32.1.3 Peeling the Membrane

or the scraper14 (flipping the ILM over, similar to how the barbed needle is used to complete the capsulorhexis), it is best performed using forceps.

•Grab the edge of the ILM.

–The two areas where ILM grabbing should be avoided are the center of the fovea and the maculopapillary bundle, especially if close to the disc margin. If the ILM tears here, try to peel the ILM from elsewhere toward/into these areas.

•Pull it at an acute angle in a predetermined direction.

–It is almost inevitable that the ILM will tear multiple times, not come off in a single piece.15

–If repeated tearing occurs in a small area (several small pieces are torn off), change the direction of pulling (see Fig. 32.5).

–Especially in eyes with thickened ILM or increased adhesion, the ILM may have to be regrabbed many times. This alone represents a higher risk of causing retinal damage, even if the forceps is in the hands of the most experienced and cautious surgeon (see Fig. 32.4b).

Pearl

The sight of white, fluffy material in the jaws of the forceps signals that the surgeon grabbed nerve fibers, not (only) the ILM.

•Never forget that, even if the risk is low, the retina may tear16 if the ILM is very adherent and/or the retina is already damaged.

–The appearance of small hemorrhages17 if typical. They rarely occur as a result of direct forceps damage (i.e., they are not found at the point of grabbing); as the ILM is separated, the wall of a small vessel is broken. The bleeding usually spontaneously disappears in a day and without clinically detectable consequences.

–Very rarely, the ILM is so adherent to the wall of a major vessel that the peeling will tear the vessel’s wall and cause a significant bleeding. Most commonly, however, the ILM actually tears along the vessel: the border of the peeling will be congruent with the course of the vessel.

14An absolute contraindication (“taNO”) in my opinion, and the inventor-genius Dr. Tano fully agreed with this statement. The risk of iatrogenic retinal damage is unacceptably high: those who boast that they are as safe with scraper use for ILM peeling as with needle use for capsulorhexis should remember that the risks are incomparable. It is not the nerve fibers that lie beneath the lens capsule.

15How often the ILM tears is partially up to the surgeon (do not proceed too fast; use a forceps with a large platform) but mostly up to nature. It depends on whether the ILM is healthy (e.g., in case of a macular hole – lower tendency to tear) or not (e.g., diabetic macular edema – high probability of tearing). The ILM comes off more readily in large pieces if retina has been detached.

16Or, in cystoid macular edema, an intraretinal cyst may get unroofed (see Fig. 49.4).

17In many thousands of ILM peeling cases, I had only one so major a hemorrhage. The bleeding stopped when the IOP was elevated, and the clot could easily be removed a few minutes later.

a

F

I

R

b

Fig. 32.5 Schematic representation of reducing the risk of ILM tearing during peeling.

Surgeon’s view. (a) If the ILM keeps tearing in the intended direction of pulling (white arrow), change the direction (granite arrow). (b) Once a larger ILM piece is removed in that area, return to the original site (shown by the granite star) and grab/pull the ILM as initially intended (white arrow) but with a slight modified peeling direction. R retina, ILM already removed, I are where the ILM is still present, F forceps

•Always proceed slowly and keep a close watch over the (advancing) border where the ILM separates from the retina.

–Although it is practically impossible to visually appreciate the curvature of the eyewall, remember that you work over a concave tissue, not a flat surface. If you do not simultaneously watch the advancing tip of the forceps, you may bump it into the retina (see Fig. 32.6). The greater the distance between the

forceps’ tips and the border of ILM separation, the higher the risk of bumping into the retina.18

F3

Fig. 32.6 Schematic illustration of the risk of retinal “bumping” during ILM peeling. The forceps (F1) approaches the retina (R) and F2 picks up the ILM (black line). If the surgeon monitors only the advancing separation between ILM and retina (arrow), but not the distance between the tip of the forceps (F3) and the retina, the forceps will hit the arching retina at some point (black star). The danger is increased if the ILM held in the forceps is a long piece and if the forceps must be kept close to the retina (edema-damaged retina; see Chap. 49)

•The peeled area may rapidly turn white. This discoloration, probably caused by temporary edema, spontaneously disappears within hours and without clinically detectable consequences.

•The peeling technique greatly depends on whether the macula is healthy or unhealthy (see Sect. 49.2).

•Inevitably, small ILM fragments get stuck to the forceps jaws. Remove them (see Fig. 32.7) before you attempt to regrab the ILM: the fragments interfere with visualization, not allowing you to see how deep into the retina you push the forceps jaws. They also make the regrabbing more difficult.

–The vitreous cavity will contain numerous ILM floaters by the end of the peeling; carefully collect all of them before the completion of the operation.

32.1.4 The Extent of ILM Peeling

How far to carry the ILM removal varies with the condition, but it is mostly the individual surgeon’s decision; there is no proven recommendation about the size of the area. A few things need to be kept in mind.

18 Think about the issue of offside in football. The linesman is supposed to simultaneously watch two locations. First, the position of the last man on defense as it relates to the position of the attacker A, who will receive the ball, and, second, attacker B, who may be far away and who will kick the ball to attacker A. The moment to determine whether attacker A is offside is when the ball is being kicked by attacker B. If the linesman is unable to simultaneously observe the situation at both locations, he will probably make the wrong call.