Introduction: The aim of this study was to evaluate the clinical characteristics and surgical outcomes of the epiretinal membrane foveoschisis (ERM-FS) with different morphological types. Methods: This retrospective observational study reviewed 44 consecutive ERM-FS patients who underwent ERM surgery. According to the optical coherence tomography images, ERM-FS was classified into three groups: group A, FS crossed the fovea with the foveola elevated; group B, FS located at the foveal edges with a near-normal central foveal point thickness; and group C, FS with undermined foveal edges with a near-normal central foveal point thickness. Results: There were 10 eyes in group A, 20 eyes in group B, and 14 eyes in group C. Preoperatively, eyes in group A had the best best-corrected visual acuity (BCVA), the thickest central foveal point thickness, and the highest ellipsoid zone (EZ) intact rate among the three groups. After surgery, a resolution of foveoschisis was observed in 40.0%, 45.0%, and 50.0% of the eyes in group A, group B, and group C (p = 0.928), respectively. BCVA was significantly improved postoperatively. Although there was no significant difference in BCVA among the three groups at 1 month postoperatively, BCVA of group A was the best at 4 and 10 months. Correlation analysis indicated that the type of ERM-FS, baseline BCVA, central foveal point thickness, and postoperative EZ continuity (all p < 0.05) were important factors for the final BCVA. Conclusions: The damage to the retinal structure and visual function was milder in group A ERM-FS. Our study emphasized the necessity of OCT-based subtyping in patients with ERM-FS.

Epiretinal membrane foveoschisis (ERM-FS) is a new terminology proposed by an international vitreoretinal experts panel in 2020, characterized as a splitting of foveal retinal layers at the level of Henle’s fiber layer (HFL) caused by ERM traction [1, 2]. From 1988, with the advent of time-domain optical coherence tomography (OCT) technology, the intraretinal split of the foveal edges was considered a feature of lamellar macular holes (LMH) [3‒5]. Subsequently, as high-definition OCT became more widely used, some researchers believe that only lesions with obvious tissue loss should be named LMH [4, 6]. The lesions with stretched foveal edges related to ERM contraction and without obvious tissue loss should belong to the macular pseudohole (MPH) spectrum [6]. At the same time, there were also people who believed that LMH should be divided into two categories according to its pathogenesis: “degenerative” and “tractional,” without considering whether there is apparent tissue loss, and that the intraretinal splitting was one of the characteristics of the tractional LMH [7]. However, these ambiguous and inconsistent definitions and categorizations would adversely affect clinical decision-making on the choice of surgical indications and timing.

Recently, to resolve this problem, an international vitreoretinal experts panel proposed consensus diagnostic criteria for LMH, ERM-FS, and MPH based on their OCT characteristics to differentiate these three clinical entities [1]. The foveoschisis associated with ERM, which is most often confused with LMH, is now referred to as “ERM-FS” including the cases that were previously called “tractional LMH” and “MPH with stretched edges” [4, 6]. This terminology emphasized the causal relationship between the traction ERM and the presence of foveoschisis. The clear division of these three distinct clinical entities enables us to explore the characteristics of these diseases more accurately. Some studies have already compared the clinical characteristics and surgical outcomes among these three entities [8‒11]. However, few studies have investigated the clinical characteristics of patients with ERM-FS as yet, especially the surgical prognosis [12‒14]. In clinical practice, we have found that even if some ERMs belong to the category of ERM-FS, their morphology varies. In some ERM-FS, the ERM covers the fovea, accompanied by increased central foveal thickness (CFT). In the other ERM-FS, the ERM spares the fovea, and the thickness of the foveola is close to normal, with or without damage to the edge of the fovea. However, it is still unclear whether these ERM-FS with different morphologies have different clinical features, whether they represent different degrees of disease severity, and whether there are differences in prognosis. Therefore, the aim of this study was to analyze the clinical characteristic and visual and anatomical outcomes of patients who were diagnosed with ERM-FS based on the new diagnostic criteria.

Study Population

This monocentric retrospective study was conducted in Beijing Tongren Hospital and followed the Declaration of Helsinki and its later amendments. The medical records of patients with idiopathic ERM-FS who underwent vitrectomy from September 2016 to October 2021 were reviewed. ERM-FS was diagnosed based on the definitions declared by Hubschman et al. [1], as: (1) contractile ERM; and (2) foveoschisis at the level of HFL. In addition, the minor criteria included the presence of microcystoid spaces in the inner nuclear layer, retinal thickening, and retinal wrinkling. Inclusion criteria: (1) patients clinically diagnosed with unilateral or bilateral iERM and requiring surgical treatment; (2) patients who meet the ERM-FS diagnostic criteria mentioned above. Patients with a history of high myopia (axial length >26.0 mm or spherical equivalent <−6.0 diopters), ocular trauma, previous vitrectomy, and combined secondary ERM or other macular and anterior abnormality that could interfere with visual results were excluded.

All the patients included in this study underwent a comprehensive ophthalmologic examination at baseline and at 1, 4, and 10 months after the operation, including measurements of best-corrected visual acuity (BCVA), axial length, intraocular pressure, slit-lamp biomicroscopy examination, dilated fundus examination, color fundus photography, and spectral domain OCT examination.

Spectral Domain Optical Coherence Tomography Evaluation

Preoperative and postoperative foveal microstructures were evaluated by spectral domain OCT (Cirrus high-definition OCT; Carl Zeiss Meditec, Dublin, CA, USA), using Macular Cube 512*128 protocol and the HD 5-line raster. The fovea center, which was defined as the point lacking the inner retina layers, was determined by continuously adjusting the B-scan lines of the horizontal and vertical sections using the “Macular Cube” mode. According to OCT images, we divided the ERM-FS into three groups (Fig. 1): The eyes in group A were characterized as the FS crossing the foveal center with the central fovea elevated; group B included eyes of FS located at the foveal edges with a nearly normal or slightly elevated central foveal point thickness; and group C included the eyes of FS with irregular and/or undermined foveal edges and their central foveal point thickness was nearly normal or slightly decreased. CFT was calculated automatically as the mean value within the innermost central 1 mm circle, according to the Early Treatment Diabetic Retinopathy Study (ETDRS) sectors. The central foveal point thickness was measured manually from the outside of the retinal pigment epithelium to the innermost of the retina at the fovea center. The integrity of the ellipsoid zone (EZ) was also recorded.

Fig. 1.

SD-OCT images of different morphological types of epiretinal membrane foveoschisis before and after the operation. a Example of a case in group A with the foveoschisis crossing the foveal center and the foveal pit absent. b Example of a case in group B with the foveoschisis at the foveal edges; the central foveal point thickness is nearly normal. c Example of a case in group C with the foveoschisis having an undermined foveal edge.

Fig. 1.

SD-OCT images of different morphological types of epiretinal membrane foveoschisis before and after the operation. a Example of a case in group A with the foveoschisis crossing the foveal center and the foveal pit absent. b Example of a case in group B with the foveoschisis at the foveal edges; the central foveal point thickness is nearly normal. c Example of a case in group C with the foveoschisis having an undermined foveal edge.

Close modal

Surgical Procedure

All patients underwent a standard 23G, 3-port vitrectomy with ERM and ILM peeling by one experienced surgeon (W.L.). Phacoemulsification cataract surgery was performed in phakic eyes first if necessary. The criteria to perform combined cataract surgery: (1) the patients over 50 years old who have cataracts that affect VA; (2) the patients who are estimated to have a rapid progression of cataracts after PPV surgery; and (3) the patient’s own willingness. After core vitrectomy, the posterior vitreous detachment was created if it was not present. The surgeon peeled off all visible ERM. Then peeled ILM of about 2–3 disc diameters with or without 0.25% indocyanine green stained the ILM, depending on the surgeon. Laser photocoagulation was applied if any retinal degeneration and breaks were observed. At the final step, fluid-air exchange was performed, and then these eyes were filled with sterile air as the tamponade agent. Every patient maintained a face-down position for 5 days.

Statistical Analysis

Continuous variables were presented as mean ± standard deviation. Qualitative data were expressed as frequency and percentage. Statistical analyses among the three groups were performed using the Fisher’s exact test for count data. Normal distribution data were compared by variance analysis, and the Kruskal-Wallis H test was used to compare nonnormal distribution data. Bonferroni adjustment was used for multiple comparisons. The paired sample Wilcoxon signed rank test was used to compare the difference in BCVA and CFT at baseline and 10 months after surgery. Pearson correlation analysis for normal distribution and Spearman correlation analysis for nonnormal data were used to estimate the factors that associated with the BCVA at the last visit. A p < 0.05 was considered statistically significant.

Baseline Characteristics

Forty-four patients (44 eyes) diagnosed with ERM-FS (9 male, and 35 female) were enrolled in the study. The mean age was 64.5 ± 7.9 years. The average course of the disease was 21.8 ± 22.4 months. The mean follow-up was 8.8 ± 2.4 months. In addition, the mean preoperative BCVA was 0.4 ± 0.3 Log MAR (Snellen: 20/50). At the time of surgery, 3 were already pseudophakic. In the other 41 phakic eyes, PPV combined cataract surgery was performed in 31 eyes (75.6%). Five patients were found to have peripheral retinal degeneration and underwent local photocoagulation therapy (superior temporal: 3 eyes, nasal: 1 eye, and inferior: 1 eye).

There were 10 eyes in group A, 20 eyes in group B, and 14 eyes in group C. The detailed comparison of baseline characteristics among the three groups is shown in Table 1. Eyes in group A had a significantly better initial BCVA (PAB = 0.004, PAC = 0.039, PBC = 1.000), a thicker central foveal point thickness (PAB = 0.003, PAC <0.001, PBC = 0.097), and a lower disruption rate of the EZ band (PAB = 0.003, PAC = 0.022, PBC = 0.728) than the other two groups.

Table 1.

Baseline characteristics of the three different types of epiretinal membrane foveoschisis

ParametersGroup AGroup BGroup Cp value
Age, years 67.7±4.9 63.2±9.3 64.1±7.2 0.332a 
Gender/male, n (%) 0 (0) 4 (20.0) 5 (35.7) 0.095b 
Symptom duration, months 29.2±24.9 19.6±21.6 19.8±22.1 0.588c 
Follow-up periods, months 9.4±1.9 8.8±2.5 8.3±2.8 0.545c 
Axial length, mm 23.4±1.0 23.4±1.0 23.7±0.9 0.276c 
Intraocular pressure, mm Hg 13.7±2.3 15.9±2.8 15.3±2.0 0.085a 
LogMAR BCVA (Snellen) 0.2±0.1 (20/33)d,e 0.6±0.3 (20/80)d 0.5±0.3 (20/66)e 0.005c 
CFT, μm 382.7±45.1 441.4±99.3 436.7±77.7 0.177a 
Central foveal point thickness, μm 332.0±51.4d,e 214.5±55.1d 167.1±41.8e <0.001 
The disruption of EZ layer, n (%) 0 (0)d,e 11 (55)d 6 (40)e 0.009b 
ParametersGroup AGroup BGroup Cp value
Age, years 67.7±4.9 63.2±9.3 64.1±7.2 0.332a 
Gender/male, n (%) 0 (0) 4 (20.0) 5 (35.7) 0.095b 
Symptom duration, months 29.2±24.9 19.6±21.6 19.8±22.1 0.588c 
Follow-up periods, months 9.4±1.9 8.8±2.5 8.3±2.8 0.545c 
Axial length, mm 23.4±1.0 23.4±1.0 23.7±0.9 0.276c 
Intraocular pressure, mm Hg 13.7±2.3 15.9±2.8 15.3±2.0 0.085a 
LogMAR BCVA (Snellen) 0.2±0.1 (20/33)d,e 0.6±0.3 (20/80)d 0.5±0.3 (20/66)e 0.005c 
CFT, μm 382.7±45.1 441.4±99.3 436.7±77.7 0.177a 
Central foveal point thickness, μm 332.0±51.4d,e 214.5±55.1d 167.1±41.8e <0.001 
The disruption of EZ layer, n (%) 0 (0)d,e 11 (55)d 6 (40)e 0.009b 

BCVA, best-corrected visual acuity; logMAR, logarithm of the minimal angle of resolution; CFT, central foveal thickness; EZ, ellipsoid zone.

aVariance analysis.

bFisher’s exact test.

cKruskal-Wallis H test.

dThere were obvious differences between group A and group B in the pairwise comparison.

eThere were obvious differences between group A and group C in the pairwise comparison.

Anatomical Outcomes of Each Type of Epiretinal Membrane Foveoschisis

Among all the patients, the mean CFT improved from baseline 426.6 ± 84.8 μm to 345.9 ± 52.9 μm at the last follow-up. The changes in CFT at every follow-up time point in each group are shown in Table 2. There was a significant difference in the CFT at 10 months after surgery among the different types of ERM-FS. Eyes in group B had significantly thicker CFT than those in group A (PAB = 0.007). No significant difference was found in any other two groups (PAC = 0.154, PBC = 0.779).

Table 2.

CFT and BCVA changes over time

Baseline (n = 44)1 month (n = 44)4 months (n = 44)10 months (n = 35)p valuea
CFT, μm 
 Group A 382.7±45.1 338.3±47.4 315.0±43.6 309.1±45.2 <0.001 
 Group B 441.4±99.3 414.6±59.0 383.9±45.2 358.4±51.0 0.002 
Group C 436.7±77.7 398.6±70.5 368.1±60.6 339.7±51.6 <0.001 
LogMAR BCVA (Snellen) 
 Group A 0.2±0.1 (20/33) 0.2±0.2 (20/33) 0.1±0.2 (20/25) 0.0±0.0 (20/20) 0.016 
 Group B 0.6±0.3 (20/80) 0.3±0.2 (20/40) 0.2±0.2 (20/25) 0.1±0.1 (20/25) 0.001 
 Group C 0.5±0.3 (20/66) 0.2±0.2 (20/33) 0.2±0.1 (20/33) 0.1±0.1 (20/25) 0.021 
Baseline (n = 44)1 month (n = 44)4 months (n = 44)10 months (n = 35)p valuea
CFT, μm 
 Group A 382.7±45.1 338.3±47.4 315.0±43.6 309.1±45.2 <0.001 
 Group B 441.4±99.3 414.6±59.0 383.9±45.2 358.4±51.0 0.002 
Group C 436.7±77.7 398.6±70.5 368.1±60.6 339.7±51.6 <0.001 
LogMAR BCVA (Snellen) 
 Group A 0.2±0.1 (20/33) 0.2±0.2 (20/33) 0.1±0.2 (20/25) 0.0±0.0 (20/20) 0.016 
 Group B 0.6±0.3 (20/80) 0.3±0.2 (20/40) 0.2±0.2 (20/25) 0.1±0.1 (20/25) 0.001 
 Group C 0.5±0.3 (20/66) 0.2±0.2 (20/33) 0.2±0.1 (20/33) 0.1±0.1 (20/25) 0.021 

CFT, central foveal thickness; Log MAR, logarithm of the minimal angle of resolution; BCVA, best-corrected visual acuity.

aWilcoxon signed rank test was used to compare the difference in CFT and BCVA at baseline and 10 months after surgery.

At the last follow-up, a complete resolution of the foveoschisis was detected in 20 eyes (45.5%). Of those eyes, 4 eyes (4/10, 40.0%) were in group A, 9 eyes (9/20, 45.0%) were in group B, and 7 eyes (7/14, 50.0%) were in group C. There was no statistical difference in the foveoschisis resolution rate among the three groups (p = 0.928). When compared the follow-up time between the eyes with foveoschisis disappeared and the eyes with foveoschisis persisted, no significant difference was found (p = 0.418).

Of the 17 eyes (38.6%) with baseline EZ disrupted, 9 eyes (52.9%) recovered their continuity at the last follow-up examination, including 7 eyes (63.6%) in group B and 2 eyes (33.3%) in group C. No statistical difference was found in the follow-up time between the eyes with and without EZ recovered (p = 0.200).

Postoperative Visual Acuity and Related Factors

The mean BCVA improved to 0.1 ± 0.1 Log MAR (Snellen: 20/25) at the final follow-up, which is significantly better than that at baseline (p < 0.001). The changes in BCVA after surgery for each type of ERM-FS are illustrated in Table 2 and Figure 2. In the comparison of the BCVA at each follow-up time point among the three groups, no significant difference was found 1 month (p = 0.124) after surgery, while a significant difference was found at 4 (p = 0.027, PAB = 0.023, PAC = 0.202, PBC = 1.000) and 10 months (p = 0.014, PAB = 0.028, PAC = 0.028, PBC = 1.000), postoperatively.

Fig. 2.

Graph showing the changes of the BCVA over time for each type of epiretinal membrane foveoschisis.

Fig. 2.

Graph showing the changes of the BCVA over time for each type of epiretinal membrane foveoschisis.

Close modal

At the final follow-up, BCVA was 20/25 or better in 41 eyes (93.2%), including 9 eyes (9/10, 90.0%) in group A, 18 eyes (18/20, 90.0%) in group B, and 14 eyes (14/14, 100.0%) in group C. As shown in Table 3, the BCVA improved in 80.0%, 85.0%, and 85.0% of the eyes in group A, group B, and group C, respectively. Compared the baseline characteristics between the eyes with postoperative VA improved and not improved, we found that the eyes with VA not improved had a better initial BCVA (0.1 ± 0.1 [20/25] vs. 0.5 ± 0.3 [20/66] Log MAR BCVA [Snellen], p < 0.001) and a lower EZ disruption rate than those of VA improved (0% vs. 45.9%, p = 0.032).

Table 3.

Postoperative visual acuity changes in each group

Improved, n (%)Remain stable, n (%)Decreased, n (%)
Group A (n = 10) 8 (80.0) 1 (10.0) 1 (10.0) 
Group B (n = 20) 17 (85.0) 1 (5.0) 2 (10.0) 
Group C (n = 14) 12 (85.7) 1 (7.1) 1 (7.1) 
Improved, n (%)Remain stable, n (%)Decreased, n (%)
Group A (n = 10) 8 (80.0) 1 (10.0) 1 (10.0) 
Group B (n = 20) 17 (85.0) 1 (5.0) 2 (10.0) 
Group C (n = 14) 12 (85.7) 1 (7.1) 1 (7.1) 

Correlation analysis indicated that the type of ERM-FS (p = 0.027), baseline BCVA (p = 0.015), central foveal point thickness (p = 0.023), and the postoperative EZ continuity (p < 0.001) were related factors for the postoperative BCVA. However, whether foveoschisis was resolved was not associated with the final BCVA.

In the present study, we reviewed the clinical characteristics of 44 patients who were diagnosed with ERM-FS based on the new diagnostic criteria. According to the depiction of the OCT images, we divided these patients into three groups according to their morphological characteristics. Also, we found that these three types of ERM-FS have different clinical characteristics and visual outcomes.

In our study, we found that the patients in group A whose retinal schisis crossing the central fovea might have a better baseline BCVA, a thicker central foveal point thickness, a more complete EZ layer, and better surgical outcomes than those with FS not crossing the foveal center. However, Hetzel et al. [13] divided the eyes with ERM-FS into the “closed” and “open” groups according to their OCT images that were similar to our classification, and found that eyes in the “closed” group had a significantly worse BCVA than that in the “open” group. The major reason for the discrepancy may be due to the different severity of disease conditions between the two studies. In the cases reported by Hetzel et al. [13], not all needed surgical treatment, and the mean initial BCVA was better than that in our study. Because there are few researches on ERM-FS at present, the exact reason for this difference is not clear. The clinical features and prognostic impact of different morphological types of the ERM-FS remain to be determined.

We speculated that the reason why BCVA in group A is better than the other two groups may be because of different foveal configurations of different types of ERMs. In group A, the ERM covers the entire surface of the foveal tissue. The traction induced by ERM pulls the underlying retinal layers of the foveal center inward. The edges of the foveal walls become elevated because of the ERM contraction. This will cause anterior traction to the foveal center and outer nuclear layer (ONL) thickening, resulting in the disappearance of the foveal pit. In this process, the HFL will be split because of the elevation of the inner foveal layers. In the studies reported by Bringmann et al. [15], this kind of foveal cyst shows little morphological alterations of the outer retinal layers. In this study, we also found that the eyes in group A had a significantly lower EZ disruption rate compared to the other two groups. Therefore, we supposed that the foveoschisis in the early stage may have a potential protection function for the photoreceptor layers to buffer the effects of the ERM traction. Due to the lack of previous studies, this is only our speculation and further research is needed to confirm. In the other two groups, the ERM spared the foveola. The ERM contraction in these groups will first cause a thickening of the inner layers of the foveal walls and parafoveal, resulting in deep foveal pits with steep slopes. As traction increases, some eyes may experience a schisis of the parafoveal and foveal walls. The Müller cells of the foveal walls could further transfer the traction to the foveola. Previous studies have shown that as Müller cells straighten, their hardness increases and their ability to transmit mechanical forces also increases, which will cause photoreceptor damage of the foveal area [15]. Therefore, in the latter two groups of patients, the ERM traction is stronger and the proportion of photoreceptor damage is higher, resulting in poorer BCVA.

Bringmman et al. [15] presumed that because of the lack of cellular connections between the outer processes of the Müller cells of the foveal walls and the Müller cell cone in the HFL/ONL, the mechanical stability of the boundary between the Müller cell cone and the HFL/ONL in the foveola was low. Therefore, due to HFL having low mechanical stability, this point of the retina is often considered the preferred location of intraretinal splitting [2, 7, 16]. The schisis of the fovea can cause an elevation of the inner foveal layers, which can further stretch the Müller cells of the foveal walls from a z-shape to a straighter shape, resulting in an easier transfer of the traction induced by ERM from the inner retinal layers to the photoreceptor layers. This hypothesis was further confirmed by Lam et al. [12]. Lam et al. [12] compared 17 eyes with ERM-FS and 100 eyes with iERM without cystoid spaces and found that the proportion of eyes with EZ disruption was significantly higher in the ERM-FS group (58.9% vs. 5.1%). In our study, EZ disruption was detected in 38.6% of the ERM-FS patients, which is higher than the rate reported by our team in 2022 in patients with iERMs without foveoschisis (13.3%) [17]. However, no EZ disruption was observed in the study performed by Omoto et al. [10]. They enrolled 17 ERM-FS cases with a relatively good BCVA of 0.2 ± 0.2 Log MAR, only 6 of which underwent ERM surgery. Therefore, this discrepancy might be attributed to a relatively mild disease condition and a small sample size in their study.

In accordance with the previous studies, the BCVA of the ERM-FS patients was significantly improved after the ERM surgery. Forty-one of 44 eyes (93.2%) had a final BCVA of 20/50 or better. Thirty-seven (84.1%) patients experienced a BCVA improvement. Further analysis of these 7 patients without VA improved showed that the preoperative BCVA was good for 3 patients with VA unchanged of 20/20 (Snellen), while of the 4 patients with VA decreased, 3 patients have a short follow-up time of 4 months and 1 patient did not undergo cataract surgery. Moreover, we found that compared with the eyes having BCVA improved after surgery, those whose postoperative BCVA was not improved were more likely to have a better BCVA and a more intact EZ band at baseline. In the subgroup analysis, no statistically significant difference in the mean BCVA was noted among these three groups 1 month after the operation, while the postoperative BCVA of the eyes in group A was significantly better than that in the other two groups at 4 and 10 months after surgery. A better VA might be related to a more continuous photoreceptor layer in the eyes of group A. However, there was no significant difference in BCVA and other anatomical parameters between the eyes in group B and group C, which was consistent with previous research, maybe because the tissue loss in the eyes of group C was negligible, so its impact on the visual function was not obvious [1].

Correlation analysis indicated a significant relationship between postoperative BCVA and preoperative ERM-FS types, initial BCVA, and postoperative EZ recovery. However, whether the foveoschisis recovered or not might have no significant impact on the final BCVA, which was coherent with the results reported by Lam et al. [12].

This study has some limitations because of its retrospective design and relatively small sample size. Previous studies indicated an incidence rate of 3.1–6.7% for ERM-FS in iERM patients [12, 13]. Moreover, we only included the patients who underwent ERM surgery, so the sample size is relatively small. In addition, cataract surgery was not performed in all enrolled cases. During surgery, except 3 eyes that were already pseudophakic, 31 eyes underwent PPV combined with cataract surgery. In the comparison of patients who underwent cataract surgery and who did not, we found that only the age (67.3 ± 6.2 vs. 55.0 ± 5.6 years, p < 0.001) and the duration of symptoms (25.4 ± 23.8 vs. 7.4 ± 4.4 months, p = 0.011) had statistically significant differences, while the other preoperative and postoperative anatomical parameters and visual acuity had no significant differences. Therefore, the patients who did not undergo cataract surgery might have no significant impact on the results of this study. Finally, some patients have a relatively short follow-up time. For patients who were followed up for 4 (n = 9) and 10 months (n = 35) after surgery, there were no significant differences in preoperative parameters, but there were significant differences in BCVA (0.3 ± 0.1 [20/40] vs. 0.1 ± 0.1 [20/25] Log MAR, p < 0.001) and the integrity of EZ layer (11.1% vs. 80.0%, p = 0.001) at the final follow-up examination. However, comparing the follow-up time among the 3 groups of patients, we found no significant difference. Therefore, some patients did not participate in the follow-up at 10 months after surgery, which may lead to an underestimate of the postoperative BCVA and EZ layer recovery in the whole cohort. However, it has little impact on the results of the comparison of the three groups.

In conclusion, we classified the ERM-FS into three morphological types according to the OCT images. ERM surgery in each type of ERM-FS eyes results in satisfactory anatomical and functional outcomes. The eyes in group A presented with better anatomical and functional result both preoperatively and postoperatively than the other two groups. Microstructural and morphological observations are useful for evaluating the visual function of these three clinical entities. Further prospective studies involving larger samples are warranted to validate our preliminary results on this prognostic impact of the different morphological types of the ERM-FS.

All procedures in studies involving human participants were performed in accordance with the Declaration of Helsinki and its lateral amendments. Approval was granted by the Ethical Review Committee of Beijing Tongren Hospital, Capital Medical University (approval number: TRECKY2020-149). Written informed consent was obtained from all participants for publishing their data and photographs.

The authors have no conflicts of interest with regard to the article.

This study was supported by National Key R&D Program of China (Grant/Award number: 2017YFA0104103) and sponsored by Wu Liu.

Xiaohan Yang and Xijin Wu: substantial contributions to the conception and design of the work; acquisition, analysis, and interpretation of data for the work; drafting and revising the work; final approval of the version to be published; and agreement to be accountable for all aspects of the work. Biying Qi, Ke Zhang, Yanping Yu, Xinbo Wang, Xiao Feng, Qinlang Jia, Zi-Bing Jin, and Wu Liu: revising the work; final approval of the work; and agreement to be accountable for all aspects of the work.

Additional Information

Xiaohan Yang and Xijin Wu contributed equally to this work.

All data generated or analyzed during this study are included in this article. Further inquiries can be directed to the corresponding author.

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