Femtosecond Lasers in LASIK Surgery

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1 Femtosecond Lasers in LASIK Surgery Dr Chan Tat Keong Senior Consultant Refractive Surgery Service Singapore National Eye Centre

2 Disclosure Speaker has no financial interest in the products to be discussed in this presentation Travel funding from Alcon, Santen & Carl Zeiss

3 Modern LASIK Surgery Today Better excimer laser design, optics & algorithms Tissue saving Customised treatments Aspheric (for spherical aberration) Wavefront-guided (for higher order aberrations) Better eye trackers Bladeless corneal flap creation: Femtosecond laser technology

4 Why use femtosecond laser technology during the first step of LASIK? Provides a 100% blade-free LASIK procedure Enables more people to achieve 20/20 (6/6) vision or better Fewer flap related complications

5 Bladed Microkeratome: Source of Serious Complications Incomplete flaps Free flaps Button holes in flaps Recurrent erosions in the cornea

6 The Femtosecond Laser A focusable infrared laser that uses ultra-short pulses in the hundred-femtosecond (100x10-15 seconds) (1052nm) duration ( fs) range.

7 Laser-Tissue Interactions ArF 193 nm KrF 248 nm XeCl 308 nm XeF 351nm Argon nm Green HeNe 543 nm HeNe 632 nm Diode 680 nm Nd:Yag 1064 nm CO 2 10,600 nm Ultraviolet Visible Infrared 400 nm 750 nm Photoablation: Excimer Not to Scale Photodisruption: Femtosecond Precise Surface Effects Precise Sub-Surface Effects 7

8 Femtosecond Laser Technology in LASIK The laser-induced vaporized tissue forms a cavitation gas bubble that consists of CO 2, N 2 H 2 O, will diffuse through cornea.

9 Femtosecond Laser Flap Creation Mehta JS et al. Femtosecond Laser-Assisted Endothelial Keratoplasty A Laboratory Model. Cornea In Press.

10 Femtosecond Lasers The laser spots are either fired in a spiral or zigzag (raster) pattern Raster IntraLase Spiral FEMTEC, (Visumax) Zeiss

11 Femtosecond Lasers in Refractive Surgery Today Intralase FS (60 & 150) (AMO) Femtec (Technolas) Femto LDV Laser (Ziemer) VisuMax (Carl Zeiss Meditech) FS 2000 Laser (Wavelight, Alcon)

12 Two Femtosecond Lasers for Refractive Surgery Service in SNEC IntraLase FS Laser VisuMax

13 History 1998: First clinical Femtosecond Laser in cornea 2000: Initial U.S. use of Femtosecond Laser keratome for LASIK 2001: Commercial launch of IntraLase FS (1 st generation) 2003: 2 nd generation IntraLase FS Laser (15 khz) 2005: 3 rd generation IntraLase FS Laser (30 khz) 2006: 4 th generation IntraLase FS Laser (60 khz) 2008: 5 th generation IntraLase FS Laser (150 khz)

14 Properties of IntraLase FS Laser 4 th Generation 60kHz Designed to enable surgeons to: Program all surgical parameters for personalized flaps Predict the precision of uniformly planar flaps Create the LASIK flap in under 30 secs Structure of the Intralase flap Smooth, precise & uniform Adjustable dimensions Sharp edge Dry corneal bed 14

15 Programmable Parameters Flap thickness Diameter Centration Hinge angle Side cut angle

16 LASIK procedure with IntraLase FS laser

17 Corneal Bed Surface Comparison IntraLase FS Laser 9x 30x 135x Microkeratome 300x

18 Precise Thin Uniform Flap Achieved = um Attempted = 90 um

19 VisuMax Femtosecond Laser System by Carl Zeiss Meditec Designed for corneal laser surgery Workstation concept Ergonomic workplace High quality surgical microscope for surgery Short laser start-up time Integrated high resolution video camera

20 VisuMax Femtosecond System Touch-screen user interface for surgical procedure Separate screen for treatment planning Interactive guidance Voice messages Full visual microscope control over entire procedure Integrated slit lamp for immediate evaluation

21 VisuMax Femtosecond Laser System Patient Bed Patient comfort Easy entry Automatic adjustment Adjustable headrest Flexible joystick position

22 VisuMax : Innovative Corneal Interface Gentle corneal interface concept Suction applied only during laser procedure Patient fixation considered for optimum flap positioning Minimal ocular discomfort, low suction Suitable for small Asian eyes VisuMax flap cut

23 Comparison of Corneal Interface Designs VisuMax Normal Eye Curved PI (same eye) IntraLase Flat PI (same eye)

24 Visumax Femtosecond System OCT flap imaging Homogeneous flap thickness Regular interface Page 24

25 Triangle of treatment parameters High pulse repetition rate Short procedure time Easy flap lift / tissue separation Extended 3D shapes typical: <300 nj (<0.3 µj) Low Spot Energy Low & very stable laser energy Excellent cut quality No adverse side effects (DLK) Precise focussing/small spot: Well defined incisions Flaps & Femtosecond lenticule extraction (FLEx) High Pulse Rate 500 khz Precise Focusing 3 6 µm

26 Femto Systems Overview IntraLase VisuMax Laser Concept Amplifier Amplifier Wavelength 1053 nm 1043 nm Patient Interface Flat Curved Interface Pressure Floating Lens Computer-controlled Suction Scleral (manual) Corneal (computer controlled) Loss of vision Yes No Flap Creation Speed Around seconds Around 18 seconds Size, Mobility Bulky, fixed Bulky, fixed Femtosecond lenticule extraction (FLEx) No Yes

27 Summary Femtosecond lasers produce stronger flap adhesion postoperatively Vertical edge flap architecture provides optimal profile for wound healing Improved epithelial preservation a significant safety advantage VisuMax & IntraLase capable of creating flaps in a very short time The VisuMax patient interface appears more gentle with less likelihood of subconjunctival haemorrhage Corneal suction of the VisuMax ideal for small Asian eyes

28 Thank you!