Ординатура / Офтальмология / Английские материалы / Step by Step Minimally Invasive Glaucoma Surgery_Garg, Melamed, Bovet, Pajic, Carassa, Dada_2006
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382 Step by Step Minimally Invasive Glaucoma Surgery
Fig. 23.12
Fig. 23.13
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0.67 ± 0.30, with a mean postoperative equivalent of -0.74 diopters ± 1.38. Seventy-one percent of the eyes gained at least 2 lines of visual acuity; 4.5 percent lost least 2 lines of visual acuity. The only complications encountered were: a malignant glaucoma treated by posterior vitrectomy; a retinal detachment in 12 diopters myopic patient, which required two procedures to flatten the retina. There was no case of migration or displacement of the drain, neither under the conjunctiva nor inside the anterior chamber.
CONCLUSIONS
Since its first description in 1989,1 deep sclerectomy (DS) has regularly evolved to attain a reproducible surgical method, which is not yet stereotyped, as every ophthalmic surgeon propose his own technique. The IOP results are fairly good,2 even though long-term results are sometimes deceiving.3 The main advantage of DS is the absence of postoperative hypotony with its well-known complications; it also gives less astigmatic change than trabeculectomy.4 From the beginning, many authors have proposed the adjunction of resorbable drainage devices, such as collagen,1 as Aquaflow® processed from lyophilized porcine scleral collagen2 or reticulated hyaluronic acid (SK-Gel®). Histopathological evaluation confirmed that the presence of a drain could form a smooth and regular intrascleral space to prevent collapse of the scleral flap over the site of the DS.5 More recently, a nonresorbable drain made of hydrophilic acrylic material and designed by E. Dahan has been commercialized (Fig. 23.14) to maintain more durably an wide opened intrascleral space. With this drain, Ates et al6 showed IOP success rates comparable to viscocanalostomy, with few complications. As it has been recently proved that the adjunction of
384 Step by Step Minimally Invasive Glaucoma Surgery
Fig. 23.14
Mitomycin-C could give better IOP results without increasing the complication rate,7 it appears logical to use this drug to reduce a possible postoperative fibrosis around this foreign body represented by the acrylic drain.
REFERENCES
1.Kozlov, et al. Non-penetrating deep sclerectomy with collagen IRTC Eye Microsurgery, Moscow, RSFSR Ministry of Public Health, 1989;44-46.
2.Shaarawy T, et al. Long-term results of deep sclerectomy with collagen implant. J Cataract Refract Surg 2004;30:122531.
3.Lachkar Y, et al. Non-penetrating deep sclerectomy: a 6- year retrospective study European Journal of Ophthalmol 2004;14;1:26-36.
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4.Egrilmez S, et al. Surgically induced corneal refractive change following glaucoma surgery: non-penetrating trabecular surgeries versus trabeculectomy J Cataract Refract Surg 2004;30:1232-39.
5.Erbiliç K, et al. Deep sclerectomy with various implants : an experimental and histopathological study in a rabbit model. Ophthalmologica 2004;218:264-69.
6.Ates H, et al. Deep sclerectomy with a non-absorbable implant (T-Flux): preliminary results Can J Ophthalmol 2003;38:482-88.
7.Neudorfer M, et al. Non-penetrating deep sclerectomy with the use of adjunctive Mitomycin-C. Ophthalmic Surg Lasers and Imaging 2004;35;1:6-12.
388 Step by Step Minimally Invasive Glaucoma Surgery
INTRODUCTION
The glaucoma filtration surgery technique has remained nearly static during the past century, mainly for the reason that the surgical tools have remained more or less the same.1 The instruments have become smaller and finer, as well as the operating microscope has become a standard aid for improved magnification. Nonetheless, the only palpable ‘revolution’ has been the making of a scleral flap. The introduction of mitomycin has improved certain case results, but it has also added many new serious complications. In spite of the availability of antibiotics, steroids, and non-steroidal anti-inflammatory medication, there has been no real breakthrough. Results remain unpredictable and there are too many serious side effects, often related to immediate collapse of the anterior chamber. For these reasons, most anterior segment surgeons avoid glaucoma filtration surgery.2 In this scenario, the arrival of a new ablative surgical tool in the form of the Fugo Plasma Blade has brought about a fundamental change in the approach to filtration surgery. This new approach could only happen thanks to the unique ability of Fugo Plasma Blade to ablate the surface of the sclera with a hair thin plasma cloud. The Fugo Blade can ablate permanent tracks through tissues such as cornea, sclera and ciliary body in a resistance free fashion. And, the plasma ablation of tissue occurs without any clinically significant collateral damage or postoperative reaction to the incision wall.
FUGO BLADE®
The Fugo Blade® is a unique cutting instrument, which employs plasma, the 4th state of matter, for ablating incision paths in tissue in a manner similar to the eximer laser and is the only electrosurgical device approved for
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intraocular use by the Food and Drug Administration (FDA) in the USA.3
The Fugo Blade is also known as the Plasma Blade in many other parts of the world, since it ablates with plasma energy.4 It consists of a console, a hand-piece with a disposable tip and an activation footswitch (Fig. 24.1). Four rechargeable “C” cell flashlight size batteries provide the energy. The power generated is about 1watt for little energy is needed to energize the cutting tip, thereby, one charge of the batteries lasts for about an hour of cutting time. The plasma is visible under high magnification, looking like bees on a honey cone or a miniature fluorescent light bulb. This plasma ablates in such a fashion that it creates a smooth wall along the ablation/incision path. The secret is that the electromagnetic waves are brought to a sharp
Fig. 24.1: The Fugo Blade® console and the hand-piece with attached disposable tip. There is an outlet for the hand-piece and one for the footswitch. There are controls to regulate the cutting power of the tip
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focus by the electronics in the console and in the handle, onto the tip of the blunt incising filament which has the thickness of a human hair.5 The electromagnetic oscillations knock electrons from their orbits in the atoms of the tissue. Thus plasma, the fourth state of matter, consisting of charged atoms and electrons is produced. This plasma cloud at the activated tip-tissue junction becomes visible to the naked eye. Surgeons such as Prof Randal Olson (Utah, USA), Prof Ike Ahmed (Toronto, Canada) and Dr I Howard Fine (Washington State, USA) have all emphatically stated that this device has nothing to do with classic electrosurgery or diathermy.
Under a high power microscope, the plasma cloud is visible as a 25-50 micron wide pulsating yellow cloud on the hair thin, blunt activated tip (Fig. 24.2).6 Around the
Fig. 24.2: The cutting power resides in the thin, inner yellow looking plasma cloud surrounding the activated filament of Fugo Blade® tip. The much wider, outer non-cutting photon cloud looks orange
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plasma cloud, there is reddish much wider photon cloud. The cutting power resides in the inner thin plasma cloud. The plasma sustains itself as long as the electromagnetic oscillations from the activated tip keep interacting with the tissue, which is ablated in the truest sense.7 The plasma cloud oscillations instantly shatter the macromolecules of the tissue into small fragments. The micro-molecular fragments thus produced mix with water vapor and are discharged at great speed as a plume; just as is seen with the eximer laser.8 During extra-ocular procedures such as touching a bleeding area, the molecular oscillation throws the particles millimeters away. This produces a process called “Autostasis” wherein these small particles plug the top of small vessels thereby producing a non-cauterizing hemostasis. Histologic sections show that cautery produces charred, blistered wound margins whereas the Fugo Blade wound margins have been shown to be pristine clean, thereby reducing swelling, redness, pain and scarring.9 The plasma energy at the tip is at a very high energy density, while possessing very low total energy since the plasma cloud has a very small volume. However, the energy field does not extend beyond 25 microns from the plasma, meaning that little or no heat is generated in tissue outside of the incision. Therefore, the Fugo Blade does not burn or cauterize. This has been demonstrated by ablating through visible conjunctival or muscle vessels, as well as the creation of bloodless pupiloplasties in seconds.10 The Fugo Blade® possesses this important function of non-cauterizing during incision of cut tissue. It does this in two waysfirstly by the ablation of the vessels in the cutting path and secondly by the particle oscillation, which tends to plug the small bleeding vessels. Finally, it should be made clear that the Fugo Blade® is completely different from a diathermy unit. The Fugo Blade® uses minute amounts of energy yet cuts