بسم الله الرحمن الرحیم LDV

Femto-LASIK Basir Eye Center Dr. Ahmad Shojaei

Femto second Laser Femto second Laser employs near- infrared pulses to cut tissue with minimal collateral tissue damage ( mode-locked, diode pump, neodymium- glass laser) Infrared wavelength range, at 1053 nm It uses a spot size of less than 3 micron Produces tissue disruption at a specified and precise level within the corneal stroma Femto second has different applications in ophthalmology Its major use at present is cutting flap in LASIK surgery

Femto LASIK General Comments The most common application of femto second Introduced in 2002 Started in practice 2006 Allow light to pass from the tissue without damage to the tissue

Femto LASIK Patterns Raster or spiral pattern→ bed Peripheral circular →posterior-anterior

Femto LASIK

Femto LASIK Flap creation The depth of the flap is typically set at 100±10 micron Studies have shown that the standard deviation of flap thickness is around 14. The flap diameter is typically set to about 9.0mm.

Femto LASIK Major advantage femto second over microkeratome Flap criteria Accuracy of flap thickness Refractive outcome Capability and choice of -Cutting thin flap (90 µm) -Different diameter, -Hinge position -Hinge length Safety and predictability Absence of moving parts ↓Complications Improved staff and physician satisfaction

Femto LASIK Flap criteria Quality of flap edges More regular (flap and Bed) Peripheral and Center

Femto LASIK

Femto Lasik Accuracy of flap thickness (Actual and expected) LDV→depth→90→100→110→140 micron By change of inter shield α< 5% variation ±4.70 µm Hansatome ±17.5 µm

Femto LASIK Refractive outcome UCDVA≥20/ % →Femto LDV 88.5% →Handsatome RE Femto LDV →+0.5 Diopter →Plano 87.5% Handsatome→ +0.5 Diopter →Plano 84.6%

Femto LASIK Possible Advantages Fewer higher order aberrations Less astigmatism Better contrast sensitivity Less epithelial ingrowth Lower enhancement rate Less dry eye

Femto LASIK Disadvantages High price Large physical size Lack of portability Speed and the time needed to prepare the flap

Femto Lasik Surgical technique and operation -Pre operation evaluations -During operation -After operation

Femto LASIK Surgical technique Pre-op evaluation -Patient selection -Machine preparation -depth -size -hinge

Femto LASIK Surgical technique During operation -Patient's position -Hand piece position -Centering -Suction (enough IOP) -Laser

Femto LASIK Surgical technique After operation -edge release -lifting of the flap -ablation -repositioning of the flap

Femto LASIK Surgical technique Special points -Suction release and re cut -Bridges -Gas bubbles -IOP -Duration

Femto LASIK Surgical technique Gas bubbles -interface →Opaque media -rare →deep stroma → tracker -rare → subepithelial loss of vacuum Button hole -rare → Between cornea and hand piece -rare → in A/C

Femto LASIK IOP During flap preparation Intralase → 135±6mm Hg Visual Max → 65±20mm Hg Femtec → 205±32mm Hg Femto LDV→ 184±28mm Hg Maximum IOP → 260±53mm Hg in interlase

Femto LASIK Surgical technique Duration: *Cutting time: -Femto LDV 25 seconds -Intralase 31 seconds *Suction time: -Femto LDV 82±22 seconds -Intralase 70±15 seconds

Femto LASIK Femto LASIK Movie

Femto LASIK Complications Absence of usual complications -Buttonhole -Small flap -Free caps -Irregular cut -…………….

Femto LASIK Complications Suction breaks Incomplete flaps Thin flaps, tears Increased postoperative inflammation Persistent bubbles Decentered flaps Slipped flaps

Femto LASIK Special complications TLSS (transient light sensitivity syndrome) Gas bubble DLK (lamellar inflammation) Glare

Femto LASIK TLSS Occur days to weeks after femto second Extreme photophobia Good V.A Absence of clinical findings Response of keratocyte Inflammatory response to surrounding tissue to gas bubble Topical corticosteroid

Femto LASIK In special case Post Lasik –PRK Post R.K- A.K Corneal scar Post P.K