Current Trends about Inner Limiting Membrane Peeling in Surgery for Epiretinal Membranes

Importance of optical coherence tomography before cataract surgery

PURPOSE

To determine the importance of optical coherence tomography (OCT) in patients scheduled for cataract surgery who present with no pathologies in biomicroscopic fundus examination.

DESIGN

Retrospective study.

METHODS

In this study, the routine ophthalmologic examination of patients who were recommended cataract surgery was performed.Occult retinal pathologies were evaluated using OCT in patients without any pathologies in biomicroscopic fundus examination.According to whether retinal pathologies were detected on OCT, the patients were divided into two groups: normal and abnormal OCT.The findings of patients with retinal pathologies on OCT and their distribution according to age were also evaluated.

RESULTS

A total of 271 eyes from 271 patients were evaluated.The number of patients with retinal pathologies on OCT despite normal fundoscopic examination findings was 38(14.0%).Of these patients,15(39.4%) had an epiretinal membrane,10(26.3%) had age-related macular degeneration, eight(21%) had vitreomacular traction, two(5.2%) had a lamellar hole, and 1(2.6%) patient each had a full-thickness macular hole, an intraretinal cyst, and photoreceptor layer damage.The age distribution of the patients with retinal pathologies was as follows: two patients,<60 years; six patients,60-70 years;14 patients,70-80 years; and 16 patients,>80 years.The rate of patients aged > 70 years and above was 78.9%.There was no statistically significant difference between the normal and abnormal OCT groups in terms of age, gender, the presence of systemic diseases, visual acuity, central macular thickness, and cataract type or density(p > 0.05 for all).

CONCLUSION

In one of seven patients evaluated, retinal pathologies were detected on OCT despite normal fundoscopic examination findings.OCT can be used to detect occult retinal pathologies that cannot be detected by biomicroscopic fundus examination before cataract surgery.

TLR2 and TLR4 Are Expressed in Epiretinal Membranes: Possible Links with Vitreous Levels of Complement Fragments and DAMP-Related Proteins

Previous studies reported the expression of toll-like receptors (TLRs), merely TLR2 and TLR4, and complement fragments (C3a, C5b9) in vitreoretinal disorders. Other than pathogens, TLRs can recognize endogenous products of tissue remodeling as damage-associated molecular pattern (DAMPs). The aim of this study was to confirm the expression of TLR2 and TLR4 in the fibrocellular membranes and vitreal fluids (soluble TLRs) of patients suffering of epiretinal membranes (ERMs) and assess their association with disease severity, complement fragments and inflammatory profiles. Twenty (n = 20) ERMs and twelve (n = 12) vitreous samples were collected at the time of the vitrectomy. Different severity-staged ERMs were processed for: immunolocalization (IF), transcriptomic (RT-PCR) and proteomics (ELISA, IP/WB, Protein Chip Array) analysis. The investigation of targets included TLR2, TLR4, C3a, C5b9, a few selected inflammatory biomarkers (Eotaxin-2, Rantes, Vascular Endothelial Growth Factor (VEGFA), Vascular Endothelial Growth Factor receptor (VEGFR2), Interferon-γ (IFNγ), Interleukin (IL1β, IL12p40/p70)) and a restricted panel of matrix enzymes (Matrix metalloproteinases (MMPs)/Tissue Inhibitor of Metallo-Proteinases (TIMPs)). A reduced cellularity was observed as function of ERM severity. TLR2, TLR4 and myD88 transcripts/proteins were detected in membranes and decreased upon disease severity. The levels of soluble TLR2 and TLR4, as well as C3a, C5b9, Eotaxin-2, Rantes, VEGFA, VEGFR2, IFNγ, IL1β, IL12p40/p70, MMP7 and TIMP2 levels were changed in vitreal samples. Significant correlations were observed between TLRs and complement fragments and between TLRs and some inflammatory mediators. Our findings pointed at TLR2 and TLR4 over-expression at early stages of ERM formation, suggesting the participation of the local immune response in the severity of disease. These activations at the early-stage of ERM formation suggest a potential persistence of innate immune response in the early phases of fibrocellular membrane formation.

Selective ILM Staining and Safety of Two Vital Dyes During a Human-Like Pars Plana Vitrectomy Ex Vivo in Porcine Eyes

PURPOSE

An ideal dye for intraocular use should effectively stain the target tissue while being easy to apply and remove. Additionally, it should not have any adverse effects resulting from prolonged contact with the retinal tissue. Recently, concerns have been raised about the safety of some vital dyes during surgical procedures as they may cross the internal limiting membrane and deposit on the retina. In this study, we aimed to investigate whether commercially available vital dyes, VIEW-ILM® and TWIN® (AL.CHI.MI.A. S.r.l., Ponte San Nicolò, Padova, Italy), have the potential to cross the internal limiting membrane during vitreoretinal surgery and deposit on the retina. Furthermore, we evaluated their safety in vitro and in vivo.

METHODS

A human-like pars plana vitrectomy was performed on porcine eyes ex vivo, with VIEW-ILM® or TWIN® used to stain the internal limiting membrane either with or without subsequent internal limiting membrane peeling. The two dyes were then extracted from retinal punches with or without internal limiting membrane, and quantified using high performance liquid chromatography. Safety was evaluated through in vitro cytotoxicity tests and in vivo skin sensitization and irritation tests according to ISO standards.

RESULTS

High performance liquid chromatography analyses demonstrated that VIEW-ILM® and TWIN® effectively stained the internal limiting membrane without crossing the membrane. No residual dyes were found in the retinal layers after internal limiting membrane removal. Furthermore, both in vitro and in vivo safety tests confirmed the absence of cytotoxicity, skin sensitization, and irritation.

CONCLUSION

The results of this study support the safety and efficacy of VIEW-ILM® and TWIN® for internal limiting membrane staining. The experimental protocol described in this study could be utilized to gain a comprehensive understanding of the characteristics of vital dyes.

Analysing early changes of photoreceptor layer thickness following surgery in eyes with epiretinal membranes

BACKGROUND/OBJECTIVES

To analyse short-term changes of mean photoreceptor thickness (PRT) on the ETDRS-grid after vitrectomy and membrane peeling in patients with epiretinal membrane (ERM).

SUBJECTS/METHODS

Forty-eight patients with idiopathic ERM were included in this prospective study. Study examinations comprised best-corrected visual acuity (BCVA) and optical coherence tomography (OCT) before surgery, 1 week (W1), 1 month (M1) and 3 months (M3) after surgery. Mean PRT was assessed using an automated algorithm and correlated with BCVA and central retinal thickness (CRT).

RESULTS

Regarding PRT changes of the study eye in comparison to baseline values, a significant decrease at W1 in the 1 mm, 3 mm and 6 mm area (all p-values < 0.001), at M1 (p = 0.009) and M3 (p = 0.019) in the central 1 mm area, a significant increase at M3 in the 6 mm area (p < 0.001), but no significant change at M1 in the 3 mm and 6 mm area and M3 in the 3 mm area (all p-values > 0.05) were observed. BCVA increased significantly from baseline to M3 (0.3LogMAR-0.15LogMAR, Snellen equivalent = 20/40-20/28 respectively; p < 0.001). There was no correlation between baseline PRT and BCVA at any visit after surgery, nor between PRT and BCVA at any visit (all p-values > 0.05). Decrease in PRT in the 1 mm (p < 0.001), 3 mm (p = 0.013) and 6 mm (p = 0.034) area after one week correlated with the increase in CRT (449.9 µm-462.2 µm).

CONCLUSIONS

Although the photoreceptor layer is morphologically affected by ERMs and after their surgical removal, it is not correlated to BCVA. Thus, patients with photoreceptor layer alterations due to ERM may still benefit from surgery and achieve good functional rehabilitation thereafter.

Enhancing Intermediate Vision in Patients Affected by Epiretinal Membrane Treated by Phaco-Vitrectomy

BACKGROUND

The aim of this research was to see if a refractive enhanced monofocal IOL (Eyhance IOL, IOL Abbott Medical Optics, Inc., Santa Ana, CA, USA) can provide better intermediate vision in patients undergoing phaco-vitrectomy due to cataract and epiretinal macular membrane (ERM).

METHODS

A nonrandomized prospective observational comparative study enrolled patients affected by cataract and ERM undergoing phaco-vitrectomy. A follow up of 6 months was established. Corrected and uncorrected visual acuity of both monocular and binocular types were assessed regarding intermediate and far distances. The CATQUEST 9-SF questionnaire was administered preoperatively and at the last follow-up.

RESULTS

Twenty-three eyes of twenty-three patients were enrolled, with 11 in the enhanced monofocal group. The uncorrected and corrected distance visual acuity after 6 months was not statistically different. Both monocular and binocular uncorrected intermediate visual acuity after 6 months were higher in the enhanced monofocal group (p < 0.001). The corrected intermediate visual acuity after 6 months was higher in the enhanced monofocal group (p = 0.01). The CATQUEST-9SF questionnaire showed significant differences in the variation between the preoperative condition and six-month postoperative results (p < 0.001).

CONCLUSIONS

This refractive enhanced monofocal IOL can provide better intermediate vision compared to a standard monofocal IOL in patients undergoing phaco-vitrectomy due to cataracts and ERM. Further studies are necessary to confirm these results.

Comparison of the morphological characteristics of the choroidal sublayer between idiopathic macular holes and epiretinal membranes with automatic analysis

PURPOSE

To compare the choroidal sublayer morphologic features between idiopathic macular hole (IMH) and idiopathic epiretinal membrane (iERM) on spectral-domain optical coherent tomography (SD-OCT) using an automatic segmentation model.

METHODS

Thirty-three patients with idiopathic IMHs and 44 with iERMs who underwent vitrectomies were involved. The enhanced depth imaging mode of SD-OCT was used to obtain the B-scan image after single line scanning of the macular fovea. The choroidal sublayer automatic analysis model divides the choroidal into the choroidal large vessel layer, the middle vessel layer and the small vessel layer (LVCL, MVCL and SVCL, respectively) and calculates the choroidal thickness (overall, LVCL, MVCL and SVCL) and vascular index (overall, LVCL, MVCL and SVCL). The morphological characteristics of the choroidal sublayer in the ERM eyes and the IMH eyes were compared.

RESULTS

The mean choroidal thickness in the macular centre of the IMH eyes was significantly thinner than that of the ERM eyes (206.35 ± 81.72 vs. 273.33 ± 82.31 μm; P < 0.001). The analysis of the choroidal sublayer showed that the MVCL and SVCL macular centres and 0.5-1.5 mm of the nasal and temporal macula were significantly thinner in the IMH eyes than in the ERM eyes (P < 0.05), and there was a difference in the macular centre of the LVCL between the two groups (P < 0.05). In contrast, the choroidal vascular index of the macular centre in the IMH eyes was significantly higher than that in iERM eyes (0.2480 ± 0.0536 vs. 0.2120 ± 0.0616; P < 0.05). There was no significant difference in the CVI of other parts of the macula, the LVCL or MVCL between the two groups.

CONCLUSION

The choroidal thickness of the IMH eyes was significantly thinner than that of the iERM eyes, which was mainly observed in 3 mm of the macular centre and the MVCL and SVCL layers of the choroid. The choroidal vascular index of the IMH eyes was higher than that of the iERM eyes. These findings suggest that the choroid may be involved in the pathogenesis of IMH and iERM.

Quantitative evaluation of dissociated optic nerve fibre layer (DONFL) following idiopathic macular hole surgery

OBJECTIVES

To quantitatively evaluate concentric macular dark spots (CMDS) on spectral-domain optical coherence tomography (SD-OCT) to determine the morphological characteristics of dissociated optic nerve fibre layer (DONFL) following the performance of internal limiting membrane (ILM) peeling in patients with full-thickness idiopathic macular hole (IMH) closure.

METHODS

Retrospective study on patients who underwent a vitrectomy with ILM peeling procedure. BCVA, cross-sectional OCT scans, and three-dimensional reconstructions of en face OCT scans were analysed preoperatively, at 2, 6, 12 months post-operatively. A novel image analysis technique was used to automatically measure DONFL logical properties through the radius, area, the nerve fibre layer dissociation index (NFLDI), and depth of the CMDS.

RESULTS

53 eyes of 51 patients were included, and the mean follow-up was 11.53 ± 6.26 months. CMDS was found in 46 (86.79%) eyes within 2 months after ILM peeling and 50 (94.34%) eyes within 6 months after ILM peeling. CMDS concentrated on the temporal side of the macula in all 50 eyes (100%) at first detection. The area, NFLDI, and depth of CMDS in four quadrants developed significantly during the postoperative 6 months (p < 0.05), and then these changes slowed down and remained unchanged 12 months post-operatively. The morphological changes in the temporal quadrant were significantly greater than those in other quadrants at 2, 6, 12 months (all p < 0.05) post-operatively.

CONCLUSIONS

CMDS mostly appeared and concentrated on the temporal side of the macula in IMHs within two months after ILM peeling and progressed within 6 months and remained unchanged after 12 months.

Evaluation of the optical coherence tomography findings of patients with idiopathic epiretinal membrane

BACKGROUND

This study aimed to determine the relationship between basal visual acuity (VA) and basal optical coherence tomography (OCT) parameters of patients with idiopathic epiretinal membrane (iERM).

METHODS

The study included 200 eyes of 200 patients with iERM. In the evaluation of basal VAs, logMAR 0.3 (0.5 on Snellen chart) was accepted as the limit, and the patients were divided into two groups as Group 1 with VA values below logMAR 0.3 and Group 2 with those above logMAR 0.3. Using OCT, the ellipsoid zone (EZ), interdigitation zone (IZ), external limiting membrane (ELM) integrity, peaked appearance of EZ in the fovea, disorganization of the inner retinal layers (DRIL), central foveal thickness (CFT), maximum retinal thickness (MRT), total photoreceptor length (TPL), photoreceptor outer segment length (PROSL), photoreceptor deformity index (PDI), and inner retinal layer irregularity index (IRLII) were evaluated and compared between the groups.

RESULTS

There were an equal number of patients in Group 1 and Group 2. The preservation of ELM, EZ, and IZ integrity and the peaked appearance of EZ in the fovea were observed at higher rates in Group 1, whereas the rate of DRIL was higher in Group 2 (p < 0.05 for all). In the multiple regression analysis performed to evaluate categorical OCT parameters, only the presence of DRIL was found to be significantly associated with VA (p < 0.003). CFT*, MRT*, and IRLII** were significantly lower in Group 1 (*p < 0.001, **p = 0.001). TPU, PROSL, and FDI were similar between the two groups (p > 0.05 for all).

CONCLUSION

According to the multiple regression analysis, only the presence of DRIL was correlated with lower VA values. Among the OCT parameters, an increase in CFT and MRT, as well as the IRLII value moving away from 1 were related to lower VA values.

Short-Term In Vitro ROS Detection and Oxidative Stress Regulators in Epiretinal Membranes and Vitreous from Idiopathic Vitreoretinal Diseases

Background

A plethora of inflammatory, angiogenic, and tissue remodeling factors has been reported in idiopathic epiretinal membranes (ERMs). Herein we focused on the expression of a few mediators (oxidative, inflammatory, and angiogenic/vascular factors) by means of short-term vitreal cell cultures and biomolecular analysis.

Methods

Thirty-nine (39) ERMs and vitreal samples were collected at the time of vitreoretinal surgery and biomolecular analyses were performed in clear vitreous, vitreal cell pellets, and ERMs. ROS products and iNOS were investigated in adherent vitreal cells and/or ERMs, and iNOS, VEGF, Ang-2, IFNγ, IL18, and IL22 were quantified in vitreous (ELISA/Ella, IF/WB); transcripts specific for iNOS, p65NFkB, KEAP1, NRF2, and NOX1/NOX4 were detected in ERMs (PCR). Biomolecular changes were analyzed and correlated with disease severity.

Results

The higher ROS production was observed in vitreal cells at stage 4, and iNOS was found in ERMs and increased in the vitreous as early as at stage 3. Both iNOS and NOX4 were upregulated at all stages, while p65NFkB was increased at stage 3. iNOS and NOX1 were positively and inversely related with p65NFkB. While NOX4 transcripts were always upregulated, NRF2 was upregulated at stage 3 and inverted at stage 4. No significant changes occurred in the release of angiogenic (VEGF, Ang-2) and proinflammatory (IL18, IL22 and IFNγ) mediators between all stages investigated.

Conclusions

ROS production was strictly associated with iNOS and NOX4 overexpression and increased depending on ERM stadiation. The higher iNOS expression occurred as early as stage 3, with respect to p65NFkB and NRF2. These last mediators might have potential prognostic values in ERMs as representative of an underneath retinal damage.

Pars plana vitrectomy for tractional diabetic macular edema with or without internal limiting membrane peeling

Background

The effectiveness of internal limiting membrane (ILM) peeling in the surgical treatment of tractional diabetic macular edema (DME), although widely examined, remains controversial. This study aimed to assess the efficacy of pars plana vitrectomy (PPV) in the management of tractional DME and to highlight any benefits of additional ILM peeling.

Methods

This was an open-label, prospective, comparative, and interventional study that enrolled 50 eyes with tractional DME that underwent PPV and allocated each to one of two groups: group A consisted of 25 eyes that had no ILM peeling and group B consisted of 25 eyes that underwent ILM peeling. Postoperative assessments of best-corrected distance visual acuity (BCDVA) in the logarithm of minimal angle of resolution (logMAR) notation and central macular thickness (CMT) were performed at 1, 3, and 6 months postoperatively.

Results

At baseline, the two groups were comparable in terms of sex ratios, phakic status, insulin use, coexistence of hypertension, and mean (standard deviation [SD]) age, BCDVA, CMT, duration of diabetes mellitus, and glycosylated hemoglobin (HbA1c) levels. In group A, the mean (SD) BCDVA improved significantly from 0.89 (0.12) logMAR preoperatively to 0.64 (0.24) logMAR (P < 0.001), and the mean (SD) CMT declined significantly from 471.28 (80.83) µm to 228.20 (26.45) µm (P < 0.001), at the 6-month postoperative assessment. Likewise, in group B, the mean (SD) BCDVA improved significantly from 0.83 (0.10) logMAR preoperatively to 0.58 (0.24) logMAR (P < 0.001), and the mean (SD) CMT decreased significantly from 496.84 (89.82) µm to 226.20 (18.04) µm (P < 0.001), after 6 months. There were no significant differences between groups A and B in the changes in BCDVA (Delta BCDVA) or CMT (Delta CMT) at 1, 3, and 6 months postoperatively with respect to the baseline values (all P > 0.05). Postoperative complications were comparable between the two groups. A significant negative correlation was detected between the preoperative HbA1c level and BCDVA improvement in all participants (r = - 0.82; P < 0.001).

Conclusions

PPV is an effective treatment for tractional DME. Additional ILM peeling was not significantly associated with functional and anatomical benefits over a short period. Long-term glycemic control plays a role in vision gain after vitrectomy in patients with diabetes. Further long-term studies are required to verify our findings.

Macular Morphology in Patients With Diabetic Retinopathy Treated by ILM Peeling: A Propensity Score-Matched Analysis

BACKGROUND AND OBJECTIVE

To analyze the effects of vitrectomy combined with internal limiting membrane (ILM) peeling in patients with diabetic retinopathy (DR) by propensity score-matched analysis.

PATIENTS AND METHODS

Patients with proliferative DR that underwent pars plana vitrectomy were divided into two groups: without or with additional ILM peeling. Propensity score-matched analyses of variables were carried out. Optical coherence tomography (OCT) was conducted at the 6-month follow-up. The primary outcome measures were epiretinal membrane (ERM), intraretinal cystic changes, recurrent macular edema, and blurring of the inner segment/outer segment (IS/OS) margin.

RESULTS

There were 41 patients in Group 1 (non-ILM peeling) and 41 patients in Group 2 (ILM peeling). ERM was observed in 11 of 41 eyes (26.8%) in Group 1, and three of 41 eyes (7%) in Group 2 at the 6-month follow-up (P = .019). Intraretinal cystoid changes were observed in 13 eyes of Group 1 and four eyes of Group 2 (P = .014). The median central macular thickness was 250.00 ± 135.09 μm in Group 1 and 235.00 ± 101.55 μm in Group 2 (P = .738). Macular edema was observed in 24 eyes (58.5%) in Group 1 and 19 eyes (46.3%) in Group 2 (P = 0.269). There was no significant difference in foveal dip angle between the groups (P = .820). The IS/OS margin was disrupted in 48.8% and 56.1% of eyes in Groups 1 and 2, respectively, without significant difference. There was also no significant difference in best-corrected visual acuity (BCVA) between two groups before surgery, and there was no significant difference in BCVA between two groups at 6 months after surgery (P = .13).

CONCLUSION

The authors' results indicate that vitrectomy combined with ILM peeling can minimize ERM formation and eliminate intraretinal cystoid changes, but the functional recovery is limited. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:420-425.].

Vitreoretinal Society of India practice pattern survey 2020: Surgical retina

Purpose:

To present the outcomes of the Vitreo-retinal Society of India (VRSI) Practice Pattern Survey 2020 in surgical retina.

Methods:

An online survey of members of VRSI was conducted in April 2020 regarding their practice patterns on varied medical and surgical retina topics concerning imaging and management approach. The results were evaluated by two independent experts in this field and compared with the evidence and other practice patterns in the world.

Results:

A total of 107 VRSI members participated in the online survey. Responses were obtained on management of wide-ranging surgical retina topics such as diabetic retinopathy, retinal detachments, Macular Hole, and Epiretinal membranes. Participants were also surveyed regarding their attitudes and perceptions about microscopes with the heads-up display system. Each of the survey question responses were then compared to contemporary literature, including evidence-based guidelines, randomized controlled trials, real-world evidence, and analogous international surveys. Comprehensive analysis related to this has been put forward in the article.

Conclusion:

This survey represents the contemporary practice patterns among vitreoretinal specialists in India. The survey results are vital for fellow practitioners to understand the “standard of care” practice in surgical retina. This will guide them to devise the best possible individualized treatment strategy for most favorable clinical outcomes.

Identification of Postoperative Foveal Displacement after Macular Surgery for Idiopathic Epiretinal Membrane

Introduction: To analyze foveal displacement after macular surgery for idiopathic epiretinal membrane (iERM). Methods: Twenty-eight patients who underwent macular surgery for symptomatic iERM in one eye by one physician were included in this retrospective study. Spectral domain optical coherence tomography (SD-OCT) volume scans were acquired with a Spectralis OCT device (Heidelberg Spectralis). Using the follow-up view mode, the displacement of the fovea was classified and measured according to its postoperative location in the horizontal and/or vertical plane. Results: One day after surgery, 86% of eyes (24/28) showed foveal displacement. Vertical displacement occurred in a superior direction in 50% eyes, and in an inferior direction in 36% of the eyes. The postoperative mean foveal displacement on the vertical plane was 99 ± 82 μm (range, 0-300). Horizontal displacement occurred in a nasal direction in 21%, and temporally in 21%. The postoperative mean foveal displacement on the horizontal plane was 35 ± 45 μm (range, 0-123). One year after the macular surgery 69% of the eyes showed still a foveal dislocation. Discussion: Most of the eyes with iERM showed a foveal dislocation after the macular surgery. Our findings emphasize the necessity to carefully study of the OCT images in such eyes after the surgery as the manually determined postoperative foveal position may be in a different vertical or horizontal plane than the machine-generated pre- and postoperative overlay for the foveal position. Our findings may thus be helpful for surgeons to avoid misinterpretation when evaluating OCT images pre- and postoperatively.

A Review of Last Decade Developments on Epiretinal Membrane Pathogenesis

Epiretinal membrane (ERM) is a pathologic tissue that develops at the vitreoretinal interface. ERM is responsible for pathological changes of vision with varying degrees of clinical significance. It is either idiopathic or secondary to a wide variety of diseases such as proliferative diabetic retinopathy (PDR) and proliferative vitreoretinopathy (PVR). A great variation in the prevalence of idiopathic ERM among different ethnic groups proposed that genetic and lifestyle factors may play a role in ERM occurrence. Histopathological studies demonstrate that various cell types including retinal pigment epithelium (RPE) cells, fibrocytes, fibrous astrocytes, myofibroblast-like cells, glial cells, endothelial cells (ECs) and macrophages, as well as trophic and transcription factors, including transforming growth factor (TGF), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) etc., are directly or indirectly involved in the pathogenesis of idiopathic or secondary ERMs. These processes are driven (on the last count) by more than 50 genes, such as Tumor Necrosis Factor (TNF), CCL2 (chemokine (C-C motif) ligand )), Metastasis Associated Lung Adenocarcinoma Transcript 1 )MALAT1(, transforming growth factor (TGF)-β1, TGF-β2, Interleukin-6 (IL-6), IL-10, VEGF and glial fibrillary acidic protein (GFAP), some of which have been studied more intensely than others. The present paper tried to summarize, highlight and cross-correlate the major findings made in the last decade on the function of these genes and their association with different types of cells, genes and gene expression products in the ERM formation.

[Spontaneous separation of secondary epiretinal membrane]

The article presents a rare clinical case of secondary epiretinal membrane (ERM) in a 67-years-old woman. The patient was diagnosed with ERM in the left eye after loss of vision complaints. One year prior to the visit the patient had underwent 2 sessions of laser photocoagulation for proliferative post-thrombotic retinopathy in the left eye. In the context of relatively high visual functions (decimal visual acuity of 0.7 at the time of the visit), observation strategy was carried out. The follow-up period was 2 years. According to optical coherence tomography data, progressive deformation of retinal profile and an increase in diffuse retinal edema up to 391 μm in the fovea were observed in the course of the year, while visual acuity decreased to 0.6. Spontaneous separation of ERM, an increase in visual acuity to 0.9 and a decrease in retinal thickness to 236 μm were found during the subsequent visit. The authors discuss the presumable mechanisms of secondary ERM formation and separation and the impact of such cases in the management of patients with ERM and relatively high visual acuity.

Transplantation of Mature Photoreceptors in Rodents With Retinal Degeneration

Purpose

To demonstrate survival and integration of mature photoreceptors transplanted with the retinal pigment epithelium (RPE).

Methods

Full-thickness retina with attached RPE was harvested from healthy adult rats. Grafts were implanted into two rat models of retinal degeneration, Royal College of Surgeons (RCS) and S334ter-3. Survival of the host and transplanted retina was monitored using optical coherence tomography (OCT) for up to 6 months. The retinal structure and synaptogenesis between the host and transplant was assessed by histology and immunohistochemistry.

Results

OCT and histology demonstrated a well-preserved photoreceptor layer with inner and outer segments, while the inner retinal layers of the transplant largely disappeared. Grafts, including RPE, survived better than without and the transplanted RPE appeared as a monolayer integrated with the native one. Synaptogenesis was observed through sprouting of new dendrites from the host bipolar cells and synaptic connections forming with cells of the transplant. However, in many samples, a glial fibrillary acidic protein–positive membrane separated the host retina and the graft.

Conclusions

Presence of RPE in the graft improved the survival of transplanted photoreceptors. Functional integration between the transplant and the host retina is likely to be further enhanced if formation of a glial seal could be prevented. Transplantation of the mature photoreceptors with RPE may be a practical approach to restoration of sight in retinal degeneration.

Translational Relevance

This approach to restoration of sight in patients with photoreceptor degeneration can be rapidly advanced to clinical testing. In patients with central scotoma, autologous transplantation of the peripheral retina can be an option.

Efficacy and safety of vitrectomy with internal limiting membrane peeling for diabetic macular edema: a Meta-analysis

AIM

To evaluate the efficacy and safety of vitrectomy with internal limiting membrane (ILM) peeling for diabetic macular edema (DME).

METHODS

The PubMed, Embase, Web of Science, Cochrane, SionMed, ClinicalTrials.gov, CNKI databases and Wanfang databases, published until Oct. 2017, were searched to identify studies comparing the clinical outcomes following vitrectomy with and without ILM peeling, for treating DME. Pooled results were expressed as odds ratios (ORs) with corresponding 95% confidence intervals (CI) for vitrectomy with and without ILM peeling with regard to best corrected visual acuity (BCVA), central macular thickness (CMT), and complication incidents.

RESULTS

A total of 14 studies involving 857 eyes were included of which three studies were Chinese and the rests were English literatures. Meta-analysis indicated that compared with vitrectomy alone, vitrectomy with ILM peeling could improve BCVA more obviously (OR=1.66, 95%CI: 1.12-2.46, P=0.01) and had higher rate of CMT reduction (OR=3.89, 95%CI: 1.37-11.11, P=0.01). There were significant statistical differences between the two surgical methods for both BCVA and CMT (P<0.05). For the incidence of intraoperative and postoperative complications, the incidence of epiretinal membrane (ERM) was slightly lower in the ILM peeling group than the group without ILM peeling (OR=0.38, 95%CI: 0.07-2.00, P=0.25), although insignificant statistically. Other incidences of overall complications, iatrogenic peripheral retinal break and increased intraocular pressure indicated no significant difference between two groups (OR=1.19, 95%CI: 0.82-1.73, P=0.36; OR=1.21, 95%CI: 0.66-2.21, P=0.53; OR=1.34, 95%CI: 0.75-2.40, P=0.32).

CONCLUSION

Vitrectomy is effective for DME and the effect can be improved by additional ILM peeling, especially for anatomical efficacy, without increasing the incidence of intraoperative and postoperative complications. However, it is imperative to gain more evaluation in the future due to the paucity of prospective randomized study.

Photothermal optical coherence tomography of indocyanine green in ex vivo eyes

Indocyanine green (ICG) is routinely used during surgery to stain the inner limiting membrane (ILM) and provide contrast on white light surgical microscopy. While translation of optical coherence tomography (OCT) for intraoperative imaging during ophthalmic surgery has enhanced visualization, the ILM remains difficult to distinguish from underlying retinal structures and ICG does not provide additional OCT contrast. We present photothermal OCT (PT-OCT) for high-specificity detection of ICG on retinal OCT images. We demonstrate our technique by performing an ILM peel in ex vivo eyes using low ICG concentrations and laser powers. These results establish the feasibility of PT-OCT for intraoperative guidance during retinal surgery.

A surgical simulator for peeling the inner limiting membrane during wet conditions

The present study was performed to establish a novel ocular surgery simulator for training in peeling of the inner limited membrane (ILM). This simulator included a next-generation artificial ILM with mechanical properties similar to the natural ILM that could be peeled underwater in the same manner as in actual surgery. An artificial eye consisting of a fundus and eyeball parts was fabricated. The artificial eye was installed in the eye surgery simulator. The fundus part was mounted in the eyeball, which consisted of an artificial sclera, retina, and ILM. To measure the thickness of the fabricated ILM on the artificial retina, we calculated the distance of the step height as the thickness of the artificial ILM. Two experienced ophthalmologists then assessed the fabricated ILM by sensory evaluation. The minimum thickness of the artificial ILM was 1.9 ± 0.3 μm (n = 3). We were able to perform the peeling task with the ILM in water. Based on the sensory evaluation, an ILM with a minimum thickness and 1000 degrees of polymerization was suitable for training. We installed the eye model on an ocular surgery simulator, which allowed for the performance of a sequence of operations similar to ILM peeling. In conclusion, we developed a novel ocular surgery simulator for ILM peeling. The artificial ILM was peeled underwater in the same manner as in an actual operation.

Intraretinal changes in idiopathic versus diabetic epiretinal membranes after macular peeling

Introduction

Epiretinal traction is not responsible only for epiretinal but also intraretinal changes. This study aims to describe structural and vascular intraretinal changes after macular peeling in idiopathic (iERM) vs diabetic ERM (dERM).

Methods

We conducted a prospective interventional study on forty-two eyes, 23 with iERMs and 19 with dERMs, undergoing ERM-ILM peeling. We performed SD-OCT preoperatively, 1 and 6 months postoperatively to assess central macular thickness (CMT), intraretinal cysts (IC) and/or continuous ectopic inner foveal layers (CEIFL), superficial and deep capillary free zone (CFZ) area on OCT-A. Glial fibrillary acidic protein (GFAP), as a Müller cells marker, was detected immunohistochemically on ILM specimens, to assess Müller cells iatrogenic damage.

Results

The CEIFLs were significantly more common in iERMs (12 (52.2%) in iERMs vs 2 (10.5%) in dERMs, p = 0.004), whereas ICs in dERMs (6 (26.1%) in iERMs vs 17 (89.5%) in dERMs, p<0.001). Median preoperative and postoperative BCVA was 20/50 [20/40-20/66] and 20/33 [20/25-20/40] in iERMs and 20/100 [20/66-20/200] and 20/50 [20/50-20/66] in dERMs, respectively. Median preoperative and postoperative CMT was 423 [370–488] and 364 [329–382] μm in iERM group and 465 [447–503] and 378 [359–433] μm in dERM group, respectively. The BCVA improvement and reduction of CMT thickness were significant in both groups (p<0.001). The presence of CEIFL was associated with lower BCVA in iERMs. Deep CFZ network significantly increased only in dERMs, passing from 0.34 [0.29–0.42] mm² preoperatively to 0.56 [0.46–0.6] mm² at 6-month follow-up (p<0.001). The GFAP expression was significantly higher in dERMs (p = 0.001).

Conclusion

The intraretinal changes are different in iERMs and dERMs, as increased expression of CEIFLs in iERMs vs ICs in dERMs. The CEIFLs are associated with worse anatomical and functional outcomes in iERMs, whereas GFAP espression in peeled ILMs is higher in dERMs.

Evaluation of TGF-Beta 2 and VEGFα Gene Expression Levels in Epiretinal Membranes and Internal Limiting Membranes in the Course of Retinal Detachments, Proliferative Diabetic Retinopathy, Macular Holes, and Idiopathic Epiretinal Membranes

Purpose

To evaluate the expression profiles of the VEGFα and TGFβ in the ERMs and ILMs in retinal disorders.

Methods

In this nonrandomized prospective study, 75 patients (34 females and 41 males) referred to pars plana vitrectomy (PPV) due to different retinal diseases were enrolled to the study. The samples of ERMs and ILMs collected during PPV were immediately put in TRIzol® Reagent (Life Technologies, USA) and stored at −70°C until RNA extraction. Gene expression analysis was done with TaqMan® Gene Expression Assays (Applied Biosystems, USA) following the manufacturer's instructions.

Results

The gene expression levels of VEGFα as well as of TGFβ2 were significantly higher in ERMs than in ILMs in all studied groups. The level of TGFβ2 expression exhibits a significantly lower values in iERMs as compared with the RRD group (p = 0.043). There were differences in TGFβ2 expression in ILM in groups studied: DR versus RRD, p = 0.003; DR versus iERM, p = 0,047; and iERM versus RRD, p = 0.004.

Conclusions

Our results revealed that factors associated with angiogenesis and wound healing processes in eyes with RRD, PDR, iERM, and MH were more upregulated in ERMs than in ILMs. This may indicate that ILM is not responsible for reproliferation and its peeling should be avoided in routine PPV.

In vitro and ex vivo models to study drug delivery barriers in the posterior segment of the eye

Many ocular disorders leading to blindness could benefit from efficient delivery of therapeutics to the retina. However, despite extensive research into drug delivery vehicles and administration techniques, efficacy remains limited because of the many static and dynamic barriers present in the eye. Comprehension of the various barriers and especially how to overcome them can improve our ability to estimate the potential of existent drug delivery vectors and support the design of new ones. To this end, this review gives an overview of the most important ocular barriers for each administration route to the back of the eye. For each barrier, its biological composition and its role as an obstacle towards macromolecules, nanoparticles and viral vectors will be discussed; special attention will be paid to the influence of size, charge and lipophilicity of drug(s) (carrier) on their ability to overcome each barrier. Finally, the most significant available in vitro and ex vivo methods and models to test the potential of a therapeutic to cross each barrier are listed.

Potential role of Müller cells in the pathogenesis of macropsia associated with epiretinal membrane: a hypothesis revisited

Pathophysiological explanations for metamorphopsia associated with retinal pathologies generally focus on photoreceptor organization disruption. However, the retinal microarchitecture is complicated, and we hypothesize that other retinal cells may also be involved. Metamorphopsia has been widely studied in eyes with epiretinal membranes and we revisit the idea that Müller cell displacement causes retinal macropsia. A PubMed query and related article search for the macula ultrastructure under normal and pathological conditions revealed an enormous amount of information, particularly ultrahigh definition optical coherence tomography and other retinal imaging modality studies. Findings of these imaging studies support our hypothesis that Müller cells, and not cone photoreceptors, are primarily responsible for macropsia in eyes with epiretinal membranes. More specifically, we conclude that displacement of Müller cell endfeet, and not photoreceptor cones, is a more likely the explanation for retinal macropsia associated with epiretinal membranes.

Internal limiting membrane: The innermost retinal barrier

Recently, peeling of internal limiting membrane (ILM) has become one of the most common and effective surgical procedures for macular disorders. The authors discuss the adverse effects of such procedures and explore the possible functions of the membrane. We also suggest a barrier function of this membrane in addition to its possible other physiological roles. Thus, apart from the well-known inner and outer retinal barriers, ILM might be the third and innermost retinal barrier. The possible evidences supporting this hypothesis are presented.

A Case of Secondary Epiretinal Membrane Spontaneous Release

Purpose. To report a rare case of secondary epiretinal membrane (ERM) spontaneous separation with subsequent visual restoration. Case Summary. We are reporting a case with the history of branch retinal vein occlusion, peripheral retinal neovascularization, and retinal photocoagulation. Our examination revealed secondary ERM associated with relatively high visual acuity (0.6), and a watchful waiting strategy was chosen. During the follow-up, slight visual deterioration, progressive deformation of the retinal profile, and an increase in diffuse retinal edema were observed. No surgical or laser treatment was performed. On the next visit, the spontaneous ERM separation with residual parapapillary fixation, the increase in visual acuity (0.9), and the decrease in retinal thickness were revealed. Conclusion. Such cases present additional evidence to a deferral surgical strategy for the management of patients with ERM and relatively high visual acuity.

From the analysis of pharmacologic vitreolysis to the comprehension of ocriplasmin safety

INTRODUCTION

Pharmacologic vitreolysis is a strategy used to treat anomalous posterior vitreous detachment, by weakening vitreoretinal adhesion with an intravitreal drug. Pharmacologic vitreolysis facilitates surgery, and abnormalities of the vitreoretinal interface including vitreomacular traction (VMT) and early stage macular hole (MH) could be resolved. Ocriplasmin is a recombinant protease, active against fibronectin and laminin, which are important components of the vitreoretinal interface. Ocriplasmin has been approved for symptomatic treatment of VMT and MH with visible traction, and it functions by dissolving the proteins that link the vitreous to the macula, thereby creating a complete posterior vitreous detachment (PVD).

AREAS COVERED

This paper reviews the current knowledge and status of investigations regarding the use of ocriplasmin for pharmacologic vitreolysis and its safety.

EXPERT OPINION

Ocriplasmin is a non-specific enzyme; therefore, it dissolves vitreal proteins as well as possibly proteins associated with visual function in the retina, choroid, and lens. Ocular adverse events (OAEs) of ocriplasmin include transient visual loss, intraocular inflammation, vitreous floaters, lens opacification, zonular instability of the lens, and intraocular hemorrhage. The prevalence of the OAEs is very low; however, on rare occasions, they can result in widespread retinal dysfunction. Research into the acute and long-term safety of ocriplasmin is required.