Femtosecond laser assisted cataract surgery

FLACS is the recent advance in cataract surgery and future of cataract surgery.

1. FEMTOSECOND LASER ASSISTED CATARACT SURGERY Dr. Bijoy Kumar Mali 2 nd Year PG Resident VSSIMSAR , Burla

2. INTRODUCTION Femtosecond: SI unit of time = 10 -15 of a second Femtosecond laser is a laser which emits optical pulses in the domain of femtoseconds. Femtosecond delivery system : Use neodymium : glass 1053 nm wavelength light. Focus light at a spot size of 3 micron. Benefits of Femtosecond laser were discovered for corneal refractive surgery.

3. MECHANISM OF ACTION Principle of photo disruption. Laser is absorbed by tissues and results in plasma formation. Expansion of the plasma creates cavitation bubbles which separates the tissue to create a tissue plane.

4. Femtosecond laser assisted cataract surgery (FLACS) Femtosecond laser first FDA approved for cataract surgery in 2010. With guidance system it used to make - Cataract clear corneal incision Capsulorhexis Lens fragmentation or softening

5. PREOPERATIVE EVALUATION VA and BCVA Slit lamp examination Tonometry Fundus examination Biometry Special attention paid to Corneal opacities Arcus senilis Pupil size Zonular dehiscence Grade and type of cataract Explain about procedure and take informed consent.

6. ANESTHESIA Topical is better as Patient can be encouraged to look at the fixation light Aid centration of eye during docking. Peribulbar block may cause chemosis and hinder docking . GA in younger children.

7. INSTRUMENTATION Available in market: Alcon lenSx AMO Catalys LensAR Technolas Victus Three basic components of instrumentation: The patient interface Laser delivery The imaging systems.

8. Patient Interface 3 basic function Maintain positional and mechanical stability of eye Coupling device to facilitate laser delivery onto target tissue. Permits acquisition of image. Two types Applanating surface:( LenSx and Victus ) Small diameter so more suitable for small palpebral aperture. Non applanating surface: ( Catalys and LensAR ) Cause less increase in IOP Incidence of SCH is lesser.

9. Imaging System Platforms used are either Spectral domain OCT 3 D confocal structural illumination

10. Most important step is centering the cornea which influences Position of corneal incision Arcuate incisions Capsulorhexis Quality of image is reduced by Any Corneal pathology that reduces corneal transparency Corneal folds during docking.

11. Steps of FLACS Femtosecond laser part Docking Planning Capsulotomy Lens fragmentation Main incision Sideport Incision Corneal relaxing incision Manual part Incision opening OVD injection Central anterior capsule removal Hydro dissection Phacoemulsification Cortex aspiration Posterior capsule polishing IOL implantation Visco removal Wound closure

12. Docking I nterface applied in patients eye , once centration is confirmed , suction is activated. IOP may rise by 10-20 mm Hg.

13. Planning Done on the planning station. Position of primary incision and side port planned as convenience to surgeon and according to preoperative corneal astigmatism. Capsulorhexis and lens fragmentation is also planned.

14. Capsulorhexis Capsulorhexis made first followed by lens fragmentation and then corneal incision because To avoid obstruction to laser by gas bubbles created To avoid increase intralenticular pressure by gas bubbles during nucleus management Gas bubbles may distort plane of capsule leading to incomplete capsulorhexis . Ideally centred on the limbus. Can be centred on the pupil (set to 5 mm)

15. Lens fragmentation Customised to suit surgeons preference Into 4-8 fragments Concentric cylinder in softer cataract. Grid pattern in harder cataract.

16. Corneal incision Arcuate incision are made at last. Set at 80% depth of cornea. Incision are water tight and safe.

17. Manual part Time taken for laser treatment 30 sec to 3 min. Patient interface is removed and patient shifted to operating room. Corneal incision by laser to be dissected with a spatula. Fill the eye with OVD. Look for incomplete capsulorhexis . If free floating capsule is found aspirate else use a capsule forcep and remove ant. Capsule in a circular fashion to avoid tears. Forceful hydro dissection avoided as gas bubbles released during nucleus fragmentation collect between lens and capsule results in capsular block syndrome with rupture of posterior capsule. Lens tapped gently on anterior surface during hydrodissection .

18. Grooves made by laser in nucleus is separated by chopper and phacoemulsification done. Cortex aspirated. It may pose challenge as laser cuts through anterior cortex during capsulotomy. IOL implantation as routinely done with advantage of more predictable lens position. Viscoelastic is removed.

19. Contraindications Eyes with small palpebral aperture Patients with neck and back problems Patients with nystagmus and attention deficit disorder Patients with glaucoma and retinal vascular disorder Corneal opacities Blood or other material in the anterior chamber White cataract Grossly subluxated lens and dislocated lens Small pupils

20. Complications unique to FLACS Machine related : Error in software and hardware Loss of suction : D/t improper docking,excessive eye or head movements Subconjunctival haemorrhage : D/t pressure of patient interface Pupillary constriction : D/t applanation of cornea or laser energy delivered Incomplete capsulotomy and anterior capsular tears : D/t presence of corneal folds on applanation , lens tilt or eye movements while firing laser Capsular block syndrome :

21. Advantages Incision : Greater reproducibility and architectural stability Capsulotomy : More precise and better IOL centration Nucleus management and phaco energy : Decrease ultrasound energy and effective phacoemulsification time Surgery in eyes with zonular weakness : Reducing stress on the zonules during capsulorhexis and nuclear chopping manuever . Posterior capsulorhexis Macular edema : Lesser edema of outer nuclear layer of retina.

22. Disadvantages Cost Training of staff Operating room logistics Total operation time : being a two step procedure require more time. Increased patient expectation