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

312 Step by Step Minimally Invasive Glaucoma Surgery

penetrative filter surgery. This reduces the risks of each, whilst increasing the long-term chances of success.4

SURGICAL TECHNIQUE IN OUTPATIENT SURGERY17

Local Anesthetic5

This anaesthetic technique has been described in the previous chapter.

Let us remember that this local anesthetic allows — thanks to the patient’s ability to participate - exposure of the operative field for dissection and its best, and variable angles of work.

Choices for Dissection

The path of dissection and flap’s localization are chosen to spare the penetrating vessels and to search for the zone that is the most avascular.

The draining vessels are on the surface, as shown by Stegmann.21

The choice of the best place for the flap to spare the penetrating vessels to find the most avascular zone, one must not forget that the draining vessels are on the surface, as shown by Stegmann in his film.

CONJUNCTIVAL SHUTTER WITH LIMB

Stages

Stages are as follows:

Dissection of the conjunctival shutter with limb, not less than 10 mm, with Vescoat scissors. Dissection in an L shape allowing the conjunctival flap to relax in the opening.

Exposing the sclera by dissecting Tenon’s capsule with care (Figs 19.1A and B).

314 Step by Step Minimally Invasive Glaucoma Surgery

Use the lightest possible electrocoagulation in order to spare the draining vessels as much as possible.

1st Scleral Flap

Incision of the scleral flap (Figs 19.2A and B).

•6 mm × 4 mm, the width being of less importance than the length

•depth of 300 microns, cut with a 30º diamond (Meyco,

Switzerland) or with a diamond for KR (Meyco, Switzerland) up to the lames corneostromales.

It is important to make a flap which is thick enough not to tear when one arrives in the corneal stroma6 (Fig. 19.3).

It is important to dissect the lames corneennes, starting from the limb, the cut allowing more room when making the incision of the second flap.

2nd Scleral Flap

5 mm dissection, with a 30º diamond (Meyco, Switzerland), of the length of the second triangular flap of all the depth of the sclera leaving some lamelles sclerales in order to just reveal the choroidien tissue. This allows getting exactly at the scleral spur, at the beginning of Descemet’s membrane (Figs 19.4A and B).

Dissection, holding on to the second flap, au tampon triangulaire pour repousser le stroma. Thus, we free Descemet’s membrane. Those who practice deep lamellar keratoplasty (“keratoplastie lamellaire”) operations will have no difficulty in finding the plane of dissection.

Separation of the Descemet from the stromal tissue is quite easy, so long as one is in the right plane.

The 1.5 mm incision in Descemet’s membrane is made in order that the Schlemm canal is not covered at the time of the cutting of the flap (Fig. 19.5).

318 Step by Step Minimally Invasive Glaucoma Surgery

On this level, each side, in the scleral tissue, a slight bleeding can be seen at the cut in the drainage vein of the Schlemm canal (Fig. 19.6).

Removal of the Second Flap

Removal of the second flap with the diamond or the Vannas scissor (Fig. 19.7).

This part of the operation is delicate and has to be done with great care. Because, on a number of occasions, when using Vannas or other scissors, Descemet’s membrane has been torn.

Cut up the Scleral Flap in Half

Cut up the scleral flap in half: one half is soaked for 5 minutes in 0.04 percent mytomicin, then rinsed.

Schlemm canal dissection (Fig. 19.8).

Using Bonn forceps with microteeth, a 5 mm dissection of the interior wall of the Schlemm canal is made, allowing us to see some seepage of the aqueous humor.

Canalostomy

The Schlemm canal vein gives the location of the Schlemm canal. Introduction of an extra fine Grieshaber cannula on both sides of the sclera of the Schlemm canal until some resistance is felt. Slow injection of high viscosity viscous fluid (Healon, G V AMO) whilst removing the microcatheter (Figs 19.9 and 19.10).

Implant/Mitomycine C

Put in place, in the bed of the second flap, the previously prepared implant, the implant having been, beforehand, soaked in mitomycine and rinsed before being used.