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Femtosecond Laser-Assisted Cataract Surgery Sizzle or Sausage ? Michael Forrest Senior Lecturer, The University of Queensland Director, The Queensland Eye Hospital Visiting Ophthalmologist, Mater Health Services

June 5, 2012, Queensland Eye Hospital

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What is Femtosecond Laser (FSL)?

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FSL systems use ultrashort pulses of laser and produce corneal tissue cutting using a photodisruption process; energy parameters and pulse rates differ between systems ✄

high pulse energy and low pulse frequency

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low pulse energy and high pulse frequency

FSLs create bubbles in cornea & other ocular tissues ✄

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a flap (eg LASIK flap) can be created if multiple bubbles are made in a plane parallel to surface of the cornea tissue can be removed if multiple layers are created

Lubatschowski H. Overview of commercially available femtosecond lasers in refractive surgery. J Refract Surg. 2008;24:S102–S107

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FSL-assisted cataract surgery - how do you do it? ✄

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1. Engagement (“docking”) ✄

IOP rise are modest ~8-12mmHg with Catalys

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all companies have different approaches to docking/suction

2. Image guidance system ✄

LensAR uses Scheimpflug-like 3D confocal structured illumination-scanning transmitter

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LenSx & Catalys use FD-OCT

3. Laser treatment ✄

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laser spot goes back-to-front possible delay between laser and intra-ocular instrumentation for lens removal may be hours, but the upper limit may be determined by PG release, BAB breakdown and miosis

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FSL-assisted cataract surgery - how do you do it? ✄

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1. Engagement (“docking”) ✄

IOP rise are modest ~8-12mmHg with Catalys

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all companies have different approaches to docking/suction

2. Image guidance system ✄

LensAR uses Scheimpflug-like 3D confocal structured illumination-scanning transmitter

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LenSx & Catalys use FD-OCT

3. Laser treatment ✄

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laser spot goes back-to-front possible delay between laser and intra-ocular instrumentation for lens removal may be hours, but the upper limit may be determined by PG release, BAB breakdown and miosis

www.ForrestEye.com

FSL-assisted cataract surgery - how do you do it? ✄

✄

✄

1. Engagement (“docking”) ✄

IOP rise are modest ~8-12mmHg with Catalys

✄

all companies have different approaches to docking/suction

2. Image guidance system ✄

LensAR uses Scheimpflug-like 3D confocal structured illumination-scanning transmitter

✄

LenSx & Catalys use FD-OCT

3. Laser treatment ✄

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laser spot goes back-to-front possible delay between laser and intra-ocular instrumentation for lens removal may be hours, but the upper limit may be determined by PG release, BAB breakdown and miosis

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Why the drive to femto-assisted cataract surgery?, or “why are 4+ companies pushing this technology”

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~170,000 cataract procedures in Australia annually (3.3 million in the US in 2010, 18.9 million worldwide); this is growing Alcon Inc posted 2010 EBIT of US$2.6 billion; surgical sales are responsible for ~45% of total revenue (>US$7 billion) FSL have been used in LASIK for 10 years, now worldwide the majority of LASIK flaps are cut with FSL

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Is it really all about the Benjamins?

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FSL Machine $600 000 FSL Service Contract $60 000 FSL “Click Fee” $350 to $550

Additional cost per eye $750 - $1000

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Why the drive to femto-assisted cataract surgery?, or “what are the supposed benefits for patients”

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Supposed improvements in safety ✄

reduction in anterior capsule tears

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reduction in phaco power

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better wound construction

Supposed improvement in outcomes ✄

better effective lens position (ELP)

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less surgically-induced astigmatism (SIA)

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more predictable astigmatism management with LRIs

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Corneal wounds

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cataract surgery is most commonly performed through a clear corneal incision (CCI) made with a blade (diamond or steel) there is a small increased risk of endophthalmitis associated with CCIs in some studies one cadaver study using Intralase FSL (Masket et al, 2010) shows that longer corneal tunnels leak less with FSL the surgeon is able to pre-determine the exact length and width of the CCI tunnel

M Taban et al. Acute endophthalmitis following cataract surgery: a systematic review of the literature. Arch Ophthalmol 2005; 123:613 – 620 S Masket et al. Femtosecond laser-assisted cataract incisions: architectural stability and reproducibility. J Cataract Refract Surg 2010; 36:1048 – 1049.

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Relaxing incisions

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advocates of LRIs for astigmatic control feel they are under-utilised ✄

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140,000 cataract operations performed in Australia in FY10, 2,500 LRIs; this has stayed static even after introduction of toric IOLs

FSL may make them more consistent and their placement more accurate ✄

whether this will make them more effective is unclear

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toric IOLs are still likely to be the preferred method of managing astigmatism >1.5D

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(some US surgeons have advocated using FSL to “mark” axis of toric IOL with a small LRI )

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Capsulotomy / “Laser-incised capsulorhexis”

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the perfect capsulotomy is: ✄ central ✄ not too big (ie not enough capsule overlap of the optic)

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tilt

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decentration

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PCO

not too small (too small means < 5.5mm) ✄

anterior capsule fibrosis and phimosis

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(hypermetropic shift)

Ravalico G, Tognetto D, Palomba M, et al. Capsulorhexis size and posterior capsule opacification. J Cataract Refract Surg 1996; 22:98–103. Walkow T, Anders N, Pham DT, Wollensak J. Causes of severe decentration and subluxation of intraocular lenses. Graefes Arch Clin Exp Ophthalmol 1998; 236:9–12. Wallace RB 3rd. Capsulotomy diameter mark. J Cataract Refract Surg 2003; 29:1866 – 1868. Sanders DR, Higginbotham RW, Opatowsky IE, Confino J. Hyperopic shift in refraction associated with implantation of the single-piece Collamer intra- ocular lens. J Cataract Refract Surg 2006; 32:2110–2112.

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Capsulotomy:

What is the evidence this matters to safety?

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anterior capsule tears ✄

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overall incidence 0.79%; almost half of these have extension to the posterior capsule 61% of these occur during capsulorhexis (54% of these were recoverable) the remaining 39% occur during hydrodissection, viscoelastic injection, IOL implantation, I/A

the 61% of tears that occurred during rhexis could be avoided with FSL, reducing incidence from 0.79% to 0.3% FF Marques et al. Fate of anterior capsule tears during cataract surgery. J Cataract Refract Surg 2006; 32: 1638-42.

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Capsulotomy:

What is the evidence that this matters to refractive outcome?

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capsulorhexis size is recognized as an important determinant of post-operative anterior chamber depth

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small rhexis is more likely to lead to greater ACD and hyperopic shift

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ELP (effective lens position)

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concept that represents the IOL A constant and “surgeon factors”

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thought to be the single biggest error variable in post-operative refraction

with FSL it is possible to precisely size and centre the capsulotomy ✄

how reliable is this?

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will this improve refractive outcomes?

Cekic O, Batman C. The relationship between capsulorhexis size and anterior chamber depth relation. Ophthalmic Surg Lasers 1999; 30:185–190. Norrby S. Sources of error in intraocular lens power calculation. J Cataract Refract Surg 2008; 34:368–376.

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How much difference does the capsulotomy make?

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SD for post-operative ACD (surrogate for ELP) is ~0.31, contribution to error 35% Warren Hill at ASCRS 2012 (Chicago) said perfect capsulotomy is worth ~0.19D For perspective: ✄

SD for post-operative refraction is 0.39 (contribution to error 27%)

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IOLs come in 0.5D increments

So, principle value is in limiting the “spread of the curve”

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FSLs cut perfect capsulotomies, most of the time

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“Early experience ...”

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largest published series to date

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Sydney-based study

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very experienced and highly-regarded group of surgeons in an excellent facility (a realistic scenario for take-up of the technology in the “real world”) this admirable study represents an effort to separate the hype from the practical reality of developing new surgical techniques and technology SJ Bali, C Hodge, M Lawless, TV Roberts, G Sutton. Early Experience with the Femtosecond Laser for Cataract Surgery. Ophthalmology. Vol 119, Issue 5, May 2012, Pages 891–899.

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“Early experience ...”

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“clear learning curve” - refractive surgeons with FSL experience had an advantage in 1st 100 cases, non-refractive surgeons “caught up”

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surgery took longer, not including the time taken for laser

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complication rate higher for FSL, even after the first 100 cases

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“This is an exciting technology, but the authors recommend that further large, prospective, multisurgeon studies be carried out and reported to evaluate the various clinically measurable outcomes to ensure that the proposed benefits of femtosecond cataract surgery indeed are achievable” SJ Bali, C Hodge, M Lawless, TV Roberts, G Sutton. Early Experience with the Femtosecond Laser for Cataract Surgery. Ophthalmology. Vol 119, Issue 5, May 2012, Pages 891–899.

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What were the complications?

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loss of suction Intralase)

convert to normal phaco 5/200 (0.06-0.27% with

anterior capsule tags 10.5% (21 cases) anterior capsule tears 4% (8 cases) 1000 phaco cases

cf 0.8% in author’s last

posterior capsule rupture 3.5% (7 cases) 1000 phaco cases

0.3% in author’s last

dropped nucleus 2% (4 cases) SJ Bali, C Hodge, M Lawless, TV Roberts, G Sutton. Early Experience with the Femtosecond Laser for Cataract Surgery. Ophthalmology. Vol 119, Issue 5, May 2012, Pages 891–899.

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So where to from here?

Is this an operation searching for an indication?

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like phaco in it’s infancy, FSL shows promise, but ✄

so far not safer, may increase risk

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so far may be better in theory but not shown to be better in practice

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vastly more expensive, and the increased cost will not be met by insurers

like DVD v BluRay, android v iPhone, different companies will develop different solutions to imaging & docking folding IOLs gave small-incision phaco an advantage over ECCE; IOL technology may give FSL an indication

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Take-home message

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Femtosecond laser cataract surgery systems represent the newest in a line of near-constant technological improvements in cataract surgery More data is required before determining a cost-benefit assessment of this technology, and determining its ultimate application

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