Histopathological Analysis of Internal Limiting Membrane Surgically Peeled From Eyes with Epiretinal Membrane

Long-Term Quantitative Analysis of Inner Retinal Dimples and Visual Function Post Internal Limiting Membrane Peeling in Macular Diseases

INTRODUCTION

Inner retinal dimples (IRDs) are frequently detected after internal limiting membrane (ILM) peeling. However, the distribution of IRDs and its effect on postoperative visual function remain unclear. We aim to quantify the distribution of IRDs after ILM peeling in different macular diseases and analyze its influence on postoperative visual function.

METHODS

We retrospectively reviewed patients undergoing vitrectomy with ILM peeling and followed up until 12 months in our center. The distribution of IRDs were quantitatively determined using optical coherence tomography (OCT) and OCT angiography in a different sector of Early Treatment Diabetic Retinopathy Study grid. Visual function was evaluated by retinal sensitivity (RS) using microperimetry. Spearman correlation was performed between RS and IRDs within the same sectors. Multivariate linear regression analysis was performed to analyze the association between baseline characteristics and IRDs.

RESULTS

A total of 43 idiopathic macular hole (iMH) cases, 56 idiopathic epiretinal membrane (iERM) cases and 42 myopic foveoschisis (mFS) cases were included. IRDs increased gradually at ILM-peeled area, interrupting ganglion cell layer. Most IRDs were observed in temporal sector. A negative correlation was depicted between the increase of IRDs and the progress of RS at both perifovea and parafovea in iERM, but only at perifovea in iMH. No significant correlation between the change of IRDs and RS was found in mFS. Multivariable linear regression model showed that preoperative axial length was significantly associated with postoperative IRDs in all patients.

CONCLUSIONS

IRDs distributed mostly at temporal sector after ILM peeling, interrupting ganglion cell layer. IRD progression may influence postoperative RS only in iMH and iERM. Ophthalmologists may avoid temporal sector especially in eyes with normal axial length or strong ILM-ERM adherence.

Effect of internal limiting membrane peeling for idiopathic epiretinal membrane

Purpose

To further evaluate the necessity of internal limiting membrane (ILM) peeling for patients with idiopathic epiretinal membrane (iERM).

Method

We searched PubMed, Web of Science, Embase, Cochrane Library, and CNKI from their inception up to August 24, 2021. Eligible meta-analyses comparing iERM removal with and without ILM peeling were included. AMSTAR and GRADE classification was used to assess the methodological quality of each study and the quality for each outcome, respectively. The primary outcomes were best-corrected visual acuity (BCVA), central macular thickness (CMT), and recurrence.

Results

10 meta-analyses were included. 75.9% of studies revealed no statistically significant difference in BCVA between the groups, while only 10.3% showed better BCVA favorable to additional ILM peeling. 54.2% reported no significant difference in CMT between the groups, followed by 41.7% showing thicker CMT due to additional ILM peeling. Compared to iERM removal alone, additional ILM peeling provided a lower recurrence rate in 66.7% of studies.

Conclusion

ILM peeling could significantly reduce recurrence rate, but not significantly improve the recovery of visual outcome or decrease the thickness of central macula.

Idiopathic epiretinal membrane: progression and timing of surgery

Primary idiopathic epiretinal membrane (iERM) is a common finding, particularly so in the era of high street spectral-domain optical coherence tomography. Clinicians often face the dilemma of early versus delayed surgical intervention in the management of iERM with macular pucker, especially in those patients with good vision. The aim of this review is to assist clinicians in their understanding of the natural history of iERM to enable decision-making and optimally advising patients. We systematically searched the Medline and EMBASE databases for relevant publications from 2001 onwards using defined search terms with pre-planned inclusion and exclusion criteria. In this article, we review the epidemiology of iERM, classifications, their effect on visual function, the natural history and factors predicting progression and finally, factors which might predict the visual outcome with surgery.

Inner retinal structure and visual function after idiopathic epiretinal membrane surgery with and without brilliant blue G

PURPOSE

Vital dyes are frequently used to visualize the internal limiting membrane (ILM) of the neuroretina. This study evaluated and compared the microstructure of the inner retina and visual function with and without brilliant blue G (BBG) staining for ILM peeling during idiopathic epiretinal membrane (ERM) surgery.

STUDY DESIGN

Retrospective, consecutive, interventional case series.

METHODS

Fifty-five patients (55 eyes) with ERM underwent ILM peeling without dyes (non-dye group) and 55 patients (55 eyes) underwent ILM peeling with BBG staining (BBG group). The logMAR visual acuity (VA) and ganglion cell complex (GCC) thickness were measured using optical coherence tomography at baseline and 12 months after surgery.

RESULTS

LogMAR VA improved significantly in both groups at 12 months and the BBG group tended to be better than the non-dye group but with no significant difference between the groups (unpaired t-test, P = 0.490). The average GCC thickness significantly decreased in both groups; however, there was no difference in the rates of change in GCC thickness between the groups. The ratio of GCC thickness to total retinal thickness (%) was significantly higher in the BBG group in the superior quadrant at 12 months postoperatively (P = 0.010).

CONCLUSION

BBG-assisted ERM surgery resulted in better visual improvement and fewer structural changes in the inner retinal layers. BBG-assisted ILM peeling is safe both functionally and anatomically.

En Face Image-Based Analysis of Epiretinal Membrane Formation after Surgery for Idiopathic Epiretinal Membrane

PURPOSE

To analyze en face epiretinal membrane (ERM) images constructed using swept-source (SS) OCT and to determine the incidence of ERM formation after ERM surgery and its effects on visual function.

DESIGN

Retrospective, consecutive observational study.

PARTICIPANTS

Consecutive series of 73 eyes (71 patients) with idiopathic ERM that underwent vitrectomy with both ERM and internal limiting membrane (ILM) peeling.

METHODS

We retrospectively reviewed the data of the 73 eyes included in the study. During surgery, the ERM was removed as extensively as possible, and the ILM was removed such that the area of ILM peeling was at least larger than the parafoveal area. All patients underwent comprehensive ophthalmologic examinations, including assessments of best-corrected visual acuity and metamorphopsia, before and at 2 weeks and 6 months after the surgery. En face images constructed using SS OCT were used to investigate ERM formation.

MAIN OUTCOME MEASURES

The incidence of ERM formation at 6 months after the surgery, effects of ERM formation on visual function, and the relationship between ERM formation and the extent of ERM and ILM peeling.

RESULTS

At 6 months after ERM and ILM peeling, 8 eyes (11.0%) showed ERM formation (formation group). Twenty eyes (27.4%) exhibited remnant ERM without ERM formation (remnant group), whereas 45 eyes (61.6%) showed no ERM (no ERM group). In both the remnant and no ERM groups, best-corrected visual acuity and metamorphopsia showed significant improvements after ERM surgery (both P < 0.01); these improvements were not seen in the formation group (P = 0.067 and P = 0.053, respectively). However, no significant differences were found in preoperative and postoperative best-corrected visual acuities and metamorphopsia among the 3 groups. In the formation group, ERM formation occurred only in the area with residual ILM. Most patients who underwent ILM peeling in which the area of the peeling covered the ERM belonged to the no ERM group (97.7%; P < 0.01).

CONCLUSIONS

Epiretinal membrane formation does not affect visual function significantly when the area of ILM peeling is larger than the parafoveal area. When the ILM peeling area covers the ERM area, postoperative ERM formation can be prevented.

Multi-scale mechanical investigation of articular cartilage suffered progressive pseudorheumatoid dysplasia

BACKGROUND

Progressive pseudorheumatoid dysplasia is a rare skeletal dysplasia mainly caused by abnormal autosomal recessive inheritance. Although the main function of cartilage is mechanical support and the characteristics of this disease is the degradation of AC, previous studies on it had been mainly focused on clinical and genetic aspects and the mechanical behavior of the cartilage affected by PPRD is still ambiguous. In this study, we investigate the mechanics and structure of the cartilage suffered disease at multi-scale, from individual chondrocytes to the bulk-scale tissue.

METHODS

Depth-sensing indenter were employed to investigate the mechanics of cartilage; we performed atomic force microscope nanoindentation to investigate the cell mechanics and scanning electron microscopy were used to explore the structure feature and chemical composition.

FINDINGS

The elastic modulus of chondrocytes harvested from cartilage suffered from progressive pseudorheumatoid dysplasia is significantly higher than from normal cartilage, same trend were also found in tissue level. Moreover, denser collagen meshwork and matrix calcification were also observed.

INTERPRETATION

The elastic modulus of cartilage should closely related to its denser structure and the calcification, and may potentially be an indicator for clinical diagnosis. The stiffening of chondrocytes during PPRD progression should play a rather important role in its pathogenesis.

IMPACT OF INNER LIMITING MEMBRANE PEELING ON VISUAL RECOVERY AFTER VITRECTOMY FOR PRIMARY RHEGMATOGENOUS RETINAL DETACHMENT INVOLVING THE FOVEA

PURPOSE

To assess the impact of inner limiting membrane peeling during vitrectomy for macula-involving retinal detachment on best-corrected visual acuity (VA).

METHODS

Retrospective analysis of 89 eyes with primary macula-involving retinal detachment, which was undergoing vitrectomy, endolaser, retinotomy, endodrainage, and SF6 tamponade. Membrane-blue-assisted membrane peeling had been performed in 61 of the eyes (Group 1) but not in the other 28 (Group 2), which served as controls.

RESULTS

Age, lens status, and incidence of proliferative vitreoretinopathy 26.2% versus 39.3%; P = 0.23 in the 2 groups were comparable. The preoperative visual acuity (Early Treatment Diabetic Retinopathy Study letters) was 25.7 ± 27.9 in Group 1 and 28.8 ± 29.9 in Group 2 (P = 0.47). After surgery, these rose from 62.3 ± 30.5 (Group 1) and 34.2 ± 35.8 (Group 2) after 1 week (P = 0.090), through 83.1 ± 8.0 and 57.2 ± 32.4 at 1 month (P = 0.0005), to 92.1 ± 4.5 and 74.4 ± 23.1 Early Treatment Diabetic Retinopathy Study letters after 6 months (P = 0.0005). More than 6-month incidences of proliferative vitreoretinopathy (13.1% vs. 28.6%; P = 0.13) were similar, whereas the redetachment rate (9.8% vs. 32.1%; P = 0.014), the incidence of secondary epiretinal membranes (1.6% vs. 35.7%; P = 0.0005), and the revitrectomy rate were lower in group 1 (9.8% vs. 53.6%; P = 0.0005).

CONCLUSION

Inner limiting membrane peeling during vitrectomy for macula-involving retinal detachment may substantially contribute to the visual recovery, reducing the incidence of secondary epiretinal membrane formation.

Free autologous internal limiting membrane transplantation in the treatment of large macular hole

We evaluated the clinical efficacy of free internal limiting membrane (ILM) flap transplantation for the treatment of large macular hole over 500 µm in 42 consecutive patients. Quantified evaluation of the post-operative macular anatomy restoration was performed by spectral-domain optical coherence tomography in the 12mo follow-up. The results showed 41 eyes achieved successful closure (97.6%). Postoperative best corrected visual acuity, ellipsoid layer, and external limiting membrane disruption were significantly improved at all follow-up time points. The central foveal thickness was significantly higher at 1mo. We concluded that free ILM flap transplantation proves to be effective to achieve anatomical and functional improvement for the treatment of large macular hole.

Three-Dimensional Analysis of Peeled Internal Limiting Membrane Using Focused Ion Beam/Scanning Electron Microscopy

Purpose

To reevaluate the effect of internal limiting membrane peeling during vitrectomy on the Müller cell damage, we examined the ultrastructure of the internal limiting membrane by using focused ion beam/scanning electron microscopy (FIB/SEM).

Methods

A total of 12 internal limiting membranes obtained during surgery in both the macular hole and the idiopathic epiretinal membrane groups were processed for observation by FIB/SEM. Three-dimensional structures of the internal limiting membrane were analyzed.

Results

The number of cell fragments in the macular hole group was 5.07 ± 1.03 per unit area of internal limiting membrane (100 μm²). The total volume of cell fragments was 3.54 ± 1.24 μm³/100 μm². In contrast, the number of cell fragments in the epiretinal membrane group was 12.85 ± 3.45/100 μm², and the total volume of cell fragments was 10.45 ± 2.77 μm³/100 μm². Data for both values were significantly higher than those observed in the macular hole group (P = 0.0024 and P = 0.0022, respectively, Mann-Whitney U test). No statistical difference was found for the mean volume of the cell fragment between the two groups.

Conclusions

All of the internal limiting membrane examined in this study showed cell fragments on the retinal surface of the internal limiting membrane. As compared with macular hole, epiretinal membrane exhibited a higher number and total volume of cell fragments, indicating that internal limiting membrane peeling for epiretinal membrane might have a higher risk of causing inner retinal damage.

Translational Relevance

FIB/SEM was a useful tool for three-dimensional quantitative analysis of the internal limiting membrane.

Use of Internal Limiting Membrane Autograft in Primary Vitrectomy for Rhegmatogenous Retinal Detachment

During a pars plana vitrectomy, an unplanned retinotomy in the raphe was performed in a 55-year-old female patient with rhegmatogenous retinal detachment and proliferative vitreoretinopathy. Since diathermy and laser therapy were not available at that moment, it was decided to peel off a small graft of the internal limiting membrane adjacent to the retinotomy site which had been previously stained with Brilliant Blue G. The graft was displaced under perfluorocarbon fluids and placed inside the retinotomy. Three weeks after surgery, the apparent closure of the retinotomy was observed clinically.