Epiretinal Membrane Treatment & Management

Isolate epiretinal membrane (ERM) as the main cause of a patient's visual impairment prior to planning a corrective procedure. Evaluate the patient carefully to rule out other pathologic conditions, such as macular holes, subfoveal choroidal neovascular membranes, cystoid macular edema, or retinal vascular occlusive disease, that may mimic the appearance of a true membrane.

Surgical treatment of epiretinal membrane is usually not an emergent procedure. Only when there is macular edema does it become a more urgent procedure.

Frequently, patients are referred for evaluation of an asymptomatic epiretinal membrane identified via OCT in primary care optometric and ophthalmologic practices. Thus, preoperative patient evaluation and counselling are important to identify surgical candidates and to set appropriate postoperative expectations. For such asymptomatic patients, the decision to intervene with surgery is not straightforward. Rahman and Stephenson demonstrated in a retrospective review that earlier intervention resulted in more rapid recovery and better final visual acuity. ^[11] However, Kofod et al evaluated early versus deferred surgery in epiretinal membrane and found that, while early surgery resulted in excellent vision, patients in the deferred surgery group did not lose 5 letters of ETDRS vision. Thus, they deemed surgery deferral a safe clinical decision. ^[12] Rouvas et al also recommended that nontractional epiretinal membranes may be monitored safely over time if the patient is not a good surgical candidate. ^[7]

Several surgical techniques exist for the treatment of epiretinal membrane. However, 3 basic stages of treatment exist.

Vitrectomy

Pars plana vitrectomy is performed to excise the posterior and central vitreous in phakic patients and the remainder of the anterior vitreous in aphakic and pseudophakic patients. This step is especially important in cases where marked adherence of the vitreous to the macula is present.

Lately, questions have been raised regarding the need for vitrectomy in epiretinal membrane peeling, especially in those cases where no significant PVR exists.

The main advantages of doing a vitrectomy are the prevention of vitreous contraction and elimination of vitreous traction on the macula. In addition, removal of the vitreous is believed by many to increase the safety of the mechanical aspects of the membrane removal.

The main disadvantages of vitrectomy include cataractogenesis and increased possibility of creating iatrogenic retinal breaks. Vitrectomy has been shown to increase the rate of cataract formation through unclear mechanisms.

Studies have shown that a 3-fold increase in the rate of significant cataract formation exists in patients that have undergone vitrectomy after a follow-up period of only 6 months.

Some surgeons feel that the effectiveness of membrane peeling is negated significantly by the cataract formation such that they have foregone vitrectomy in selected cases, opting to perform no-infusion/no-vitrectomy membrane peelings. The main disadvantage of this technique is the persistence of floaters postoperatively, which may be very bothersome to some patients. Furthermore, some surgeons have seen no significant difference in either cataractogenesis or development of retinal breaks/detachments in their series comparing vitrectomizing and nonvitrectomizing techniques.

Management of epiretinal membrane with vitrectomy is predisposed to smaller-gauge vitrectomies (25-gauge, 27-gauge). ^{[13, 14, 15]} These systems are transconjunctival with the potential to create self-sealing wounds. Complications appear low while affording the potential for more rapid surgical and visual recovery.

Use of intravitreal steroids such as triamcinolone or dexamethasone has been associated with a more rapid visual recovery and better final surgical outcomes. ^[16]

Epiretinal membrane peeling

From the time Machamer developed the concept of membrane peeling in the mid-1970s, several variations and refinements in both technique and instrumentation have been developed.

This procedure basically involves identifying the outer edge of the membrane and creating a dissection plane with the use of a blunt-tipped pick or a bent needle.

Once the edge of the membrane is seen, it may be gently lifted off the retinal surface with the use of a pick or fine forceps.

The membrane should be lifted in a tangential rather than an anteroposterior fashion so as not to pull on the underlying retina and create tears. This maneuver is relatively straightforward if the edge of the membrane is visible.

Charles developed a maneuver that approaches the membrane from inside out in cases where the edge is difficult to identify. ^[17] It involves creating a slit on the thickest part of the membrane with a straight microvitreoretinal blade and using this opening as the edge with which to start the peeling. The peeling is performed moving the forceps in a circular fashion similar to capsulorrhexis. The freed membrane should be removed either by pulling it out with the forceps through the sclerotomy or by using the vitreous cutter.

Internal limiting membrane (ILM) peeling

Removal of the ILM at the time of epiretinal membrane peeling is a current controversy, both for use of vital dyes and the necessity to peel the ILM in addition to the epiretinal membrane.

Vital stains, such as indocyanine green (ICG) dye and Trypan blue dye, have been used to assist ILM and epiretinal membrane peeling. Another ophthalmic stain, brilliant blue G (TissueBlue), was approved by the FDA in December 2019. It is a disclosing agent administered intravitreally that selectively stains the ILM. Dyes that stain the ILM highlight foci of epiretinal membrane and potentially reduce the risk of recurrence or the persistence of symptoms.

Similar to its use in macular hole surgery, the use of ICG has proponents and detractors on the basis of its potential toxic effects. Haritoglou et al suggested that ICG-assisted ILM peeling may adversely affect the functional outcome of surgery for epiretinal membrane. ^{[18, 19]}

Hillenkamp et al prospectively evaluated the effect of ICG dye in the setting of epiretinal membrane surgery. ^[20] No difference or evidence of ICG toxicity was observed. Both visual function and macular morphology improved in patients with and without ICG dye use.

However, Garweg et al suggested that ILM peeling with ICG dye, but not with trypan blue dye, may result in loss of the central visual field over time. ^[21] No difference in visual acuity was noted. This study suggests that the ICG dye, not necessarily the ILM peeling, may have an adverse effect following epiretinal membrane surgery.

Liu et al performed a meta-analysis of epiretinal membrane surgery with and without ILM peeling and found that patients who underwent ILM peeling had better visual acuity at 12 months postsurgery. However, by 18 months postoperatively, the meta-analysis of two papers suggested that patients who had not undergone ILM peeling had marginally better visual acuity. ^[22]

Microperimetric analysis of patients undergoing ILM peeling versus no ILM peeling during epiretinal membrane surgery suggested a benefit to not peeling ILM. The sensitivity of the central 4° showed faster recovery and fewer absolute microscotomas in patients who did not undergo ILM peeling. ^[23]

Management of retinal breaks

Once the membrane is removed, it is imperative for the surgeon to look for any breaks in the retina, both in the posterior pole and in the periphery.

Any maneuvers completed to remove the membranes, no matter how elegant, become irrelevant if the retina detaches because of missed breaks.

Careful scleral depression of the anterior retina combined with indirect ophthalmoscopy should be performed to detect breaks in the periphery.

Breaks without subretinal fluid accumulation can be treated by laser retinopexy or cryoretinopexy.

The presence of significant amounts of subretinal fluid necessitates internal drainage under air, retinopexy, and gas tamponade.

Intraoperative

The most frequently encountered intraoperative complications with vitrectomy and membrane peeling include intraocular bleeding and the development of retinal breaks.

Petechial hemorrhage along the internal retinal surface may be seen as the membrane is peeled off the retina but usually resolves within days of the operation.

More significant bleeding is encountered when an underlying vessel is damaged as a strongly adherent membrane is being peeled. This bleeding usually can be controlled by raising the intraocular pressure temporarily and waiting for the vessel to stop bleeding spontaneously or by applying cautery on the offending vessel.

The development of retinal breaks is the most important intraoperative complication that may be encountered. The incidence of intraoperative posterior pole breaks ranges anywhere from 0-15%, while that of peripheral breaks ranges from 5-6%.

Chung et al reviewed 174 eyes undergoing a vitrectomy for epiretinal membranes. The incidence of iatrogenic retinal breaks was 6.9%. They identified that the induction of a posterior vitreous detachment was a key risk factor for the development of iatrogenic retinal breaks. Only 28 (16%) of 174 eyes required the induction of a posterior vitreous detachment during surgery. However, this group accounted for 9 of 12 retinal breaks in this series. When a posterior vitreous detachment was already present, the incidence of iatrogenic retinal breaks was only 2.1%. ^[24]

Meticulous peeling of the membrane and careful examination of the peripheral retina are the most effective means to minimize postoperative problems associated with these retinal breaks.

Postoperative

The most frequent postoperative complication that may be seen is the accelerated progression of nuclear sclerosis of the lens, which may occur in as many as 75% of eyes over time.

Most patients have to undergo cataract extraction within 2 years to maximize the benefits afforded by membrane peeling.

Postoperative retinal detachment may be caused either by a missed break or by a new break that developed after further contraction of the remaining anterior vitreous. This detachment happens in 3-6% of patients and nearly always is treated successfully by another operation.

Recurrence of epiretinal membrane happens in less than 5% of idiopathic cases but may be higher for postdetachment and postinflammatory cases.

Postoperative macular holes following epiretinal membrane surgery are estimated to occur infrequently. In a review of 423 cases of epiretinal membrane surgery with internal limiting membrane peeling, 11 cases (2.6%) of postoperative macular holes were identified. The majority of holes (9 of 11) were eccentric primarily found along the margin of the internal limiting membrane peel. The incidence of central macular holes, requiring additional vitrectomy and gas tamponade, was 0.5% (2 of 423). ^[25]

Yannuzzi et al proposed that ILM peeling at the time of rhegmatogenous retinal detachment repair may decrease the likelihood of symptomatic ERM development and the need for subsequent surgery. A meta-analysis of six studies suggested that the rate of symptomatic ERM following retinal detachment repair without ILM peeling was 29% versus 3% with ILM peeling at the time of retinal detachment repair. The subsequent surgical rate was 16% for patients with retinal detachment repair without ILM peeling and 0% for patients with retinal detachment repair and ILM peeling. Yannuzzi et al suggest that the decreased rate of secondary pars plana vitrectomy (PPV) and ERM peeling may justify ILM peeling at the time of retinal detachment repair for prevention of symptomatic ERM. ^[26]

It is important to monitor patients with epiretinal membrane (ERM) long term because of reoccurrence of the condition.