5. Removal of trocar cannulas, suture sclerotomies if silicone oil tamponade

The trocars are removed, as described above.

5.3Epiretinal Membranes and Macular Holes

This procedure is suitable for beginners with 50–100 vitrectomies. Both procedures are discussed here, as they involve similar techniques but different dyes. In macular hole surgery, one removes the ILM, which is stained with Brilliant Blue G. In macular pucker or idiopathic ERM, the ERM, which is usually stained with trypan blue, is peeled. Some surgeons recommend a subsequent peeling of the ILM, but there currently is no consensus on this. In a high proportion of cases, the ILM will already be removed together with the ERM. If you wish to peel the ILM after removal of an ERM, you can attempt to stain the ILM with trypan blue. If you do not see the ILM well enough, do not hesitate to stain the ILM with Brilliant Blue G. You will never regret a proper staining of tissue.

Pits & Pearls

Combined stains for macular peeling (Brilliant blue and Trypan blue in one preparation) are now commercially available (DORC).

DVD

Video 7a, b Epiretinal membrane and peeling following a fungal infection

Instruments

1. 3-port trocar

2. 120D lens, for peeling: 60D lens or plano concave contact lens

3.Vitreous cutter

4.Fluid needle

5.Eckardt forceps

6.Tano diamond-dusted membrane scraper or CRVO knife

7.Scleral depressor

Dye

ERM: triamcinolone acetonide, trypan blue Macular hole/ILM: Brilliant Blue G

For injection, use a 3-ml syringe with 23-gauge backflush needle (Fig. 5.11 and see material)

Tamponade

20% SF6-air, silicone oil (with macular holes in which no postoperative head positioning is possible)

Fig. 5.11 A 3-ml syringe filled with trypan blue and a 23-gauge backflush needle (DORC 1281. A5D06). This syringe size is easy to handle

Individual steps

1.3-port system

2.Core vitrectomy

3.Induction of PVD 4a. Staining of the ERM 4b. Staining of the ILM

5.Peeling of epiretinal membrane or ILM

6.Tamponade

Macular holes: Gas tamponade, Epiretinal membrane: None (BSS)

7. Removal of the trocars

1.3-port system

2.Core vitrectomy

3.PVD

Insert the trocars. If the patient is older than 60 years, consider a combined phaco/ IOL before the vitrectomy.

Perform a core vitrectomy and induce a PVD. Position the vitreous cutter in front of the optic disc, the aspiration port almost touching the optic disc – induce maximal suction. Meanwhile, cortex and posterior hyaloid will be engaged in the aspiration port and pull the vitreous cutter slowly towards the lens. The posterior hyaloid membrane can be seen as a fine silky parachute structure (See Sect. 4.2 on induction of a PVD). If you are not sure whether you induced a posterior vitreous detachment successfully, stain the vitreous with triamcinolone or trypan blue. If the posterior vitreous detachment has not been successful, you will now recognize the stained vitreous cortex adjacent to the posterior pole.

4a. Staining of the ERM (epiretinal membrane)

The next step is the staining of the ERM with triamcinolone or trypan blue. Stop the infusion. Then take the syringe with the dye in one hand and eject a few drops of the dye outside the eye in order to avoid blockage of the cannula and injection of air. Then insert the syringe until the tip is placed above the macula and slowly inject 3–5 drops of the dye to fall on the macula, as trypan blue is heavier than water (Fig. 5.12).

Fig. 5.12 Injection of trypan blue in a BSS-filled eye. The infusion is closed. After 15 s, the dye can be aspirated

(Note: The handling of the syringe can be difficult.) After a period of about 15–30 s, turn on the infusion and aspirate the dye with a fluid needle.

Pits & Pearls No. 40

Trypan blue

1. Trypan blue can easily block the injection cannula. This may result in too much force being applied during injection, and a sudden jet of dye can be injected into the eye and that may potentially cause retinal damage. We recommend three steps to avoid such problems: (a) Try to inject yourself. This takes some practice at the beginning but increases your control. (b) Always inject a small amount of dye outside the eye immediately before injecting inside the eye. Once inside the eye, point the cannula towards your light pipe and away from the posterior pole before pointing it at the target area. Any initial jet of dye will hit the light pipe and not the retina.

2. Trypan blue is a very strong dye that temporarily obscures your view of the retina. When injecting too much, one cannot see the vitreous cutter or fluid needle that is needed for its removal. Do not apply suction if you cannot see the tip of your instrument. In such cases, let BSS run through the system and the eye until you can see the tips of your instruments, then start removing the dye from behind the lens and work your way towards the posterior pole.

Fig. 5.13 Perform first a water/air exchange and leave a puddle of water. Then drop about 5 drops of Brilliant Blue G into the puddle. In the picture, you see the blue- coloured puddle on the posterior pole

Pits & Pearls

For optimal staining of membranes including ILM with trypan blue, perform a fluid–air exchange, apply several drops of the dye and then wait for 3 min before air–fluid exchange. This is cumbersome but significantly improves your staining in tricky cases.

Pits & Pearls

PVD: If you plan to stain with trypan blue, then use it also for PVD. It makes surgery so much easier. But if you stain the vitreous, you need to restain for the membrane.

4b. Staining of the ILM

The internal limiting membrane (ILM) stains with Brilliant Blue G particularly well. Because Brilliant Blue G mixes with the water in the vitreous cavity, we use a different staining method: Carry out a water–air exchange and leave a small puddle of water on the central pole. Use a 2-ml syringe with a backflush needle for injection. Inject 2–3 drops of Brilliant Blue G into the puddle, wait 15 s (Fig. 5.13), position the fluid tip in the puddle and remove the dye (Fig. 5.14). Then perform an air/ water exchange. The advantage here is: the dye acts only in the water puddle, and the surgeon can remove it more quickly than if the dye is distributed throughout the vitreous cavity.

Fig. 5.14 Now, the blue puddle is aspirated with a fluid needle and then an air/ water exchange performed. The advantage of this method is that (1) only the macula is particularly stained and that

(2) the dye can be removed in a short amount of time

Fig. 5.15 Preparation for macular surgery. A plano concave contact lens has been placed on the cornea DORC: 1284.DD

5. Peeling of ERM and ILM

Before you start with the peeling, you need to change to a higher resolution lens. You may take a macular lens (60D) or a plano concave contact lens, which is placed with contact gel on the cornea (Fig. 5.15).

Caution: If you work with a contact lens, you only have a small part of the fundus in your field of view. And the risk of ramming an instrument into the retina is pretty high. Insert, therefore, an instrument only under minimal zoom.

Fig. 5.16 A slight incision of the ILM is performed with a CRVO knife. Alternatively, you can also use a Tano diamond-dusted membrane scraper

Fig. 5.17 An ILM rhexis. The ILM was stained with Brilliant Blue G. The circular removal of the ILM is comparable with the capsulorhexis. But it should be remembered that, in contrast to the convex capsulorhexis, the ILM rhexis runs concave. If you do not consider this, you can quickly drive the forceps into the retina

Peeling of ILM

To mobilize the ILM, brush the retinal surface with the Tano diamond-dusted membrane scraper or scrape it with the CRVO knife (temporal, superior or inferior to the macula), until a small defect is created (Fig. 5.16). You can also pinch the ILM with the Eckardt forceps but the risk of retinal bleeding is higher with this technique. Grasp the edge with Eckardt forceps and pull the ILM parallel to the retina (Fig. 5.17). Perform a circular rhexis in the ILM (Fig. 5.18). Always perform the ILM peeling in a circular fashion pulling around and towards the macular