2PreSurgRef) or not (Holladay2NoRef). TheOLCRdeviceusedinthestudywas

theLenstar L5900andthePCI device, theIOLMaster.

RESULTS: Theformulaswererankedby thestandarddeviationof thepredictionerror (optical low-

coherence reflectometry [OLCR], partial coherence interferometry [PCI]) as follows: OlsenStandalone

(0.361, 0.446), Barrett Universal II (0.365, 0.387), OlsenOLCR (0.378, not applicable), Haigis (0.393,

0.401), T2 (0.397, 0.404), Super Formula(0.403, 0.410), Holladay 2NoRef (0.404, 0.417), Holladay

1(0.408,0.414),Holladay2PreSurgRef (0.423,0.432),HofferQ(0.428,0.432),andSRK/T(0.433,0.44).

CONCLUSIONS:Theformulasgavedifferentresultsdependingonwhichmachinemeasurementswere

used.TheOlsenformulawasthemostaccuratewithOLCRmeasurements,significantlybetter thanthe

best formulawithPCI measurements. TheOlsenwasbetter, regardlessof AL. If onlyPCI measure-

ments(without lensthickness)wereavailable,theBarrettUniversal IIperformedthebestandtheOlsen

formulaperformedtheworst. Thepreinstalledversionof Olsenwas not as goodas thestandalone

version. TheHolladay2formulaperformedbetter whenthepreoperativerefractionwasexcluded.

Financial Disclosure: Neither author has a financial or proprietary interest in any material or

methodmentioned.

JCataract Refract Surg2016; 42:1157–1164Q 2016ASCRSandESCRS

Several intraocular lens (IOL) power calculation for-

mulas are in use today. Many have been compared

with each other. In a previous paper,1 we compared

6 formulas to determine which formulas were better

“out of thebox” on 2different optical biometers. This

study broadens the topic to include formulas that

werenot availableon thesebiometersat the time the

first study was performed. The discussion section of

thispaper isorganized by each of thesenew formulas.

Thefollowing6formulaswerepreviouslyevaluated

on our dataset of 1079 eyes: Haigis,2 Holladay 1,3

Hoffer Q,4–6 Sanders-Retzlaff-Kraff/ Theoretical

(SRK/ T),7 SRK II,8 and Olsen.9 These formulas came

preinstalled on the IOLMaster (Carl Zeiss Meditec

AG) or theLenstar LS900 (Haag-Streit AG), theonly

optical biometersavailable in theUnited Stateswhen

this study was initiated. The IOLMaster is based on

partial coherenceinterferometry (PCI) and theLenstar

on optical low-coherence interferometry (OLCR).

The SRK II has been shown to bemarkedly worse

than other formulas.1 It wasthusexcluded from anal-

ysis in thisstudy. Theadditional formulasused were

the purchased (standalone) version of the Olsen for-

mula, Holladay 2,A T2,10 Super Formula,11 and the

Barrett Universal II.B

We present predictions from 9 formulas in this

study. However, some tables present up to 12 for-

mulas. This isbecausewepresent 2 distinct forms of

3formulas. Welisted themasthough they weresepa-

rate formulas because each gave distinctly different

Q 2016 ASCRSand ESCRS

Published by Elsevier Inc.

http://dx.doi.org/10.1016/j.jcrs.2016.06.029 11570886-3350

ARTICLE


Giacomo Savini

Confronto di 7 formule (3241 pazienti)

Occhi corti (n=

156): no differenze

fra le 7 formule

Occhi lunghi (n= 77):

Barrett

SRK/T

Haigis

Kane et al. JCRS 2016


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Confronto di 9 formule (1454 pazienti):

Barrett e Olsen = formule migliori

IOLMaster

Barrett = migliore

Lenstar

Olsen = migliore


Giacomo Savini

Un errore di predizione entro 0.5 D può essere ottenuto nel

70-80% dei casi


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La percentuale cala al 60% negli occhi corti (<22 mm) ed in

quelli lunghi (>26 mm)

OTTIMIZZAZIONE COSTANTI

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Le costanti fornite dai costruttori di IOL

dovrebbero essere usate solo nei primi casi,

quando non si conosce ancora la Rx postop

L’ottimizzazione della constante ci permette

di eliminare errori sistematici fra la refrazione

predetta e quella postop (azzerare l’errore di

predizione)


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Giacomo Savini

Come si ottimizzano le costanti

Metodo più semplice: software biometri

Metodo tradizionale: ULIB website

Metodo più accurato: Excel

ESEMPIO

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IOL impiantata = 24.5 D

Rx postop = 0 D

IOL TORICHE

Considerate sempre l’astigmatismo

corneale posteriore

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IOL TORICHE

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Il meridiano posteriore più curvo è quasi

sempre orientato verticalmente. 1-4

Questo allineamento genera un

astigmatismo contro regola, che si

somma a quello anteriore.

1 - Ho et al. AJO 2009

2 - Koch et al. JCRS 2012

3 - Savini et al. JCRS 2014

4 - Tonn et al. IOVS 2015

IOL TORICHE

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Anteriore Posteriore

Esempio

IOL TORICHE

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Correlazione significativa (p<0.001, r2=0.5683) fra astigmatismo

corneale posteriore ed anteriore

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IOL TORICHE

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Quali sono i risultati?

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IOL TORICHE

Giacomo Savini Giacomo Savini

Keratometric astigmatism

(D)

Total corneal astigmatism

(D)

WTR -0.59 +/-0.34 -0.13 +/-0.42

ATR 0.32 +/-0.42 0.07 +/-0.59

Curvital power

Negative = overcorrection

Positive = undercorrection

ERA = Error in Refractive astigmatism

(difference between predicted and measured astigmatism)

Sovracorrezione

Sottocorrezione

IOL TORICHE

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Quali sono i risultati?

Giacomo Savini

IOL TORICHE

Giacomo Savini Giacomo Savini, MD

64 eyes Mean absolute error (MAE)

in astigmatic power

% of eyes with absolute

error ≤0.5 D

KA (Keratron) 0.70 ±0.39 D 26.56%

TCA (Pupil / Zone) 0.69 ±0.40 D 39.06%

TCA (Pupil / Ring) 0.73 ±0.51 D 43.75%

TCA (Apex/ Zone) 0.73 ±0.48 D 40.63%

TCA (Apex/ Ring) 0.75 ±0.48 D 37.50%

TCA Sirius 0.64 ±0.38 D 43.75%

Barrett 0.55 ±0.32 D 56.25%

Abulafia-Koch 0.62 ±0.48 D 54.69%

Næser-Savini

Optimized KA

0.52 ±0.33 D 57.81%

IOL TORICHE


Næser/Savini Optimized KA

Optimized KA = 0.103 + 0.836 * Measured KA + 0.457 *cos(2*α)

https://www.soiweb.com/toric-calculator/





GRAZIE

Giacomo Savini

www.studiodazeglio.it

www.biometria-bologna.it

[email protected]

http://www.studiodazeglio.it/

http://www.biometria-bologna.it/



mailto:[email protected]

METODOLOGIE DI CALCOLO - oopi.it€¦ · METODOLOGIE DI CALCOLO Giacomo Savini Studio Oculistico...

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