Pits & Pearls No. 28

PFCL against silicone oil exchange

1.If unsure whether there still is some heavy liquid left behind, pause and wait. The heavy liquid will collect and the interface will be clearly visible after 15–20 s.

2.Removing the final puddle of heavy liquid is not an easy step. The danger is to aspirate retina into the fluid needle at the posterior pole or to damage the optic disc. Either try to remove the final bubble ‘in one go’ or let it collect over the optic disc. Then increase the pressure with the silicone oil injection and touch the bubble with the opening of the fluid needle. For small remnant bubbles, indent the eye with your ring finger. This will give you a much better pressure control than the injection of silicone oil with the foot pedal. Aspirate the heavy liquid bubble and immediately cover the opening of your fluid needle before withdrawing it from the eye, otherwise the heavy liquid bubble will drop back onto the posterior pole.

Pits & Pearls No. 29

Silicone oil injection: If you have no silicone oil 23-gauge cannula in place, take a second infusion line instead. Attach the oil-filled syringe to a second infusion line, and insert it in the nasal trocar cannula. Then you inject the silicone oil (active injection modus) into the air-filled eye. Make sure that the opening points towards the centre of the eye. If the opening points forward towards the lens, this may push silicone oil through the zonules into the anterior chamber.

Pits & Pearls No. 30

Methylcellulose in anterior chamber: If zonular lysis is present and oil flows into the anterior chamber, you can aspirate the oil with irrigation and aspiration. Inject methylcellulose (not viscoelastics) into the anterior chamber and leave it there postoperatively. The IOP will not increase after surgery. This procedure works only in a silicone oil–filled eye; it does not work in a gasfilled eye.

13. Removal of the trocar cannulas

It is useful to remove the trocars in the following order: first the instrument trocars, then the chandelier light, and finally the infusion cannula. The infusion cannula

remains in place until the end to avoid hypotension when removing the trocars. The infusion should therefore remain open until removal of the infusion cannulas.

To remove the trocars, pull out the trocar with the trocar forceps, then press the edges of the sclerotomy together with a forceps and massage the sclerotomy with a cotton swab. Lastly, the infusion cannula is removed. Before you do this, check the intraocular pressure manually. If it is hypotensive, refill the eye with gas until the eye is normotensive. Then the infusion cannula with running infusion (BSS, air or oil) is removed. The sclerotomies are usually not sutured. Exceptions are silicone oil tamponades because the oil may cause subconjunctival cysts.

A major advantage of not suturing a gas-filled eye is that the eyes are rarely hypertensive, as the expanding gas can escape postoperatively through the nonsutured sclerotomies. If you observe uveal tissue or even a vitreous prolapse out of the sclerotomy, you should remove it with the vitreous cutter because otherwise there is a possible wicking and endophthalmitis risk. If the sclerotomy is still leaking, it should be closed with a suture. The sclerotomy should be covered by conjunctiva; otherwise, it is recommended that the sclerotomy be sutured.

Pits & Pearls No. 31

Sclerotomy

1. For beginners, we recommend opening the conjunctiva in the area of the sclerotomies in order to recognize the sclerotomies clearly. This is particularly important if you want to suture the sclerotomy at the end of the procedure.

2. In the case of doubt, suture the sclerotomy. The potential disadvantages of a leaking sclerotomy outweigh the discomfort of a single suture.

3.To displace a vitreous wick, inject fluid (BSS, antibiotic solution) into the conjunctival stroma adjacent to the wick. The conjunctiva will balloon and the vitreous wick will retract. Alternatively, remove the vitreous wick with the vitreous cutter.

14.Sclerotomy sutures

A 23-gauge sclerotomy can be sutured with an 8-0 Vicryl suture and a 20-gauge sclerotomy with a Vicryl 8-0 cross suture. To suture a sclerotomy is harder than you assume. Grasp one edge of the sclerotomy with surgical forceps, move the needle through the sclerotomy edge, then grasp the opposite edge of the sclerotomy with the forceps and pull the needle through the second edge. Test with the swab whether the sclerotomy is closed. If it still leaks, remove the suture and place a new suture.

Pits & Pearls No. 32

Leaking sclerotomies

1.A leak can be identified by a chemotic conjunctiva above the sclerotomy in a fluid-filled eye or by air bubbles in an air-filled eye. If the sclerotomies

leak, then place a Vicryl 8-0 on the sclerotomy (Fig. 4.12a, b).

2. These can occur after multiple vitrectomies and a large opening, for example, for silicone oil removal or if multiple sclerotomies have been placed in the same location. It is not uncommon in high myopes with a thin sclera. To close these large sclerotomies, do not use multiple single sutures (they make it worse) or large sutures (the larger needles may cause additional holes in the sclera). Use a 7-0 or 8-0 Vicryl single cross suture over the sclerotomy. Stay very superficially within the sclera and do not go ‘deep’. Use a long intrascleral path. Finally, use 4 instead of 3 throws for your first knot and ask the scrub nurse to close the infusion temporarily while you tighten the knot.

a

b

Fig. 4.12 (a) Leakage of air from a sclerotomy in an eye with air tamponade. In this case, the sclerotomy should be sutured. (b) After suturing the sclerotomy with a Vicryl 8-0 single suture, the sclerotomy is closed airtight