•The goal is not to have a perfectly shaped opening (e.g., a square) but one that gives adequate access to the posterior segment.

•Upon removal, unhook the retractors before pulling them out. Never grab the retractor between the hook and the disc but distal to the disc to avoid pulling the disc off.

25.2.2.4 Iris Ring

There are several ring designs.20 They all provide for a stable iris, but the degree of dilation depends on the design.21 The rings are also somewhat cumbersome to insert and remove.

25.2.2.5 Iridotomy

If all else fails and the surgeon must have a wide pupil, he can cut the iris with scissors.

•A few longer cuts can be made at the most appropriate locations.22

–As described above, visco can used to create space for the blade of the scissors.

–Use 20 g scissors with long blades.

–As needed, the iridotomies can be sutured later (see Sect. 48.2.2).

•Several “mini” cuts can be made at the pupillary margin.

•This can be achieved with smaller-gauge scissors.

–If the sphincter is cut, the pupil may remain wide open. If such an iris needs to be sutured, the iris purse string (cerclage) suture may be the best option (see Sect. 48.2.3).

25.2.3 Lens

25.2.3.1 Cataract

The most common cause of preexisting visual interference, cataract can be minimal enough so as not to require removal. Alternatively, it can be removed in a prior procedure or during PPV if, despite prior expectations, it proves to be too much of a hindrance (see Chap. 38).

25.2.3.2 “Feathering”

This type of temporary, intraoperative lens opacity is a rather unique one, occurring intraoperatively in some patients,23 especially if the operation is long. It is bothersome but rarely so much as to seriously interfere with surgical success.

20Malyugin ring (Microsurgical Technology, Redmond, WA, USA); Morcher Pupil Dilatator (Morcher GmbH, Stuttgart, Germany); Beehler Pupil Dilator (Moria SA, Antony, France).

21It is not adjustable such as with the retractors.

22Where the adhesion of the iris is strongest to the lens.

23Usually in older people.

25.2.3.3 “Gas Cataract”

It is a condition very similar to feathering, but is seen postoperatively, in the presence of intravitreal gas. It rarely persists but may justify lens removal if early reoperation is needed.

25.2.3.4 “Lens Touch”

An inexperienced surgeon24 is especially at risk of bumping the probe or the light pipe into the lens. This leaves an imprint in the posterior cortex, visible as a linear opacity, whose size is determined by the area of contact.25

•The opacity is restricted to an area small enough so as not to seriously interfere with visualization.

•If the lens touch is really just that,26 it rarely turns into cataract and can therefore be left alone. The opacity usually disappears in a few days.

–Unfortunately, some surgeons also call a true bite into the lens capsule a lens touch. The difference is that in this case cataract is inevitable. Since the protective vitreous “cushion” is missing, the lens can swell rather fast, especially in children (see Table 41.2). The cataract is accompanied by a fast and significant IOP elevation.

–If a lens bite occurs, it is best to remove the cataract during the same setting.

25.2.4 IOL

There are several ways the capsule/s and the IOL can interfere with visualization.

25.2.4.1 Phimosis of the Anterior Capsule

Constriction, and subsequent opacification, of the anterior capsule is rather common with certain types of IOLs.27 In the presence of these conditions, the visual field may be too small for the VR surgeon to view the periphery.

•Through a temporal paracentesis, use scissors28 to make several radial cuts in the capsule, and then the vitrectomy probe to remove the capsule in-between the cuts.

–It may be necessary to make two paracenteses if scissors are used and the capsule needs to be cut 360°.

24Although it occasionally happens even to experienced surgeons.

25Obviously, the width is determined by the gauge of the instrument. The linear opacity on one end points toward the sclerotomy where the instrument was inserted.

26The posterior capsule is not broken.

27Such as hydrophilic acrylic, biconvex lenses. This is why the capsulorhexis should be at least

4mm in diameter.

28The capsule is usually too strong and rigid and offers no edge, for the probe to directly bite into.

–If the capsule is too strong for the probe to bite into, the surgeon can try a bimanual method: holding the capsule with forceps and complete the cutting with scissors.29

Pearl

If you are using nondisposable scissors, consider the damage the strong tissue (capsule, membrane) will do to the blades. The scissors are very expensive and so is the sharpening of a blunted blade.

A phimotic anterior capsule can also twist an IOL and cause a true subluxation, which is an additional element in the loss of proper visualization (see below).

25.2.4.2 Deposit on the Anterior IOL Surface

Cells, dried blood from an old hemorrhage, fibrin etc., can collect on the IOL surface and prevent adequate visualization of fine posterior-segment structures. There are several ways to deal with this.

•AC irrigation with the jetstream directed toward the IOL surface.

•Vacuuming: the probe’s port is turned downward, and at high vacuum/flow the material covering the IOL is aspirated without activating the cutting.

•“Window cleaning” (see Fig. 25.1).

–Make a 20 g paracentesis temporally.

–Take a 23 g crocodile forceps and a very small piece of cotton30 from a cottontip applicator.

Fig. 25.1 “Window cleaning” of the IOL surface. (a) The anterior surface of the implant has numerous deposits, severely interfering with visualization of the posterior segment. (b) A 23 g serrated forceps, with a small piece of cotton in its jaws, is inserted into the AC through a 20 g paracentesis. A cannula forceps is used to atraumatically secure the eyeball during insertion. (c) The anterior IOL surface has been cleaned and the debris irrigated

29Alternatively, consider using a larger gauge and try to reduce the cut rate to a few hundred cpm.

30Only enough to wrap the jaws; otherwise, it will be difficult or traumatic to push the forceps into the AC.

–Wrap the jaws of the forceps with the cotton while it is still dry.31

–Dip the forceps into BSS so that the cotton is completely wet and gently push the cotton-wrapped forceps into the AC.

–Insert a long, curved, blunt spatula into the vitreous cavity from the nasal sclerotomy.32 The spatula will serve as a counterforce and support the IOL during the AC manipulations.

–Gently wipe all deposits off the IOL surface. Do not push downward with the forceps too hard,33 and try to coordinate your movements: push up the IOL with spatula exactly where the forceps pushes it down and with the same force.

25.2.4.3 Problems with the IOL Itself

•After a too-high-power YAG capsulectomy, there may be small impurities in the optic itself. Depending on their extent, they can cause minor or very severe visual interference.

–Occasionally the only option is to remove IOL.

•Multifocal IOL. It may prevent having a sharp image of the macula.

–These lenses are quite expensive, and unless the patient is also bothered by it,34 the surgeon must try to work around the problem and complete his VR task even if visibility is suboptimal.

•The edge of the IOL may be visible if the pupil is really wide or if the IOL is subluxated.

–If the IOL is in normal position, the surgeon must live with the problem and work in the periphery by alternatively viewing the retina through or outside the optic of the IOL. Because of the parallaxis, the image of the retinal area just viewed may suddenly disappear or an intravitreal tool’s shaft apparently split, its straight course broken; this is a problem mostly encountered during panretinal laser treatment (see Sect. 30.3.2).

–If the IOL is subluxated, the surgeon may try to reposition it.35

If combined surgery is performed, the surgeon may consider delaying the IOL implantation until all retinal work is finished so as to avoid some of the issues detailed above.

25.2.4.4 Fluid Condensation

After F-A-X fluid condensation (fogging) may occur on the back surface of the IOL in the area of capsulectomy (see Chap. 31 and Fig. 25.2).36

31Once the cotton is wet, it becomes impossible to use it for wrapping.

32The anterior vitrectomy should have been completed beforehand.

33To avoid tearing the zonules or dislocating the IOL.

34I was asked to remove such lenses on a number of occasions.

35If the subluxation gave a lot of complaints to the patient, removing the IOL and replacing it with another one should be discussed preoperatively, during counseling (see Sect. 5.2).

36PFCL in an air-filled eye causes the same problem (see Sect. 14.4).