•Aim for an IOP of ~30 mmHg at the conclusion of surgery.26

•F-A-X: an air-filled eye is less prone to insufficient wound closure.

–Conversely, the ciliary body may take longer to reach full aqueous production than it takes the air to absorb.

•Proper cannula withdrawal and wound “massaging.”

•If the hypotony is realized intraoperatively, suture the leaking wound and refill the eye with BSS or air/gas.

–A single-loop suture is sufficient in most cases, even for 20 g wounds.

–If silicone oil has been implanted, a special suturing technique is required (see

Fig. 14.3).

21.8.4 Hypotony: Postoperative Management

•Inject air/gas/BSS with a 27 g needle through the pars plana.

•If the eye is filled with silicone oil, the fill is less than 100% (this is more of the problem, less the hypotony itself [see Sect. 35.4.2]) Only a reoperation suffices.

21.920 g PPV27

Only a few selected comments28 are made here.

•Open the conjunctiva and Tenon’s capsule as a single layer.

•Make two separate openings, a larger one (~2 to 5 o’clock in the left eye) temporally and a shorter one (9–10 o’clock) nasally.

–Grab and lift the conjunctiva with a toothed forceps and make a ~2 mm radial cut 1 mm from the limbus. If one such incision is sufficient per site, there is no need to do two. This will help when you suture it at the end of the surgery.

–Do the incision in the most superior edge of the intended dissection area.

•Insert blunt scissors into the opening, keep it parallel to the surface, and bluntly dissect the subconjunctival space in an area larger than the incisions.

•Consider whether the bleeding vessels need to be cauterized.29

•Make the three sclerotomies with a 19 g MVR blade.

–Technically, the 20 g blade should also work; however, it makes it very difficult to insert a blunt instrument, and also it increases the risk of iatrogenic choroidal detachment by forceful penetration efforts (see Fig. 21.10).

26Too high an IOP is just as problematic as a too low one (see Sect. 21.8.1).

27No transscleral cannulas are used.

28Based on my personal preferences.

29I had used to do extensive diathermy but then stopped unless a well-identifiable vessel caused a major bleeding or the patient had an increased tendency to bleed (see Sect. 40.1). The small hemorrhages soon stop spontaneously.

C O

S

Fig. 21.10 Schematic representation, seen from the surgeon’s perspective, of incising the eyewall with an MVR blade. The sclera is inelastic; the choroid is not. Even though it was the same-sized blade that penetrated both, the choroid’s wound is shorter than the one in the sclera. This is not a problem unless the instrument is a blunt one with non-slanted tip (some light pipes are configured exactly like that (question to industry: why?; see the text for details)). The longer the incision (such as one to remove a larger IOFB), the greater the discrepancy between the length of the two de facto openings. In these cases, Vannas scissors needs to be used to cut the choroid at both ends to prevent loss of the IOFB at the incision or detaching the choroid if blunt instruments such as a non-slanted light pipe is forcefully pushed into the wound. C Choroid, O opening in the sclera and choroid: the actual sclerotomy, S sclera

–The incision should be perpendicular to the limbus, to follow the course of the scleral collagen bundles (see above, Sect. 21.3).

–If the eye has already been vitrectomized, only the sclerotomy for the infusion cannula is prepared, the two superior ones follow once the infusion cannula is in place and the infusion is open.

•The infusion cannula may be self-retaining or require a suture30 to be held in place.

–The suture may be preplaced, i.e., before the incision is made with the MVR blade. Especially if silicone oil is likely to be used, it makes sense to use a preplaced X suture (the suture is identical to that seen on Fig. 14.3), which in this case will be used to close the incision at the conclusion of the surgery.

•The infusion cannula should be normal sized (4 mm) unless it is difficult to visualize it or there is a bullous RD; in these cases, use a 6 mm cannula.

Pearl

The risk of iatrogenic lens damage greatly increases with a long infusion cannula.

•If there is a need to have a larger than 20 g incision,31 a current one can be enlarged (the choroid must be separately enlarged; see Fig. 21.10) and then resized or a separate incision be prepared.32 I prefer the latter option.

306-0 or 7-0 vicryl.

31e.g., to remove a larger IOFB.

32The original one is plugged until the fourth sclerotomy is sutured.

•Suturing of the 20 g sclerotomy requires a single, usually 7-0, vicryl suture, but it must be in the very center of the incision.

–A sclerotomy, which was enlarged or is the last one to be closed and silicone oil has been used, should be closed with the X suture (see above).

•If silicone oil has been used, first irrigate the subconjunctival space thoroughly so that no oil is retained (see Sect. 35.4).

•Suture the conjunctiva with the same vicryl; try to stay further back from the limbus so that the suture stumps do not to irritate the cornea.

–Do not make the knot too large.

–Cut the suture so that the stumps are ~2 mm. This seems to cause less irritation than either shorter or longer ones.