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

Glaucoma Surgery Techniques with the Fugo Blade® 403

Fig. 24.12: A conjunctival fold is pulled down with forceps, revealing the sharp edge of the conjunctival limbus.A blade holder with a blade fragment is ready to be placed at the sharp line

this point, we press down on the conjunctiva with the dull edge of a razor blade fragment, held in a blade holder, so that the conjunctiva shall not slide back.

3.A Fugo Blade tip of 100 microns or 300 microns is chosen according to the surgeon’s choice. The tip is placed at the chosen pre-selected point and directed towards the plane just posterior to and parallel with the iris (Fig. 24.13).26

The tip is activated and made to ablate a track between the posterior chamber and the subconjunctival space (Fig. 24.14). The system energy is turned off and the tip is withdrawn.

The completion of the track is signaled by the flow of fluid and sometimes uveal pigment.

Glaucoma Surgery Techniques with the Fugo Blade® 405

Fig. 24.15: A filtering bleb starts getting raised, as the conjunctiva is allowed to fall back to its normal place

4.The conjunctiva is allowed to fall back (Fig. 24.15). The filtering fluid begins elevating the conjunctiva. The hole in the conjunctiva may be closed with a suture.

Microtrack Filtration (Singh MTF)27

This technique employs a transconjunctival approach using a 100 microns Fugo Blade filament to create a filtering track between the anterior chamber and the subconjunctival space. The objective is to have a minimally invasive procedure for a variety of glaucoma cases having normal or deep anterior chambers. It can deal with emergency situations such as traumatic and inflammatory glaucomas if the intraocular pressure is uncontrolled by medical means. Sometimes there is a case with extensive scarring with a small area of virgin conjunctiva remaining, therein only a technique such as this shall work. The track is made

406 Step by Step Minimally Invasive Glaucoma Surgery

right under the attachment of the conjunctiva to the cornea. The width of the track created with the Fugo Blade is 200 microns. A very small 1-2 mm fold of conjunctiva is pulled down over the cornea before making the track. There is no involvement of the uveal tissues in the surgery. There is minimal disturbance of the reactive Tenon’s tissue. The fine microtrack is created with the hope that the iris shall not block the internal pore opening and scarring shall not occur over the external pore opening. The procedure is as follows:

The pupil is constricted prior to the operation.

The operation may be performed under topical anesthesia, subconjunctival anesthesia or general anaesthesia. The important point is that the eye should not move during the fraction of a second that it takes to perform the actual operation.

1.Make a note of the attachment of the conjunctiva to the cornea. The track has to be made right under it without creating a buttonhole.

2.The conjunctiva has to be brought down not with a forceps but with a dull sapphire or ruby knife (Fig. 24.16). The dull knife should be able to hold the conjunctiva down but not cut it. One can use a diamond knife with 0.6 mm or 1 mm tip. Even a sharp knife shall not cut the conjunctiva if it is not moved side to side and is not pressed to firmly. Why use such a sharp tool for bringing down the conjunctiva ? Because we need a moderately sharp but poor electrical conductor to hold down the conjunctiva. The inactivated Fugo Blade Plasma tip has to touch this instrument before it is activated and pushed into the anterior chamber (Fig. 24.17). A plastic tool may perform the same function but is not yet available. A metallic tool possesses a high electrical conductivity.

408 Step by Step Minimally Invasive Glaucoma Surgery

The knife edge is placed lightly about 1 to 1.5 mm from the conjunctival limbus. It is used to press and push the conjunctival towards the cornea, until its further progress is stopped by the root of the conjunctiva. In other words, the conjunctival flap cannot be pulled further because of traction from its attachment at the lumbus.

3.The inactivated Fugo Blade tip is pressed against the conjunctiva retracting knife, then it is activated with the foot switch. With a smart jab, the activated Fugo Blade tip is pushed in then out of the anterior chamber (Fig. 24.18). A track is instantly created in a resistance free fashion. A small air bubble may be injected if desired.

4.The conjunctival fold steadying knife is lifted and the conjunctiva is allowed to retract back to normal. The aqueous seepage through the track starts raising a bleb (Fig. 24.19).

5.A bandage contact lens is put in place, to prevent excessive leakage (Fig. 24.20). It is removed after 2 weeks.

Following creation of the MTF, the lymphatics are seen

to fill at the limbus (Fig. 24.21). The bandage contact lens slows down the movement of aqueous in order to inhibit excessive anterior chamber decompression with subsequent collapse of the anterior chamber. Soon the lymphatics become invisible due to bleb formation.

Postoperative management requires close attention. The pupil is kept constricted for at least one month when the fluid movement through the track becomes stabile, and there is no further tendency of the iris to block the internal opening. If the track becomes blocked with iris, the intraocular pressure will rapidly rise. On gonioscopy, the blocked internal opening of the Micro Transciliary

Glaucoma Surgery Techniques with the Fugo Blade® 411

Filtration track shall be seen to be plugged with a fine wick of iris (Fig. 24.22). This wick can be blown away with a single shot of YAG laser and the filtration will be restored (Fig. 24.23). The idea of making the track under the most distal part of the conjunctiva is to minimize the chance of iris blockage as well as to minimize Tenon’s scarring. In case of failure, the procedure can be easily and quickly redone in an adjoining area. The procedure is not suitable as such for angle closure cases. An additional manual iridectomy is needed.

Since the procedure is minimally traumatic and completed in a minute or two, it has the possibility of becoming a frontline field tool to fight worldwide glaucoma. It is particularly suitable for very sick and uncooperative patients. A primary success rate of over 80 percent is achievable. MTF fills a void in the vast world, where millions go blind for lack of costly glaucoma medication and for lack of costly surgical care. Like all other filtration procedures, there is need for regular follow-up. Since we are decompressing the anterior chamber of the eye, the possibility of postoperative collapsed anterior chamber is a consideration.

Non-perforating Filtration (NPF)

Non-perforating filtration has been around for some years in the form of viscocanalostomy and deep sclerectomy with or without a collagen implant. The objective is to tap Schlemm’s canal and not to open the anterior chamber. Both of these techniques require meticulous dissection under high magnification of the microscope. The techniques have not attracted many converts, mainly because they are considered more difficult to perform and the reported results have shown uneven success, compared