YAG Laser Photodisruption Research Articles

Pars plana posterior capsulectomy with a 27-gauge microincision vitrectomy system for dense posterior capsule opacification

We describe a surgical technique of pars plana posterior capsulectomy using a transconjunctival sutureless 2-port 27-gauge microincision vitrectomy system to deal with dense posterior capsule opacification (PCO). The technique was used successfully in 5 eyes of 5 patients with dense PCO that hadbeen unsuccessfully treated by neodymium:YAG laser photodisruption.

Successful Treatment of Corneal Larva Migrans by Nd:YAG Laser Photodisruption.

Successful Treatment of Corneal Larva Migrans by Nd:YAG Laser Photodisruption.

Recurrence of a small primary iris stromal cyst following treatment with Nd:YAG laser photodisruption in an adult

Introduction. Primary acquired iris stromal cyst is rare in adults. In this group, they are generally stable lesions which require no treatment. Case outline. We describe a rare case of a small primary iris cyst in a 39-year-old patient, associated with unusual signs of irritation. Ultrasound biomicroscopy demonstrated iris stromal cyst measuring 3 ? 2 mm. A neodymium-doped yttrium aluminium garnet (Nd:YAG) laser cystotomy was engaged as the least invasive treatment approach. However, the cyst recurred soon after repeated laser treatment and sector iridectomy with excision of the cyst was performed. Five years after surgery there was no evidence of recurrence. Conclusion. Although more benign clinical course of primary stromal iris cyst is generally assumed in adults as compared to children, complete cyst removal seems to be mandatory for preventing cyst recurrence regardless of the cyst size or patient age. To the authors? knowledge this is the first documented report of Nd:YAG laser photodisruption of acquired primary iris stromal cyst in an adult.

Ophthalmomyiasis interna masquerading as orbital cellulitis

Ophthalmomyiasis interna posterior is a rare condition caused by the invasion of the ocular posterior segment by the larval form of certain flies in the order Diptera. The main clinical features are reduced visual acuity, intense posterior uveitis, and neuroretinitis. Treatment of this condition is predominantly surgical, including argon laser photocoagulation for subretinal larva and pars plana vitrectomy for intravitreal infection. We report a case of ophthalmomyiasis interna posterior in a 12-year-old girl that masqueraded as orbital cellulitis and was successfully treated with Nd:YAG laser photodisruption.

Vitrectomy for vitreous floaters

SummarySymptomatic vitreous ‘floaters’ are one of the most common presenting complaints in the clinics of ophthalmologists. Although most patients will accept observation as the symptoms often improve spontaneously, in a subset of patients the symptomatic, persistent vitreous opacifications do not disappear with time and may become highly bothersome in daily life. During the past two decades, more and more patients have been treated for persistent floaters. Pars plana vitrectomy (PPV) and Nd:YAG laser photodisruption have been considered.Since Robert Machemer introduced PPV in the early 1970s, and with the progressively decreasing gauge size, the idea of using this surgical technique for vitreous opacities has become a hot topic in the ophthalmologic community. PPV is the gold standard for mechanical removal of vitreous opacities. The so called ‘floaterectomy’ shows resolution of vitreous opacities in over 95% of cases and patient satisfaction rates range from 85 to 94%, with improvement in contrast sensitivity and quality of life. Microincisional vitrectomy surgery (MIVS) has been shown to decrease operative times, surgically induced trauma and postoperative inflammation, leading to a more rapid recovery and in a more safety manner.

Photodisruption of a thin membrane near a solid boundary: an in vitro study of laser capsulotomy

A Nd:YAG laser photodisruption is a well-established tool for intraocular surgery, such as treatment of posterior capsule opacification that affects the visual function. During the intraocular procedure, called laser capsulotomy, the excitation pulse is focused several times just behind the posterior capsule and intraocular lens to create the central opening in the opacified capsule. We built an in vitro experiment to (1) clarify the influence of the distance between the intraocular lens and the posterior capsule on the total pulse energy required for the capsulotomy, and (2) investigate the main mechanisms responsible for the posterior capsule opening. In our in vitro model, different distances between the solid boundary (imitating an intraocular lens) and the membrane (imitating the posterior capsule) simulate different types of posterior capsule opacification. Our results show that procedure efficiency decreases by decreasing distance between the lens and the capsule. We also explain that for smaller distances between the pulse focus and the membrane, plasma and shock wave are responsible for the capsule disruption. Here, a risk of collateral damage significantly increases. On contrary, the membrane and the bubble jet disrupt the membrane, when pulse focus is moved away and the risk of intraocular lens damage decreases. However, the membrane disruption is not very effective, if it is placed near the solid boundary that inhibits the membrane jet.

Vitreous Humor Rheology After Nd:YAG Laser Photo Disruption

This work aimed to consider the hazardous side effect of eye floaters treatment with Q-switched Nd:YAG laser on the protein and viscoelastic properties of the vitreous humor, and evaluate the protective role of vitamin C against laser photo disruption. Five groups of New Zealand rabbits were divided as follows: control group for (n = 3) without any treatment, the second group (n = 9) treated with Q-switched Nd:YAG laser energy of 5 mJ × 100 pulse delivered to the anterior, middle, and posterior vitreous, respectively (n = 3 for each). The third group (n = 9) received a daily dose of 25 mg/kg body weight vitamin C for 2 weeks, and then treated with laser as the previous group. The fourth group (n = 9) treated with 10 mJ 9 50 pulse delivered to the anterior, middle, and posterior vitreous, respectively (n = 3 rabbits each). The fifth group (n = 9) received a daily dose of 25 mg/kg body weight vitamin C for 2 weeks, and then treated with laser as the previous group. After 2 weeks of laser treatment, the protein content, refractive index (RI), and the rheological properties of vitreous humor, such as consistency, shear stress, and viscosity, were determined. The results showed that, the anterior vitreous group exposed to of 5 mJ × 100 pulse and/or supplemented with vitamin C, showed no obvious change. Furthermore, all other treated groups especially for mid-vitreous and posterior vitreous humor showed increase in the protein content, RI and the viscosity of vitreous humor. The flow index remained below unity indicating the non-Newtonian behavior of the vitreous humor. Application of Q-switched Nd:YAG laser should be restricted to the anterior vitreous humor to prevent the deleterious effect of laser on the gel state of the vitreous humor.

Macro-anévrysme artériel rétinien compliqué d’une hémorragie prérétinienne: traitement par photocoagulation au laser YAG

Retinal arterial macroaneurysms are ectatic modifications of the arterial wall. They are a relatively uncommon condition that can threaten visual function by pre- or subretinal hemorrhage if rupture or massive macular exudation occurs. We report a case of a 59-year-old patient with arterial hypertension who presented an arterial macroaneurysm complicated by premacular hemorrhage. We performed Nd: YAG laser photodisruption, which resulted in drainage of preretinal blood, with complete hemorrhage regression and visual recovery. Retinal macroaneurysms are acquired malformations, often isolated and located in a temporal artery. Their progression is unpredictable, evolving toward spontaneous occlusion, occurrence of chronic exudative retinopathy, or hemorrhagic complications by fissuration or rupture of the arterial wall. Through this observation, the authors discuss the value of YAG laser photodisruption for preretinal hemorrhage caused by retinal macroaneurysm.

Visual prognosis and macular pathology in eyes with retinal macroaneurysms

We studied retrospectively the visual outcome of 20 eyes of 19 patients with symptomatic retinal arterial macroaneurysm. The macular pathology responsible for the acute visual loss was categorized as macular edema (5 eyes), preretinal hemorrhages alone (3 eyes), subretinal hemorrhages with or without preretinal hemorrhages (10 eyes) and vitreous hemorrhage (2 eyes). Thirteen eyes were treated with argon or dye laser photocoagulation. Five eyes with preretinal hemorrhage underwent YAG laser photodisruption of the posterior hyaloid membrane to release the preretinal hemorrhage into the vitreous space. Five eyes with macular edema, 3 eyes with preretinal hemorrhage without subretinal hemorrhage and 2 eyes with vitreous hemorrhage showed final vision of 0.5 or better, but of the other 10 eyes with subretinal hemorrhage with or without preretinal hemorrhage, 9 showed final visual acuity of 0.2 or worse. Visual prognosis of submacular hemorrhage due to ruptured retinal macroaneurysm is poor, but that of macular edema, preretinal hemorrhage or vitreous hemorrhage is relatively good.

Ultrasound biomicroscopic analysis of pseudophakic pupillary block glaucoma induced by Soemmering's ring

AIMTo perform ultrasound biomicroscopic analysis of pseudophakic pupillary block glaucoma induced by lens capsule and a Soemmering's ring and its resolution, and to elucidate the pathophysiology of this glaucoma.METHODSA woman...

Nd:YAG LASER PHOTODISRUPTION FOR PRERETINAL HEMORRHAGE DUE TO RETINAL MACROANEURYSM

To document the clinical course of Nd:YAG laser photodisruption for eyes with preretinal hemorrhage following rupture of a retinal macroaneurysm. We reviewed six eyes of five patients with preretinal hemorrhage due to retinal macroaneurysm that received Nd:YAG laser photodisruption. Nd:YAG laser created a focal opening in the anterior surface of the preretinal hemorrhage, permitting the blood to enter the vitreous cavity where it would be absorbed more rapidly. Three eyes showed both subhyaloid hemorrhage, which was resorbed without treatment within 2 months, and hemorrhagic detachment of the internal limiting membrane (ILM), which required Nd:YAG laser photodisruption. All eyes showed disappearance of the preretinal hemorrhage and improvement of vision within 1 week of Nd:YAG laser photodisruption. Visual recovery was less prominent in eyes associated with subretinal macular hemorrhage. Preretinal hemorrhage due to a ruptured retinal macroaneurysm could be dispersed into the vitreous cavity with Nd:YAG laser photodisruption. It should be considered in the decision of Nd:YAG laser photodisruption that the visual increment may be limited in eyes that also have subretinal hemorrhage in the macula and that the hemorrhage beneath the ILM tends to remain longer than the subhyaloid hemorrhage.

Free Radical Production by Nd: YAG Laser Photodisruption

Plasma and cavitation bubble formation during optical breakdown in aqueous media may produce hydroxyl (*OH) radicals. The authors' objectives were to detect *OH produced by a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser photodisruptor and to determine *OH concentration in relation to laser energy. *OH was assayed by measuring absorbance of triiodide (I3-) in a potassium iodide (KI) solution exposed to optical breakdown by an Nd:YAG laser. The concentration-dependent reduction of radical production in relation to cystamine concentration was evaluated. I3- concentration increased linearly with total irradiation energy and decreased exponentially with increasing cystamine concentration. *OH concentration was calculated using extinction coefficients of I3- and chemical equations relating I3- formation to *OH. The authors calculated that approximately 4 x 10(-12) moles of *OH are produced in a typical posterior capsulotomy of 100 mJ of total energy. This *OH concentration could produce strand breaks in approximately 0.4% of vitreous hyaluronic acid molecules, but is unlikely to produce clinical effects.

Analysis of blast waves induced by Q-switched Nd:YAG laser photodisruption of absorbing targets

An experimental investigation on photoacoustic effects originated in plasma-mediated laser photodisruption by a Q-switched Nd:YAG was done by means of a pump-and-probe set up providing time-resolved shadowgraphy of the shock wave produced onto the target surface. Estimations of coupled specific momentum and of the explosion energy were obtained by modelling the process on the basis of the variable energy blast wave theory. A comparison with the instantaneous (constant energy) explosion model is also discussed.

Mechanisms of intraocular photodisruption with picosecond and nanosecond laser pulses.

Nd:YAG laser photodisruption with nanosecond (ns) pulses is an established method for intraocular surgery. In order to assess whether an increased precision can be achieved by the use of picosecond (ps) pulses, the plasma size, the shock wave characteristics, and the cavitation bubble expansion after optical breakdown with ps- and ns-laser pulses were investigated by time-resolved photography and acoustic measurements. Nd:YAG laser pulses with a duration of 30 ps and 6 ns, respectively, were focused into a water-filled glass cuvette. Frequency doubled light from the same laser pulses was optically delayed between 2 ns and 136 ns and used as illumination light source for photography. Since the individual events were well reproducible, the shock wave and bubble wall position could be determined as a function of time. From the slope of these r(t) curves, the shock wave and bubble wall velocities were determined, and the shock wave pressure was calculated from the shock velocity. The plasma size at various laser pulse energies was measured from photographs of the plasma radiation. The breakdown thresholds at 30 ps and 6 ns pulse duration were found to be 15 microJ and 200 microJ, respectively. At threshold, ps-plasmas are shorter than ns-plasmas, but at the same pulse energy they are always approximately 2.5 times longer. The initial shock pressures were 17 kbar after ps-pulses with an energy of 50 microJ, and 21 kbar after 1 mJ ns-pulses. The pressure amplitude decayed much faster after the ps-pulses. The maximum expansion velocity of the cavitation bubble was 350 m/s after a 50 microJ ps-pulse, but 1,600 m/s after a 1 mJ ns-pulse. The side effects of intraocular microsurgery associated with shock wave emission and cavitation bubble expansion can be considerably reduced by the use of ps-pulses, and new applications of photodisruption may become possible.

Effect of neodymium:YAG laser photodisruption on intraocular lenses in vitro

Poly(methyl methacrylate) (PMMA) based intraocular lenses (IOLs) such as injection-molded PMMA and lathe-cut PMMA IOLs and soft IOLs such as silicone and poly(hydroxyethyl methacrylate)(polyHEMA) IOLs were tested for vulnerability to Nd:YAG laser photodisruption. The laser beam was focused on the posterior surface and inside of the IOLs in balanced salt solution. Cracks and central defects with radiating fractures were observed in PMMA IOLs; blistered lesions and localized pits were observed in silicone and polyHEMA IOLs, respectively. A molten edge surrounding the large hole, which was an indication of the thermal effect of the laser, was observed in the injection-molded PMMA while only a minute lesion was found in the polyHEMA IOL which contained 38% water. The size of the superficial damage of the IOL increased as tb 2 power of laser irradiation increased and PMMA IOLs showed greater damage than soft IOLs (P < .05).

Use of the Neodymium-YAG laser to manage subinternal limiting membrane haemorrhage

Australian and New Zealand Journal of OphthalmologyVolume 19, Issue 1 p. 81-83 Free Access Use of the Neodymium-YAG laser to manage subinternal limiting membrane haemorrhage Peter Chau MRCP(UK), FRACS, FRACO, Corresponding Author Peter Chau MRCP(UK), FRACS, FRACO Royal Victorian Eye and Ear Hospital, MelbourneDr P. Chau, 688 Whitehorse Road, Mont Albert, Victoria 3127, Australia.Search for more papers by this authorJoseph A. Reich DO(Melb), FRACS, FRACO, Joseph A. Reich DO(Melb), FRACS, FRACO Royal Victorian Eye and Ear Hospital, MelbourneSearch for more papers by this author Peter Chau MRCP(UK), FRACS, FRACO, Corresponding Author Peter Chau MRCP(UK), FRACS, FRACO Royal Victorian Eye and Ear Hospital, MelbourneDr P. Chau, 688 Whitehorse Road, Mont Albert, Victoria 3127, Australia.Search for more papers by this authorJoseph A. Reich DO(Melb), FRACS, FRACO, Joseph A. Reich DO(Melb), FRACS, FRACO Royal Victorian Eye and Ear Hospital, MelbourneSearch for more papers by this author First published: February 1991 https://doi.org/10.1111/j.1442-9071.1991.tb01807.xCitations: 10AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat References 1 Gabel VP, Birngruber R., Gunther-Koszka H., Puliafito CA. Nd: YAG laser photodisruption of hemorrhagic detachment of the internal limiting membrane. Am J Ophthalmol 1989; 107: 33– 37. Citing Literature Volume19, Issue1February 1991Pages 81-83 ReferencesRelatedInformation

Nd:YAG Laser Photodisruption of the Vitreous Traction in Avulsed Retinal Vessel Syndrome

We applied Nd:YAG laser photodisruption to vitreous traction in three patients with avulsed retinal vessel syndrome. In every case the vitreous traction on the avulsed vessels was relieved and the vessel that had been avulsed in the vitreous cavity returned to the retinal surface postoperatively. There were no serious intraoperative and postoperative complications, nor was there any evidence of recurrence of vitreous hemorrhage after the treatment.

Nd:YAG Laser Photodisruption of Hemorrhagic Detachment of the Internal Limiting Membrane

We used a Q-switched Nd:YAG laser to create an opening in the internal limiting membrane in three eyes with hemorrhagic detachment of the internal limiting membrane. In all instances, after membranotomy blood was rapidly cleared from the preretinal space resulting in prompt improvement in visual acuity. No retinal injury was observed. Nd:YAG laser photodisruption may be useful in the treatment of some cases of subinternal limiting hemorrhages.

Influence of indomethacin on PGE2 in rabbit aqueous humor after YAG laser photodisruption of the iris.

In an experimental study with rabbits, the influence of indomethacin on the postoperative PGE2 level in the aqueous humor was investigated, following YAG laser traumatization of the iris. Indomethacin is a drug with an inhibitory effect on the synthesis of prostaglandins. Using albino rabbits, the right eye was treated with indomethacin eye drops three times daily for 3 days. On the 4th day, high-energy YAG laser was applied to the iris of both eyes (Q-switched Nd: YAG Laser, Model Cilco Lasertek PV 135; ten photodisruptive lesions, with 50 mJ to the midperiphery of the iris). Subsequently, the rabbits were subdivided into three groups. In group 1 the aqueous humor was removed from both eyes 12 h postoperatively; in group 2 the aqueous humor was tapped 36 h after the intervention; for group 3, it was 60 h afterwards. The results from 15 rabbits were evaluated. Local indomethacin treatment was continued until tapping of the aqueous humor. As a control, another group was used with 3 rabbits without treatment. Twelve hours after YAG laser treatment there was still a clearly significant difference in the PGE2 concentrations between the eyes that had received indomethacin and the untreated eyes; 36 h postoperatively, the difference was no longer statistically significant, and after 60 h the PGE2 concentrations of the treated and untreated eyes were the same.

Nd:YAG laser photodisruption: an experimental investigation on shielding and multiple plasma formation.

In an ocular model plasmas were induced by Q-switched, commercially available Nd:YAG lasers that operated in low order or fundamental mode. Plasma shielding was measured and analysed in relation to energy input, number of plasmas and plasma evolution. Near breakdown threshold, attenuation or shielding of the laser beam resulting from absorption and scattering by the plasma is low and is characterized by high variability from shot to shot. More importantly, shielding does not increase when multiple plasmas are formed, possibly due to a competitive mechanism between these plasmas. Further evidence of this mechanism was obtained from measurement performed using a streak camera. The effectiveness of shielding is scarcely changed by an increase in the cone angle of the incident radiation. In the light of these experiments and other published data, safety guidelines for the clinical use of the Nd:YAG laser have been formulated.