Not long ago, vitreoretinal surgeons routinely peeled epiretinal membranes, even removing the internal limiting membranes as well. But most surgeons generally take a more conservative approach today. As you may know, the tendency is to spare the ILM, to hold off on performing ERM peels in many cases and to rule out potential adverse effects related to comorbidities before deciding when and how to proceed.
Here, veteran vitreoretinal surgeons discuss their current and evolving approaches.
Scope of the Problem
The incidence of epiretinal membranes varies widely, depending on co-existing pathologies, regions of the world studied and diagnostic testing used to identify ERMs. Spectral-domain coherence tomography has opened the door to much wider recognition in recent years, identifying the greatest number of affected patients in the United States to date, including up to 34 percent of eyes examined during the 20-year follow-up of the Beaver Dam Eye Study population1 and a range of 2.2 to 11 percent in eyes with no pre-existing pathologies that were examined before cataract surgeries in two separate studies.2,3
Risk factors for ERM remain the same, of course, including increasing age, uveitis, ocular inflammatory diseases and retinal pathologies, such as posterior vitreous detachment, retinal breaks, retinal vein occlusions and diabetic retinopathy.4,5
“Epiretinal membranes are common and most patients identified with OCT don’t need intervention,” says Charles Wykoff, MD, PhD, director of research at Retina Consultants of Houston, and deputy chair of ophthalmology for the Blanton Eye Institute at the Houston Methodist Hospital.
Dr. Wykoff says he lets a patient’s symptoms and vision guide his management strategy. “That’s a key point to keep in mind,” he says. “So if a patient is asymptomatic and functioning normally, without any problems, my inclination is generally to observe. If the patient is symptomatic—experiencing symptoms that could include metamorphopsia, crooked lines, haze over vision, a cellophane-like manifestation over their vision or even just blurry vision—at that point I would think about a surgical intervention.”
Dr. Wykoff acknowledges that debate among retinal specialists on using visual acuity thresholds to determine when to peel a membrane continues. “To me, though, using a patient’s symptoms and the impact of ERM on his or her activities of daily living are much more important than a specific visual acuity threshold,” he says. “If patients are bothered by their vision, and I think it’s attributable to an ERM, then I believe it’s reasonable to consider mentioning surgery to them. If they aren’t bothered by the ERM, then I will typically leave the ERM alone, even if their vision is decreased. It’s hard to make asymptomatic patients happier.”
Even if the architecture of the macula looks meaningfully distorted in the presence of an ERM, and the patient’s vision measurement is decreased, Dr. Wykoff sticks to his practice of observation, provided the patient is functional and content with his or her vision.
“Now, I definitely discuss the option of intervention with the patient, and I show the pictures, so that he or she knows what’s going on,” he notes. “But as I said, the patient’s symptoms drive my decision-making here.”
Akbar Shakoor, MD, a retinal and uveitis specialist at the John A. Moran Eye Center, and assistant professor of ophthalmology at the University of Utah, agrees with Dr. Wykoff’s approach. He considers qualitative and quantitative measurements of vision before deciding if an ERM peel is appropriate.
“Generally, I try to avoid doing a membrane peel when vision is 20/30 or better,” says Dr. Shakoor, who’s also an associate professor of ophthalmology and program director of the uveitis fellowship program at the University of Utah. “Of course, I’m not going to suggest surgery to a patient whose vision is 20/30 or better or if the patient isn’t bothered by poor vision. The vision could be almost anything, really, but if the patient isn’t bothered by his or her vision, I’m only going to make it worse by doing surgery.”
This can be especially true when an ERM manifests as an isolated condition.
Dr. Wykoff notes that many of these cases seen in practice are idiopathic. “Idiopathic ERMs are probably related to migrating glial cells or migrating fibroblasts that, for unknown reasons, become attracted to the inner retinal surface and then proliferate and form contractile tissue,” he says. “Many of these cases are most likely related to retinal pigment epithelial cells that have migrated to the anterior surface of the neurosensory retina and have proliferated there. The reason they begin to proliferate there is unknown. Certainly, there are also important risk factors for ERM—such as retinal tears, retinal breaks, history of trauma—that we also always need to consider.”
Figure 1. The first OCT scan (top) shows a preop, dense epiretinal membrane in a patient whose vision is 20/80. One month after an epiretinal membrane peel, the postop OCT scan (bottom) shows an improving macular contour. The patient’s vision is 20/25.
Role of Comorbidities
Retinal specialist Marc Mathias, MD, an assistant professor of ophthalmology at the University of Colorado, says many comorbidities play an increasingly significant role in triaging patients with ERMs.
“For example, in a glaucoma patient, I’m a little more hesitant to go ahead and do a ERM peel,” he notes. “I usually discuss such a case with the glaucoma specialist who’s taking care of the patient to find out how significant the glaucoma is and what effects an ERM peel might create. In relatively modest glaucoma, an ERM peel can be realistic, and the outcomes are good. However, I’ve gotten away from peeling the ERM in moderate cases of glaucoma. The risks of ganglion cell layer thinning and decreasing vision are too great if you do an ILM peel on these patients. For advanced glaucoma, meanwhile, I try to avoid surgery at all costs. The same goes for age-related macular degeneration, another significant underlying disease that raises risk factors.
With a diabetic patient, however, Dr. Mathias initiates a different type of conversation.
“Medications won’t improve that patient’s diabetic macular edema,” he says. “Those are the cases when an ERM peel can be more reasonable and I usually proceed with the procedure.”
At first glance, Dr.
Shakoor doesn’t like accepting the label of idiopathic ERM, as common as it may be. He approaches ERM patients with what he considers a healthy degree of skepticism, seeking answers to questions.
“You’ll find that a lot of these patients actually do have an underlying process,” he says. “You want to look specifically for inflammatory or vascular disease. Specifically, I want to find out if the patient has uveitis or retinal vasculitis. Does he or she have a history of endophthalmitis? I want to know if a vein occlusion is involved. How about microvascular disease? Does the patient have diabetes? Those are the issues you should explore.
“If there’s an active disease process going on, including uveitis, then it should be controlled before a decision is made on whether to do a surgical procedure such as an ERM peel,” he says.
Failing to identify another active process will increase the chance of ERM recurrence or a recurrence of inflammation that leads to other structural damage, he points out. “If you have a patient who has any inflammation, bringing that inflammation under control before surgery is very important,” he adds. “You don’t want to operate on eyes affected by an inflammatory process.”
Sara J. Haug, MD, PhD, a retinal specialist at Southwest Eye Consultants in Durango, Colorado, and surrounding areas, says the phakic status of patients can also play an important a role in her selection of candidates for an ERM peel.
“If the patient is over 50 and phakic, I can almost guarantee you that the patient will develop a cataract six months to a year after my ERM surgery,” she says. “Therefore, I may be more amenable to doing surgery on a pseudophakic patient who’s more of a borderline case than I would a phakic patient.”
Dr. Shakoor adds this additional perspective: “I think you need to consider the degree of vision loss that a cataract contributes and the degree of vision loss that an ERM contributes,” he says. “It may just be that once the cataract is removed, the patient’s vision improves to the point at which poor vision won’t be a significant issue anymore.”
Dr. Shakoor also looks at patients’ OCT scans for evidence of outer retinal disease. “Besides signs of macular degeneration, you may see RPE loss,” he explains. “If you see any of these processes, you still might be able to do a membrane peel. But then you have to temper your patients’ expectations. I’ll tell them: ‘You have this epiretinal membrane and it may be causing some distortion. But you also have these other conditions. So your vision may consequently be limited to some extent by the other processes.’ The last thing your patient wants to hear is that the membrane is gone, that the macula looks good but that he or she will see no better than before the ERM peel was removed. It’s always important to talk your patient through these processes and the prognosis.”
Figure 2. This OCT scan shows a macula with an epiretinal membrane as well as subretinal fibrosis related to exudative age-related macular degeneration. The patient wasn’t suitable for surgery.
Despite the trend away from peeling the ERM in many cases, Dr. Haug carefully evaluates each affected patient to recognize when a peel might still be needed.
“The OCT scan can sometimes be misleading, indicating the vision is better than it is, for example,” says Dr. Haug. “I’ve seen some 20/20 eyes peeled because you have some distortion. There’s going to be a lot of debate about this. Every surgeon has his or her own threshold. The threshold that I use is at about the 20/40 mark. When you hit 20/40 and your patient’s vision is bothering him or her in everyday life, and I also see a pretty good membrane, then I feel pretty confident about moving ahead with the peel.”
Dr. Shakoor sometimes relies on waiting periods to see if symptoms get better before performing a peel. “After all, every surgery has risks,” he notes. “You don’t want to end up in a situation in which the patient was not keen on undergoing surgery and feels he was coerced into surgery after he or she ends up with a bad outcome. This sort of preoperative questioning and assessment of the patient can be more important than the surgery itself.”
During the preop period, Dr. Shakoor says he covers every aspect of the procedure and the possible outcomes—right up until he’s at the patient’s bedside before he performs the procedure.
“I discuss the possible need for postop steroids after surgery to control macular edema, for example,” he says. “I want to manage their expectations realistically, emphasizing that this isn’t like cataract surgery, after which you will see beautifully the next day. After this procedure, it may take weeks or even months before patients start to notice improvement. Or their vision may not end up being as good as we had hoped. Their final outcome won’t be known until about six months down the road. Some patients will get back to 20/20 and others will only get to 20/30 and may still experience distortion. These conversations are very important to have and they’re the reasons why I always emphasize informed consent. You could say I am more aggressive with informed consent and than I am with surgery.”
ILM: To Peel or Not to Peel
Peeling the internal limiting membrane was once a routine part of peeling the ERM. “Peeling the ILM with the ERM has always given us a sense of security,” explains Dr. Haug. “There’s plenty of evidence that peeling the ILM will reduce recurrence of the ERM by 10 to 15 percent or more. But the latest evidence also says peeling the ILM can lead to thinning of the retina, although I personally don’t think it can lead to major problems.”
In a 2019 Preferred Practice Pattern published by the American Academy of Ophthalmology, a review of 10 studies compared the results of isolated ERM removal to the results of combined ERM and ILM removal.6 Five of the studies found that peeling the ILM with the ERM led to a lower incidence of recurrent ERM, although removing ILM was also associated with loss of inner retinal tissue.
“Most of us are less aggressive about when we peel the ILM these days,” says Dr. Haug. “In my mind, I’m least likely to peel the ILM if the patient has macular degeneration. Sometimes, though, you can’t help peeling the ILM because the ILM and ERM will come off together. You can stain and see where you haven’t removed the ILM and decide whether or not you want to remove all of it. The exception to this tendency against peeling the ILM would be in patients with diabetes. When a patient has diabetes, we’re more likely to peel the ILM.”
Dr. Shakoor says he doesn’t have a firm opinion on whether it’s best to peel the ILM. He approaches the issue on a case-by-case basis.
“If you peel the ILM, the upside is that you have the reduced chance of recurrence of the ERM,” he says. “The downside of doing an ILM peel is that you risk damaging the retinal nerve fiber layer, even if you’re a very good surgeon. The ILM is a structure that is completely apposed to the retinal nerve fiber layer. However, if you can carefully and successfully remove the ILM, the risks of doing the ERM peel only and the ERM and ILM peel together are both the same, so three months down the road, both patients should be happy.”
Dr. Shakoor peels the ILM in cases of inflammatory disease because he believes it reduces the incidence of cystoid macular edema and inflammation in the future. “Not everyone believes that, but that is my belief,” he says.
Like other retinal specialists, he also routinely peels the ILM in diabetic patients because he feels it helps decrease the re-emergence of diabetic macular edema. “It limits—but doesn’t eliminate—your need for further treatment,” he says. “Also, in the presence of an ERM, when a macular hole also exists, then it’s a no-brainer to peel the ILM.”
Dr. Wykoff says he continues to remove the ILM routinely, adding, “I tend to remove just a small area of the ILM centrally.” His practice is guided by an extensive evaluation of ERM peels performed by him and his colleagues.
A Trend of His Own?
The trend among retinal specialists may be to hold off on peeling the ERM unless it’s significantly disrupting vision, affecting activities of daily living or making the patient unhappy. However, Marc Mathias, MD, sometimes takes a more individualized approach.
“As I’ve become more comfortable with doing surgery in my career, my threshold for performing this procedure has lowered a little bit,” says Dr. Mathias. “It involves focusing on how we may be able to improve the patient’s experience and vision, and how that patient’s life is being affected, rather than focusing on straight cut-offs or thresholds that we might’ve followed in the past.”
He offers an example. “For a patient who has really good visual acuity, say 20/25, but also significant metamorphopsia, I might’ve been a little hesitant to consider surgical intervention in the past. But now, based on my experience, I may be comfortable proceeding with surgery. I’m more inclined to take this approach after discussing procedures with patients who may have acceptable visual acuity but also have complaints that you can’t objectively measure. I also see patients with good visual acuity whose retinal architecture is quite distorted. I’ll remove the ERM because the patient is complaining of metamorphopsia. We’ve had a relatively high degree of success in terms of improving functional vision in these patients.”
Dr. Mathias says he still relies heavily on objective means of evaluation, however. “Before proceeding with any case, I do try to coordinate my findings with OCT,” he says. “We’ve encountered patients whose testing reveals no distorted anatomy at all, and they’re complaining of metamorphopsia. I can get a little more hesitant to peel those patients.”
One conservative approach to surgery that Dr. Mathias shares with his colleagues involves patients who have wildly unrealistic expectations that can’t be tamed by serious preop counseling. “We will see patients who are expecting a result they might get after cataract surgery or LASIK,” he notes. “Many of them are expecting perfection, and it’s a challenge to communicate to them that we’re operating on the sensitive tissue of the retina. We’re modifying the architecture, treating traction and maculopathy, not replacing anything. These patients can be difficult in a different way.”
“The rate of recurrence was low in both groups but appeared to be lower in the group in which we removed the ILM,” he says. “So I feel I’m trying to get rid of the problem instead of allowing it to come back. But whether or not we should peel the ILM remains an important, unanswered question. Does removing the ILM interfere with visual function? I think the field would really benefit if prospective data provided guidance on that issue.”
Dr. Wykoff is a consultant for Genentech and Regeneron and does research for both companies. Drs. Haug, Shakoor and Mathias report no relevant financial disclosures.
1. Meuer SM, Myers CE, Klein BE, et al. The epidemiology of vitreoretinal interface abnormalities as detected by spectral-domain optical coherence tomography: The Beaver Dam Eye Study. Ophthalmology 2015;122:787-795.
2. Klein BR, Brown EN, Casden RS. Preoperative macular spectral-domain optical coherence tomography in patients considering advanced-technology intraocular lenses for cataract surgery. J Cataract Refract Surg 2016;42:4:537-541.
3. Zafar S, Siddiqui MAR, Shahzad R, et al. Swept-source optical coherence tomography to screen for macular pathology in eyes having routine cataract surgery. J Cataract Refract Surg 2017;3:3:324-327.
4. Bu SC, Kuijer R, Li XR, et al. Idiopathic epiretinal membrane. Retina 2014;34:12:2317-2335.
5. Cheung N, Tan SP, Lee SY, et al. Prevalence and risk factors for epiretinal membrane: The Singapore epidemiology of eye disease study. Br J Ophthalmol 2017;101:3:371-37.
6. Idiopathic Epiretinal Membrane and Vitreomacular Traction Preferred Practice Pattern, American Academy of Ophthalmology; 2019;167-169.