Intraretinal immunohistochemistry findings in proliferative vitreoretinopathy with retinal shortening

Effect of race and ethnicity on surgical outcomes for rhegmatogenous retinal detachments

OBJECTIVE

To evaluate the effect of socioeconomic and demographic factors on outcomes in rhegmatogenous retinal detachments (RRDs).

DESIGN

Retrospective cohort study.

METHODS

A total of 71 white and 124 black and/or Hispanic patients who had surgical repair of RRDs between October 2013 and September 2021 at a single-centre safety net hospital. Main outcomes were single surgery success rates (SSSR) and postoperative visual acuity at 6-month and final follow-up.

RESULTS

Black and (or) Hispanic patients were significantly younger (black and [or] Hispanic, 50.7 years vs white, 57.6 years; p = 0.003), had lower mean household incomes (black and [or] Hispanic, $80,932 vs white, $92,911; p = 0.007), were more likely to have more than 1 retinal break (black and [or] Hispanic, 65% vs white, 49%; p = 0.04), and had higher rates of proliferative vitreoretinopathy (PVR) at presentation (black and [or] Hispanic, 35% vs white, 18%; p = 0.02). SSSR was similar (black and [or] Hispanic, 73.4% vs white, 73.2%; p = 0.98), but black and (or) Hispanic patients had worse visual acuity postoperatively (black and [or] Hispanic, 20/63 vs white, 20/40 at final follow-up; p = 0.03). While race was linked to visual outcome in univariate testing; multivariate analysis revealed only macula status (p = 0.007 at 6 months; p = 0.01 at final follow-up), presence of PVR (p < 0.001 at both time points), and SSSR (p = 0.003 at final follow-up) as predictors of worse visual outcomes.

CONCLUSIONS

Preoperative factors such as higher rates of PVR may contribute to worse vision outcomes in black and (or) Hispanic patients undergoing surgical repair for RRD.

Proliferative vitreoretinopathy: an update on the current and emerging treatment options

Proliferative vitreoretinopathy (PVR) remains the main cause of failure in retinal detachment (RD) surgery and a demanding challenge for vitreoretinal surgeons. Despite the large improvements in surgical techniques and a better understanding of PVR pathogenesis in the last years, satisfactory anatomical and visual outcomes have not been provided yet. For this reason, several different adjunctive pharmacological agents have been investigated in combination with surgery. In this review, we analyze the current and emerging adjunctive treatment options for the management of PVR and we discuss their possible clinical application and beneficial role in this subgroup of patients.

Proliferative Vitreoretinopathy: A Reappraisal

Proliferative vitreoretinopathy (PVR) remains the main cause of failure after retinal detachment (RD) surgery. Despite the development of modern technologies and sophisticated techniques for the management of RD, the growth of fibrocellular membranes within the vitreous cavity and on both sides of the retinal surface, as well as intraretinal fibrosis, can compromise surgical outcomes. Since 1983, when the term PVR was coined by the Retina Society, a lot of knowledge has been obtained about the physiopathology and risk factors of PVR, but, despite the proposal of a lot of therapeutic challenges, surgical skills seem to be the only effective way to manage PVR complications.

Single-Cell Protein and Transcriptional Characterization of Epiretinal Membranes From Patients With Proliferative Vitreoretinopathy

Purpose

Proliferative vitreoretinopathy (PVR) remains an unresolved clinical challenge and can lead to frequent revision surgery and blindness vision loss. The aim of this study was to characterize the microenvironment of epiretinal PVR tissue, in order to shed more light on the complex pathophysiology and to unravel new treatment options.

Methods

A total of 44 tissue samples were analyzed in this study, including 19 epiretinal PVRs, 13 epiretinal membranes (ERMs) from patients with macular pucker, as well as 12 internal limiting membranes (ILMs). The cellular and molecular microenvironment was assessed by cell type deconvolution analysis (xCell), RNA sequencing data and single-cell imaging mass cytometry. Candidate drugs for PVR treatment were identified in silico via a transcriptome-based drug-repurposing approach.

Results

RNA sequencing of tissue samples demonstrated distinct transcriptional profiles of PVR, ERM, and ILM samples. Differential gene expression analysis revealed 3194 upregulated genes in PVR compared with ILM, including FN1 and SPARC, which contribute to biological processes, such as extracellular matrix (ECM) organization. The xCell and IMC analyses showed that PVR membranes were composed of macrophages, retinal pigment epithelium, and α-SMA-positive myofibroblasts, the latter predominantly characterized by the co-expression of immune cell signature markers. Finally, 13 drugs were identified as potential therapeutics for PVR, including aminocaproic acid and various topoisomerase-2A inhibitors.

Conclusions

Epiretinal PVR membranes exhibit a unique and complex transcriptional and cellular profile dominated by immune cells and myofibroblasts, as well as a variety of ECM components. Our findings provide new insights into the pathophysiology of PVR and suggest potential targeted therapeutic options.

Managing PVR in the Era of Small Gauge Surgery

Proliferative vitreoretinopathy (PVR) is the leading cause of failed rhegmatogenous retinal detachment (RRD) surgery. Based upon the presence of clinical features and due to associated underlying risk factors, it is classified into various grades based upon its severity and extent of involvement. Despite excellent skills, flawless techniques, and high-end technology applied in the management of RRD, PVR still occurs in 5–10% of cases. Due to the advancements in wide angle viewing systems, advance vitrectomy machines and fluidics, early identification, use of long-term heavy silicon oil tamponades, high-speed cutters, small-gauge vitrectomies, use of perfluorocarbon liquid (PFCL), and small-gauge forceps and scissors, the success rate in the management of PVR has increased leading to improved anatomical outcomes. However, functional outcomes do not correlate well with improved anatomical outcomes. Various complications occur after RRD repair that are responsible for re-retinal detachment and recurrence of PVR. This article highlights causes, risk factors, classification, grading, diagnosis, and approach to management of PVR and post-PVR surgery complications.

Increased Glial Fibrillary Acid Protein and Vimentin in Vitreous Fluid as a Biomarker for Proliferative Vitreoretinopathy

Purpose

Glial fibrillary acid protein (GFAP) and vimentin are type III intermediate filament proteins, ubiquitously expressed in retinal glial cells. Under retinal stress, both GFAP and vimentin are well-known sensitive markers for retinal gliosis. However, little is known about whether these proteins are released into the vitreous body in response to retinal gliosis or are related to the severity of retinal gliosis seen in proliferative vitreoretinopathy (PVR).

Methods

Vitreous fluids were collected from 44 patients who underwent pars plana vitrectomy for macular hole (Group 1; n = 8), epiretinal membrane (Group 2; n = 8), or retinal detachment (RD) with various degrees of PVR (Group 3; n = 28). The severity of PVR was determined by cumulative scores using PVR classification. GFAP, vimentin, and total protein levels from the vitreous samples were measured.

Results

Both GFAP and vimentin levels were significantly elevated in vitreous fluid from Group 3 (RD) compared with Groups 1 and 2 (P < 0.01). GFAP levels (ng/mL) were 12.4 ± 9.8, 17.5 ± 17.7, and 572.0 ± 11659.7, and vimentin levels (ng/mL) were 40.8 ± 61.9, 88.6 ± 86.8, and 3952.8 ± 8179.5 in Groups 1, 2, and 3, respectively. Total protein levels were not significantly different among the three groups. Elevated GFAP and vimentin levels in Group 3 were positively correlated with the areas of RD (P < 0.01, r = 0.53 in GFAP and P < 0.05, r = 0.46 in vimentin) and PVR scores (P < 0.05, r = 0.46 in GFAP and P < 0.00001, r = 0.76 in vimentin).

Conclusions

Our data suggest that human vitreous GFAP and vimentin are protein biomarkers for PVR, and reactive gliosis may play a part in PVR formation.

A brief review of the histopathology of proliferative vitreoretinopathy (PVR)

Proliferative vitreoretinopathy (PVR) is thought to represent an exaggerated and protracted scarring process following rhegmatogenous retinal detachment (RD) and following RD surgery. Following detachment, a combination of retinal ischaemia, inflammation and cell proliferation lead to the formation of tractional membranes on the epiretinal and subretinal surfaces and to marked gliosis within the retina that leads to retinal shortening. Both of these factors convert a rhegmatogenous RD into a tractional one are a major feature of RD surgery failure. The major cell types that are involved in PVR are retinal pigment epithelium (RPE), glial cells (principally Muller cells) and inflammatory cells (macrophages and lymphocytes). These cells interact with numerous growth factors and cytokines derived from the breakdown of the blood-retinal barrier and from vitreous contact that trigger a cascade of cellular processes, such as epithelial-mesenchymal transition (EMT), cell migration, chemotaxis, proliferation, elaboration of basement membrane and collagen and cellular contraction, that lead to overt retinal pathology. This review covers the histopathology of PVR and touches upon the cellular processes involved in the pathogenesis of PVR.

Proliferative Vitreoretinopathy: A Review

Proliferative vitreoretinopathy (PVR) is the most common cause for failure of rhegmatogenous retinal detachment repair and is characterized by the growth and contraction of cellular membranes within the vitreous cavity and on both sides of the retinal surface as well as intraretinal fibrosis. Currently, PVR is thought to be an abnormal wound healing response that is primarily driven by inflammatory, retinal, and RPE cells. At this time, surgery is the only management option for PVR as there is no proven pharmacologic agent for the treatment or prevention of PVR. Laboratory research to better understand PVR pathophysiology and clinical trials of various agents to prevent PVR formation are ongoing.

Retinal shortening: Ultrasonic evaluation of proliferative vitreoretinopathy

Purpose:

To evaluate the effect of extraretinal proliferative vitreoretinopathy (PVR) on retinal shortening in eyes with rhegmatogenous retinal detachment (RD) using ultrasound (USG) and objectively prove the presence of intraretinal PVR (iPVR).

Methods:

This is a double-masked pilot prospective controlled case series. Patients with total RD planned for vitreoretinal surgery were included in the study. USG was used to determine retinal-to-choroidal length ratios (RCRs) in all the quadrants. Group 1 included 10 patients with preoperative PVR more than Grade B while Group 2 had 14 with PVR of Grades A or B. Severe retinal shortening was defined as RCR < 0.8. Primary outcome measures were severe retinal shortening and an early unexplained recurrence of RD within 15 days of surgery.

Results:

Mean RCRs were significantly low in all the four quadrants of Group 1 upon comparison with Group 2. The mean RCR had a good negative correlation with number of quadrants of PVR (R = −0.66, P ≤ 0.001). Overall, severe quadrantic retinal shortening was detected in nine patients. In these 9 patients, 11 of the 36 retinal quadrants had severe retinal shortening in the absence of extraretinal PVR (ePVR). Six patients developed early unexplained RD, and all of these belonged to Group 1. Severe quadrantic retinal shortening had the highest odds ratio of developing early unexplained RD (odds ratio = 58, P = 0.01).

Conclusion:

Retinal shortening occurs both due to ePVR and iPVR, and iPVR occurs independently at least in some cases. Severe quadrantic retinal shortening indicates poor primary anatomical prognoses.

Functional characterization of rs2229094 (T>C) polymorphism in the tumor necrosis factor locus and lymphotoxin alpha expression in human retina: the Retina 4 project

Purpose

The objective of this study is to determine the expression and localization of lymphotoxin alpha (LTA) in human retinas and the functionality of one of its polymorphisms rs2229094 (C13R) (T>C), previously associated with proliferative vitreoretinopathy (PVR) development.

Materials and methods

Total RNA from three healthy human retinas were extracted and subjected to reverse transcription-polymerase chain reaction (RT-PCR) analysis, using flanking primers of LTA cDNA. In addition, three human eyes with retinal detachment (RD) and three healthy control eyes were subjected to immunohistochemistry (IHC) with a specific antibody against LTA. The functionality of T and C alleles was assessed by using pCEFL-Flag expression vector and transient transfection assays in COS-1 cell line. In addition, expression analysis by RT-PCR, Western blot and subcellular localization of both alleles and by immunofluorescence assay was performed.

Results

RT-PCR analysis revealed no significant levels of messenger RNA (mRNA) LTA in healthy human retinas. Sequential IHC staining showed differences between healthy human and RD retinas. No differences in mRNA and protein expression levels and in subcellular localization between both alleles were found. Both alleles were located in the cytoplasm of COS-1 cells.

Conclusion

Although results suggest lack of functionality, the differences found in IHC study and its strong association with PVR and its relationship with tumor necrosis factor locus, warrant further studies and could justify the use of this polymorphism as a valid biomarker to identify high-risk patients to develop PVR after RD.

Objective Quantification of Retinal Shortening: Sonographic Evidence of Intraretinal Proliferative Vitreoretinopathy

BACKGROUND AND OBJECTIVE

To evaluate retinal shortening with ultrasound (USG) in patients with retinal detachment (RD).

PATIENTS AND METHODS

This was a pilot, prospective, investigative study. Ten consecutive patients undergoing surgery for total RD with anterior or posterior proliferative vitreoretinopathy (PVR) graded more than grade C1 were included. Longitudinal USG B-scan was done for all patients to calculate retinal-to-choroidal length ratio (RCR). Quadrant-based RCRs and mean RCRs were calculated. All patients were followed for a minimum period of 3 months for unexplained recurrent retinal detachment.

RESULTS

Mean duration of RD was 14.2 months and a mean of 2.8 retinal quadrants had epiretinal PVR, subretinal PVR, or both. Mean RCR was 0.81 and was the least in superior temporal quadrant. Seven patients developed recurrent RD, five at the first weekly visit. All of these patients had an RCR of less than 0.8 in at least one quadrant, whereas none of the remaining three patients had a quadrantic RCR of less than 0.8 (P = .008). Mean RCR was less than 0.8 in four of seven patients with recurrent RD (P = .2) CONCLUSION: Retinal shortening can be measured objectively with USG based RCRs. Low RCR in any retinal quadrant is a serious concern deserving appropriate patient counseling. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:746-750.].

Classifications for Proliferative Vitreoretinopathy (PVR): An Analysis of Their Use in Publications over the Last 15 Years

Purpose. To evaluate the current and suitable use of current proliferative vitreoretinopathy (PVR) classifications in clinical publications related to treatment. Methods. A PubMed search was undertaken using the term "proliferative vitreoretinopathy therapy". Outcome parameters were the reported PVR classification and PVR grades. The way the classifications were used in comparison to the original description was analyzed. Classification errors were also included. It was also noted whether classifications were used for comparison before and after pharmacological or surgical treatment. Results. 138 papers were included. 35 of them (25.4%) presented no classification reference or did not use any one. 103 publications (74.6%) used a standardized classification. The updated Retina Society Classification, the first Retina Society Classification, and the Silicone Study Classification were cited in 56.3%, 33.9%, and 3.8% papers, respectively. Furthermore, 3 authors (2.9%) used modified-customized classifications and 4 (3.8%) classification errors were identified. When the updated Retina Society Classification was used, only 10.4% of authors used a full C grade description. Finally, only 2 authors reported PVR grade before and after treatment. Conclusions. Our findings suggest that current classifications are of limited value in clinical practice due to the inconsistent and limited use and that it may be of benefit to produce a revised classification.

Small Interfering RNA Targeted to ASPP2 Promotes Progression of Experimental Proliferative Vitreoretinopathy

Background. Epithelial-mesenchymal transition (EMT) of retinal pigment epithelium (RPE) is vital in proliferative vitreoretinopathy (PVR) development. Apoptosis-stimulating proteins of p53 (ASPP2) have recently been reported to participate in EMT. However, the role of ASPP2 in PVR pathogenesis has not been identified. Methods. Immunohistochemistry was used to investigate the expression of ASPP2 in epiretinal membranes of PVR patients. ARPE-19 cells were transfected with ASPP2-siRNA, followed with measurement of cell cytotoxicity, proliferation, and migration ability. EMT markers and related inflammatory and fibrosis cytokines were measured by western blot or flow cytometry. Additionally, PVR rat models were induced by intravitreal injection of ARPE-19 cells transfected with ASPP2-siRNA and evaluated accordingly. Results. Immunofluorescence analysis revealed less intense expression of ASPP2 in PVR membranes. ASPP2 knockdown facilitated the proliferation and migration of RPE cells and enhanced the expression of mesenchymal markers such as alpha smooth muscle actin, fibronectin, and ZEB1. Meanwhile, ASPP2-siRNA increased EMT-related and inflammatory cytokines, including TGF-β, CTGF, VEGF, TNF-α, and interleukins. PVR severities were more pronounced in the rat models with ASPP2-siRNA treatment. Conclusions. ASPP2 knockdown promoted EMT of ARPE-19 cells in vitro and exacerbated the progression of experimental PVR in vivo, possibly via inflammatory and fibrosis cytokines.

BAX and BCL-2 polymorphisms, as predictors of proliferative vitreoretinopathy development in patients suffering retinal detachment: the Retina 4 project

PURPOSE

To compare the distribution of BCL-2 -938C>A (rs2279115) and BAX -248G>A (rs4645878) genotypes among European subjects undergoing rhegmatogenous retinal detachment (RRD) surgery in relation to the further development of proliferative vitreoretinopathy (PVR).

METHODS

A case-control gene association study, as a part of Retina 4 project, was designed. rs2279115 and rs4645878 polymorphisms were analysed in 555 samples from patients with RRD (134 with PVR secondary to surgery). Proportions of genotypes and AA homozygous groups of BCL-2 and BAX polymorphisms between subsamples were analysed in two phases. Genotypic and allelic frequencies were compared in global sample and in subsamples.

RESULTS

BAX: Differences were observed in the genotype frequencies and in AA carriers between controls and cases in the global series. The odds ratio (OR) of A carriers in the global sample was 1.7 (95% CI: 1.23-2.51). Proportions of genotypes in Spain + Portugal were significant different. The OR of A carriers from Spain and Portugal was 1.8 (95% CI: 1.11-2.95). BCL-2: No significant differences were observed in genotype frequencies. However, proportions of genotypes in Spain + Portugal were significant. A protective effect (OR: 0.6 95% CI: 0.43-0.96) was found in A carriers from Spain and Portugal.

CONCLUSIONS

Results suggest that A allele of rs4645878 could be a biomarker of high risk of developing PVR in patients undergoing RD surgery. The possible role of BCL-2 (inhibitor of necroptosis pathway) as a possible new target in PVR prophylaxis should be investigated.

Proliferative vitreoretinopathy: A new concept of disease pathogenesis and practical consequences

During the last four decades, proliferative vitreoretinopathy (PVR) has defied the efforts of many researchers to prevent its occurrence or development. Thus, PVR is still the major complication following retinal detachment (RD) surgery and a bottle-neck for advances in cell therapy that require intraocular surgery. In this review we tried to combine basic and clinical knowledge, as an example of translational research, providing new and practical information for clinicians. PVR was defined as the proliferation of cells after RD. This idea was used for classifying PVR and also for designing experimental models used for testing many drugs, none of which were successful in humans. We summarize current information regarding the pathogenic events that follow any RD because this information may be the key for understanding and treating the earliest stages of PVR. A major focus is made on the intraretinal changes derived mainly from retinal glial cell reactivity. These responses can lead to intraretinal PVR, an entity that has not been clearly recognized. Inflammation is one of the major components of PVR, and we describe new genetic biomarkers that have the potential to predict its development. New treatment approaches are analyzed, especially those directed towards neuroprotection, which can also be useful for preventing visual loss after any RD. We also summarize the results of different surgical techniques and clinical information that is oriented toward the identification of high risk patients. Finally, we provide some recommendations for future classification of PVR and for designing comparable protocols for testing new drugs or techniques.

Triple-layered mixed co-culture model of RPE cells with neuroretina for evaluating the neuroprotective effects of adipose-MSCs

Mesenchymal stem cell (MSC) therapy is promising for neuroprotection but there is no report of an appropriate in vitro model mimicking the situation of the in vivo retina that is able to test the effect of MSCs in suspension or encapsulated with/without a drug combination. This study aims to establish a viable mixed co-culture model having three layers: neuroretina explants (NRs), retinal pigment epithelium (RPE) cells and adipose tissue-derived MSCs (AT-MSCs) for evaluating adipose-MSC effects. AT-MSCs were grown on the lower surface of a transwell membrane and RPE cells were grown on the bottom of a culture plate as monocultures. A transwell membrane was inserted into a culture plate well. NR was placed as an organotypic culture on the upper surface of the transwell membrane. Thus, a triple-layered co-culture setup was constructed. In double-layered setups, NR were co-cultured with AT-MSCs or RPE cells. Optimum medium, experiment execution period and transwell membrane permeability (TMP) were determined. MSC effects on RPE cell proliferation and NR reactive gliosis were evaluated. Limitations were discussed. Our study shows that neurobasal A with DMEM (1:1) mixed medium was suitable for viability of all three layers. AT-MSC growth decreased TMP significantly, 30-60 % in 3- to 6-day periods. Spontaneous NR reactive gliosis limits the experiment execution period to 6 days. AT-MSCs maintained their undifferentiated nature and showed no or limited neuroprotective effects. In this study, we successfully assembled viable double- and triple-layered co-culture setups for AT-MSCs, RPE and NR, optimised conditions for their survival and explored setup Limitations.

The T309G MDM2 gene polymorphism is a novel risk factor for proliferative vitreoretinopathy

Proliferative vitreoretinopathy (PVR) is still the major cause of failure in retinal detachment (RD) surgery. It is believed that down-regulation in the p53 pathway could be an important key in PVR pathogenesis. The purpose was to evaluate the impact of T309G MDM2 polymorphism (rs2279744) in PVR. Distribution of T309G MDM2 genotypes among European subjects undergoing RD surgery was evaluated. Proportions of genotypes between subsamples from different countries were analyzed. Also, a genetic interaction between rs2279744 in MDM2 and rs1042522 in p53 gene was analyzed. Significant differences were observed comparing MDM2 genotype frequencies at position 309 of intron 1 between cases (GG: 21.6%, TG: 54.5%, TT: 23.8%) and controls (GG: 7.3%, TG: 43.9%, TT: 48.7%). The proportions of genotypes between sub-samples from different countries showed a significant difference. Distribution of GG genotype revealed differences in Spain (35.1–53.0)/(22.6–32.9), Portugal (39.0–74.4)/(21.4–38.9), Netherlands (40.6–66.3)/(25.3–38.8) and UK (37.5–62.4)/(23.3–34.2). The OR of G carriers in the global sample was 5.9 (95% CI: 3.2 to 11.2). The OR of G carriers from Spain and Portugal was 5.4 (95% CI: 2.2–12.7), whereas in the UK and the Netherlands was 7.3 (95% CI: 2.8–19.1). Results indicate that the G allele of rs2279744 is associated with a higher risk of developing PVR in patients undergoing a RD surgery. Further studies are necessary to understand the role of this SNP in the development of PVR.

Histology and immunochemistry evaluation of autologous translocation of retinal pigment epithelium-choroid graft in porcine eyes

PURPOSE

To evaluate structure and cellular functionality of retinal pigment epithelium (RPE)-choroid grafts after autologous translocation in porcine eyes.

METHODS

Retinal pigment epithelium-choroid grafts were obtained from the nasal midperiphery donor site and translocated to the central area in 12 pigs (12 eyes). Grafts were placed under the central retina through a retinotomy. Ophthalmoscopic and pathological evaluations were performed immediately (n = 1) and at 15 (n = 3) and 30 (n = 3) days after surgery. Untranslocated nasal RPE-choroid grafts were obtained at time of surgery and used as controls. Specimens were evaluated by standard histology and by immunochemical studies of RPE65, CRALBP and GFAP.

RESULTS

Five animals were lost to follow-up owing to surgery or anaesthesia complications. Ophthalmoscopic examination revealed that the grafts remained in place at all time-points studied. Fifteen and thirty days postsurgery, some areas of the transplanted RPE maintained a monolayered structure. Retinal pigment epithelium cells were firmly attached to Bruch's membrane and predominantly preserved polarity and pigment distribution. However, RPE65, CRALBP and GFAP patterns of expression and distribution were diminished and modified during follow-up. Ophthalmoscopic retinal detachment and proliferative vitreoretinopathy (PVR), confirmed by microscopic evaluation, complicated all cases at 30 days of follow-up.

CONCLUSION

Autologous RPE-choroid grafts survived up to 30 days in porcine eyes. Histological and immunochemical evaluation revealed preserved transplanted RPE cells morphology accompanied by alterations in the immunoreactivity expression of functional proteins, and development of significant PVR. The data presented in this manuscript provide insights into the fate, viability and cellular functionality of the transplanted RPE-choroid graft, serving as foundation for further knowledge and improvement of this technique.

Time course modifications in organotypic culture of human neuroretina

The purpose of this study was to characterize organ culture of human neuroretina and to establish survival and early degeneration patterns of neural and glial cells. Sixteen neuroretina explants were prepared from 2 postmortem eyes of 2 individuals. Four explants were used as fresh retina controls, and 12 were evaluated at 3, 6, and 9 days of culture. Neuroretina explants (5 × 5 mm) were cultured in Transwell(®) dishes with the photoreceptor layer facing the supporting membrane. Culture medium (Neurobasal A-based) was maintained in contact with the membrane beneath the explant. Cryostat and ultrathin sections were prepared for immunohistochemistry and electron microscopy. Neuroretinal modifications were evaluated after toluidine blue staining and after immunostaining for neuronal and glial cell markers. Ultrastructural changes were analyzed by electron microscopy. From 0 to 9 days in culture, there was progressive retinal degeneration, including early pyknosis of photoreceptor nuclei, cellular vacuolization in the ganglion cell layer, decrease of both plexiform layer thicknesses, disruption and truncation of photoreceptor outer segments (OS), and marked reduction in the number of nuclei at both nuclear layers where the cells were less densely packed. At 3 days there was swelling of cone OS with impairment of pedicles, loss of axons and dendrites of horizontal and rod bipolar cells that stained for calbindin (CB) and protein kinase C (PKC-α), respectively. After 9 days, horizontal cells were pyknotic and without terminal tips. There were similar degenerative processes in the outer plexiform layer for rod bipolar cells and loss of axon terminal lateral varicosities in the inner plexiform layer. Glial fibrillary acidic protein (GFAP) staining did not reveal a dramatic increase of gliosis in Müller cells. However, some Müller cells were CB immunoreactive at 6 days of culture. Over 9 days of culture, human neuroretina explants underwent morphological changes in photoreceptors, particularly the OS and axon terminals, and in postsynaptic horizontal and bipolar cells. These early changes, not previously described in cultured human samples, reproduce some celullar modifications after retinal damage. Thus, this model may be suitable to evaluate therapeutic agents during retinal degeneration processes.

Neuronal and glial alterations in complex long-term rhegmatogenous retinal detachment

PURPOSE

To explore neuronal and glial alterations in eyes with complex long-term rhegmatogenous retinal detachment (RRD).

METHODS

Morphological analysis was performed on eight retinal specimens derived from patients treated with peripheral retinectomy for RRD complicated by retinal shortening or retinal thinning. All eyes had undergone previous surgeries including silicone oil tamponade, and had a median total detachment time of 2.5 months (range 2-12). Specimens were examined with hematoxylin and eosin staining and immunohistochemistry directed against activated Müller cells, ganglion cells, rod bipolar cells, and photoreceptors.

RESULTS

Retinal specimens displayed severe loss of photoreceptor and rod bipolar cells. Remaining neuronal cells exhibited disorganized perikarya and neurites with disruption of the normal retinal lamination. Müller cell activation was evident in all specimens with subretinal and epiretinal hypertrophy present in tissue derived from shortened retinal detachments.

CONCLUSION

Long-term RRD leads to retinal remodeling characterized by loss of first and second order retinal neurons, disruption of the entire retinal lamination and gliosis. The severity of histopathological changes indicates that anatomical as well as functional recovery of the involved retina is precarious. The findings may be important when devising surgical strategies to avoid permanent retinal detachment.

High-density silicone oil (Densiron) as a primary intraocular tamponade: 12-month follow up

BACKGROUND

The high-density silicone oil (Densiron 68), a mixture of F6H8 with silicone oil, seems to be a therapeutic option, at least in selected patients with complex inferior retinal re-detachment, where standard procedures have already failed. In an interventional case series we used Densiron as a primary endotamponade.

METHODS

Twelve eyes of 12 patients aged 31 years to 85 years with inferior complex rhegmatogenous retinal detachment with secondary proliferative vitreoretinopathy (PVR) grades CP2 to CA8 were included. Surgical techniques (pars plana vitrectomy, membrane peeling, retinotomy, retinectomy, endophotocoagulation, cryocoagulation, endotamponade) did not include a scleral buckling procedure (except one eye). Mean duration of the Densiron endotamponade was 78.3 +/- 29.74 days, with a mean follow up after removal of 400.6 +/- 85.4 days.

RESULTS

After Densiron removal, four patients (33.3%) showed a stable reattached retina without further interventions, while, in six patients (50%), recurrent retinal re-detachment appeared during endotamponade, generally within 2 months. One patient (8.3%) developed re-detachment 5 months after Densiron removal. One eye (8.3%) lost light perception due to severe intraretinal fibrosis with chronic hypotonia, despite complete retinal re-attachment. Visual acuity improved from mean logarithm of the minimum angle of resolution (logMAR) of 2.95 +/- 1.21 to 1.87 +/- 1.32 (statistically significant, P = 0.022). Side effects included temporary inflammatory reaction/fibrin accumulation (n = 2/2), moderate-to-severe intraretinal fibrosis (n = 3), elevated intraocular pressure (IOP) (n = 3), emulsification (n = 2), sterile hypopyon (n = 1), vitreous haemorrhage (n = 1) and chronic hypotony (n = 1).

CONCLUSION

Primary anatomical success rate of 33.3% was less encouraging than as expected. Especially, re-detachments within the posterior staphyloma in highly myopic patients were common during Densiron endotamponade. However, the surgical success increased to 75% after reintervention, even without the use of an additional encircling band. The observed adverse effects and the functional outcomes do not contraindicate the use of Densiron as an internal tamponade for a period of 3 months.