Fig. 5.7 Silicone oil removal with the Alcon silicone oil removal set and the Constellation vitrectomy machine. The removal time for light and heavy silicone oils is 1–2 min

Active removal of heavy silicone oil (e.g. Oxane Hd® or Densiron 68®)

Densiron 68® is heavier than Oxane Hd® (see density, Table 2.1) but has a viscosity comparable to 1,000-cSt silicone oil and is therefore easier to remove than Oxane Hd®.

1.Oxane Hd® or Densiron 68®: Use the 19-gauge metal cannula from Alcon and active extraction modus (Figs. 5.5 and 5.6). Pull the residual heavy oil bubble upwards to the centre of the vitreous cavity and remove it safely here.

2.Oxane Hd® or Densiron 68®: Removal of heavy silicone oils with the Constellation vitrectomy machine is also simple and fast. Attach the adapter to a valveless 23-gauge trocar and aspirate actively the silicone oil (Fig. 5.7). The removal time is approximately 2 min.

3.Densiron 68®: An alternative method is to remove Densiron 68® through a conventional 23-gauge trocar system using a short 23-gauge cannula (MedOne, DORC). Remove the silicone oil bubble as one would with conventional silicone oil, always staying in touch with the bubble with active suction. The residual bubble will stay connected to the short cannula through the ‘siphoning’ effect and will move upwards towards the cannula and can easily be removed this way. Small remnant bubbles at the posterior pole can then be collected with the fluid needle (Romano et al. 2009).

Pits & Pearls No. 34

When removing Densiron 68® through a 23-gauge trocar system, it is important not to lose contact with the bubble before it starts ‘floating up’ towards the cannula. In order to guarantee uninterrupted suction, check the residual volume that is left to be aspirated in your suction line just before you are about to ‘pick up’ the residual bubble. If only a few millilitres are left in your syringe, remove the oil from the syringe by switching to injection mode outside the

Fig. 5.8 After passive or active silicone oil removal, a fluid/air exchange is performed. This procedure is repeated approximately three times with help of the BIOM in order to remove the residual oil bubbles and the emulsified silicone oil bubbles. Hold the tip of the fluid needle onto the meniscus in order to aspirate the floating oil bubbles

eye, then go back in to remove the residual bubble with uninterrupted suction. If you lose contact with the bubble and it is too small to be reached with the short cannula, you either need to proceed with a long 23-gauge cannula (which takes a long time) or switch to the method using the 19-gauge cannula outlined above.

3. Water/air exchange: aspiration of silicone oil bubbles from the water meniscus

Then perform a water–air exchange through the BIOM. Take the fluid needle and try to ‘fish’ residual oil from the water surface at the water/air interface (meniscus). The water–air exchange should be performed approximately three times (Figs. 5.8 and 5.9). If there is a bigger residual oil bubble, it will be time consuming to remove it with the fluid needle. In this case, attach the fluid needle to active aspiration (Fig. 2.10) or use a vitreous cutter to aspirate the residual bubble.

Pits & Pearls No. 35

Suprachoroidal haemorrhage (SCH): A SCH can develop suddenly due to strong aspiration especially when the water instead of silicone oil is aspirated. If a SCH develops, you should react quickly. First, perform a fluid/air exchange and in case of valveless trocars, close all ports with plugs to increase the intraocular pressure. This should stabilize the situation. Then inject silicone oil and end the procedure.

Fig. 5.9 Inflowing water during an air/fluid exchange. Position the fluid needle behind the IOL in order to evacuate the air

4. Internal search

Subsequently, we check for peripheral tears or membranes, treat these pathologies and perform a tamponade if necessary. Perform an internal search for breaks and residual membranes, using endoillumination and indentation with a scleral depressor. Try to identify problems that may cause trouble at a later stage, for example, potential new retinal breaks, epiretinal membranes or fibrovascular proliferations. These are best dealt with straightaway rather than during a later, potentially unnecessary additional procedure. The internal search will also identify larger remnant silicone oil bubbles that may hide in the vitreous base. If left behind, these larger residual bubbles can be extremely annoying for the patient.

5. Removal of the trocars

Remove the trocars as usual. In most cases, we install a simple air tamponade in order to seal the sclerotomy sites. The 19-gauge sclerotomy should be sutured with a single knot 6-0 Vicryl or a Vicryl 8-0 cross suture.

Pits & Pearls

Always check the anterior chamber for residual oil bubbles. In particular, in cases with secondary glaucoma, it is advisable to flush the chamber angle to remove residual bubbles.

Pits & Pearls

In pseudophakic patients with an intact posterior capsule, perform a posterior capsulotomy with the vitreous cutter via the pars plana at the end of the procedure. These patients will otherwise almost always develop a thick posterior capsular fibrosis, and a YAG capsulotomy is more difficult in eyes in which the retrolental vitreous has been removed.

Pits & Pearls No. 36

‘Sticky silicone oil’ has sometimes been described after removing conventional or heavy silicone oils. This describes patches of silicone oil that are firmly attached to the retina and cannot be removed with suction alone. In our experience, this is most commonly caused by residual vitreous cortex in the area of adhesion, and the best prevention of sticky silicone oil is a complete removal of this layer during the primary surgery. If you are faced with ‘sticky’ silicone oil, try to fill the eye with heavy liquid. This usually dissolves the sticky patches of oil that can then be removed with conventional suction.

Pits & Pearls No. 37

If a silicone IOL has previously been implanted, small remnant silicone oil bubbles can remained stuck on the posterior IOL surface. They may cause severe visual disturbances if the centre is affected. It may be difficult and sometimes impossible to remove these remnant bubbles. Again, prevention is better in such cases – never use silicone IOL in cases of combined phaco and vitrectomy or cases that have a higher risk for retinal problems. If faced with such residual bubbles, you can try removing them by soaking a small piece of gauze or a cotton bud in heavy liquid and then wiping the posterior IOL surface with this solution. However, if you are unable to remove the remnant bubbles this way, it may be necessary to exchange the IOL. It is, therefore, best to know if a silicone IOL has previously been implanted. If, in addition, you know the optical power of the previously implanted silicone IOL, one can plan for an IOL exchange if needed, thus avoiding additional surgery at a later stage.