Epiretinal membranes (ERMs) are sheet-like fibroglial membranes over the inner surface of the macula.1–3 They can be idiopathic, often associated with advanced age4,5 and/or a posterior vitreous detachment,1 or they can develop secondary to a number of ocular pathologies such as retinal detachments and tears, uveitis, retinal vascular diseases, or after surgeries or laser procedures.2,6–8 In the United States, ERMs affect approximately 30 million adults ages 43 to 86 years.4 ERMs can induce symptoms such as blurry vision, diplopia, micropsia, and metamorphopsia.2
The present management for ERMs is either watchful waiting and refraction for patients with tolerable symptoms or pars plana vitrectomy with membrane peel for patients with intolerable symptoms who feel the potential benefits of surgery out-weigh the risks. Traditionally, surgery was reserved for patients with 20/50 or worse visual acuity or for those with absolutely intolerable symptoms, whereas patients with better vision were monitored.9 More recently, reports on surgery for symptomatic eyes with vision better than 20/50 or 20/60 have indicated favorable outcomes.10–13 These reports suggest that although eyes with good baseline vision have a smaller vision gain from the preoperative to postoperative state than eyes with worse baseline vision, the good-vision eyes tend to have a better absolute postoperative result. This suggests that more advanced ERMs may contain a certain level of irreversible vision loss. For patients with good vision who can currently tolerate their symptoms, a common and important consideration is the risk for ERM progression if watchful waiting is elected. The thought process is that if progression to poor vision is certain within a short time period, then it behooves the patients to undergo surgery early and achieve a better absolute postoperative vision result. However, if progression to poor vision or intolerable symptoms is gradual and prolonged, then the patient may choose to continue to monitor.
Few studies on the natural histories of ERMs exist. The Blue Mountain Study performed in Australia showed that in eyes with ERM, 29% progressed, 26% regressed, and 39% remained stable at 5 years based on fundus photography.14 A study by Byon et al,15 looked at 62 eyes with 20/40 or better vision and showed that less than 10% had a decrease in vision while 6.5% had an improvement in vision at 2 years. This current study elaborates on the previous works to look at the progression to surgery for eyes with ERMs and good vision.
Patients and Methods
This is a retrospective, consecutive case series of all patients with newly diagnosed idiopathic ERMs referred to the Retina Service at the Ophthalmic Consultants of Boston between January 2009 and May 2015. Institutional review board approvals for a retrospective chart review were obtained. The research adhered to the tenets of the Declaration of Helsinki and was conducted in accordance with regulations set forth by the Health Insurance Portability and Accountability Act of 1996. Included eyes had 20/40 or better visual acuity (best available but not best corrected) without intolerable symptoms. Eyes with baseline lamellar holes, baseline vitreomacular traction, secondary ERMs (such as from retinal detachment, vascular occlusions, or uveitis), and the absence of baseline or final optical coherence tomography (OCT) were excluded. Surgical membrane peeling was typically offered when vision worsened to 20/50 or beyond and/or when patients were unable to tolerate symptoms attributable to the ERM. The primary outcome measure was progression to surgery.
All eligible eyes were categorized by baseline OCT morphology into normal foveal contour, mild or incomplete loss of foveal contour, and total loss of foveal contour as illustrated in Figure 1. For eyes with normal foveal contours, signs of ERM presence must be noted on OCT including hyperreflectivity overlying the macula or retinal striae; otherwise, the eye was excluded. Visual acuities were analyzed through conversion to logMAR. Kaplan-Meier survival curves for progression to surgical membrane peel were calculated and analyzed. Microsoft Excel version 15.41 (Microsoft Corporation, Redmond, WA) and GraphPad Prism version 7.0c (GraphPad Software, La Jolla, CA) were used for all analyses.
All epiretinal membranes were categorized by the morphology seen on their baseline optical coherence tomography. The three groups included a normal foveal contour, mild/incomplete loss of the foveal contour, and complete loss of the foveal contour.
A total of 201 eyes from 170 patients were included in the study (Table). Overall age averaged 67 years. Of the study eyes, 29.8% had normal foveal contour, 18.9% had mild loss of foveal contour, and 51.2% had complete loss of foveal contour on baseline OCT morphology. Average baseline visual acuity was 20/28 overall and worsened with further loss of foveal contour. Eyes with complete loss of the foveal contour had statistically worse baseline visual acuity compared with eyes with normal foveal contour and eyes with mild loss of foveal contour (P = .0001).
Baseline Characteristics of 201 Study Eyes
Kaplan-Meier survival curves show that 13% of ERM eyes with good vision progressed to surgery at 7 years. Additionally, there appears to be a point in the curve at 4 years in which eyes that had not progressed by this point, remain stable without surgery to 7 years (Figure 2).
Kaplan-Meier survival curves for all 201 eyes showed a 13% progression to surgery at 7 years. Additionally, it appears that if an eye had not progressed to surgery by 4 years, its likelihood of doing so was negligible.
When categorized by baseline OCT morphology, only 5% of eyes with normal foveal contour progressed to surgery by 5.5 years, whereas 17% of eyes with incomplete and 16% of eyes with complete loss of foveal contour progressed to surgery at 6 and 7 years, respectively.
Additionally, while the final rate of progression is similar between the latter two groups, eyes with complete loss of foveal contour appear to have a more rapid initial rate of progression that eventually converged with the incomplete loss of the foveal contour group (Figure 3).
Kaplan-Meier survival curves for all 201 eyes separated by baseline optical coherence tomography morphology. Only 5% of eyes with normal foveal contours progressed to surgery at 5.5 years, whereas approximately three times as many eyes with mild or complete loss of foveal contours progressed to surgery in a similar time frame. Additionally, when comparing the rate of progression, eyes with complete loss of the foveal contour progressed faster than eyes with mild loss of the contour.
Next, we looked at the survival curves categorized by the presence or absence of symptoms typically correlated with ERMs such as blurry vision, metamorphopsia, and diplopia. A greater number of initially symptomatic eyes (15%) progressed to surgery compared with asymptomatic eyes (9%) at 7 years (Figure 4). However, this visual trend was not statistically significant (P = .38).
Kaplan-Meier survival curves for all 201 eyes separated by the presence of baseline symptoms such as blurry vision, metamorphopsia, and diplopia that can be attributable to the epiretinal membrane. Eyes with symptoms showed a higher rate of surgical progression than eyes without symptoms throughout all time points; however, this trend was not found to be statistically significant (P = .38).
The management options for ERMs currently consist of watchful waiting, possibly with refraction, or vitrectomy surgery. Pars plana vitrectomy with membrane peel has been shown to improve the visual function and vision-related quality of life in properly selected patients.16 Approximately 80% of patients with ERM or vitreomacular traction who undergo surgery will improve by at least two lines of visual acuity.17 However, past studies suggest that the majority of ERMs will remain relatively stable and do not require surgical intervention.17
Surgery for ERMs is associated with possible complications such as retinal detachments and tears, infection, and accelerated cataract formation; typically, surgery is not recommended unless the patient is symptomatic from the ERM. On the other hand, fibrotic changes from ERMs cause distortion of the retinal architecture, and there is supportive evidence suggesting irreversible damage to the macula with severe membranes.18 Unfortunately, the exact time point when irreversible damage begins is presently unknown2; therefore, for patients with moderate, currently tolerable symptoms and good vision, it is unknown whether surgery for their ERMs can be safely delayed until their symptoms worsen to a level that truly affects their activities of daily living.
This study aims to answer some of these questions and shows that a minority of these patients progressed to surgery within 7 years. For patients with newly diagnosed ERMs and good vision who were referred to a retina practice, only 13% became sufficiently symptomatic to consider surgery at 7 years. Additionally, the progression of ERMs with good vision is associated with baseline OCT morphology; no eyes with normal foveal contours progressed to surgery at 7 years, and eyes with complete loss of foveal contour progressed faster than those with incomplete loss of foveal contour with the curves converging at 4 years. The correlation of visual acuity and symptoms with OCT morphology is a widely studied area and goes beyond our simple categorization by foveal contour. However, we specifically chose this categorization because it is quick and easy to identify in a real-world setting and also easy to explain to patients. It also appears that if a patient with an ERM has not progressed to surgery by 4 years, then the likelihood of progression is negligible.
Our study is limited by its retrospective nature. The best available visual acuity was used as opposed to the best corrected visual acuity. Additionally, these are all eyes of patients referred to a retina practice, which may be a more selective population of eyes with presumably more advanced ERMs than that of general ophthalmology practices, which would suggest that our statistics are an over-estimate of the ERM progression rate in the general population. Additionally, we all know that as surgeons, whether intentional or not, we do hold influence over our patients' decisions, and surgeon bias to waiting versus observation in particular circumstances can affect a patient's perception of whether his or her symptoms are tolerable. Furthermore, most patients in this cohort deferred surgery until 20/50 or worse vision with a few opting for surgery with better vision but significant metamorphopsia. This preference trend may vary by patient population. The best study paradigm for this clinical question about progression of ERMs in patients with good vision would be a prospective study using a potential acuity meter for visual acuity to bypass any contributions from the anterior segment, a quantitative measurement of metamorphopsia, and a validated questionnaire measuring the effects of visual symptoms on the quality of life (eg, the VFQ-25) extending over several years; however, in the absence of a more rigorous prospective study, our report offers some initial data to this common clinical question posed by patients. The purpose of this study is not to advocate for early or late surgery for ERMs in patients with good vision but rather to produce statistics to help counsel patients and allow them to make an informed decision in conjunction with their retina specialist.
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Baseline Characteristics of 201 Study Eyes
|n||Age(Years)||Baseline VA(Snellen)||Follow-Up Duration(Years)|
|Overall||201||67 ± 9.4||20/28||2.9 ± 1.5|
|Normal Foveal Contour||60 (29.8%)||69.6 ± 10.0||20/26||2.6 ± 1.3|
|Mild Loss of Foveal Contour||38 (18.9%)||65.4 ± 9.5||20/26||3.1 ± 1.4|
|Loss of Foveal Contour||103 (51.2%)||65.9 ± 8.8||20/30||3.1 ± 1.5|