Ординатура / Офтальмология / Английские материалы / Step by Step Minimally Invasive Glaucoma Surgery_Garg, Melamed, Bovet, Pajic, Carassa, Dada_2006

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to the “gold standard” trabeculectomy. The basic problem has been that surgeons must first perform a standard trabeculectomy type scleral flap, then proceed to perform a second scleral flap under the first flap. This second flap requires the surgeon to use a blade to bisect the thin scleral layer under the first scleral flap – truly a daunting surgical feat. This maneuver cannot be repeatedly performed by most surgeons. Dr Ike Ahmed is performing a series of non-perforating glaucoma filtration procedures at the University of Toronto with the Fugo Blade. Dr Ahmed and his fellows now use the Fugo Blade to perform what they have coined “erasing tissue” from the scleral flap bed. They erase the scleral tissue until aqueous percolates through the thinned scleral window. This procedure requires less than a minute to perform and according to Dr Ahmed eliminates the last remaining hurdle for all ophthalmologists to perform the non-perforating glaucoma procedure (personal communication).

There are many ways to perform NPF with the Fugo Blade. They are as follows:

a.Open non-perforating filtration.

b.NPF under a limbus based sclero-corneal flap.

c.NPF under a fornix based corneo-scleral flap.

Open Non-perforating Filtration (Singh NPF)

The surgery is done under local anesthesia as described previously.

1.The conjunctiva is detached from the limbus for about 5 mm.

2.Any blood ooze is hemostased with a minimum energy setting of the Fugo Blade 600 microns tip (Fig. 24.24).

3.Any Tenon’s capsule in the exposed area is cut with forceps and scissors.

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Fig. 24.24: The conjunctiva has been detached from the limbus. The blood vessels in the area of surgery are being ablated with 600 microns tip of Fugo Blade

4.Fugo Blade Ablation of the limbal area to expose the canal of Schlemm’s. A 600 microns Fugo Blade tip is used to ablate the limbal area by moving the tip from the corneal to the scleral side. With every passage, the limbal pit becomes deeper (Fig. 24.25). The pit is also widened in a sloping fashion to facilitate deeper ablation in the center. The ablation involves the tissues on either side of the surgical limbus. The surgical limbus overlies the anterior corneoscleral trabeculae. Thus, we would expect to find the canal of Schlemm just posterior to it. Thinning of the cornea anterior to the surgical limbus may help later on in producing a filtration pore with the YAG laser, in cases where enhancement of filtration is needed. The thinning of the limbal tissues by Fugo Blade ablation is continued at the lowest energy

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Fig. 24.28: The conjunctiva has been sutured back to the limbus with multiple sutures

NPF Under a Limbus Based Sclerocorneal Flap

The steps of operation are as follows:

1.The limbus is detached as usual and the scleral surface is cleared of Tenon’s capsule and bleeding points.

2.A triangular scleral flap about 1/3 mm thick and 2 mm wide is made with its base towards the limbus.

3.The flap is held with a forceps, while ablation of the limbal tissues is performed as before until aqueous begins to percolate though the thinned window.

4.The conjunctiva is sutured back to the limbus.

Note that the scleral flap is not sutured, since it is not

required. Mitomycin may be applied under the flap before the exteriorization of the Schlemm’s canal, in selected cases. In case a collagen implant is desired, a rectangular scleral flap is fashioned, which is sutured back at the end of

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surgery. Collagen implants create a space under the flap and are absorbed in about 6 months.

NPF Under a Fornix Based Corneoscleral Flap (Singh)

The steps of operation are as follows:

1.The conjunctiva is detached for 6-7 mm.

2.A 0.3 mm thick and 2.5 mm wide flap of corneosclera is raised anterio-posteriorly.

3.The exposed base is ablation-thinned. The edges of the base are also ablated.

4.The tissue ablation is done as before to start seepage of fluid from the area of Schlemm’s canal.

5.The corneoscleral flap is sutured back with two 30 micron sutures.

6.The conjunctiva is sutured back at the limbus.

The point to note is that there is no trauma to the Tenon’s

capsule and the episcleral blood vessels. The filtering aqueous escapes from the ablated edges of the base under the corneoscleral flap.

FOLLOW-UP

A careful follow-up of non-perforating filtration cases is required. In the first few days, the filtration may become blocked by a blood clot. A pressure bandage may relieve the block. Sluggish aqueous flow may raise the intraocular pressure beyond normal. In such a case, the fluid flow can be augmented by making a YAG laser pore in the thinned limbal area.

The surgery of non-perforating filtration has a learning curve. The filtration area may not be found as desired. It may open into the anterior chamber, in which case a peripheral iridectomy is done with the Fugo Blade and the case finished like any anterior chamber filtration. In this

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case, placement of a TCF pore may serve to protect against anterior chamber collapse. On the other hand, the ciliary body area may be exposed without finding Schlemm’s canal. In this case, the operation is finished with a transciliary filtration (TCF) procedure. A case may be finished as double filtration track-one in the anterior chamber and the other transciliary (Atwal procedure). With a little experience, Fugo Blade filtration procedures may be performed with 6 X or 8 X head worn loop magnification, which underscores the value for Third World glaucoma, especially since the procedures require minutes to perform.

Besides the techniques described above, the Fugo Blade is helpful in the placement of valves and setons.29 It can make a gutter on the sclera that accommodates and holds the silicone tubing of the valve. It can be used to remove tenon cyst formation around the valve and tubing to restart the function of the valve. The Fugo Blade is an excellent tool to cut and destroy Tenon’s cysts without extensive dissection. The conjunctiva is ballooned around the cyst. A special 300 or 600 microns Fugo Blade tip is introduced from one side to ablate the walls of the tenon cyst from edge to edge, at the same time removing much of the scar tissue. A suture is applied to the entry point of the tip.

CONCLUSION

The Fugo Blade is an important surgical tool that is fundamentally different from all the previous devices that have been employed in surgery.30 It does not cut, but it ablates much like excimer laser, with clinically insignificant collateral damage.31 This has been confirmed by such leaders in our field such as Dr I Howard Fine, Dr Ike Ahmed, Dr Herbert Kaufman and Dr F Hampton Roy. Rather, the Fugo Blade creates tracks even through vascular

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tissues such as the ciliary body. It closes the blood vessels as it makes an ablation path in the tissues by autostasis. It is not a cautery, and causes no charring. A note of extreme caution is warranted wherein no surgeon should attempt the herein presented procedures with any other electrosurgical device besides the Fugo Blade.32 The Fugo Blade uses a small amount of energy in the form of plasma to ablate, remove, or “erase” tissue. It has the potential for application in every field of ophthalmology, general surgery, even dentistry.33

Glaucoma surgery shall never be the same with the introduction of Fugo Blade. Transciliary filtration and nonperforating techniques substantially remove all worries connected with anterior chamber integrity. Microtrack filtration needs further development and refinement for an application on a mass scale to fight the worldwide menace of glaucoma. The future surgical techniques shall take into account the importance of preserving a healthy lymphatic network under the conjunctiva and strive for minimally traumatic operations.

During the time of Galen circa 150AD, Roman physicians possessed over 150 distinct operations in their surgical repertoire in areas such as abdominal surgery, brain surgery and eye surgery. The surgical trays from the era of Galen had impressive, refined surgical equipment which if examined carefully were not much different from present day equipment except for the material used in their production. Over the last century, we have added standard electrosurgery, fiberoptics and laser. Now, ophthalmology has introduced a technology which shall provide a quantum leap in surgical capability. This technology is known as the Fugo Blade wherein tissue is “erased” by thin layers of plasma. This requires minimal energy, cuts resistance free and leaves incision walls pristine clean. This

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work represents an intense collaboration between the two authors. With a solid background in biophysics, Dr. Fugo has concentrated on the equipment while Dr Singh has focused on truly remarkable clinical applications which require a combination of imagination and the skill of a master surgeon. This work has been accomplished at much personal sacrifice. Nonetheless, it is an honor to be a part of a project that has the potential to elevate the quality of healthcare worldwide….for the industrialized world but also for the poorest of the poor. One of the authors (DS) refers to this new technology as “the great equalizer”. This new solid state technology will allow the poorest clinic in a remote part of the world to have access to the most advanced medical technology in the world.

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3.Sabbagh LB. The leading edge: Harnessing electrons for a faster, smarter incision. Eyeworld 1998,3,4:88.

4.Kronemyer B. Fugo Blade uses low-level energy to create anterior capsulotomy. Ocular Surgery News 2000;18,21:4546.

5.Kellan R, Fugo RJ. Device increases safety, efficiency of cataract surgery. Ophthalmology Times 2000;25,22:7-9.

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8.Fine IH, Hoffman RS, Packer M. Highlights of the 2002 ASCRS Symposium, Part I. Eyeworld 2002;7,7:38.