Femtosecond Laser: Techniques & Technology Ashok Garg, Jorge L Alio, Eric D Donnenfeld
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Femtosecond Laser: Current Technology and Future Prospects1

Ashok Garg
(India)
Chapter Outline
  • • Future Prospects of Femtosecond Laser Technology
Femtosecond laser is the latest innovation in the field of ophthalmology with great future. The femtosecond laser was first introduced in 2001. It shall completely revolutionize the minimally invasive ophthalmic surgery in next five years with wider applications. Femtosecond laser (FS) shall offer new possibilities in the field of refractive surgery specially when using the laser as microkeratome. By generating microplasms inside corneal stroma with femtosecond pulses, it is possible to achieve a cutting effect inside tissue while leaving the anterior layer intact. The femtosecond laser employs near infrared pulses to cut tissue with minimal collateral tissue damage.
The highly localized tissue effect of low energy femtosecond laser may expand the capabilities and precision of this technology may be used to create three dimensional intrastromal resection with micron precision. The main technical specifications of femtosecond laser are:
  1. Laser pulse repitition rate
  2. Spot size, pulse energy and pulse pattern.
The use of femtosecond laser in LASIK is effective and safe procedure with less corneal higher-order aberrations resulting in better uncorrected visual acuity and contrast sensitivity.
Femtosecond laser can be also used to make channels for implant of intracorneal ring (Intacs) in the treatment of keratoconus and pellucid marginal corneal degeneration.
The use of femtosecond laser in the treatment of presbyopia is currently gaining acceptance. Presbyopia is by far the most common refractive error worldwide with no permanent therapeutic option available. All efforts to restore accommodation by the use of surgery have not led to a generally accepted therapy. However, there is evidence from recent research data that the use of femtosecond laser might influence the modulus of elasticity in the lens by creating intralenticular disruption.
Femtosecond laser photodisruption of the ocular lens yields a self-limited lesion with bubble that resolve with time. This suggests that the use of a low-energy femtosecond laser might be safe when modifying the lens for correction of presbyopia. A new procedure for presbyopia called intracor is being evolved with this platform.
Femtosecond laser technology offer a promising approach to minimally invasive anterior and posterior keratoplasty (Femto-PLAK) through small tunnel incision in corneal endothelial diseases. Femtosecond laser enables the surgeon to cut cornea none mechanically with cutting accuracy of ± 10 microns.
Penetrating keratoplasty can be performed with femtosecond laser safely and accurately. Femtosecond laser is highly useful in applanation free corneal surgery.
Recently FDA approved studies have showed that femtosecond laser corneal dissection provides an alternative to more challenging manual dissection methods for keratoprosthesis implantation.
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Femtosecond laser allows highly precise and reproducible subsurface using long infrared wave lengths. One of the most important applications of this method is in glaucoma surgery. Permanent drainage channel may be created to reduce the elevated intraocular pressure.
Femtosecond laser enhance by indocyanine green can be used for photodynamic therapy because of effective closure of corneal neovascularization at a low energy level.
Femtosecond laser with specific dynamic light scattering and photon correlating spectroscopy shall be useful for diabetic and senile macular degeneration.
A number of commercially available femtosecond laser devices are in the market since the introduction of this new field by intralase. The various FS laser machines available as follows:
  1. Intralase (Abbott Medical Optics).
  2. Wavelight ultraflap LDV (Ziemer Ophthalmic System, Switzerland).
  3. Femtec 20/10 lasers (Technolas Perfect Vision, Germany)
  4. Visumax (Carl Zeiss)
  5. Lens Sx (Alcon)
  6. Lens AR
  7. Optimedica FS system. (Santa Clara, USA). (Catalys precision laser system).
  8. Wavelight FS 200 ultraflap laser system.
  9. VICTUS femotsecond laser platform (Bausch and Lomb and Technolas).
New refinements are being systemactically introduced with improvements in pulserate, spot size, pulse energy and customized approaches for the use of the laser.
 
FUTURE PROSPECTS OF FEMTOSECOND LASER TECHNOLOGY
Femtosecond laser has evolved potentially over the past 10 years and further revolutionally advances are expected in next 5 years. With its ultra precise (minimal focal spots size), shorter laser pulse, 3D processing quality and photodisruption from mJ to nJ, it shall guide the major surgical changes in the ophthalmology. FS laser shall be used in a bigger way in following anterior and posterior segment indications with best diagnostic and therapeutic results.
  • Refractive Surgery (cutting of laser in situ keratomileusis), intracor procedure based on controlled biomechanical manipulation for presbyopia and OCT controlled keratomileusis.
  • Femtosecond laser cataract surgery is the major advancement in the near future. The new machines with a high resolution 3D confocal structured illumination shall help in well centered capsulotomy and minimal residual corneal astigmatism, excellent incision architecture and less energy used and better lens fragmentation. It shall also help in more precise refractive lens exchange and limbal relaxing incisions.
  • OCT controlled microsurgery shall be more accurate in relation to vision and predictability.
  • Femtosecond laser shall be highly useful in astigmatic correction. FS assisted astigmatic correction in higher degree astigmatism (laser astigmatic keratotomy) shows greater accuracy and lens complication advanced refinements are being introduced in new generation femtosecond laser devices.
  • Femtosecond Laser lentotomy for presbyopia treatment. This shall allow increased flexibility and sliding of lens fibers that can partially restore the accommodative loss of the lens with aging.
  • Nonrefractive corneal applications specially laser assisted anterior and posterior lamellar keratoplasty, cutting of donor buttons in endothelial keratoplasty, customised trephination in penetrating keratoplasty and keratolimbal autografts, Laser DSAEK and anterior lamellar keratoplasty (ALK).
  • Cutting corneal pockets for insertion of biopolymer Keratoprosthesis.
  • Femtosecond laser technology shall bring advances in non-refractive surgery procedures like noninvasive transcleral glaucoma surgery. FS laser created trans-scleral channels.
  • Femtosecond lasers with dynamic light scattering spectroscopy shall be highly useful in retinal imaging, vitreous analysis in diabetes, photodynamic therapy (PDT) and senile macular degeneration (ARMD), femtosecond Laser pulses shall be guiding force in sebum precision retinal surgery with adaptive optics.
  • Femtosecond laser assisted applanation free corneal processing and in corneal biopsy.
  • Femtosecond laser assisted tattooing shall serve to correct leukoria (cosmetic procedures).
Advances in femtosecond ultrafast laser technology continue to improve the surgical safety, efficiency, speed and versatility in ophthalmology.
New technologies in femtosecond laser specially complex polarization shaped pulse, stimmulated emission depletion (STED), ablation with different time delay, coherent control and algorithm 3D nanostructuring by photons polymerization, tissue engineering using 2 PP cross-linking shall change completely the scenario of modern ophthalmic surgery to actual minimal hands free noninvasive ophthalmic surgery.
Bibliography
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