Erbium‐YAG and holmium‐YAG laser ablation of the lens

Abstract

Er-YAG (2.9 microns, 200 microseconds pulsewidth) and Ho-YAG (2.12 microns, 250 microseconds pulsewidth) lasers were used to irradiate bovine crystalline lenses. Mass ablated increased with increasing fluence for both lasers and was greater for the Er-YAG than the Ho-YAG laser at all fluences. The mass loss vs. fluence curve was nonlinear for the Er-YAG and linear for the Ho-YAG laser. Ablation threshold was lower for the Er-YAG. Grossly, the Er-YAG laser produced less charring and expressed fewer, smaller tissue pieces than the Ho-YAG. Scanning electron microscopy indicated that the Er-YAG produced smoother walled craters. The Ho-YAG laser produced more dessicated and disrupted craters. The Er-YAG radiation, delivered by fiberoptic probes, may provide a method of performing minimally invasive cataract surgery.

Erbium: yttrium–aluminum–garnet laser induced vapor bubbles as a function of the quartz fiber tip geometry

“…26 The threshold for ablating altered lens structures has been investigated carefully to be in the range of 1-2 J/cm 2 by different authors. [5][6][7]27 Nevertheless, a major problem of erbium:YAG laser phacoemulsification seems to be the 4 -5 times higher treatment time compared to the ultrasonic systems when using a core diam- Fig. 9 Sequence of the vapor bubble formation for different refractions of the distal end of the fiber tip.…”

“…Some reports [5][6][7][8]24,25 investigated the use of pulsed erbium:YAG lasers as an alternative in phacoemulsification to liquefy the cataract lens of the eye. Basically, there are concerns over potential effects of ultrasonic energy delivery by the phacoemulsification probe on such nontarget ocular structures as the corneal endothelium and the lens capsule.…”

“…In particular, this mid-infrared laser is useful for various applications in ophthalmology such as sclerostomy and trabecolectomy in glaucoma treatment, phacoemulsification in cataract surgery as well as in posterior segment surgery for removal of vitreous structures. [2][3][4][5][6][7][8][9][10][11][12][13] Beside the precise tissue ablation, due to the high absorption in water containing tissue, microsurgical applications of pulsed erbium: YAG lasers require flexible ͑such as low OH Ϫ quartz fibers͒ and high transparent optical waveguides ͑such as ZrF 4 fibers͒ for efficient light transmission that do not hinder surgeons. While standard low OH Ϫ quartz fibers are not sufficiently transparent ͑attenuation 100 dB/m͒ to guide 2.94 m radiation, the ZrF 4 fibers with an attenuation of less than 0.1 dB/m seem to be most applicable.…”

In vitro spectroscopic investigation of human cataract lens capsule hydropermeability

“…In recent times, the use of a microsecond Yb,Er:Glass laser radiation with a wavelength of 1.54 µm has been discussed [19] for efficient fragmentation of the cataract lens and for performing anterior capsulorhexis [20]. On the other hand, for performing a capsulorhexis it is also possible to use the radiation of lasers on crystalline media activated by erbium ions; the use of Er:YAG laser radiation for lens fragmentation was investigated in [21][22][23].The radiation of Er:YAG laser with a wavelength of 2.94 µm is very effectively absorbed by water [24,25]; as a result, the penetration depth of this radiation into water-saturated tissues, to which the lens capsule can be attributed, is close to 1 µm. It is obvious that in the process of laser capsulorhexis, during the action of the radiation pulse, the capsule is dehydrated, and in a pause between laser pulses it is saturated with water again.…”

In situ Monitoring of Laser Modification Process in Human Cataractous Lens and Porcine Cornea Using Coherence Tomography

“…Laser ablation of biological tissue involves many fascinating aspects of the fundamentals of laser interactions with composite materials. [1][2][3][4] From the practical point of view this process is of great importance for creation of a reliable laser scalpel. The radiation of IR and UV lasers is the most feasible candidate for that, because of the strong absorption by biological tissues.…”