Retinal pigment epithelium translocation after choroidal neovascular membrane removal in age-related macular degeneration

Transcriptional comparison of adult human primary Retinal Pigment Epithelium, human pluripotent stem cell-derived Retinal Pigment Epithelium, and ARPE19 cells

The therapeutic potential of pluripotent stem cells is great as they promise to usher in a new era of medicine where cells or organs may be prescribed to replace dysfunctional tissue. At the forefront are efforts in the eye to develop this technology as it lends itself to in vivo monitoring and sophisticated non-invasive imaging modalities. In the retina, retinal pigment epithelium (RPE) is the most promising replacement cell as it has a single layer, is relatively simple to transplant, and is associated with several eye diseases. However, after transplantation, the cells may transform and cause complications. This transformation may be partially due to incomplete maturation. With the goal of learning how to mature RPE, we compared induced pluripotent stem cell-derived RPE (iPSC-RPE) cells with adult human primary RPE (ahRPE) cells and the immortalized human ARPE-19 line. We cultured ARPE-19, iPSC-RPE, and ahRPE cells for one month, and evaluated morphology, RPE marker staining, and transepithelial electrical resistance (TEER) as quality control indicators. We then isolated RNA for bulk RNA-sequencing and DNA for genotyping. We genotyped ahRPE lines for the top age-related macular degeneration (AMD) and proliferative vitreoretinopathy (PVR) risk allele polymorphisms. Transcriptome data verified that both adult and iPSC-RPE exhibit similar RPE gene expression signatures, significantly higher than ARPE-19. In addition, in iPSC-RPE, genes relating to stem cell maintenance, retina development, and muscle contraction were significantly upregulated compared to ahRPE. We compared ahRPE to iPSC-RPE in a model of epithelial-mesenchymal transition (EMT) and observed an increased sensitivity of iPSC-RPE to producing contractile aggregates in vitro which resembles incident reports upon transplantation. P38 inhibition was capable of inhibiting iPSC-RPE-derived aggregates. In summary, we find that the transcriptomic signature of iPSC-RPE conveys an immature RPE state which may be ameliorated by targeting "immature" gene regulatory networks.

New Prospects for Retinal Pigment Epithelium Transplantation

ABSTRACT

Retinal pigment epithelium (RPE) transplants rescue photoreceptors in selected animal models of retinal degenerative disease. Early clinical studies of RPE transplants as treatment for age-related macular degeneration (AMD) included autologous and allogeneic transplants of RPE suspensions and RPE sheets for atrophic and neovascular complications of AMD. Subsequent studies explored autologous RPE-Bruch membrane-choroid transplants in patients with neovascular AMD with occasional marked visual benefit, which establishes a rationale for RPE transplants in late-stage AMD. More recent work has involved transplantation of autologous and allogeneic stem cell-derived RPE for patients with AMD and those with Stargardt disease. These early-stage clinical trials have employed RPE suspensions and RPE monolayers on biocompatible scaffolds. Safety has been well documented, but evidence of efficacy is variable. Current research involves development of better scaffolds, improved modulation of immune surveillance, and modification of the extracellular milieu to improve RPE survival and integration with host retina.

Human Retinal Pigment Epithelial Cells Overexpressing the Neuroprotective Proteins PEDF and GM-CSF to Treat Degeneration of the Neural Retina

BACKGROUND

Non-viral transposon-mediated gene delivery can overcome viral vectors' limitations. Transposon gene delivery offers the safe and life-long expression of genes such as pigment epithelium-derived factor (PEDF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) to counteract retinal degeneration by reducing oxidative stress damage.

OBJECTIVE

Use Sleeping Beauty transposon to transfect human retinal pigment epithelial (RPE) cells with the neuroprotective factors PEDF and GM-CSF to investigate the effect of these factors on oxidative stress damage.

METHODS

Human RPE cells were transfected with PEDF and GM-CSF by electroporation, using the hyperactive Sleeping Beauty transposon gene delivery system (SB100X). Gene expression was determined by RT-qPCR and protein level by Western Blot as well as ELISA. The cellular stress level and the neuroprotective effect of the proteins were determined by measuring the concentrations of the antioxidant glutathione in human RPE cells and immunohistochemical examination of retinal integrity, inflammation, and apoptosis of rat retina-organotypic cultures (ROC) exposed to H2O2.

RESULTS

Human RPE cells were efficiently transfected, showing a significantly augmented gene expression and protein secretion. Human RPE cells overexpressing PEDF and/or GM-CSF or pre-treated with recombinant proteins presented significantly increased glutathione levels post-H2O2 incubation than non-transfected/untreated controls. rPEDF and/or rGM-CSF-treated ROC exhibited decreased inflammatory reactions and cell degeneration.

CONCLUSION

GM-CSF and/or PEDF could be delivered successfully to RPE cells by combining the use of SB100X and electroporation. PEDF and/or GM-CSF reduced H2O2-mediated oxidative stress damage in RPE cells and ROC offering an encouraging technique to re-establish a cell-protective environment to halt age-related retinal degeneration.

Tracking the Transplanted Neurosphere in Retinal Pigment Epithelium Degeneration Model

Introduction

Retinal Pigment Epithelium (RPE) layer deterioration is a leading cause of Age-Related Macular Degeneration (AMD), i.e., the most significant reason for irreversible blindness. The present study aimed to track the Neurosphere-Derived (NS) from Bone Marrow Stromal Stem Cells (BMSCs) grafted into the sub-retinal space (destruction of the RPE layer by sodium iodate).

Methods

RPE degeneration model was performed using the injection of 5% sodium iodate performed in the retro-orbital sinus of Wistar rats. BMSCs were extracted from the examined rat femur and induced into NS, using EGF, bFGF, and B27. BrdU-NS labeled cells were transplanted into the sub-retinal space. For detecting BMSCs and NS markers, immunocytochemistry was performed. Moreover, immunohistochemical was conducted for tracking the transplanted cells in the RPE and sensory retina.

Results

The immunocytochemistry of BMSCs cells displayed the expression of mesenchymal stem cells markers (CD90; 99%±1), CD166 (98%±2), CD44 (99%±1). Additionally, the expression of neural lineage markers in NS, such as SOX2, OCT4, Nanog, Nestin, and Neurofilaments (68, 160, 200) revealed the differentiation from BMSCs. Tracking BrdU-NS labeled suggested these aggregations in most layers of the retina.

Conclusion

Our study data indicated that BMSCs derived neurosphere had the potential to migrate in injured retinal and integrate into the neurosensory retina. These data can be useful in finding safe cells for replacement therapy in AMD.

Surgical Transplantation of Human RPE Stem Cell-Derived RPE Monolayers into Non-Human Primates with Immunosuppression

Recent trials of retinal pigment epithelium (RPE) transplantation for the treatment of disorders such as age-related macular degeneration have been promising. However, limitations of existing strategies include the uncertain survival of RPE cells delivered by cell suspension and the inherent risk of uncontrolled cell proliferation in the vitreous cavity. Human RPE stem cell-derived RPE (hRPESC-RPE) transplantation can rescue vision in a rat model of retinal dystrophy and survive in the rabbit retina for at least 1 month. The present study placed hRPESC-RPE monolayers under the macula of a non-human primate model for 3 months. The transplant was able to recover in vivo and maintained healthy photoreceptors. Importantly, there was no evidence that subretinally transplanted monolayers underwent an epithelial-mesenchymal transition. Neither gliosis in adjacent retina nor epiretinal membranes were observed. These findings suggest that hRPESC-RPE monolayers are safe and may be a useful source for RPE cell replacement therapy.

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hRPESC-RPE monolayer transplanted under macula of non-human primates

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Transplanted hRPESC-RPE recovers in vivo and maintains healthy photoreceptors

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Transplanted cells did not undergo epithelial-mesenchymal transition

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Gliosis was not observed in adjacent retina for up to at least 3 months

Long-term clinical outcomes of submacular blood removal with isolated autologous retinal pigment epithelium-choroid patch graft transplantation in long-standing large-sized submacular hematomas: An Indian experience

Purpose:

To study the outcomes of submacular blood removal with isolated autologous full-thickness retinal pigment epithelial (RPE)-choroid patch graft transplantation in long-standing large-sized submacular hematomas in Indian population.

Methods:

A retrospective study was done on eight consecutive patients of long-standing large-sized submacular hematoma from east India. In all cases, 23G vitrectomy was performed with the induction of retinal detachment (performed with or without 38G or 41G subretinal cannula) and a temporal 180° retinectomy was done. Submacular blood along with choroidal neovascular tissue was removed. A full-thickness RPE-choroid autologous patch graft was taken from a relatively healthy quadrant at the mid periphery and then the graft transferred under perfluorocarbon liquid (PFCL) to place it in the subfoveal area. Then, retina was re-attached using PFCL and laser completed. Silicone oil (5000 cst) was used as a tamponade. Post-operatively, wide-field fundus photographs (Optos), serial optical coherence tomography (OCT), indocyanine green angiography (ICGA), and multifocal electroretinography (ERG) were done.

Results:

The mean age of the patients at presentation was 67.88 ± 10.03 years. Mean pre-operative best corrected visual acquity (BCVA) was 2.64 ± 0.3 log MAR and mean postoperative BCVA was 1.095 ± 0.27 log MAR (P < 0.05). The mean follow-up was 20 ± 16.57 months. ICG showed re-vascularization of translocated graft in all at 2 months. Multifocal ERG (after 6 months) showed some waveform in all. None of the cases developed re-bleed.

Conclusion:

Removal of submacular blood and neovascular membrane with autologous RPE-choroid graft is a viable option in cases with long-standing large submacular hematomas.

Stem cell therapies for retinal diseases: from bench to bedside

As the human retina has no regenerative ability, stem cell interventions represent potential therapies for various blinding retinal diseases. This type of therapy has been extensively studied in the human eyes through decades of preclinical studies. The safety profiles shown in clinical trials thus far have indicated that these strategies should be further explored. There are still challenges with regard to cell source, cell delivery, immuno-related adverse events and long-term maintenance of the therapeutic effects. Retinal stem cell therapy is likely to be most successful with a combination of multiple technologies, such as gene therapy. The purpose of this review is to present a synthetical and systematic coverage of stem cell therapies that target retinal diseases from bench to bedside, intending to appeal to both junior specialists and the broader community of clinical investigators alike. This review will only focus on therapies that have already been studied in clinical trials. This review summarizes key concepts, highlights the main studies in human patients and discusses the current challenges and potential methods to reduce safety concerns while enhancing the therapeutic effects.

Autologous translocation of the choroid and retina pigment epitelial cells(RPE) in age-related macular degeneration: Monitoring the viability of choroid and RPE patch with indocyanine green angiography(ICGA) and fundus autofluorescence(FAF)

PURPOSE

To investigate the functional and anatomical results of autologous retinal pigment epithelial(RPE) cells and choroidal translocation after removal of the subfoveal choroidal neovascular membrane(CNVM) in patients with exudative age-related macular degeneration(AMD). To monitor the viability of choroidal patch with indocyanine green angiography(ICGA) and fundus autofluorescence(FAF) METHODS: This study was conducted as a retrospective, interventional case series, and evaluation of 8 patients ;4 patients had large (> 1 disk diameter) subfoveal choroidal membranes, 3 with massive subretinal hemorrhage and 1 case with suprachoroidal hemorrhage(SCH) + rhegmatogenous retinal detachment(RRD). After removal of the CNVM, the autologous full-thickness patch of the RPE, bruch's membrane, choriocapillaris, and choroid was excised from the midperiphery and placed under the macula. At the 1 st month, 3rd month, 6th month and final examination, color fundus pictures and optical coherence tomography (OCT) were performed by preferred fixation of the OCT-light. Visual test with the early treatment of diabetic retinopathy study(ETDRS), OCT imaging with fixation, scanning with laser ophthalmoscopy autofluorescence, and ICGA were performed to evaluate the viability of choroidal patch at each visits.

RESULTS

This study was carried out in 8 patients with a mean follow-up of 14.12 ± 8.16 (range 7-30 months) months. The mean age was 73 ± 7.17(range, 60-80 years) years. Pre-operative visual acuity ranged from hand motion (HM) (20/2000) to light perception (LP)(20/20000). Post-operative vision ranged from HM (20/2000) to 0.15(20/125). In 6 patients, autofluorescence was reflected in FAF imaging and lipofuscin activity was evaluated as viable. Post-operative subretinal hemorrhage was encountered in 1 (12.5%) patient and it also resolved spontaneously. There was a statistically significant increase in visual acuity at the postoperative final visit compared to baseline. (p = 0.027) CONCLUSIONS: After removal of the CNVM, translocation of a full-thickness patch with the autologous peripheral RPE and choroid can be performed at the macula, resulted in survival and functional graft for 6 months and moreover, hereby viability of the choroid and RPE patch were monitored by imaging methods such as FAF and ICGA.

Optimizing Donor Cellular Dissociation and Subretinal Injection Parameters for Stem Cell-Based Treatments

Subretinal delivery of stem cell‐derived retinal cells as a strategy to treat retinal degenerative blindness holds great promise. Currently, two clinical trials are underway in which human fetal retinal progenitor cells (RPCs) are being delivered to patients by intravitreal or subretinal injection to preserve or restore vision, respectively. With the advent of the induced pluripotent stem cell (iPSC), and in turn three‐dimensional derivation of retinal tissue, it is now possible to generate autologous RPCs for cell replacement. The purpose of this study was to evaluate the effect of commonly used cell isolation and surgical manipulation strategies on donor cell viability. iPSC‐RPCs were subjected to various conditions, including different dissociation and isolation methods, injection cannula sizes, and preinjection storage temperatures and times. The effects of commonly used surgical techniques on both host and donor cell viability were evaluated in Yucatan mini‐pigs (n = 61 eyes). We found a significant increase in cell viability when papain was used for RPC isolation. In addition, a significant decrease in cell viability was detected when using the 41G cannula compared with 31G and at storage times of 4 hours compared with 30 minutes. Although 96.4% of all eyes demonstrated spontaneous retinal reattachment following injection, retinal pigment epithelium (RPE) abnormalities were seen more frequently in eyes receiving injections via a 31G cannula; interestingly, eyes that received cell suspensions were relatively protected against such RPE changes. These findings indicate that optimization of donor cell isolation and delivery parameters should be considered when developing a subretinal cell replacement strategy. stem cells translational medicine2019;8:797&809

Deep Scleral Exposure: A Degenerative Outcome of End-Stage Stargardt Disease

PURPOSE

To describe a distinct phenotypic outcome of outer retinal degeneration in a cohort of genetically confirmed patients with recessive Stargardt disease (STGD1).

DESIGN

Retrospective case series.

METHODS

Twelve patients, who were clinically diagnosed with STGD1 and exhibited a unique degenerative phenotype, were included in the study. Two disease-causing mutations were found in all patients by direct sequencing of the ABCA4 gene. Clinical characterization of patients were defined on fundus photographs, autofluorescence images (488-nm and 532-nm excitation), spectral-domain optical coherence tomography (SD-OCT), and full-field electroretinogram (ffERG) testing.

RESULTS

Mean age at initial presentation was 67.8 years and reported age of symptomatic onset was 14.1 years (mean disease duration = 53.8 years). Best-corrected visual acuity ranged from 20/400 to hand motion. All patients exhibited advanced degeneration across the posterior pole resulting in a reflectively pale, blonde fundus owing to unobstructed exposure of the underlying sclera. SD-OCT revealed complete loss of the outer retinal bands (external limiting membrane, ellipsoid zone, interdigitation zone, and retinal pigment epithelium) and choroidal layers. Scotopic and photopic waveforms on ffERG were nonrecordable or severely attenuated in 8 patients who were tested.

CONCLUSIONS

Widespread scleral exposure is a clinical outcome in a subset of STGD1 following a long duration of disease progression (∼50 years). The blonde fundus in such cases may exhibit phenotypic overlap and shared therapeutic implications with other aggressive chorioretinal dystrophies such as end-stage choroideremia, gyrate atrophy, or RPE65-Leber congenital amaurosis.

COMBINED AUTOLOGOUS TRANSPLANTATION OF NEUROSENSORY RETINA, RETINAL PIGMENT EPITHELIUM, AND CHOROID FREE GRAFTS

PURPOSE

To evaluate the feasibility and initial functional and anatomical outcomes of transplanting a full-thickness free graft of choroid and retinal pigment epithelium (RPE), along with neurosensory retina in advanced fibrosis and atrophy associated with end-stage exudative age-related macular degeneration with and without a concurrent refractory macular hole.

METHODS

During vitrectomy, an RPE-choroidal and neurosensory retinal free graft was harvested in nine eyes of nine patients. The RPE-choroidal and neurosensory retinal free graft was either placed subretinally (n = 5), intraretinally to cover the foveal area inside an iatrogenically induced macular hole over the RPE-choroidal graft (n = 3) or preretinally (n = 1) without a retinotomy wherein both free grafts were placed over the concurrent macular hole. Silicone oil endotamponade was used in all cases.

RESULTS

Mean follow-up was 7 ± 5.5 months (range 3-19). The mean preoperative visual acuity was ∼count fingers (logarithm of the minimum angle of resolution = 2.11, range 2-3), which improved to ∼20/800 (logarithm of the minimum angle of resolution 1.62 ± 0.48, range 0.7-2, P = 0.04). Vision was stable in 5 eyes (55.6%) and improved in 4 eyes (44.4%). Reading ability improved in 5 eyes (55.6%). Postoperative complications were graft atrophy (n = 1), epiretinal membrane (n = 1), and dislocation of neurosensory retina-choroid-RPE free graft (n = 1).

CONCLUSION

Combined autologous RPE-choroid and neurosensory retinal free graft is a potential surgical alternative in eyes with end-stage exudative age-related macular degeneration, including concurrent refractory macular hole.

The current state of stem cell therapy for ocular disease

Herein, we review the safety, efficacy, regulatory standards and ethical implications of the use of stem cells in ocular disease. A literature review was conducted, registered clinical trials reviewed, and expert opinions sought. Guidelines and codes of conduct from international societies and professional bodies were also reviewed. Collated data is presented on current progress in the field of ocular regenerative medicine, future challenges, the clinical trial process and ethical considerations in stem cell therapy. A greater understanding of the function and location of ocular stem cells has led to rapid advances in possible therapeutic applications. However, in the context of significant technical challenges and potential long-term complications, it is imperative that stem cell practices operate within formal clinical trial frameworks. While there remains broad scope for innovation, ongoing evidence-based review of potential interventions and the development of standardized protocols are necessary to ensure patient safety and best practice in ophthalmic care.

Phase 1 clinical study of an embryonic stem cell-derived retinal pigment epithelium patch in age-related macular degeneration

Age-related macular degeneration (AMD) remains a major cause of blindness, with dysfunction and loss of retinal pigment epithelium (RPE) central to disease progression. We engineered an RPE patch comprising a fully differentiated, human embryonic stem cell (hESC)-derived RPE monolayer on a coated, synthetic basement membrane. We delivered the patch, using a purpose-designed microsurgical tool, into the subretinal space of one eye in each of two patients with severe exudative AMD. Primary endpoints were incidence and severity of adverse events and proportion of subjects with improved best-corrected visual acuity of 15 letters or more. We report successful delivery and survival of the RPE patch by biomicroscopy and optical coherence tomography, and a visual acuity gain of 29 and 21 letters in the two patients, respectively, over 12 months. Only local immunosuppression was used long-term. We also present the preclinical surgical, cell safety and tumorigenicity studies leading to trial approval. This work supports the feasibility and safety of hESC-RPE patch transplantation as a regenerative strategy for AMD.

Delayed Atrophy of the Retinal Pigment Epithelium after Submacular Surgery

PURPOSE

We report a case of delayed atrophy of the retinal pigment epithelium (RPE) eighteen months after apparently successful excision of submacular choroidal new vessels (CNV) in a patient with age-related macular degeneration (AMD).

METHODS

Case report.

RESULTS

Submacular surgery for CNV was achieved without visible disturbance of the underlying RPE in an 83 year old man diagnosed with AMD. At the time of surgery the CNV displayed clinical features consistent with lying internal to Bruch's membrane (Type 2 configuration). There was no visible RPE defect at the fovea and vision improved during the subsequent 12 months follow-up. Eighteen months later, however, an atrophic central RPE defect appeared, with a similar shape to the CNV originally excised.

CONCLUSIONS

This case demonstrates that submacular CNV with Type 2 configuration can occur in AMD and lead to an initially favourable outcome following submacular surgery. Atrophy of the RPE nevertheless did eventually occur and in a pattern consistent with damage during the original operation. It is important to consider results of longer term follow-up when interpreting success rates for surgery in AMD.

Stem cells: a promising candidate to treat neurological disorders

Neurologic impairments are usually irreversible as a result of limited regeneration in the central nervous system. Therefore, based on the regenerative capacity of stem cells, transplantation therapies of various stem cells have been tested in basic research and preclinical trials, and some have shown great prospects. This manuscript overviews the cellular and molecular characteristics of embryonic stem cells, induced pluripotent stem cells, neural stem cells, retinal stem/progenitor cells, mesenchymal stem/stromal cells, and their derivatives in vivo and in vitro as sources for regenerative therapy. These cells have all been considered as candidates to treat several major neurological disorders and diseases, owing to their self-renewal capacity, multi-directional differentiation, neurotrophic properties, and immune modulation effects. We also review representative basic research and recent clinical trials using stem cells for neurodegenerative diseases, including Parkinson’s disease, Alzheimer’s disease, and age-related macular degeneration, as well as traumatic brain injury and glioblastoma. In spite of a few unsuccessful cases, risks of tumorigenicity, and ethical concerns, most results of animal experiments and clinical trials demonstrate efficacious therapeutic effects of stem cells in the treatment of nervous system disease. In summary, these emerging findings in regenerative medicine are likely to contribute to breakthroughs in the treatment of neurological disorders. Thus, stem cells are a promising candidate for the treatment of nervous system diseases.

Induced pluripotent stem cell-based therapy for age-related macular degeneration

INTRODUCTION

In age-related macular degeneration (AMD), stem cells could possibly replace or regenerate disrupted pathologic retinal pigment epithelium (RPE), and produce supportive growth factors and cytokines such as brain-derived neurotrophic factor.  Induced pluripotent stem cells (iPSCs)-derived RPE was first subretinally transplanted in a neovascular AMD patient in 2014. Areas covered: Induced PSCs are derived from the introduction of transcription factors to adult cells under specific cell culture conditions, followed by differentiation into RPE cells. Induced PSC-derived RPE cells exhibit ion transport, membrane potential, polarized VEGF secretion and gene expression that is similar to native RPE. Despite having similar in vitro function, morphology, immunostaining and microscopic analysis, it remains to be seen if iPSC-derived RPE can replicate the myriad of in vivo functions, including immunomodulatory effects, of native RPE cells.  Historically, adjuvant RPE transplantation during CNV resections were technically difficult and complicated by immune rejection. Autologous iPSCs are hypothesized to reduce the risk of immune rejection, but their production is time-consuming and expensive.  Alternatively, allogenic transplantation using human leukocyte antigen (HLA)-matched iPSCs, similar to HLA-matched organ transplantation, is currently being investigated. Expert opinion: Challenges to successful transplantation with iPSCs include surgical technique, a pathologic subretinal microenvironment, possible immune rejection, and complications of immunosuppression.

Stem cell therapies for retinal diseases: recapitulating development to replace degenerated cells

Retinal degenerative diseases are the leading causes of blindness worldwide. Replacing lost retinal cells via stem cell-based therapies is an exciting, rapidly advancing area of translational research that has already entered the clinic. Here, we review the status of these clinical efforts for several significant retinal diseases, describe the challenges involved and discuss how basic developmental studies have contributed to and are needed to advance clinical goals.

Allogenic iPSC-derived RPE cell transplants induce immune response in pigs: a pilot study

Stem cell strategies focused on replacement of RPE cells for the treatment of geographic atrophy are under intense investigation. Although the eye has long been considered immune privileged, there is limited information about the immune response to transplanted cells in the subretinal space of large animals. The purpose of this study was to evaluate the survival of allogenic induced pluripotent stem cell-derived RPE cells (iPSC-RPE) delivered to the subretinal space of the pig as well as determine whether these cells induce an immune response in non-diseased eyes. GFP positive iPSC-RPE, generated from outbred domestic swine, were injected into the subretinal space of vitrectomized miniature swine. Control eyes received vehicle only. GFP positive iPSC-RPE cells were identified in the subretinal space 3 weeks after injection in 5 of 6 eyes. Accompanying GFP-negative cells positive for IgG, CD45 and macrophage markers were also identified in close proximity to the injected iPSC-RPE cells. All subretinal cells were negative for GFAP as well as cell cycle markers. We found that subretinal injection of allogenic iPSC-RPE cells into wild-type mini-pigs can induce the innate immune response. These findings suggest that immunologically matched or autologous donor cells should be considered for clinical RPE cell replacement.

Enhancing RPE Cell-Based Therapy Outcomes for AMD: The Role of Bruch's Membrane

Age-related macular degeneration (AMD) is the leading cause of legal blindness in older people in the developed world. The disease involves damage to the part of the retina responsible for central vision. Degeneration of retinal pigment epithelial (RPE) cells, photoreceptors, and choriocapillaris may contribute to visual loss. Over the past decades, scientists and clinicians have tried to replace lost RPE cells in patients with AMD using cells from different sources. In recent years, advances in generating RPE cells from stem cells have been made and clinical trials are currently evaluating the safety and efficiency of replacing the degenerated RPE cell layer with stem cell-derived RPE cells. However, the therapeutic success of transplantation of stem cell-derived RPE cells may be limited unless the transplanted cells can adhere and survive in the long term in the diseased eye. One hallmark of AMD is the altered extracellular environment of Bruch's membrane to which the grafted cells have to adhere. Here, we discuss recent approaches to overcome the inhibitory environment of the diseased eye and to enhance the survival rate of transplanted RPE cells. Our aim is to highlight novel approaches that may have the potential to improve the efficacy of RPE transplantation for AMD in the future.

Choice of Cell Source in Cell-Based Therapies for Retinal Damage due to Age-Related Macular Degeneration: A Review

Background. Age-related macular degeneration (AMD) is a complex disorder that affects primarily the macula involving the retinal pigment epithelium (RPE) but also to a certain extent the photoreceptor layer and the retinal neurons. Cell transplantation is a promising option for AMD and clinical trials are underway using different cell types. Methods. We hypothesize that instead of focusing on a particular cell source for concurrent regeneration of all the retinal layers and also to prevent exhaustive research on an array of cell sources for regeneration of each layer, the choice should depend on, precisely, which layer is damaged. Results. Thus, for a damage limited to the retinal pigment epithelial (RPE) layer, the choice we suggest would be RPE cells. When the damage extends to rods and cones, the choice would be bone marrow stem cells and when retinal neurons are involved, relatively immature stem cell populations with an inherent capacity to yield neuronal lineage such as hematopoietic stem cells, embryonic stem cells, or induced pluripotent stem cells can be tried. Conclusion. This short review will prove to be a valuable guideline for those working on cell therapy for AMD to plan their future directions of research and therapy for this condition.

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.

Cell-replacement therapy and neural repair in the retina

Visual impairment severely affects the quality of life of patients and their families and is also associated with a deep economic impact. The most common pathologies responsible for visual impairment and legally defined blindness in developed countries include age-related macular degeneration, glaucoma and diabetic retinopathy. These conditions share common pathophysiological features: dysfunction and loss of retinal neurons. To date, two main approaches are being taken to develop putative therapeutic strategies: neuroprotection and cell replacement. Cell replacement is a novel therapeutic approach to restore visual capabilities to the degenerated adult neural retina and represents an emerging field of regenerative neurotherapy. The discovery of a population of proliferative cells in the mammalian retina has raised the possibility of harnessing endogenous retinal stem cells to elicit retinal repair. Furthermore, the development of suitable protocols for the reprogramming of differentiated somatic cells to a pluripotent state further increases the therapeutic potential of stem-cell-based technologies for the treatment of major retinal diseases. Stem-cell transplantation in animal models has been most effectively used for the replacement of photoreceptors, although this therapeutic approach is also being used for inner retinal pathologies. In this review, we discuss recent advances in the development of cell-replacement approaches for the treatment of currently incurable degenerative retinal diseases.

A free retinal pigment epithelium-choroid graft in patients with exudative age-related macular degeneration: results up to 7 years

PURPOSE

To report and analyze long-term best-corrected visual acuity (BCVA) outcomes following a free autologous retinal pigment epithelium (RPE)-choroid graft translocation in patients with exudative age-related macular degeneration (AMD).

DESIGN

Prospective cohort study.

METHODS

SETTING

Institutional.

STUDY POPULATION

One hundred and thirty consecutive patients (133 eyes) with AMD underwent RPE-choroid graft translocation between October 2001 and February 2006. All patients had a subfoveal choroidal neovascular membrane with or without hemorrhage and/or an RPE tear. All were either ineligible for or nonresponsive to photodynamic therapy, the standard treatment at the time of surgery.

OBSERVATION PROCEDURES

Data collection included preoperative and postoperative visual acuity measurements, fundus photography, fluorescein and indocyanine green angiography, and microperimetry.

MAIN OUTCOME MEASURES

Postoperative BCVA.

RESULTS

The mean preoperative BCVA was 20/250. Four years after surgery, 15% of the eyes had a BCVA of >20/200, and 5% had a BCVA of ≥20/40. One patient achieved a BCVA of 20/32, which was maintained at 7 years after surgery. Complications consisted of proliferative vitreoretinopathy (n = 13), recurrent neovascularization (n = 13), and hypotony (n = 2).

CONCLUSIONS

RPE-choroid graft transplantation may maintain macular function for up to 7 years after surgery, with relatively low complication and recurrence rates. Retinal sensitivity, BCVA data, and fixation on the graft suggest that the graft, rather than simply the removal of submacular hemorrhage and/or choroidal neovascular membrane, was responsible for the preservation of macular function. This surgery may be an alternative for patients with AMD who cannot undergo other standard treatment.

Subretinal transplantation of putative retinal pigment epithelial cells derived from human embryonic stem cells in rat retinal degeneration model

OBJECTIVE

To differentiate the human embryonic stem cells (hESCs) into the retinal pigment epithelium (RPE) in the defined culture condition and determine its therapeutic potential for the treatment of retinal degenerative diseases.

METHODS

The embryoid bodies were formed from hESCs and attached on the matrigel coated culture dishes. The neural structures consisting neural precursors were selected and expanded to form rosette structures. The mechanically isolated neural rosettes were differentiated into pigmented cells in the media comprised of N2 and B27. Expression profiles of markers related to RPE development were analyzed by reverse transcription-polymerase chain reaction and immunostaining. Dissociated putative RPE cells (10(5) cells/5 µL) were transplanted into the subretinal space of rat retinal degeneration model induced by intravenous sodium iodate injection. Animals were sacrificed at 1, 2, and 4 weeks after transplantation, and immnohistochemistry study was performed to verify the survival of the transplanted cells.

RESULTS

The putative RPE cells derived from hESC showed characteristics of the human RPE cells morphologically and expressed molecular markers and associated with RPE fate. Grafted RPE cells were found to survive in the subretinal space up to 4 weeks after transplantation, and the expression of RPE markers was confirmed with immunohistochemistry.

CONCLUSION

Transplanted RPE cells derived from hESC in the defined culture condition successfully survived and migrated within subretinal space of rat retinal degeneration model. These results support the feasibility of the hESC derived RPE cells for cell-based therapies for retinal degenerative disease.

Autologous translocation of the retinal pigment epithelium and choroid in the treatment of neovascular age-related macular degeneration

PURPOSE

To evaluate clinical results of an autologous translocation of retinal pigment epithelium (RPE) and choroid in the treatment of neovascular age-related macular degeneration (AMD).

METHODS

Twelve eyes which underwent surgery for neovascular AMD were included into the study, in four eyes moderate or massive submacular haemorrhage was present. The surgical procedure included standard pars plana vitrectomy; cataract surgery in phakic patients; peripheral 180°-retinotomy; extraction of the submacular neovascular complex and removal of blood if present; preparation of a full-thickness graft consisting of RPE, Bruch's membrane and choroid; translocation of the graft to the macular area; and silicone oil endotamponade.

RESULTS

Visual acuity (VA) ranged from perception of hand movements (HM) to 20/125 (median, counting fingers (CF)-1/50) before surgery. During follow-up (FU) mean, 11.1 months, VA increased to a maximum median of 1/10 (range, HM-20/40). At the end of FU, VA had dropped to a median of CF-1/40 (range, HM-20/50). Comparing VA preoperatively and at the end of FU, VA had improved in six eyes, was unchanged in three eyes, and had deteriorated in three eyes. One eye had reading ability. Surgery-associated postoperative complications impairing the functional outcome occurred in five eyes, including rhegmatogenous retinal detachment and proliferative vitreoretinopathy. Revision surgery had to be performed in four eyes (30%). Three eyes had to be left with permanent silicone endotamponade. Results tended to be better in the subgroup of eyes with massive submacular haemorrhage preoperatively.

CONCLUSION

Functional results of a translocation of RPE and choroid were heterogeneous and rather disappointing in this study. Results may have been influenced negatively by case selection. We found a relatively high rate of adverse events in the postoperative course. In selected cases, e.g. massive submacular haemorrhage or progressive neovascular AMD unresponsive to other treatment options, autologous translocation of RPE and choroid may still be considered.

Barely visible 10-millisecond pascal laser photocoagulation for diabetic macular edema: observations of clinical effect and burn localization

PURPOSE

To investigate the morphologic features and clinical efficacy of barely visible Pascal (Optimedica Corporation) photocoagulation burns in diabetic macular edema (DME) using Fourier-domain optical coherence tomography (FD OCT) and fundus autofluorescence (AF).

DESIGN

Interventional case series.

METHODS

Retrospective evaluation of 10 eyes with newly diagnosed DME that underwent barely visible Pascal photocoagulation using an array of 10-microm, 10-millisecond photocoagulation burns. FD OCT and camera-based AF was performed at baseline and at 1 hour, 2 weeks, 4 weeks, and 12 weeks after laser. Changes in retinal thickening after laser treatment were measured using retinal thickness maps within the treated sector and the central foveal subfield.

RESULTS

At 1 hour after treatment, burns were visualized partially with clinical biomicroscopy. AF demonstrated spots lacking autofluorescence that confirmed effective laser uptake within the Pascal arrays. Sequential changes in hyperreflectivity on FD OCT correlated with morphologic alterations seen on AF. Burns became increasingly hyperautofluorescent between 2 and 4 weeks. There were significant reductions in the retinal thickness within treated sectors on FD OCT at 2 weeks (26 +/- 32 microm; P = .012) and 3 months after laser (20 +/- 21 microm; P = .02) compared with baseline. Clinical biomicroscopic reduction of DME was the most common finding in 80%.

CONCLUSIONS

Barely visible 10-millisecond Pascal laser seems to produce an effect at the level of the inner and outer photoreceptor segments and apical retinal pigment epithelium, with minimal axial and lateral spread of burns. FD OCT confirmed spatial localization of AF signal changes that correlated with laser burn-tissue interactions over 3 months. The technique of lower-fluence barely visible 10-millisecond laser may reduce retinal edema within affected sectors and effectively treat DME with minimization of scar formation.

Surgery for CNV and autologous choroidal RPE patch transplantation: exposing the submacular space

BACKGROUND

To evaluate the feasibility of transplanting a full-thickness patch of choroid, choriocapillaries, Bruch's membrane and RPE (RPE-choroid FTAP) from the peripheral to the subfoveal area of the same eye, after performing a 180 degrees peripheral retinotomy and removing subfoveal choroidal neovascularization. Thereafter, to study the surgical complications, anatomical outcome and patch perfusion during follow-up.

METHODS

A retrospective case series of 13 eyes of 13 consecutive patients with a follow-up of 4 to 20 months. All patients suffered from advanced subfoveal choroidal neovascularization and were non-responders to standard care. After performing a complete vitrectomy, a 180 degrees peripheral temporal retinotomy and the removal of subfoveal neovascularization, a FTAP of choroid, choriocapillaris, Bruch's membrane and the RPE were isolated from the mid periphery of the uveal bed, transpositioned under the fovea and covered with the retina. Patients received a complete ophthalmic examination, fluorescein angiography (FA), indocyanin green angiography (ICGA) and optical coherence tomography (OCT) during follow-up.

RESULTS

An FTAP could be harvested in every eye and transplanted under the fovea. No intraoperative complications occurred. The FTAP was recognizable at FA, ICGA and OCT at each time point, up to 20 months postoperatively. Perfusion of the choroidal bed were observed into the FTAP during follow-up, from one week after surgery.

CONCLUSION

The creation of an FTAP through a 180 degrees peripheral retinotomy is feasible and safe. The FTAP is vital and perfused. Further studies are needed to collect more data.

Stem-cell therapy in retinal disease

PURPOSE OF REVIEW

Stem-cell research is being investigated for the treatment of retina diseases. Cell replacement strategies have the potential to improve vision in patients who were previously considered to be untreatable. This review summarizes progress within the field and obstacles which must be overcome to make stem-cell therapy a viable treatment for select retinal disease.

RECENT FINDINGS

Researchers have demonstrated that stem-cell transplants can survive, migrate, differentiate, and integrate within the retina. Stem cells from various developmental stages have been used in these experiments, including embryonic stem cells, neural stem cells, mesenchymal stem cells, retinal stem cells, and adult stem cells from the ciliary margin. Not only can these transplants adopt retina-like morphologies and phenotypes, but they have also shown evidence of synaptic reconnection and visual recovery in both animal and human studies. Still, work must be done to achieve higher yields of functioning retinal neurons and to promote better integration within the host retina.

SUMMARY

Although many obstacles remain, stem-cell-based therapy is a promising treatment to restore vision in patients with retina disease.

Fundus autofluorescence and progression of age-related macular degeneration

Fundus autofluorescence imaging is an imaging method that provides additional information compared to conventional imaging techniques. It permits to topographically map lipofuscin distribution of the retinal pigment epithelial cell monolayer. Excessive accumulation of lipofuscin granules in the lysosomal compartment of retinal pigment epithelium cells represents a common downstream pathogenetic pathway in various hereditary and complex retinal diseases including age-related macular degeneration (AMD). This comprehensive review contains an introduction in fundus autofluorescence imaging, including basic considerations, the origin of the signal, different imaging methods, and a brief overview of fundus autofluorescence findings in normal subjects. Furthermore, it summarizes cross-sectional and longitudinal fundus autofluorescence findings in patients with AMD, addresses the pathophysiological significance of increased fundus autofluorescence, and characterizes different fundus autofluorescence phenotypes as well as fundus autofluorescence alterations with disease progression.

Autologe RPE-Chorioidea-Translokation bei exsudativer AMD

BACKGROUND

To evaluate the retinal sensitivity and fixation pattern after removal of choroidal neovascularisation (CNV) and autologous retinal pigment epithelium (RPE)-choroid translocation in patients with exudative age-related macular degeneration (AMD).

METHODS

The functional and morphologic results of 10 consecutive patients (nine with exudative AMD, one with geographic atrophy) were analysed. The mean follow-up was 16.8 (14-20) months. Functional evaluation was performed with the MP1 microperimeter.

RESULTS

Preoperative visual acuity ranged from hand motion to 0.2 (decimal), and postoperative visual acuity ranged from hand motion to 0.4. Fixation on the graft was shown in four patients. Microperimetry proved light increment sensitivity over the graft in five patients. Light increment sensitivity could be kept on a constant level in four of these patients. Postoperative complications included retinal detachment (three), proliferative vitreoretinopathy (one), and development of CNV (one).

CONCLUSION

Autologous RPE-choroid sheet translocation is feasible and comparatively safe. Fixation and light perception on the graft proved to be possible. Light increment sensitivity can be kept on a constant level for at least 20 months.

RPE transplantation and its role in retinal disease

Retinal pigment epithelial (RPE) transplantation aims to restore the subretinal anatomy and re-establish the critical interaction between the RPE and the photoreceptor, which is fundamental to sight. The field has developed over the past 20 years with advances coming from a large body of animal work and more recently a considerable number of human trials. Enormous progress has been made with the potential for at least partial restoration of visual function in both animal and human clinical work. Diseases that have been treated with RPE transplantation demonstrating partial reversal of vision loss include primary RPE dystrophies such as the merTK dystrophy in the Royal College of Surgeons (RCS) rat and in humans, photoreceptor dystrophies as well as complex retinal diseases such as atrophic and neovascular age-related macular degeneration (AMD). Unfortunately, in the human trials the visual recovery has been limited at best and full visual recovery has not been demonstrated. Autologous full-thickness transplants have been used most commonly and effectively in human disease but the search for a cell source to replace autologous RPE such as embryonic stem cells, marrow-derived stem cells, umbilical cord-derived cells as well as immortalised cell lines continues. The combination of cell transplantation with other modalities of treatment such as gene transfer remains an exciting future prospect. RPE transplantation has already been shown to be capable of restoring the subretinal anatomy and improving photoreceptor function in a variety of retinal diseases. In the near future, refinements of current techniques are likely to allow RPE transplantation to enter the mainstream of retinal therapy at a time when the treatment of previously blinding retinal diseases is finally becoming a reality.

Autologous translocation of the choroid and RPE in age-related macular degeneration: 1-year follow-up in 30 patients and recommendations for patient selection

AIM

To evaluate the long-term (1 year) functional and anatomical outcome of autologous translocation of peripheral choroid and retinal pigment epithelium (RPE) in 30 patients with age-related macular degeneration (AMD).

METHODS

After the extraction of the neovascular complex, an autologous peripheral full-thickness graft of RPE and choroid was positioned under the macula. Functional tests included ETDRS vision, reading (Radner test), and microperimetry (scanning laser ophthalmoscope). Fluorescein, indocyanine green angiography, and autofluorescence were monitored.

RESULTS

Preoperative visual acuity ranged from 20/40 to 20/800 (0.3-1.6 log MAR). Vision ranged from 20/25 to LP (0.1-2.1 log MAR) 1 year after surgery, with stabilization in six eyes, an increase in five eyes, and a decrease in 19 eyes. Deterioration mostly occurred within the first 3 months after surgery. In patients who demonstrated vascularization of the graft after 3 months, this persisted up to 12 months as did fixation when initially stable. Autofluorescence decreased significantly from 6 to 12 months postoperatively. Eleven cases showed a recurrence of choroidal neovascularization (CNV) within this period.

CONCLUSION

Patch translocation results in a viable graft. There is no evidence of graft failure within a 1-year follow-up. Nevertheless, there is risk for late CNV formation originating from the edges of the excision side of the CNV and growing peripheral to the graft.

Retinal pigment epithelium and choroid translocation in patients with exudative age-related macular degeneration: long-term results

BACKGROUND

To study the results of the translocation of a free autologous retinal pigment epithelium (RPE)-choroid graft after removal of a subfoveal choroidal neovascular membrane in patients with exudative age-related macular degeneration (AMD), and to determine whether preoperative variables may predict visual outcome at 1 year after surgery.

METHODS

Prospective interventional case series of 84 eyes of 83 consecutive eligible patients with exudative AMD with a minimal follow-up of 1 year after surgery. Of this group, 45, 24 and 11 patients reached a follow-up of respectively 2, 3 and 4 years. Pre- and postoperative evaluation included ETDRS visual acuity (VA), fixation testing and color fundus photography. Preoperative fluorescein angiograms were assessed by masked readers for lesion size, size of hemorrhage and lesion composition according to the MPS criteria. The relationship between lesion composition adjusted for preoperative delay and VA, lesion size, percentage of blood, and visual outcome at 1 year after surgery was analyzed.

RESULTS

The mean VA (logMAR) improved slightly at 1 and 2 years (0.89, Delta = -0.06), 3 years (0.79, Delta = -0.16) and 4 years (0.74, Delta = -0.21) after surgery. Five patients had a preoperative VA better than 20/80, compared to 19 out of 84, six out of 45, four out of 24 and two out of 11 after 1, 2, 3 and 4 years respectively. Fixation was located on the graft in 62 patients (74%) up to the last examination. Predominantly classic and occult lesions had a significant better prognosis than minimally classic or hemorrhagic (> or = 50% blood) lesions. Retinal detachment occurred in seven patients; two caused by rhegmatogenous detachment and five caused by proliferative vitreoretinopathy. In 11 eyes, a recurrent or persisting neovascular membrane was observed.

CONCLUSION

An autologous free RPE-choroid graft may stabilize or improve vision in patients with exudative AMD up to 4 years after surgery.

Histological evidence for revascularisation of an autologous retinal pigment epithelium--choroid graft in the pig

BACKGROUND

Translocation of a free autologous graft consisting of retinal pigment epithelium (RPE), Bruch's membrane, choriocapillaris and choroid in patients with exudative age-related macular degeneration is currently being evaluated in clinical practice. Angiographic studies in these patients suggest that their grafts become revascularised.

AIM

To investigate the histological evidence of revascularisation of the graft in a porcine model.

METHODS

In 11 pigs (11 eyes), an RPE-choroid graft was translocated from the mid-periphery to an intact or an intentionally damaged RPE and Bruch's membrane at the recipient site. The eyes were enucleated 1 week or 3 months after surgery. Tissue sections were evaluated using immunohistochemistry.

RESULTS

Bridging vessels between recipient layer and graft were identified from 1 week to 3 months after surgery. This reconnection occurred regardless of whether the Bruch's membrane of the recipient site was left intact or intentionally damaged at the time of transplantation. The vasculature of the graft appeared open and perfused. Vessels with transcapillary pillars and conglomerates of small new vessels were present in the graft.

CONCLUSIONS

This study showed histological evidence for revascularisation by angiogenesis of a free autologous RPE-choroid graft.

Surgical treatment of age-related macular degeneration: will there be a role in the future?

Surgical treatment has been shown to be able to improve vision that is lost as a result of age-related macular degeneration. Surgery is complex, such that improvement has always to be weighed against risk of complications. The availability of Ranibizumab and Bevacizumab is set to dramatically alter our management options. Surgical treatment will have a limited role to play in the next few years.

Autologous translocation of the choroid and retinal pigment epithelium in patients with geographic atrophy

PURPOSE

To evaluate the functional and anatomical outcomes of autologous translocation of peripheral choroid and retinal pigment epithelium (RPE) in patients with geographic atrophy.

DESIGN

Prospective nonrandomized study.

PARTICIPANTS

Twelve consecutive patients with geographic atrophy secondary to age-related macular degeneration presenting with recent loss of reading vision.

METHODS

An autologous peripheral full-thickness graft of RPE, Bruch's membrane, and choroid was positioned under the macula in patients with geographic atrophy.

MAIN OUTCOME MEASURES

Functional tests included Early Treatment Diabetic Retinopathy Study distant vision, reading (Radner Test, measured as logarithm of the reading acuity determination [logRAD]), threshold static perimetry, and determination of the point of fixation. Fluorescein and indocyanine green angiography, autofluorescence, and optical coherence tomography served to evaluate the anatomical outcome in a 6-month follow-up (12 months in 7 patients).

RESULTS

Preoperative visual acuity (VA) ranged from 20/800 to 20/40 (mean, 0.6+/-0.4 logarithm of the minimum angle of resolution), and reading vision from 1.1 to 0.5 logRAD (mean, 0.8+/-0.2). Three patients were unable to read. Six months after surgery, VA ranged from hand movements to 20/32, with an increase of > or =5 letters in 2 eyes. Two patients without reading ability preoperatively were able to read after surgery. Reading was possible in a total of 8 patients after 6 months (1.3-0.4 logRAD). In 7 patients who were observed for 1 year, VA remained stable (+/-1 line) in 5 eyes and decreased in 2 eyes between 6 months' and 1 year's follow-up. In all eyes but 2, revascularization was visible on indocyanine green angiography as early as 3 weeks after surgery. Autofluorescence of the RPE was independent of revascularization of the graft and persisted throughout follow-up. Four eyes had unstable fixation and/or extrafoveal fixation before surgery. Two of these eyes stabilized during follow-up. Areas overlying atrophic areas demonstrated low threshold sensitivities that persisted after translocation of a free graft with only limited recovery. Revisional surgery due to proliferative vitreoretinopathy was required in 5 eyes.

CONCLUSIONS

The translocation of a full-thickness graft usually results in a vascularized and functioning graft in patients with geographic atrophy, although is associated with a high risk of complications and visual loss. Longer follow-up is necessary to learn about the long-term survival and functionality of the graft.