Initial clinical experience with the picosecond Nd:YLF laser for intraocular therapeutic applications

Abstract

Aims/background-Compared with nanosecond (ns) pulses of conventional Nd-YAG lasers, picosecond (ps) laser pulses allow intraocular surgery at considerably lower pulse energy. The authors report initial clinical experiences using a Nd:YLF ps laser for the treatment of various indications for photodisruption. Methods-A Nd:YLF laser system (ISL 2001, wavelength 1053 nm) was used to apply pulse series of 100-400 µJ single pulse energy at a repetition rate of 0.12-1.0 kHz. Computer controlled patterns were used to perform iridectomies (n=53), capsulotomies (n=9), synechiolysis (n=3), and pupilloplasties (n=2). Other procedures were vitreoretinal strand incision (n=2) and peripheral retinotomy (n=1). For comparison, 10 capsulotomies and 20 iridotomies were performed with a Nd:YAG ns laser. The ps laser cut of an anterior capsule was assessed by scanning electron microscopy (SEM). Results-Open, well defined iridectomies (mean total energy 4028 mJ, mean diameter 724 µm) were achieved at first attempt in 92% of the cases. In 64% an iris bleeding and in 21% an IOP increase of >10 mm Hg occurred. All capsulotomies were performed successfully (mean energy 690 mJ/mm cutting length) but with a high incidence of intraocular lens damage. The attempted vitreoretinal applications remained unsuccessful as a result of optical aberrations of the eye and contact lens. Although ps laser capsulotomies and iridectomies required much higher total energy than ns procedures, the resulting tissue eVects of the ps pulses were more clearly defined. SEM examination of a ps incision of the anterior lens capsule demonstrated, nevertheless, that the cut was more irregular than the edge of a continuous curvilinear capsulorhexis. Conclusion-Series of ps pulses applied in computer controlled patterns can be used eVectively for laser surgery in the anterior segment and are considerably less disruptive than ns pulses. The ps laser is well suited for laser iridectomies while the ns laser is preferable for posterior capsulotomies. As vitreoretinal applications remained unsuccessful, the range of indications for intraocular photodisruption could not be extended by the ps laser.(Br J Ophthalmol 1998;82:504-509)

Nanosecond, high‐intensity pulsed laser ablation of myocardium tissue at the ultraviolet, visible, and near‐infrared wavelengths: In‐vitro study

“…But as described above, our experiment showed that the efficient ablation could be obtained through a photodisruption process when used nanosecond, high-intensity laser pulses. For the intraocular surgery [28][29][30], neurosurgery [31,32], etc., a photodisruption process is applied only when it is induced by low-energy, ultrashort (picosecond or femtosecond) laser pulses to minimize mechanical damage. But for macro ablation such as TMLR, nanosecond pulsed lasers can be used if the mechanical damage could be appropriately controlled.…”

Clinical Effects of the Nd:YAG Laser Operating in the Photodisruptive and Thermal Modes

“…Theoretically, ps pulses (and even more so, fs pulses) should be able to solve delicate tasks even more efficiently, since then pulse energies can be reduced to less than 1,000 times what would be required when ns pulses are used [25]. Here, in order to cope with the time limits imposed by clinical constraints, a high-frequency operation would be required.…”

“…Specific studies were soon undertaken on the mechanisms of optical breakdown [17, 18, 19, 20, 21, 22, 23, 24]. Extended studies were also carried out by the Vogel research group on the physics of optical-breakdown-related phenomena and their applicability to biology and medicine [25, 26, 27, 28, 29, 30, 31, 32, 33]. …”

The Use of the Fugo Blade in Corneal Surgery

“…[1][2][3] These lasers produce optical breakdown of the transparent medium, resulting in plasma formation in the focal area of the laser beam. Laserbased cutting instruments have failed so far to achieve widespread acceptance in surgical practice because of their prohibitively high cost, large size, and relatively slow pace.…”