**7. Complications**

Epiretinal membrane removal is generally a safe procedure. Intraoperative complications involve retinal breaks, retinal haemorrhage, retinal whitening and retinal surface damage. Postoperative complications include cataract formation, rhegmatogenous retinal detachment (RRD), cystoid macular oedema, endophthalmitis and the recurrence of fibrotic tissue.

A common intraoperative complication is the creation of iatrogenic retinal breaks. These occur during vitrectomy; thus, careful examination of the periphery with indentation at the conclu‐ sion of surgery is crucial for their early/prompt diagnosis. Their treatment is straightforward, that is, through the application of intraoperative laser retinopexy or cryopexy. However, a break can also occur at the posterior pole (due to pinching or during the dissection of a highadherent membrane) and in this case, laser treatment may be hazardous to the fovea and should be performed with caution.

Haemorrhage at the site of pinching or grasping or at the area where the membrane detaches from a retinal vessel is also common. In this case, recovery is usually short and uneventful. More extensive bleeding may occur less often when a vessel is damaged during the dissection and can be controlled by increasing intraocular pressure or intraoperative cautery.

Retinal whitening is the result of ischaemia that usually resolves intraoperatively; nevertheless, sometimes it may persist for an extended period of time. Membrane manipulation can also cause surface tissue damage, which may or may not be symptomatic. Symptoms involve primarily visual field defects and one should differentiate if these are due to tissue deficits or ischaemia. In the first case, direct damage may be the result of pinching or gripping of the membrane; additionally, indirect damage to the inner retina can occur if ILM peeling had been part of the surgical procedure.

The most frequent postoperative complication of ERM surgery is the progression of nuclear sclerosis of the crystalline lens. Most often, visual acuity improves during the first six to nine months, but then slowly decreases as the cataract develops. The majority of phakic patients undergo cataract extraction within two years in order to maximize the benefits of the initial operation. For this reason, some surgeons prefer a combined operation of phacoemulsification, ERM peeling and IOL implantation [74-76, 90].

Rhegmatogenous retinal detachment is another important postoperative event. The cause in this case is usually a peripheral break caused by traction or incarceration of vitreous in the sclerotomies and demands surgical treatment.

Recurrence of ERMs may be seen in up to 5% of eyes with idiopathic membranes. Younger individuals, patients with a prior history of retinal detachment and patients with a prior history of uveitis tend to have a higher recurrence rate, which in some studies have been up to 12% [71]. Remarkably, recurrence is reported to be higher by many studies when ILM is left intact [69, 91].

Endophthalmitis is quite rare after standard 20g vitrectomy (0.02 to 0.14%) [92]. For transcon‐ juctival sutureless vitrectomy (TSV) and especially when using the 25g system, higher rates have been reported (0.04 to 1.55%) [92]. Nevertheless, this finding has not been conclusively confirmed in the literature; thus, the question regarding the increased risk of infection after TSV is yet to be clarified [93-97].
