COMBINATION OF HYPEROPIC AND MYOPIC

ABLATION ALGORYTHMS FOR CORRECTION

OF SPHERIC ABERRATION APPEARING DURING

CORNEA ABLATION FOR MYOPIA CORRECTION

COMBINATION OF HYPEROPIC AND MYOPIC

ABLATION ALGORYTHMS FOR CORRECTION

OF SPHERIC ABERRATION APPEARING DURING

CORNEA ABLATION FOR MYOPIA CORRECTION

IRTC Eye Microsurgery State Enterprise named after S.N. Fyodorov, Moscow, Russia

Ekaterinburg Branch11

IRTC Eye Microsurgery State Enterprise named after S.N. Fyodorov, Moscow, Russia

Ekaterinburg Branch11

Kh.P.TakhchidiKh.P.Takhchidi, , O.A. KostinO.A. Kostin11, , A.V.DogaA.V.Doga, , S.V. Rebrikov,S.V. Rebrikov,11, ,

A.A. StepanovA.A. Stepanov11 , A.I. Ovchinnikov , A.I. Ovchinnikov11. .

Kh.P.TakhchidiKh.P.Takhchidi, , O.A. KostinO.A. Kostin11, , A.V.DogaA.V.Doga, , S.V. Rebrikov,S.V. Rebrikov,11, ,

A.A. StepanovA.A. Stepanov11 , A.I. Ovchinnikov , A.I. Ovchinnikov11. .

J Refract Surg. 2000 Jul-Aug;16(4):407-13J Refract Surg. 2000 Jul-Aug;16(4):407-13

AIMAIMAIMAIM

• To develop the technology for correction To develop the technology for correction of spheric aberration appearing during of spheric aberration appearing during

excimer laser cornea ablation for myopia excimer laser cornea ablation for myopia correctioncorrection

• To compare refraction, visual acuity, and To compare refraction, visual acuity, and spheric aberration after wavefront-guidedspheric aberration after wavefront-guided

and combined excimer laser surgeryand combined excimer laser surgery

• To develop the technology for correction To develop the technology for correction of spheric aberration appearing during of spheric aberration appearing during

excimer laser cornea ablation for myopia excimer laser cornea ablation for myopia correctioncorrection

• To compare refraction, visual acuity, and To compare refraction, visual acuity, and spheric aberration after wavefront-guidedspheric aberration after wavefront-guided

and combined excimer laser surgeryand combined excimer laser surgery

PATIENTS AND METHODSPATIENTS AND METHODS • Aberrometry with 6 mm diameter - WASCA aberrometer (Carl Zeiss

Meditec)• Keratotopography – ATLASTM 995 (Carl Zeiss Meditec) • Flap formation - Hansatome Excellus microkeratome (B&L) • Excimer laser ablation with 6 mm diameter - MEL-80 excimer laser

(Carl Zeiss Meditec)

Wavefront-guided ablation was performed with the use of CRS-Master (Carl Zeiss Meditec)

Combined ablation was performed in 2 steps during one operation: 1. Myopic ablation with the depth corresponding to the degree of

myopia increased by 2.0 D for mild myopia and by 2.5 D for moderate myopia.

2. Hyperopic ablation with the depth corresponding to +1.0 D for mild myopia and +1.5 D for moderate myopia.

PATIENTS AND METHODSPATIENTS AND METHODS

Group 1Group 1

• 20 20 patientspatients (40 (40 eyeseyes))

• SESE – 4,67 D– 4,67 D ± ± 1,94D 1,94D (range,(range, -1 -1,5,5 D to D to –– 7,63D 7,63D))

• UCVAUCVA 0,05±0,02 0,05±0,02• BCVABCVA 1,0±0,06 1,0±0,06• Z (4,0) Z (4,0) 00,08,08 ±± 0, 0,23 23 μμmm

(Malacara notation)(Malacara notation)• RMS HORMS HO: 0,: 0,2828 ± 0, ± 0,2211μμmm

wavefront-guided LASIKwavefront-guided LASIK

Postoperative follow-upPostoperative follow-up 6 6 months months

• SESE – – 33,,9393 D D ± ± 1, 1,0505DD (range,(range, - -2,2,75 75 D to D to –– 77,,0000DD))

Group 2Group 2

• 14 14 patientspatients (20 (20 eyeseyes))

• UCVAUCVA 0,05±0,020,05±0,02• BCVA BCVA 1,001,00• Z (4,0) Z (4,0) 0,01 0,01 ±± 0,19 0,19 μμmm

(Malacara notation)(Malacara notation)• RMSRMS HO HO 0,24 ± 0,070,24 ± 0,07μμmm

combined LASIKcombined LASIK

RESULTSRESULTS

achieved

p l a n n e d

REFRACTIVE EFFECT (6 months)

Group 1Group 1 - - wavefront-guidedwavefront-guided LASIKLASIK Group 2Group 2 - - combined LASIKcombined LASIK

RESULTSRESULTS

REFRACTION CHANGES

beforebefore 11monthmonth

33mos.mos.

66mosmos..

Group 2Group 2 - - combined LASIKcombined LASIK

beforebefore 11monthmonth

33mosmos..

66mosmos..

Group 1Group 1 - - wavefront-guidedwavefront-guided LASIKLASIK

VISUAL ACUITY CHANGES

RESULTSRESULTS

0

0,2

0,4

0,6

0,8

1

1,2

before 1 month 3 months 6 months

UCVA - wavefront-guidedLASIK

BCVA - wavefront-guidedLASIK

UCVA - combined LASIK

BCVA - combined LASIK

RESULTSRESULTS

HIGHER ORDER ABERRATIONS

RMS HO (RMS HO (μμm)m)

Spheric Spheric aberrationaberration (Malacara (Malacara

notation,notation,μμm)m)WAVEFRONT-WAVEFRONT- GUIDED LASIKGUIDED LASIK

COMBINED COMBINED LASIKLASIK

WAVEFRONT-WAVEFRONT- GUIDED GUIDED LASIKLASIK

COMBINED COMBINED LASIKLASIK

BeforeBefore 0,0,2424 ± ± 0,0,0707

0,0,2828 ± ± 0,0,2211

0,08 0,08 ±± 0,230,23

0,01 0,01 ±± 0,190,19**

66 months months afterafter

0,48 0,48 ±± 0,230,23

0,33 0,33 ±± 0,130,13

-0,53 -0,53 ±± 0,210,21

-0,01 -0,01 ±± 0,260,26**

** pp>0,05>0,05

RESULTSRESULTS

Numerical keratotopographic map 6 months after surgery. A significant increase of corneal refraction (marked with red oval) from cornea center (0 mm) to the periphery (6 mm) is seen in wavefront – guided LASIK group (∆ 0,94 D) while it is almost absent in combined LASIK group (∆ 0,17 D).

Numerical keratotopographic map 6 months after surgery. A significant increase of corneal refraction (marked with red oval) from cornea center (0 mm) to the periphery (6 mm) is seen in wavefront – guided LASIK group (∆ 0,94 D) while it is almost absent in combined LASIK group (∆ 0,17 D).

COMBINED LASIK OSCOMBINED LASIK OSWAVEFRONT-WAVEFRONT- GUIDED LASIK GUIDED LASIK ODOD

RESULTSRESULTSWAVEFRONT-WAVEFRONT- GUIDED LASIK GUIDED LASIK ODOD

The value of spheric aberration 6 months after surgery (red arrow indicates the numeric value of spheric aberration). A significant increase of negative spheric aberration in wavefront – guided group (Z(4,0) - 0.674 µm, Malacara notation) compared to combined LASIK (Z(4,0) 0.000 µm, Malacara notation).

The value of spheric aberration 6 months after surgery (red arrow indicates the numeric value of spheric aberration). A significant increase of negative spheric aberration in wavefront – guided group (Z(4,0) - 0.674 µm, Malacara notation) compared to combined LASIK (Z(4,0) 0.000 µm, Malacara notation).

COMBINED LASIK OSCOMBINED LASIK OS

CONCLUSIONSCONCLUSIONS

• During customized correction of higher order aberrations it is During customized correction of higher order aberrations it is

necessary to take into consideration not only preoperative necessary to take into consideration not only preoperative

wavefront aberration data, but also biomechanical changes wavefront aberration data, but also biomechanical changes

of the cornea taking place during ablationof the cornea taking place during ablation

• Combination of myopic and hyperopic ablation during Combination of myopic and hyperopic ablation during

correction of myopia is able to correct spheric aberration correction of myopia is able to correct spheric aberration

appearing due to ablation-induced biomechanical changes of appearing due to ablation-induced biomechanical changes of

the corneathe cornea