This brief article will discuss how to remove silicone oil from the vitreous cavity. While there are other factors to consider, such as the indications for using silicone, the type of silicone, the recommended duration, and associated complications, the primary objective of this review is to help you understand the removal procedure. Later, we will expand the information and update on the properties of different tamponade agents in retinal surgery.

Let's begin:

Although it is not the primary goal of this article, it is worth emphasizing that silicone in the vitreous cavity typically remains for an average of 4 to 6 months, depending on the case. However, some circumstances necessitate a different duration to prevent retinal detachment upon removal.

1. Procedure Preparation

The first step is to place the trocars via pars plana, 3.5 to 4 mm from the sclero-corneal limbus, as done in any vitrectomy procedure. Infusion is placed, and verifying that the trocar is positioned in the vitreous cavity is crucial to avoid complications if the infusion leaks into the choroidal space.

2. Silicone Removal

Silicone is generally removed through one of the superior ports, either nasal or temporal. It can be done manually, using a 5 cc to 10 cc syringe to suction the silicone step by step, or with a syringe adapted to an automated aspiration system on the vitrectomy machine (vacuum fluid control- VFC). An automated system is recommended to better control silicone suction and avoid vitreous cavity collapse, which could lead to complications such as choroidal detachment, subretinal bleeding, or a new retinal detachment.

Inspecting the anterior chamber for small particles or emulsified silicone pearls is also important. In such cases, perform a paracentesis with a 15-degree blade to irrigate with a balanced solution (BSS) using a 5 cc syringe. A useful tip is to gently press the entry of the paracentesis to allow silicone remnants to move toward the opening. Since silicone tends to float, performing the paracentesis in the superior position, preferably at the 12 o'clock meridian, facilitates drainage in the anterior chamber. Tilting the eye slightly downward helps the silicone move toward the paracentesis opening.

Once the anterior chamber is clean, verify that there are no leaks from the paracentesis to avoid anterior chamber collapse when activating the infusion in the vitreous cavity.

3. Using the VFC System

Start the silicone removal with the VFC system. Some literature suggests slightly increasing the infusion pressure to expedite silicone removal (1). However, this is not always recommended, as it may unnecessarily increase intraocular pressure. To avoid vitreous cavity collapse, it is crucial to visualize the lumen of the trocar from where the silicone is being drained, ensuring that silicone is being aspirated and not BSS.

Initially, it might be difficult to aspirate, and this part can be tedious since there may be minimal movement in the vitreous cavity. Ensure that silicone gradually enters the aspiration syringe. Once you have aspirated approximately 20% of the silicone, you will notice a slight notch with laminar flow directed toward the trocar. At this point, reduce the pedal pressure and proceed cautiously, as the solution in the posterior part of the eye will cause the silicone to rise, creating turbulence that may move the silicone bubble and potentially aspirate BSS, leading to chamber collapse.

Some literature recommends not placing the aspiration syringe in the same quadrant or near the active infusion site to avoid accidentally aspirating BSS and collapsing the cavity (1). However, the most important aspect is to ensure that the trocar tip is within the silicone bubble, regardless of the infusion location or aspiration site.

Once you observe the slight jump or turbulence of the silicone, the process becomes more dynamic. You will see increased movement of bubbles and particles toward the trocar. Tilt the eye slightly downward to help the silicone float toward the aspiration trocar for quicker drainage. Always verify that you are within the silicone bubble.

4. Washing the Vitreous Cavity

When the central silicone bubble is removed, it is crucial to check that the retina is flat and stable under the solution. At this point, you might notice a detachment or elevated areas, which may require restarting the procedure with silicone in the cavity. If everything is satisfactory, proceed with washing the vitreous cavity. Perform a series of liquid-to-air exchanges. During the air exchange, you can visualize the solution's anterior surface, where silicone remnants migrate. Aspiring the entire solution is unnecessary, but maintaining at least 20% will allow you to visualize and evaluate any remaining silicone.

Some special substances help eliminate silicone residues, such as F4H5® Washout (Fluoron GmbH) (2), but these may not always be available. While aspirating the solution, position the tip of the vitrector or extraction cannula on the solution's surface and move it slightly in and out to facilitate the movement of the silicone and make it easier to aspirate. Typically, 3 to 4 vitreous cavity washes are performed. Although tedious, it is necessary to remove the maximum amount of silicone.

Finally, assess the retina under air. In high-risk cases of re-detachment, leaving gas, such as SF6 or C3F8, is advisable for added safety. Evaluate whether additional laser treatment or membrane removal is needed. Each case should be individualized.

Sometimes, when BSS is still present in the vitreous cavity between the third and fourth washes, it is recommended to consider performing a posterior capsulotomy if indicated. If the capsulotomy is performed and vision becomes obscured when switching to air, irrigate the posterior lens with BSS or place viscoelastic to maintain visibility.

Once the retina is stable under air, remove the trocars. First, remove the two superior ones and check for leaks. Many recommend suturing them, though it is not always necessary. You can also apply scleral needling to address leaks from sclerotomies that do not seal themselves upon trocar removal. (Watch this video for scleral needling technique https://youtu.be/kFQaYKCdcBs?si=taEtHcIO2rr4f7J) Finally, remove the infusion trocar only when you are sure there are no leaks from the superior sclerotomies.

Done! The case is considered complete. Remember that each eye may behave differently, but following these steps will help you achieve the best possible outcome. I hope this article will be helpful. Don't forget to watch our illustrative video to complement what you've learned. As always, your interest makes us better.

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References

1. Vitreoretinal Surgery Online, 10.2 Removal of Non-dissolving Endotamponades (Silicone Oil, Heavy Oil, Heavy Liquids) by Adrian Fung- link: https://www.vrsurgeryonline.com/10-rhegmatogenous-retinal-detachment-vitrectomy/02-removal-of-endotamponades/index.php?r=1918

2.  Coppola M, Del Turco C, Querques G, Bandello F. Perfluorobutylpentane (F4H5) Solvent-Assisted Silicon Oil Removal Technique. Retina. 2017 Apr;37(4):793-795. doi: 10.1097/IAE.0000000000001314. PMID: 27668932.