Nd:Y AG Laser Photodisruptors MARTIN A. MAINSTER, MD, PhD, * PATRICK C. HO, MD, * KATHLEEN J. MAINSTER, CORT Commercial laser photocoagulators consist of: (1) a high power, short-pulse laser source, usually a Q-switched or mode-locked Nd:Y AG laser producing invisible near- infrared radiation at 1064 nm; (2) an aiming/focusing laser system, using a continuous-wave He-Ne laser pro- ducing visible, red light at 632.8 nm; (3) a condensing lens that focuses the infrared treatment beam into a small focal spot at the working distance of the photodisruptor slit lamp; (4) an attachment system that connects the laser sources to the slit-lamp microscope to aim and focus the He-Ne laser (and thus the Nd:Y AG treatment beam) on target tissues. Basic principles, design, safety, and appli- cations of photodisruptors are described elsewhere. I ,2 In general, commercial photodisruptors may be dif- ferentiated on the basis of their: (1) pulse lengths, (2) aiming/focusing systems, and (3) attachment systems. 1 (1) Q-switched lasers produce single pulses or bursts of 1 to 9 pulses, each pulse of which is between 2 and 14 ns (l ns = 10- 9 sec), depending on the commercial pho- todisruptor (Table 1). Mode-locked lasers produce a pulse- train of seven to nine spikes over roughly a 30 ns interval. Each spike is 30 psec in duration (l ps = 10- 12 sec). (2) With a single-beam focusing system, the operator moves the slit lamp forward and backward to minimize the size of a single red spot on the target tissue. With a double- beam focusing system, the operator moves the slit lamp forward and backward until the two red spots fuse into From the Retina Associates,· Eye Research Institute of Retina Foundation,· and Harvard Medical School: Boston. Massachusetts, The authors have no commercial or proprietary interest in any laser deVice or system, 45 one on the target tissue. Accurate focusing systems are required because tissue targets are often subtle transparent membranes that cannot be disrupted until their axial po- sition is localized precisely. (3) Since the treatment beam is invisible, the operator must depend on the manufacturer to provide reliable alignment of the aiming/focusing laser and the treatment laser systems. Two types of attachment systems are in use: direct-coupled systems in which both lasers are attached directly to the slit lamp, and mechanical linkage systems, in which the laser beams are coupled to the slit lamp by an articulated mirror arm. The information in Tables 1-3 was provided by the manufacturers whose excellent cooperation is acknowl- edged. Other companies developing photodisruptors were contacted, but failed to provide information requested for this survey. At least one other photodisruptor (Stortz) has been introduced since this survey was completed (April 1, 1983). Photodisruptors are currently marketed under investigational device exemption status (as are many intraocular lenses), and each clinical treatment must be reported to provide information on the efficacy and safety of individual instruments. REFERENCES 1, Mainster MA, Sliney DH, Belcher CD III, Buzney SM. Laser photo· disruptors: damage mechanisms, instrument design and safety, Oph· thalmology, 1983 90:973-991, 2, Belcher CD III, Mainster MA, Buzney SM, The current status of neo- dymium: YAG laser photodisruptors in ophthalmology, Ann Ophthal- mol, in press,