Jack M. Dodick

Experimental studies on the development and propagation of shock waves created by the interaction of short Nd:YAG laser pulses with a titanium target

ABSTRACT The formation and propagation of shock waves created by the interaction of high powered Nd:YAG laser pulses with a titanium target are photographed and analyzed. The titanium target is located at the distal end of a probe, similar to an irrigation/aspiration probe used in cataract surgery, and the Nd:YAG laser is delivered by a cladded 300 &mgr;m quartz fiber. This device, and the results of this study, are being applied to develop a device for fragmenting nuclear material for cataract extraction.

Dodick photolysis for cataract surgery: Early experience with the Q-switched neodymium:YAG laser in 100 consecutive patients

OBJECTIVEnTo evaluate the safety and efficacy of a Q-switched neodymium:YAG (Nd:YAG) laser for removal of the human cataract.nnnDESIGNnA multicenter, prospective, noncomparative study.nnnPARTICIPANTSnA total of 100 consecutive eyes undergoing cataract extraction with the Dodick Photolysis, Q-switched Nd:YAG laser.nnnMAIN OUTCOME MEASUREnCorneal endothelial cell loss, visual acuity improvement, intraocular pressure change, total intraocular energy used, and intraoperative and postoperative complications.nnnRESULTSnThe mean values were postoperative visual acuity improvement from 20/46.5 (0.43) to 20/26.6 (0.75), decrease in endothelial cell count of 177 cells/mm2 (7.55%), and intraocular energy used of 6.7 J. Minor complications were encountered in three cases.nnnCONCLUSIONSnThese data suggest that Dodick Photolysis may be a safe and effective new technology for cataract removal in human eyes. It appears to offer low intraocular energy and heat release, a clear-cornea incision less than 1.5 mm in size, and safe operation within the capsular bag.

Prospective, randomized vector analysis of astigmatism after three-, one-, and no-suture phacoemulsification

Purpose: To compare surgically induced astigmatism and visual outcomes after three‐, one‐, and no‐suture phacoemulsification. Setting: Johns Hopkins Hospital, Baltimore, Maryland, and Manhattan Eye, Ear, and Throat Hospital, New York, New York, USA. Methods: This prospective, randomized study followed 131 patients treated with phacoemulsification with a 5.5 mm self‐sealing scleral tunnel and implantation of a 5.5 mm poly(methyl methacrylate) posterior chamber lens. Radial 10‐0 nylon sutures were used in the three‐ and one‐suture groups. Results: Mean astigmatism was greatest in the first postoperative week in all groups and stabilized after 8 weeks. The percentage of patients with with‐the‐rule (WTR) astigmatism increased from baseline in the one‐ and three‐suture groups and decreased in the sutureless group. Mean uncorrected Snellen acuity was significantly better in the no‐ and one‐suture groups than in the three‐suture group at 1 week. There were no significant differences in uncorrected acuity at other times. No statistically significant differences in the surgically induced spherical equivalent were noted among the three groups during the 1 year follow‐up. There was significantly less surgically induced keratometric astigmatism in the one‐suture group at 4 (P = .03) and 8 (P = .007) weeks postoperatively. At all follow‐ups, the sutureless group had the greatest proportion of patients with significant ATR astigmatic shift (1 week, 17%; 4 weeks, 32%), and the lowest proportion of patients with significant WTR astigmatic shift (10% after 1 week). At 4 weeks, the percentage of patients with significant WTR shift in the one‐suture group dropped to that in the sutureless group (10%); however, those in the one‐suture group had less ATR astigmatic shift (16%). Conclusion: Sutureless and one‐suture surgery resulted in a low percentage of WTR induced astigmatism 4 weeks postoperatively. Compared with sutureless surgery, the one‐suture surgery resulted in less ATR shift.

Explantation of a Foldable Silicone Intraocular Lens

PURPOSEnWe used a novel technique for explanting an improperly oriented silicone intraocular lens.nnnMETHODSnThe elastomeric property of silicone was used to deform the optic and remove the intraocular lens in one piece.nnnRESULTSnWe explanted a flexible intraocular lens without compromising the integrity of the original wound, posterior lens capsule, or corneal endothelium.nnnCONCLUSIONSnThe technique offers a superior means of intraocular lens explantation while retaining the benefits of small-incision cataract surgery.

Bilateral and Extensive Xanthelasma Palpebrarum in a Young Man

A 25-year-old white man had been aware since childhood of yellow discolorations of the medial aspects of his upper lids. The skin changes progressively spread to involve all four eyelids, the inferior skin of the brow, and the lateral and medial canthal skin. The clinical diagnosis was extensive bilateral xanthelasmas . The patient had no manifest abnormality of lipid metabolism, although his father and grandfather had both developed xanthelasmas early in childhood. A snip biopsy of upper lid skin was performed and studied by both light and electron microscopy. The light microscopic appearance confirmed the diagnosis of xanthelasma, in that the upper dermis contained mono- and multinucleated foamy xanthoma cells beset with myriad cytoplasmic vacuoles. Cells displaced outwardly into the interstitium evidenced degradation phenomena within the vacuoles, consisting of lamellar bodies or fingerprint-like inclusions, presumably the result of fusion of lysosomes with the lipidic inclusions. Scattered non- lipidized mononuclear histiocytes with abundant profiles of smooth-surfaced endoplasmic reticulum possibly represented a reserve population of monocytes for conversion into xanthoma cells.

Experimentelle Laser-Phakolyse mit dem ARC-Puls-Nd-YAG-Laser

ZusammenfassungBereits in den 80iger Jahren wurden Versuche unternommen, verschiedene Laser in der Katarakt-Chirurgie zur „Phakolyse“ einzusetzen. Derzeit kommen vorwiegend Festkörperlaser (Er-YAG und Nd-YAG) zum Einsatz. Der vorgestellte Nd-YAG-Laser (1064 nm) arbeitet nach dem gleichen Prinzip, wie von der YAG-Kapsulotomie bekannt: der Plasmaformation und Bildung von Schockwellen (Dodick-Laser-Phakolyse).Die Studie wurde mittels eines gepulsten Nd-YAG-Lasers mit einer Ausgangsenergie von 10 mJ und einer Pulslänge von 14 ns durchgeführt. Die Einzelpulse werden dabei über eine Quarzfiberoptik (Durchmesser 0,4 mm) in das spezielle Phakohandstück übertragen. Die divergent austretende Strahlung trifft auf ein „Target“ aus Titan und erzeugt einen Plasmadurchbruch mit nachfolgender Druckwelle. An Linsen humaner Spenderbulbi wurde der Effekt dieser neuartigen Laser-Phakolyse-Sonde in vitro studiert.Der Widerstand der hinteren Linsenkapsel gegen die entstehende Druckwelle wird bei unterschiedlichen Abständen untersucht.Eine Temperaturmessung in einer künstlichen Vorderkammer sowie in der Vorderkammer von humanen Spenderbulbi kann nachweisen, daß – im Gegensatz zur mechanischen Phakospitze – am Ende der Lasersonde keine klinisch signifikante Temperaturerhöhung auftritt.Die vorliegenden In-vitro-Untersuchungen zeigen, daß potentiell duch die „Laser-Phakolyse“ (mit dem ARC-Puls-Nd-YAG-Laser) einige der bekannten Risken und Nebenwirkungen der routinemäßig durchgeführten Ultraschall-Phakotechnik (d. h. vor allem Erwärmung und Kapselruptur) verringert werden könnten.SummaryAttempts to utilise lasers with different wave lengths in cataract surgery were started in the mid-eighties. The development in laser technology has led to two only types of solid-state lasersystems for cataract extraction, the Er-YAG and Nd-YAG, that are currently being tested.The Nd-YAG and Nd-YAG, Laser (1064 nm) discussed in this presentation, works based on the principle that has been used for several years in YAG-capsulotomy: the generation of plasma and Shockwaves (“Dodick-Laser-Phacolysis”). The study has been carried out using a pulsed Neodymium-YAG-Laser (wavelength 1064 nm), the energy was set at 10 mJ and the duration of pulses 14 nanosec. The light pulse is carried by a 400 um quartz fibre to the laser phacolysis probe. The laserlight hits a titanum target inside the tip, which leads to an optical breakdown that causes a shockwave. The generation of both, plasma and Shockwave are responsible for the disrupting of nuclear material.The reaction of the posterior capsule exposed to the Shockwave in different distances from the laser-phacolysishandpiece has been studied.Temperature-measurements were carried out in a special designed measuring device and in the anterior chamber of donor eyes from the Salzburg eye-bank with the laser phacolysis and the ultrasonic phaco handpiece. There is no clinical significant rise of heat at the laser tip.This initial in-vitro study demonstrates that some of the wellknown risks of ultrasonic phacoemulsification (e.g. rupture of the posterior capsule and heat at the phacotip) could be deminished with laser phacolysis.

Corneal complications of cataract surgery.

Recent advances in cataract surgery have reduced the incidence of corneal complications. Review of the current literature reveals a trend toward early visual rehabilitation and minimization of postoperative astigmatism by careful selection of incision type and location for small-incision cataract surgery. Since the introduction of intraocular lenses, endothelial cell loss has been a concern. Preservation of corneal endothelial cell function continues to be a major goal as cataract surgery continues to evolve. Recent studies have been undertaken to determine the effect of incision location and size on endothelial cell loss. Several reports on iatrogenically induced corneal decompensation are of interest as this complication can be avoided if proper precautions are taken. Although improvements in surgical technique have lead to a decreased incidence of Descemets membrane detachments and of epithelial and fibrous downgrowth, early recognition and intervention are imperative.

Thermal Damage from Laser Ablation

hours. In these cases, we inject two-component fibrin glue (Tissucol®) subconjunctivally with a blunt cannula introduced under the conjunctiva in the upper limbus or with a 30 gauge needle from the temporal side. Aprotinin drops (Trasylol®) can be applied four times daily for some days. The intraocular pressure usually rises in the first 24 hours (and has to be treated appropriately) and normalizes thereafter. It is sometimes necessary to repeat the procedure. Only seldom is a surgical revision necessary.