(This definition follows U.S. usage in which a billion is a thousand million and a trillion is a 1 followed by 12 zeros.) A Femtosecond is one millionth of a nanosecond or 10 -15 of a second and is a measurement sometimes used in laser technology FEMTOSECOND
10 -3 10 3 6 9 1 -6 Thermal/Heat Radiation Ionizing Radiation Gamma Rays X-RaysUltravioletInfrared Radio Waves Microwaves Television FM Radio Short Wave AM Radio Lasers Wavelength (µm) LIGHT SPECTRUM
I NTRA L ASE ® FS laser Femtosecond laser – (Nd:Glass) 1053 nm (near infrared) Each pulse of focused laser light lasts approximately 10 -15 seconds (500-800 femtoseconds) In one second, light travels 7.5 times around the globe In 100 femtoseconds, light travels across a human hair Power = Energy/Time, extremely high power attained at relatively low energy
INTRALASE - FS 60
Model- FS 60 Repetition Rate- 60kHz Energy per pulse - > or equal to 1uJ 9mm flap time – 17- 20 Degree Hinge Angle - 30-90 Degree Hinge location - Variable Procedures - Flap, AK, Wedge, ICR, IEK, LK INTRALASE - FS 60
Flap Shape - Planar Visual Procedure Control - Yes Cut Direction - Interface first Focus - X, Y, Z Flap Thickness Control - Computer 90-400 uM Diameter Control - Computer Cut Pattern - Raster/Spiral Side cut angle - Computer 30-90 INTRALASE - FS 60
Beam pattern - Continuous Centeration control -Computer software IOP increase vs microkerotomes -low Loss of sight during suction -Yes Docking arm - Automated Mobile - No INTRALASE - FS 60
LASIK / ZYOPTIX Step 1 : Creating corneal flap Step 2 : Folds the flap back and perform laser procedure which corrects vision.
CORNEAL FLAP Accuracy of thickness Flap Stability Nice / Sharp edges No complication Patient comfort during flap creation
HOW DO WE CREATE….. Equipment - Microkeratome Tissue cut by Blade Desired thickness - Blade Holder Flap Diameter – Suction ring IOP increases > 65mmHg Total Time of Increased IOP ~ 60-80 sec.
LIMITATION Meniscus flap – Non Uniform Flap Thickness ~10 -35 µ Flap Diameter Steep corneas Deep set eyes Thin corneas with Higher ref correction
BLADE MICROKERATOME COMPLICATIONS Microkeratome complications occur in up to 10 percent of all LASIK procedures, including the most serious complications that may affect the visual outcome of a LASIK procedure (Ambrosio and Wilson, Osman).
POSSIBLE COMPLICATIONS Partial and Incomplete Flaps Free Flap Button Hole Suction Loss Epithelial Abrasion. Diff. thickness at different curvatures. Dry eye Problem
POSTPONE ….???? If any of the Flap related complication occurs like incomplete flap, Button Hole, etc., the only option left is to reschedule the surgery.
INTRALASE Blade free method Flap creation Intralase FS laser is an advanced technology and represents a major improvement in LASIK surgery. Offers versatile capability and flexibility in customizing flap creation with even, clean edges, regardless of the size or shape of the eye. With programmed parameters, the Intralase performs exactly as programmed with precise, predictable outcomes, transforming the science of creating the corneal flap into an artful application of technology. Patient Comfort -fast surgical procedure hence there is no trauma to the eye, no patient discomfort, patients tend to be very relaxed during the surgery, confident that the laser is performing as expected.
LOWER IOP The suction ring used with the INTRALASE FS Laser creates an intraocular pressure (IOP) of approximately 40 mm Hg. In contrast, the suction ring used with a microkeratome raises IOP to 80 mm Hg or more, a much higher and potentially less safe level.
FLAP THICKNESS Desired flap thickness accuracy ~ 5-10µ In reality the thickness ~3-8µ
UNIFORM FLAP THICKNESS The entire Cornea is applanated (flatten) uniformly then the laser works on planner surface. The Highly precise Laser pulses focused to precise intrastromal locations. Flap is always uniform thickness from side to side. Furthermore the uniform thickness and Vertical cleavage plane fits the flap like a manhole cover, minimise the chance of flap slippage or wrinkling if accidentally rubbed or bumped during healing after surgery.
IMMEDIATE REPETITION WITH NO ADVERSE EFFECTS If the surgeon encounters a loss of vacuum during flap creation with the Intralase laser, the flap creation can be repeated immediately with no known adverse affects. In contrast, complications occurring during the creation of a flap with a microkeratome may require three months of healing before a repeat procedure can be attempted.
REDUCED RISK OF COMPLICATIONS As there are little to no possibilities of corneal abrasion, such situations as thin flap, thick flap, partial flap, incorrect diameter or buttonhole flap can be addressed. In addition, with the resulting flap has uniform thickness across the diameter, use of the IntraLASIK approach is ideal for hyperopes, large pupils, moderate to high astigmatism, and small corneal diameters where producing a large enough flap for a blend zone is an issue. Producing a uniform ablation far into the periphery is critical in these cases.
EPITHELIAL INGROWTH - CONTROLLED Further, the laser’s ability to create a very thin flap maintains optimal stromal bed thickness when treating higher refractive errors or thinner corneas. Because the IntraLASIK software enables the laser to produce flaps with vertical edges, it is more difficult for epithelial cells to migrate down under the flap into the interface since the length of the route for those cells is increased.
EXCEPTIONAL SURGEON CONTROL Surgeons gain exceptional control in the creation of corneal flaps. The computerized IntraLASIK software allows the surgeon to set predictable controls for micron precision and consistency in flap diameter, depth, hinge location and width and side cut architecture, which varies by individual patient corneal anatomy. Such precision virtually eliminates corneal flap complications.
INTRALASE IN EYE SURGERY Intralase is not only used for Lasik for glass free vision but also for treatment of conical (keratoconus) cornea and corneal (eye) transplants for better results
PATIENTS GAIN CONFIDENCE Patients gain confidence in choosing vision correction surgery. The higher degree of comfort and safety, virtually no risk of complications, and more predictable outcomes increase patient satisfaction in their experience and outcome.
CONCLUSION 1.Major advancement in lasik 2.Higher degree of safety and precision 3.Predictable outcome 4.Faster visual recovery 5.Increased patient satisfaction and comfort 6.Enhanced quality of vision 7.Approved by FDA, NASA for astronaut and US air force