میحرلا نمحرلا الله مسب

LDV

Femto-LASIK

Basir Eye Center Dr. Ahmad Shojaei

www.iranophthalex.com

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

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 • Safety and predictability • Absence of moving parts • ↓Complications -Hinge length • 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

Femto LASIK

Femto LASIK

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 107.43±4.70 µm • Hansatome 125.90±17.5 µm

Femto LASIK Refractive outcome • UCDVA≥20/20 91.7% →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