Comparison of histopathological findings between idiopathic and secondary epiretinal membranes

Pathophysiology and clinical aspects of epiretinal membrane - review

The epiretinal membrane (ERM) is a pathological tissue formed at the vitreoretinal interface. The formation of this tissue is associated with numerous symptoms related to disturbances of vision. These types of lesions may arise idiopathically or be secondary to eye diseases, injuries and retinal surgeries. ERM tissue contains numerous cell types and numerous cytokines, which participate in its formation. The aim of this paper is to summarize information about the etiology, epidemiology, pathophysiology and treatment of ERM, with a brief description of the main cells that build the ERM - as well as the cytokines and molecules related to ERM pathogenesis - being provided in addition.

Effect of Internal Limiting Membrane Peeling or Not on Blood Flow Signal in Macular Area of Diabetic Patients with Preretinal Membrane

PURPOSE

To study the effect of intraoperative internal limiting membrane (ILM) peeling on the macular vascular structure in patients with diabetic epiretinal membrane (ERM).

METHODS

Patients with diabetic ERM were divided into an ERM + ILM peeling group (18 eyes) and an ERM peeling group (19 eyes), all of whom underwent standard vitrectomy and were followed up until 6 months postoperatively. Best-corrected visual acuity (BCVA), Central macular thickness (CMT), Vessel density (VD) and vessel length density (VLD) of the superficial as well as deep retinal capillary plexus were compared between the two groups.

RESULTS

There was no significant difference in BCVA (p = .188, .410, .901, .916) and CMT (p = .164, .128, .110, .105) between the two groups at the week 1, month 1, month 3 and month 6 after operation. In the superficial capillary plexus (SCP), the change in VD (p = .106) and VLD (p = .438) was not affected by ILM peeling, and there was no significant difference in VD (p = .154, .063, .100, .162) and VLD (p = .386, .263, .431, .391) between the two groups during the four follow-up after operation. For the deep capillary plexus (DCP), there was an effect of ILM peeling on the changes in VD (p = .024) and VLD (p = .012), ILM peeling delayed the recovery time of the VD and VLD; The VD (p = .026, .000, .003) and VLD (p = .005, .000, .000) of ERM + ILM peeling group were lower than those of ERM peeling group from the month 1 to the month 6 after operation.

CONCLUSION

Intraoperative peeling of the ILM in patients with diabetic ERM delayed the improvement of blood flow signal in the DCP but did not affect the recovery of postoperative BCVA and CMT.

Visual outcomes of primary versus secondary epiretinal membrane following vitrectomy and cataract surgery

PURPOSE

To compare visual outcomes, incidence of cystoid macular edema (CME), and rate of repeat epiretinal membrane (ERM) surgery following phacovitrectomy for primary and secondary ERM.

METHODS

Retrospective review of 178,856 cataract surgeries from 2003 to 2015. Eyes that underwent cataract surgery combined with ERM peel were included (n = 708). Eyes were divided into primary (n = 538) and secondary (n = 170) ERM groups. Patient demographics, visual acuity (VA), and postoperative CME were recorded.

RESULTS

Patients with secondary ERM had worse preoperative VA, 0.9 ± 0.6 logMAR (20/160 Snellen equivalent) as compared to patients with primary ERM, 0.6 ± 0.3 (20/80), respectively (p < 0.0001). There was no difference between the secondary and primary ERM groups in postoperative vision (0.5 ± 0.4 logMAR vs. 0.5 ± 0.3; p = 0.9962) or proportion with VA ≥ 20/40 (46.4% vs. 43.1%; p = 0.6744) at 12-24 weeks. Postoperative CME was twice as likely in the secondary ERM group (16.5%) compared to the primary ERM group (7.8%) (p = 0.0018). There was no difference in the rate of repeat ERM surgery between the secondary ERM group (1.8%) and the primary ERM group (1.5%) (p = 0.7308).

CONCLUSION

Eyes with secondary ERM had significant postoperative improvement in VA. They had worse preoperative VA and had a twofold increase in postoperative CME than primary ERM.

Transplantation Site Affects the Outcomes of Adipose-Derived Stem Cell-Based Therapy for Retinal Degeneration

Adipose-derived stem cells (ASCs) have shown a strong protective effect on retinal degenerative diseases (RDD) after being transplanted into the subretinal space in an animal model. Recently, several clinical trials have been conducted to treat RDD with intravitreal transplantation of stem cells, including ASCs. However, the outcomes of the clinical trials were not satisfactory. To investigate if the transplantation site alters the outcome of stem cell-based therapy for RDD, we isolated rat ASCs (rASCs) and labeled them with green fluorescent protein. Autologous rASCs were grafted into the vitreous chamber or subretinal space in a rat RDD model induced by sodium iodate (SI). The electric response was recorded by ERG. The anatomic structure of the retina was observed in cryosections of rat eyes at posttransplantation weeks 1, 2, and 4. Neural retina apoptosis and epiretinal membrane- (ERM-) like structure formation were investigated by immunostaining. The intravitreal transplantation of rASCs resulted in an extinguished electric response, although the rosette formation and apoptosis of neural retina were reduced. However, the rASCs that grafted in the subretinal space protected the retina from the damage caused by SI, including a partial recovering of the electric response and a reduction in rosette formation. Intravitreally grafted rASCs formed a membrane, resulting in retina folding at the injection site. Müller cells, retinal pigment epithelial cells, and microglial cells migrated from the retina to the rASC-formed membrane and subsequently formed an ERM-like structure. Furthermore, vitreous fluid promoted rASC migration, and rASC-conditioned medium enhanced Müller cell migration as indicated by in vitro studies. These data suggested that the vitreous chamber is not a good transplantation site for ASC-based therapy for RDD and that a deliberate decision should be made before transplantation of stem cells into the vitreous chamber to treat RDD in clinical trials.

Epiretinal membrane following pars plana vitrectomy for rhegmatogenous retinal detachment repair

AIM

To determine the rate and possible contributors for post-pars plana vitrectomy (PPV) epiretinal membrane (ERM) in patients treated for rhegmatogenous retinal detachment (RRD).

METHODS

This prospective, nonrandomized study comprised 47 consecutive patients (47 eyes) with acute RRD treated with 23 G post-PPV. All participants were followed prospectively for 6mo for the development of ERM using spectral domain optical coherence tomography. Preoperative and intraoperative data were collected by questionnaires to surgeons. Main outcome measure was the percentage of the ERM formation following post-PPV for RRD.

RESULTS

ERM developed postoperatively in 23 eyes (48.9%), none necessitated surgical removal. There was a statistically significant difference between patients with and without ERM postoperatively in preoperative best corrected visual acuity (median logMAR 1.9 vs 0.3, respectively; P=0.003) rate of macula-off (69.6% vs 37.5%, respectively, P=0.028), and rate of ≥5 cryo-applications (55.6% and 18.8%, respectively, P=0.039). ERM developed mainly between the 1^st and 3^rd months of follow-up. Macula-off status increased the risk of ERM, with the odds ratio of 3.81 (P=0.031).

CONCLUSION

ERM is a frequent post RRD finding, and its development is associated with macula-off RRD.