Membrane peeling and internal limiting membrane (ILM) peeling are the topic and more delicate maneuvers during macular surgery. Different dyes on the market nowadays helps to better and safer perform this maneuver; nevertheless, some complications can occur during peeling.

ILM peeling can be performed by making a small opening and a flap tear in the ILM with a bent Microvitreal – retinal blade. The ILM flap is then grasped with end-gripping forceps and carefully started in a circular capsulorhexis maneuver [69]. In another technique of ILM peeling, the membrane can be removed by directly grasping the membrane with end-gripping forceps, without creation of a flap [70]. The reported complications associated with ILM peeling are postoperative hyphemas and retinal incarceration into the silicone soft-tip aspirator [71].

One complication of peeling is bleeding (Fig. 13.2). Epiretinal or subretinal bleeding can occur during peeling above all during ILM peeling that is usually strongly adherent to the retina. When the ILM is stretched over a vessel, it can bleed. When this complication occurs, the surgeon should immediately raise the intraocular pressure (IOP) up to at least 60 mmHg in order to stop the bleeding. If it occurs over the retina, the blood clot can be easily sucked by the vitrectomy probe, and if the vessel continues to bleed, it is helpful to touch it with the end of the vitrectomy probe and push gently for few seconds. Usually the vessel stops to bleed with this simple maneuver. If the bleeding is under the retina, raising the IOP is mandatory. The surgery can be continued and at the end a fluid-gas exchange is suggested. A prone position of the patient for 1–2 days can help the blood displacement far away from the macula area. If there is a macular hole, the under-retina blood could be spontaneously evacuated from the hole; to suck it using a back-flush is not a good procedure because the hole can enlarge. If the under-retina bleeding occurs in a pucker or macular edema, in order to facilitate the blood displacement, it could be useful to detach the macula using balanced salt solution (BSS) injection under the retina through a 41-G needle.

Another not so infrequent complication is retinal break in the macula during peeling (Figs. 13.3 and 13.4). It can occur for the strong adherence of the membrane to the retina or more frequently directly by the forceps. Macular breaks don’t need to be treated by laser because laser can damage the visual acuity and also a retinal detachment from a macular break is very rare to occur. What we suggest if it happens is to leave it and continue the procedure as programmed.

On the opposite, if a posterior retinal break occurs during peeling in high myopic eyes, it should be laser treated and tamponated using air or gas at the end of the surgical procedure.

Iatrogenic macular hole could happen during ILM peeling for macular edema. If it happens, it should be treated as a macular hole with gas injection at the end of the procedure. In order to avoid it, the peeling must be in a centripetal way and very slowly manner.

Another complication reported by Karacorlu et al. during ILM peeling is “iatrogenic punctate chorioretinopathy” [72]. This is an unintentionally chorioretinal lesion created during grasping the ILM with end-gripping forceps. In this study, fluorescein and indocyanine green angiographic findings indicate that iatrogenic punctate chorioretinopathy affects the choriocapillaris as well as the RPE. Choroidal neovascularization did not develop, and the lesion remained unchanged during follow-up.

Fluid-air exchange is a very important step in macular surgery above all in macular holes. The most common complication is the opacity of the posterior capsule of the IOL in pseudophakic eyes caused by air. If the opacity occurs, there are two possible solutions: (1) inject through the trocar some viscoelastic over the posterior capsule of the IOL, and (2) turn air into BSS and direct the infusion cannula against the posterior capsule. The BSS can clean the posterior capsule from the fogging; then, turn again the infusion into air and complete the exchange.

There are different techniques for intraocular gas injection as the last surgical procedure after macular surgery. The one we use is injecting the air-gas mixture through the cannula. Once one trocar is removed, the air-gas mixture siring is connected to the cannula. While it is manually injected into the eye through the cannula, a back-flush needle is inserted in the other trocar in order to permit the air to come out. In this maneuver, the only complication is hypotony once the cannula is removed, because the scleral wound can remain open. If this happens, the surgeon should close the sclerotomy and inject air-gas mixture through the pars plana with a 30-gauge needle until the eye pressure is normal.

In this chapter, we tried to include all the possible complications during macular surgery. In every surgery, all the steps of the procedure can potentially encounter complications. The most common complications are iatrogenic retinal breaks during vitrectomy or, less common, during peeling. The expert surgeon should know how to avoid and treat these complications for the good surgical outcome.