Era Of Laser Surgery
In the last 20 years, laser has become a popular method of management for patients with benign prostatic hyperplasia, tumors, stones, urinary strictures, or lesions of the external genitalia. Lasers were first introduced in India in 2000. Currently, the most commonly used lasers in urology are KTP:YAG (potassium titanyl phosphate), LBO:YAG (lithium borate), diode lasers, holmium (Ho):YAG, and thulium (Tm):YAG lasers. In the past many other types were used; however, due to many complications, their use was discontinued.
Nd:YAG laser was the most commonly used laser in the past. It has more than 1 cm tissue penetration and 1064 nm wavelength. The Nd:YAG laser can be used for non-contact visual laser ablation of the prostate (VLAP), contact ablation, or interstitial laser coagulation (ILC) of the prostate. However, oedema frequently occurs after the procedure and it is now used to a lesser extent in Indian markets. The Ho:YAG laser is a pulsed type of laser that emits energy absorbed by water, with a wavelength of 2140 nm and pulse duration of 350 ms. The depth of penetration is only 0.4 mm. Therefore the depth of necrosis and thermal damages is limited. The Ho-laser causes rapid coagulation of small and medium-sized vessels to the depth of about 2 mm. The prostate can be precisely incised, dissected, and enucleated, and ablation of urothelial tumours, strictures, and flexible uretroscopy (RIRS) can be done using the no-cut technique to break stones inside the kidney also. It is one of the most common and useful lasers in the market as it has dual use of breaking stones and being used in soft tissues as well.
The KTP: YAG laser, also known as green light laser, is derived from the Nd: YAG laser. Passing the invisible Nd:YAG beam via a KTP crystal, doubles the frequency and halves the wavelength from 1064 nm to 532 nm. Its energy is selectively absorbed by hemoglobin, but not by water. The penetration depth is about 0.8 mm. It has a very good coagulation effect, which results in perfect hemostasis. Because the energy of the KTP laser is absorbed only by hemoglobin, it is possible to perform noncontact operations called as photoselective vaporization of tissue with minimal necrosis of the tissue localized beneath. The Tm:YAG laser produces a continuous 2000-nm wave. As in the Ho-laser, energy is absorbed only by water and a slightly shorter wavelength of thulium laser decreases the depth of penetration to 0.25 mm. The Tm-laser is used for transurethral vaporization, enucleation, or resection of the prostate. The lithium triborate (LBO) laser is derived from the KTP-laser. The wavelength of both lasers is equal. However, the LBO-laser has an accelerated and a more efficient energy transfer and enhanced working distance (from 0.5 mm for KTP to 3 mm for LBO). A significant disadvantage of this laser is a marked decrease in hemostatic ability in comparison to the KTP laser.
Diode lasers have been available for a long time, yet, their clinical application has been limited. Diode lasers emit a beam of wavelength between 940 and 1470 nm. Their energy is absorbed by both water and hemoglobin. As a result, good hemostatic and vaporizative effects are obtained. Data regarding the penetration depth of diode lasers differs considerably between particular reports; higher incidence of complications, such as postoperative irritative symptoms and epididymitis, is noted.
In many centers, after all the possibilities of pharmacological treatment have been exhausted, lasers are used as the primary treatment for patients with benign prostatic hyperplasia, with therapeutic results that are better than those obtained through open or endoscopic operations. The use of lasers in the treatment of urolithiasis, urinary strictures, and bladder tumours has made treatment of older patients with multiple comorbidities safe, without the further necessity to modify the anticoagulant drug treatment. Laser procedures are additionally less invasive, reduce hospitalization time, and enable a shorter bladder catheterization time, sometimes even completely eliminating the need for bladder catheterization. Such procedures are also characterized by more stable outcomes and a lower number of reoperations. There are also indications that with increased competition among laser manufacturers, decreased purchase and maintenance costs, and increased operational safety, laser equipment will become a mandatory and indispensable asset in all urology wards with young urologists rapidly adopting the technology and becoming laser surgeons.
