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Fig. 32.12 To remove an EMP from over retinal folds. (If the ILM is wrinkled, the same rule applies.) (a) Virtually the entire macular area is wrinkled. (b) Schematic representation of the incorrect approach to grabbing tissue over a folded retina. The forceps jaws are held parallel with the folds, making it likely that numerous nerve fibers will also be picked up. Surgeon’s view. (c) Schematic representation of the correct approach to grabbing tissue over a folded retina: the forceps jaws are held perpendicular to the folds’ axis. Nerve fiber damage can still occur, but for this, the surgeon must push the forceps jaws unreasonably deep. Cross-sectional view at a much higher magnification than on the previous image. RF retinal folds, F forceps. The double arrow is in the direction of the width of the forceps jaws
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32.2.2.6 The Speed of Peeling
This advice is very simple: be slow. It is not that uncommon for a membrane to easily separate from the retina initially and in most areas subsequently, only to show strong adherence in a small area later on. If the surgeon is too fast, he can easily cause an iatrogenic tear.
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Fig. 32.13 A very thick, dense EMP. The underlying retina is invisible; there is foveal ectopia and the exact location of the foveola is up to guesswork. Such a membrane is best tackled with a barbed needle first. The needle allows separation of the membrane from the retina in a very small area and under constant viewing, without fear of the forceps jaws blocking it. The barbed needle also helps finding the correct plane of cleavage if the membrane is multilayered, which, in this case, is rather likely. The point of attack should again be at the periphery of the membrane, probably at the 9:30 o’clock from the presumed foveola location (arrow). Depending on the behavior of the membrane, a new point of attack may become necessary
If a point of strong adhesion is found, it may be preferable to cut the membrane, instead of forceful peeling.
32.2.2.7 The Extent of Peeling
Definitely remove the membrane from the entire macular area. If the ILM is also removed (see below), it is not necessary to separate the EMP further toward the periphery; if, however, the ILM will not be removed, try to peel the entire membrane to prevent its regrowth into the fovea.
32.2.2.8 ILM Peeling
The rationale for also removing the ILM is the up to 10% recurrence rate if the ILM is intentionally retained.36 If the ILM has also been removed, the risk of EMP recurrence is eliminated.
I always remove the ILM in pucker surgery. If the EMP is thin and rather small, I try to remove the two membranes together, otherwise as a second maneuver. If ICG was used prior to EMP removal, it may have to be repeated once the EMP is off.
36 Small fragments or even large pieces of the ILM are inadvertently peeled in almost all eyes as the EMP is too strongly adherent to the ILM in at least a few areas.
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Q&A
Q Which is technically easier, ILM or EMP removal?
AAlthough such a question is difficult to answer, my general response is that the EMP removal is much more complex and requires a lot more decision-making and good dexterity. A young surgeon should, once he has gained sufficient experience with other aspects of VR surgery, try ILM peeling first and EMP removal only after he became comfortable with ILM peeling. Even then, an experienced surgeon should be sitting next to him when he tackles EMPs until he gained considerable experience with it.
32.2.2.9 Completion of Surgery
The surgical field after EMP removal may look like a battlefield: there are hemorrhages, folds, and circumscribed areas of retinal detachment. Some surgeons prefer to use an air or gas tamponade and ask the patient to be in facedown position to speed up the process of normalization of the appearance of the posterior pole.37
Removal of the ILM virtually assures that the retina will look normal the following day.
32.3Proliferative Membranes38
32.3.1 PVR39
32.3.1.1 Recognition
The membranes are rarely vascularized and, unless immature, are clearly visible; they can also be stained (see Chap. 34); a PVD may also have occurred spontaneously, although it is usually only partial. Even if a membrane is not conspicuous, there are indirect signs that reveal them:
•Distorted course of retinal blood vessels, similar to what certain EMPs cause (see Fig. 32.13, the area just beneath the arrow).
•Star fold (see Fig. 32.14).
•Decreased mobility of the detached retina.
37The inside joke is that this is actually done so that the surgeon won’t have to look at the ugly image he just created.
38See also various parts of Chap. 13 for the use of intraocular instruments.
39An EMP is, strictly speaking, also a proliferative membrane; in clinical practice, however, it is not perceived as such because of its limited extent.
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Fig. 32.14 Retinal star fold in PVR. The retina has radially oriented folds, pointing toward a center where the membrane is presumably the thickest
32.3.1.2 The Goals of Surgery
To achieve retinal reattachment and hopefully prevent redetachment, the following need to be done:
•The vitreous removal must be complete (see Sect. 27.2).
•All tractional membranes, whether subretinal40 or preretinal, must be removed.
– ILM removal should be considered.
•All breaks must be sealed.
•The retina must be mobile and not shortened (stretched) upon reattachment (airtest; see Sect. 31.1.2).
32.3.1.3 Instrumentation
•Scraper to pick up immature, difficult-or-impossible-to-visualize membranes.
•Barbed needle to search for and lift membranes.41
•Spatula to bluntly separate membrane from retina.
40Subretinal membranes that do not prevent retinal reattachment may be left behind (see below).
41While this is very safe, its use over detached, mobile retina is not easy (see Sect. 53.2).