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Apr 19, 2023 161 likes •388 views

Comparison of Elasticity and Fracture Strength of Manual, Femtosecond laser and Selective Laser Capsulotomies SHERAZ M. DAYA MD FACP FACS FRCSE FRCOphth SOON-PHAIK CHEE FRCOphth FRCS(Ed), FRCS(G), MMed(Spore) SENG EI TI FRCS(Ed),

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Comparison of Elasticity and Fracture Strength of Manual, Femtosecond laser and Selective Laser Capsulotomies

SHERAZ M. DAYA

MD FACP FACS FRCSE FRCOphth

SOON-PHAIK CHEE

FRCOphth FRCS(Ed), FRCS(G), MMed(S’pore)

SENG EI TI

FRCS(Ed), MMed(S’pore)

RICHARD PACKARD

MD, FRCS, FRCOphth

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Financial Disclosure

Company Code 1. Abbott Medical Optics Inc. S 2. Bausch + Lomb C,L 3. Carl Zeiss Meditec C 4. Clarvista C 5. Ellex L 6. Excellens C, O 7. LinCor Biosciences C 8. Lumenis C 9. Medicem C 10. Nidek, Inc. C,L 11. Omeros C 12. Physiol L 13. PRN O 14. STAAR Surgical C,O 15. Strathspey Crown C 16. Scope Pharmaceuticals C 17. Rayner C

C = Consultant / Advisor E = Employee L = Lecture Fees O = Equity Owner P = Patents / Royalty S = Grant Support

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Anterior Capsulotomy

Increased interest

– Circular, central and consistent sizing

Rapid, reproducible and affordable

– Automated devices

Femtosecond laser
Radiofrequency cautery (Zepto, Mynosys)
Selective Laser Capsulotomy (CAPSULaser, EXCEL-lens)

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Non-pulsatile Laser Capsulotomy

CAPSULaser

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Capsule strength

Anterior capsule tears – hazardous

– Posterior capsule involvement – up to 50%* – Lens tilt, decentration

* Marques, F. F., et al. (2006). "Fate of anterior capsule tears during cataract surgery." J Cataract

Refract Surg 32(10): 1638-1642.

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STUDY- Purpose

Compare capsule strength

– Femtosecond Laser capsulotomy (FLACS) – Continuous curvilinear capsulorrhexis (CCC) – Selective Laser Capsulotomy (SLC)

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Materials and Methods

Human cadaver paired eye study

– 3 GROUPS of 10 paired eyes each – Study group 1: SLC to CCC – Study group 2. CCC to FLACS – Study group 3 FLACS to SLC

Scanning electron microscopy of capsule edge

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Parameters that affect Capsule strength

Laboratory study – influence of:

– Capsule size 4.7-5.0 vs 5.2-5.7mm- Bigger is better – Capsule continuity – discontinuous is weaker

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Materials and Methods

All eyes, Cornea and iris removed for visibility Exclusion Criteria:

Circularity

– minor axis was less than 90% of the major axis – 4πarea of the best-fit-circle / perimeter distance from point to point being less than 90%.

Size

– outside diameter of 5.0 mm of +/- 0.2 mm.

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Materials & Methods

Lens nucleus hydroexpressed
I/A of remaining cortex
Waxed probe inserted into bag
Zonules cut and bag removed
Instron device used to measure load

and extension to tear

STATISTICAL ANALYSIS

Wilcoxon Signed Ranks Tests

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RESULTS: Comparative Extension and Perimeter

Extension (mm) Perimeter (mm) Load (mN) Study 1 SLC 7 ± 1 29 ± 2 277 ± 38 CCC 5 ± 1 25 ± 2 190 ± 37 Study 2 CCC 5 ± 1 24 ± 2 186 ± 37 FLACS 5 ± 1 23 ± 2 145 ± 35 Study 3 FLACS 5 ± 1 23 ± 2 148 ± 31 SLC 7 ± 1 28 ± 2 269 ± 38

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RESULTS Group 1 SLC to CCC

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 1 2 3 4 5 6 7 8 9 10

Threshold Perimeter (mm) Pair #

PERIMETER: SLC vs CCC

SLC CCC

p= <0.01

50 100 150 200 250 300 350 1 2 3 4 5 6 7 8 9 10

Threshold Load (mN) Pair #

LOAD: SLC vs CCC

SLC CCC

p= <0.01

p= <0.01 p= <0.01

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RESULTS Group 2 CCC to FLACS

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 11 12 13 14 15 16 17 18 19 20

Threshold Perimeter (mm) Pair #

PERIMETER: CCC vs FLACS

CCC FLACS

50 100 150 200 250 300 350 11 12 13 14 15 16 17 18 19 20 Threshold Load (mN) Pair #

LOAD: CCC vs FLACS

CCC FLACS

p= <0.01 p= <0.2

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RESULTS Group 3 SLC vs FLACS

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 21 22 23 24 25 26 27 28 29 30 Threshold Perimeter (mm) Pair #

PERIMETER: SLC vs FLACS

SLC FLACS

p= <0.01

50 100 150 200 250 300 350 21 22 23 24 25 26 27 28 29 30 Threshold Load (mN) Pair #

PERIMETER: SLC vs FLACS

SLC FLACS

p= <0.01

p= <0.01 p= <0.01

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RESULTS

SLC CCC FLACS

PERIMETER (mm)

28 ± 2 24 ± 2 23 ± 2

Relative to CCC

120 ± 10% 100% 95 ± 10% LOAD

(mN)

273 ± 37 186 ± 40 146 ± 32

Relative to CCC

146 ± 20% 100% 78 ± 20%

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SEM CCC

10 µm 10 µm

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10 µm

Figure 4C: Femtosecond Laser Assisted Cataract Surgery (FLACS)

20 µm

REGIONS OF ABERRANT HOLES

SEM - FLACS

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SEM SLC

ANTERIOR CAPSULE

250 µm

EDGE EDGE EDGE EDGE AMORPHOUS COLLAGEN

10 µm

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SLC Strength

1. doubling of the capsular edge thickness 2. the rolled-over folded edge which itself increases mechanical strength 3. smooth edge devoid of irregularity and defect 4. thermal change of the anterior capsule = regular ordered Collagen Type IV to amorphous collagen with increased elasticity

AMORPHOUS COLLAGEN

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Study Strengths

1. Pairwise HUMAN cadaver eyes 2. Standardised variables: size and circularity 3. Consistent load and perimeter findings between groups (SLC vs CCC vs FLACS)

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CONCLUSIONS

1. SLC significantly stronger than both CCC and FLACS 2. CCC significantly stronger than FLACS (not previously evaluated in human eyes) 3. SLC strength may be accounted for by SEM findings

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Thank you…

Courtesy of Burkhard Dick