–While the oil cannot be removed, an inferior RD can be left to persist29 under the oil as long as the detachment does not involve/threaten the macula.

•Recurrent VH. Most often seen in diabetic patients; they may have a full panretinal laser treatment, no visible proliferation, and good systemic control of the diabetes and blood pressure, yet the intravitreal bleeding keeps recurring unless a silicone oil tamponade is present.

35.4.4 Implantation

•Consider removing the lens (see Sect. 4.5 and Chap. 38).

•If an IOL is present, perform a large posterior capsulectomy.

–Posterior capsular opacification is inevitable.

•Hydrophobic IOLs (e.g., silicone) should be removed since the oil sticks to them.

•It is much faster and technically easier to implant the oil under air than BSS (see below, Sect. 35.5).

•To achieve a truly 100% fill, make sure you remove all the vitreous, suprachoroidal, and subretinal fluid/blood and do not overinflate the AC with visco.30

•The fastest way is to suture-close the infusion sclerotomy and inject the oil superonasally, directly through a short needle attached to the syringe, while draining the air through the superotemporal sclerotomy with the flute needle.

•The easiest way to implant is to attach the syringe containing the oil to the tubing of the infusion cannula at the stopcock; this way the tubing is short.

–Use the vitrectomy machine’s “viscous fluid injection” mode (or ask the nurse to do it31).

–Do not apply too high an injection pressure – the tubing can disconnect at either end and the oil will be lost. You can gradually increase the pressure if all goes well.

–While you are pressing the pedal and inject the oil, have the nurse monitor the syringe and the tubing to make sure that nothing gets disconnected.

•Simultaneously aspirate the PFCL (BSS) with the flute needle held in the dominant hand. Aspiration in these cases is from the bottom of the eye.

•If the eye is filled with air (the recommended option), aspirate it from the anterior part of the vitreous cavity, through the temporal sclerotomy.

–There is no initial need to aspirate the air; it is compressible plus almost always leaks spontaneously through the cannula, even if it is valved. Use the time dur-

ing this initial phase of oil implantation to suture the nasal sclerotomy (see below).

29That is, reoperation is not necessarily indicated.

30Visco may be needed in the AC to prevent silicone oil prolapse; see below.

31This obviates the need for the rather expensive disposables.

Pearl

Suturing the sclera is a rare chance for the VR surgeon to experience tactile feedback. Even if the needle is invisible underneath a swollen conjunctiva, the surgeon will feel the sclera’s extra resistance against the needle’s advancement. However, if the eye is soft, this feedback disappears, and the only way the surgeon can determine whether the needle indeed engaged the sclera is to try to lift the tip of the needle. If he caught only conjunctiva, the needle will easily lift it; if the sclera has also been penetrated, the needle’s tip cannot be lifted.

–As the air bubble is becoming truly small, you will notice that the image through the microscope32 is darkening.

–The size reduction of the air bubble is a saccadic motion;33 fluids show a smooth, continual decrease.

–The remaining small air bubble can spontaneously escape via the superotemporal cannula,34 or if the valve prevents this, it can be removed with the flute needle. If the eye is phakic, do not use the flute needle:35 remove the cannula and let the air out that way.

•Suture the superotemporal sclerotomy before you complete the oil injection.

•Inject silicone oil to achieve an IOP that is slightly higher than normal (~30 mmHg).

•Take a tooth forceps36 in your nondominant hand and a cannula-forceps in your dominant hand. Grab and lift the sclera with the tooth forceps so that the scleral wound is immediately closed as you remove the cannula with the other forceps.

–Exchange this forceps for the needle holder and put in the “X” suture (see Fig. 14.3).37

–The suture may inadvertently be pulled through during tightening if the thread has been caught by the speculum (see Sect. 19.1) or a sticky drape.

–Pulling the needle through the loop you just created helps to close the wound immediately.

•If, despite these precautions, the oil has leaked, check whether the IOP is still slightly high.

–If the IOP is too low (too much oil lost), inject more by reinserting the cannula.

–If the IOP is as desired, try to remove the subconjunctival oil. It is cosmetically unappealing, takes years to spontaneously disappear – if at all, since it often gets encapsulated. In the worst case, puncture these oil-containing cysts at the time of silicone oil removal (see Fig. 35.2).

32Since the intraocular task had been completed before the air was injected, there is no need to observe the oil implantation inside the vitreous cavity through the BIOM.

33In other words, it is not proportional to the amount of oil being implanted.

34Rotate the eye so that the superotemporal area is the uppermost part of the globe.

35The risk of lens damage is rather high.

36The “colibri” forceps is the ideal tool for this: it has teeth that are sharp and large enough to grab sclera through the conjunctiva, but small enough to minimize the risk of tissue damage.

37This suture looks like an X underneath the sclera; the 2 threads are parallel on the surface.

Fig. 35.2 Subconjunctival silicone oil. (a) A large amount of silicone oil has escaped subconjunctivally. Multiple bubbles are present, requiring the surgeon to make several punctures with a 23 g needle. A muscle hook is then used to push the oil toward the holes (not shown here). (b) The large cysts have been emptied, but the surgeon should not expect that he can drain all oil bubbles completely (nor encourage his patient that the procedure will fully restore the eye’s native appearance.)

•If silicone oil enters the AC, it typically does so during implantation (see below for postoperative oil prolapse).

–A small bubble is well tolerated and need not be removed. A bubble that is large enough to interfere with the patient’s vision or with fundus examination may also damage the endothelium and should therefore be removed.

–After all sclerotomies have been sutured, make a temporal paracentesis that is larger than the cannula you intend to use.

–Place a blunt cannula, on a syringe containing cohesive38 visco, into the AC and push the cannula to the far end of the AC (see Figs. 35.3 and 14.5). Do not use BSS since this may escape posteriorly, pushing even more oil forward; air occasionally also works.

–Slowly inject the visco while pressing down the lower lip of the paracentesis to allow the oil to escape.

–Do not try to remove the visco; it would restart the oil prolapse.

–Constricting the pupil is not going to reduce the risk of oil prolapse; it just hides the oil from view.

If the eye is aphakic, a few special rules apply.

•Before the F-A-X, prepare a 6 o’clock (Ando) iridectomy39 to prevent angleclosure glaucoma.40

–Insert the probe with the port facing upward.

–Make sure the port is at the desired location.41 Aspirate before cutting into the tissue, and do not be surprised if a small bleeding occurs. Unless rubeosis is present there is no need to use the diathermy, which does not work well anyway: it causes tissue contraction (see Table 40.1).

38To avoid coating the AC structures; this reduces the severity and duration of IOP rise.

39The iridectomy is much more difficult to perform if air in the vitreous cavity is pushing the iris forward. Create the iridectomy before the F-A-X.

40It develops if the aqueous is misdirected posteriorly, behind the oil and thus pushing forward.

41Which is the periphery of the iris, away from the sphincter.