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

Incisional choroidal surgery

The choroid is a thin layer of highly vascular uveal tissue enclosed externally by sclera and internally by neurosensory retinal tissue. The choroid is a "middle layer" ocular tissue with anatomically challenging surgical access. The primary functional role of the choroid is to provide rapid, oxygenated, and nutrient-rich blood flow to both the highly metabolic retinal pigment epithelium and outer retina (i.e. photoreceptors) while simultaneously removing waste products. Historically, incisional choroidal surgery (ICS) has involved tumor biopsy or excision, removal of choroidal neovascular complex or autologous choroidal translocations; however, ICS also holds unique potential for novel and innovative approaches to address macular pathology. Using large-animal surgical studies, researchers have explored ICS with the objective of finding safer and more effective techniques to reduce surgical risks such as bleeding, tissue contraction, and scar tissue formation. We explore the relevant anatomy and embryology, existing surgical techniques, discuss the implications for retinal drug delivery, define ICS guiding principles, and offer a rationale for implementation of ICS into a vitreoretinal surgical practice. We also identify other future challenges and anticipate future innovations that will advance ICS.

Retinotomies and retinectomies: A review of indications, techniques, results, and complications

Retinotomy refers to "cutting" or "incising" the retina, whereas retinectomy denotes "excising" the retina. Retinotomies and retinectomies aid in tackling traction and retinal shortening that persist following membrane dissection and scleral buckling. We performed a literature search using Google Scholar and PubMed, followed by a review of the references procured. All relevant literature was studied in detail and summarized. We discuss the indications of retinotomies and retinectomies for relaxing retinal stiffness, accessing the subretinal space for choroidal neovascular membrane, hemorrhage and abscess clearance, drainage retinotomies to allow retinal flattening, radial retinotomies to release circumferential traction, harvesting free retinal grafts, and prophylactic chorioretinectomies in trauma.

Safety and performance of a suprachoroidal sensor for telemetric measurement of intraocular pressure in the EYEMATE-SC trial

AIM

To investigate the safety and performance of a telemetric suprachoroidal intraocular pressure (IOP) sensor (EYEMATE-SC) and the accuracy of its IOP measurements in open angle glaucoma (OAG) patients undergoing simultaneous non-penetrating glaucoma surgery (NPGS).

METHODS

Prospective, multicentre, open-label, single-arm, interventional clinical trial. Twenty-four eyes of 24 patients with OAG regularly scheduled for NPGS (canaloplasty or deep sclerectomy) were simultaneously implanted with an EYEMATE-SC sensor. Six-month follow-up on the sensor's safety and performance as well as on the level of agreement between the EYEMATE-SC measurements and IOP measurements with Goldmann applanation tonometry (GAT).

RESULTS

The eyes underwent canaloplasty (n=15) or deep sclerectomy (n=9) and achieved successful implantation of the sensor. No device migration, dislocation or serious device-related complications occurred. A total of 367 comparisons were included in the IOP agreement analysis. The overall mean difference between GAT and EYEMATE-SC measurements was 1.31 mm Hg (lower limit of agreement (LoA) 7.55 mm Hg; upper LoA -4.92 mm Hg). The maximum difference of 2.5 mm Hg ±3.96 (LoA 0.30-2.29) was reached on day 10 and continuously improved to an agreement of -0.15 mm Hg ±2.28 (LoA -1.24 to 0.89) after 6 months. Accordingly, the percentage of eyes within an IOP difference of ±5 mm Hg improved from 78% (day 3) to 100% (6 months).

CONCLUSIONS

After 6 months, the EYEMATE-SC sensor was safe and well tolerated, and allowed continual IOP monitoring.

TRIAL REGISTRATION NUMBER

NCT03756662.

EYEMATE-SC Trial: Twelve-Month Safety, Performance, and Accuracy of a Suprachoroidal Sensor for Telemetric Measurement of Intraocular Pressure

PURPOSE

Measuring and controlling intraocular pressure (IOP) provide the foundation for glaucoma treatment. Self-tonometry has been proposed as an alternative to measure IOP throughout the entire day better. The novel EYEMATE-SC sensor (Implandata) is implanted in the suprachoroidal space to enable contactless continual IOP monitoring. The aim of the present study was to investigate the 1-year safety, performance, and accuracy of the EYEMATE-SC in patients with primary open-angle glaucoma undergoing simultaneous nonpenetrating glaucoma surgery (NPGS).

DESIGN

Prospective, multicenter, open-label, single-arm, interventional clinical trial.

PARTICIPANTS

Twenty-four eyes of 24 patients with primary open-angle glaucoma who were due to undergo NPGS (canaloplasty or deep sclerectomy).

METHODS

An EYEMATE-SC sensor was implanted during NPGS. Goldmann applanation tonometry (GAT) measurements were compared with the sensors' IOP measurements at all postoperative visits through 12 months.

MAIN OUTCOME MEASURES

Device position and adverse events.

RESULTS

Fifteen eyes underwent canaloplasty, and 9 underwent deep sclerectomy. Successful implantation of the sensor was achieved in all eyes with no reported intraoperative difficulties. Through the 12-month follow-up, no device migration, dislocation, or serious device-related complications were recorded. A total of 536 EYEMATE-SC measurements were pairwise included in the IOP agreement analysis. The overall mean difference between GAT and EYEMATE-SC measurements was 0.8 mmHg (95% confidence interval [CI] of the limits of agreement [LoA], -5.1 to 6.7 mmHg). The agreement gradually improved, and from 3 months after surgery until the end of the follow-up, the mean difference was -0.2 mmHg (95% CI of LoA, -4.6 to 4.2 mmHg) over a total of 264 EYEMATE-SC measurements, and 100% of measurements were within ±5 mmHg of GAT.

CONCLUSIONS

The EYEMATE-SC sensor was safe and well tolerated through 12 months. Moreover, it allowed accurate, continuous IOP monitoring.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

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.

[Modern aspects of the treatment of submacular hemorrhages secondary to macular degeneration]

Age-related macular degeneration complicated by submacular hemorrhage if not treated timely leads to permanent loss of central vision. The basis of effective therapy is its early start, dislocation of blood from central parts of the retina and blockage of neovascularization. This review examines the current methods of treatment of submacular hemorrhages, anatomical and functional outcomes, risks of postoperative complications, as well as trends in the use of combined methods of surgical intervention.

Methodological Approach to Improve Surgical Outcomes of a Pig Subretinal Implantation Model

Purpose

To improve outcomes for subretinal implantation surgery in pigs.

Methods

Analysis of variables affecting the success of subretinal implantation surgery was performed on videos of 37 surgeries. Ex vivo experiments were conducted to measure intraocular pressure (IOP) and test various prototyped implanters for effectiveness at maintaining IOP.

Results

A video analysis revealed a prolonged sclerotomy open time owing to a combination of uncontrolled bleeding and excessive fluid outflow often resulting in retinal prolapse. Precauterization of the choroid before full-thickness sclerotomy (n = 10) resulted in a reduced incidence of uncontrolled bleeding from 39.1% (9/23) versus 0% (0/10) (P = 0.005) and improved implantation success from 73% to 90%. An ex vivo analysis of the IOP revealed a mean decrease in the IOP from 30.2 ± 3.0 mm Hg to 5.0 ± 2.1 mm Hg after a fully penetrating sclerotomy. To address this situation, we produced a series of plugs that integrated with a custom implant insertion device to seal the sclerotomy during implantation. The use of the plugs was cumbersome, however, and so we opted instead to increase the width of the inserter tip to fill the open sclerotomy. This improved device restored and maintained IOP during implantation (27.1 ± 1.9 mm Hg). Combined with precauterization the improved inserter resulted in 100% successful implantation (n = 4).

Conclusions

For subretinal implantation in pigs, a modified procedure to precauterize the choroid before sclerotomy combined with an instrument that better fills the scleral opening decreases bleeding, hypotony, and open sclerotomy time, improving the success rate.

Translational Relevance

Better management of IOP and bleeding from a sclerotomy will improve implant-based therapies.

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.

[Management of submacular hemorrhage : What, when, how?]

BACKGROUND

Subretinal hemorrhage involving the macula is a typical complication in a variety of retinal diseases, whereby age-related macular degeneration (AMD) is by far the leading cause.

METHOD

A literature search was carried out in PubMed.

RESULTS

Numerous studies have demonstrated the effectiveness of various approaches to the management of submacular hemorrhage, including intravitreal anti-VEGF treatment, pneumatic displacement supported by fibrinolytic agents or surgical drainage.

DISCUSSION

There is currently no consensus regarding evidence-based standard treatment for macular hemorrhage, although there is a trend towards minimally invasive approaches. Regardless of the choice of the primary treatment approach, the time to treatment and an accompanying intravitreal treatment with VEGF inhibitors are decisive for the functional outcome.

The pattern and gender disparity in global burden of age-related macular degeneration

PURPOSE

To explore the trend patterns and gender disparity in global burden of age-related macular degeneration (AMD) by year, age, and socioeconomic status using disability-adjusted life-years (DALYs) from Global Burden of Disease (GBD) study 2017.

METHODS

DALYs and impairment data caused by AMD were extracted from GBD Study 2017. World Bank income level (WBIL) and human development index (HDI) in 2017 were cited as indicators of socioeconomic status. The Gini coefficients and the concentration indexes were calculated to unveil trends in between-country inequality. The association between gender inequality and socioeconomic levels was analyzed by Pearson correlation.

RESULTS

Total age-standardized DALYs of AMD showed a slightly descending pattern in recent years. However, gender disparity has existed since 1990 for almost three decades, with female being more heavily impacted. This pattern became more obvious with aging and varied among different WHO and WBIL regions. Meanwhile, female subjects tended to have higher vision impairments. Gini coefficients of AMD burden increased from 0.423 to 0.448, while the ones of female-to-male ratio fluctuated around 0.11 between 1990 and 2017, with concentration indexes changing from 0.024 to -0.057 and 0.046 to 0.029 respectively. Female-minus-male difference (r = 0.1721, p = 0.0195) and female-to-male ratio (r = 0.2072, p = 0.0048) of age-standardized DALYs rates were positively related to HDI.

CONCLUSIONS

Though global AMD health care is progressing, gender imbalance in disease burden of AMD distribution barely improved. Gender sensitive health policy should be emphasized for the increasing elder population and relieving the higher AMD burden of females.

RETINAL PIGMENT EPITHELIUM-CHOROID GRAFT WITH A PERIPHERAL RETINOTOMY FOR EXUDATIVE AGE-RELATED MACULAR DEGENERATION: Long-Term Outcome

PURPOSE

To investigate the long-term outcome of autologous retinal pigment epithelium -choroid transplantation with a peripheral retinotomy for exudative age-related macular degeneration.

METHODS

In a retrospective study, we selected all patients who underwent a retinal pigment epithelium-choroid transplantation from 2007 through 2013. Exclusion criteria were age <60 years, <12 months of follow-up, and retinal pigment epithelium-choroid graft for other diseases than age-related macular degeneration. The main outcome measure was best-corrected visual acuity converted into logarithm of the minimum angle of resolution.

RESULTS

In this study, 81 patients were included with a mean follow-up of 38 months (SD = 19). Median best-corrected visual acuity improved from 1.30 logarithm of the minimum angle of resolution (20/400 Snellen) to 0.90 logarithm of the minimum angle of resolution (20/160 Snellen) 1 year after surgery (P < 0.001). A ≥3-line gain was achieved in 43 patients (53%) 1 year postoperatively and 37 patients (46%) preserved their visual gain until last visit. Of 4 patients with an 8-year follow-up, 3 patients had a ≥6-line gain at last visit. Severe complications were submacular hemorrhage (n = 8, 10%), macular hole (n = 6, 7%), and proliferative vitreoretinopathy (n = 3, 4%).

CONCLUSION

Best-corrected visual acuity improved significantly after retinal pigment epithelium-choroid transplantation in patients with age-related macular degeneration and preservation of visual gain was possible in the long term.

Intravitreal Recombinant Tissue Plasminogen Activator and Sulphur Hexafluoride Gas for Submacular Haemorrhage Displacement in Age-Related Macular Degeneration: Looking behind the Blood

PURPOSE

To evaluate the effectiveness of recombinant tissue plasminogen activator (rtPA) and sulphur hexafluoride gas (SF6) intravitreal injection for the displacement of large submacular haemorrhages (SMH) secondary to neovascular age-related macular degeneration and for guiding the selection of additional treatments or observations for choroidal neovascularization (CNV).

METHODS

The medical records of consecutive patients with recent-onset, large SMH, treated at Sacro Cuore Hospital from January 2004 to May 2016, were retrospectively analysed. All eyes underwent a 0.05-mL intravitreal injection of 50 μg rtPA, 0.3 mL of 100% SF6, and then face-down positioning. Afterwards, the eyes received additional treatments for CNV or observation, based on the severity and extent of the underlying pathology. The multimodal imaging features revealed after blood displacement were analysed and then correlated to the treatment selected as a second therapeutic option.

RESULTS

A total of 96 eyes met the inclusion criteria and was evaluated in this study. SMH was displaced from the fovea in the majority of the eyes (76%), allowing several diagnostic tools to evaluate the underlying macular features. In 19 cases (19.8%) exhibiting severe macular damage, no additional treatment was applied. In the remaining eyes, subsequent treatments included anti-vascular endothelial growth factor injections (44.8%), photodynamic therapy (n = 2), and submacular surgery (35.4%). Statistically significant correlations were found between the macular findings revealed after blood displacement and the additional treatments or observations selected for the underlying disease. The mean follow-up was 35 months. Improvements in visual acuity were statistically significant up to 3 years.

CONCLUSION

Intravitreal rtPA and gas injection was found to be effective for the displacement of large SMH, allowing postoperative diagnostic testing, and thus guiding the opportunity to apply further treatments. The addition of subsequent individualized treatments may allow long-term visual gain in selected cases.

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.

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.

Cellular regeneration strategies for macular degeneration: past, present and future

Despite considerable effort and significant therapeutic advances, age-related macular degeneration (AMD) remains the commonest cause of blindness in the developed world. Progressive late-stage AMD with outer retinal degeneration currently has no proven treatment. There has been significant interest in the possibility that cellular treatments may slow or reverse visual loss in AMD. A number of modes of action have been suggested, including cell replacement and rescue, as well as immune modulation to delay the neurodegenerative process. Their appeal in this enigmatic disease relate to their generic, non-pathway-specific effects. The outer retina in particular has been at the forefront of developments in cellular regenerative therapies being surgically accessible, easily observable, as well as having a relatively simple architecture. Both the retinal pigment epithelium (RPE) and photoreceptors have been considered for replacement therapies as both sheets and cell suspensions. Studies using autologous RPE, and to a lesser extent, foetal retina, have shown proof of principle. A wide variety of cell sources have been proposed with pluripotent stem cell-derived cells currently holding the centre stage. Recent early-phase trials using these cells for RPE replacement have met safety endpoints and hinted at possible efficacy. Animal studies have confirmed the promise that photoreceptor replacement, even in a completely degenerated outer retina may restore some vision. Many challenges, however, remain, not least of which include avoiding immune rejection, ensuring long-term cellular survival and maximising effect. This review provides an overview of progress made, ongoing studies and challenges ahead.

OCT angiography documented reperfusion of translocated autologous full thickness RPE-choroid graft for complicated neovascular age-related macular degeneration

PurposeThe purpose of this study is to investigate the reperfusion of translocated retinal pigment epithelium (RPE)-choroid graft in the treatment of patients with neovascular age-related macular degeneration (nAMD), using OCT angiography (OCTA), a novel non-invasive, high-resolution imaging modality.Patients and methodsEighteen eyes of 18 consecutive patients suffering from complicated nAMD underwent RPE-choroid patch graft translocation surgery using a peripheral retinotomy and flap-over technique. We analyzed functional and anatomical outcome using visual acuity, Spectral Domain OCT and OCTA.ResultsWith a mean follow-up of 11 months, out of 18 patients, 15 gained vision, 1 remained stable, and 2 lost vision. Overall, the visual acuity improved with a mean of 30 letters. Perfusion of the graft tissue was confirmed in all patients. Two patients developed signs of a recurrent neovascular membrane during follow-up. No cases of proliferative vitreoretinopathy occurred in this series.ConclusionsOCTA images show signs of perfusion in all grafts. Encouraging functional results and low risk of severe complications suggest that RPE-choroid graft translocation is a valid option in patients with complicated nAMD.

VISUAL RECOVERY AFTER AUTOLOGOUS RETINAL PIGMENT EPITHELIUM AND CHOROIDAL PATCH IN A PATIENT WITH CHOROIDAL NEOVASCULARIZATION SECONDARY TO ANGIOID STREAKS: LONG-TERM RESULTS

PURPOSE

To describe a successfully treated case of autologous retinal pigment epithelium and choroidal patch in a patient with choroidal neovascularization secondary to angioid streaks.

METHODS

A 53-year-old man with angioid streaks and a subfoveal choroidal neovascularization underwent autologous retinal pigment epithelium and choroid transplantation. Lensectomy, pars plana vitrectomy, 200° peripheral temporal retinotomy, isolation of the patch, endolaser, and silicone oil tamponade 1,000 cts were performed. Preoperative and postoperative ophthalmic examinations included best-corrected visual acuity, fluorescein angiography, indocyanine green angiography, autofluorescence, and optical coherence tomography.

RESULTS

Two months after surgery, best-corrected visual acuity (Snellen equivalent) improved from 20/200 to 20/100. At 6 months, best-corrected visual acuity further increased to 20/40 and the reading ability, which was absent preoperatively, improved to J2. Visual results were maintained after 2.5 years and no recurrence of choroidal neovascularization was observed.

CONCLUSION

Transplantation of a full-thickness patch of retinal pigment epithelium and choroid under the fovea may be considered to prevent retinal atrophy with significant visual improvement in the case of a low active choroidal neovascularization secondary to angioid streaks. Moreover, preoperative optical coherence tomography might guide in highlighting those patients in whom the outer retinal layers are still visible as the best candidate for surgery.

[Review of approaches to cell therapy in ophthalmology]

The review covers global trends in cell therapy research and clinical trials aimed at the treatment of ophthalmic diseases. Some definitions are provided and mechanisms of action of cell products studied to date are listed.

Direct Blood Flow Measurements in a Free RPE-Choroid Graft with Phase-Resolved Doppler OCT

PURPOSE

We directly demonstrated the revascularization in a free retinal pigment epithelium (RPE)-choroid graft with direct blood flow detection by experimental phase-resolved Doppler optical coherence tomography (PRD-OCT).

METHODS

Seven patients with age-related macular degeneration underwent an RPE-choroid graft translocation in a prospective institutional cohort study. Spectral domain optical coherence tomography (SD-OCT) was used to measure the revascularization stage. With PRD-OCT the presence of flow was imaged postoperatively.

RESULTS

The PRD-OCT confirmed flow in three patients when SD-OCT indicated the afferent vessel ingrowth stage, and in all seven patients when the SD-OCT indicated the efferent vessel ingrowth stage.

CONCLUSIONS

The PRD-OCT study was able to detect the presence of blood flow in a free RPE-choroid graft. The PRD-OCT findings directly confirmed the revascularization that was otherwise based on the more circumstantial evidence provided by SD-OCT images and angiography.

TRANSLATIONAL RELEVANCE

The use of both techniques to monitor the revascularization process in a free graft in patients are an interesting example of replacing more invasive by noninvasive techniques. There is potential future use of PRD-OCT for the visualization of vascularization patterns in other pathologies.

25th RCOphth Congress, President's Session paper: 25 years of progress in vitreoretinal surgery

Over the past 25 years, vitreoretinal surgery has undergone considerable change in technology, techniques, and professional organisation. Many conditions that were considered untreatable in 1988 are now treated routinely by vitreoretinal surgeons. Over the same period, vitreoretinal surgery has become a separate subspecialty with its own scientific meetings and professional organisation. This article describes a noncomprehensive selection of some of the highlights of the past 25 years, including the establishment and growth of BEAVRS (British and Eire Association of Vitreoretinal Surgeons), the revolution in the management of macular holes, the development of submacular surgery, and the introduction of sutureless vitrectomy.

ARPE-19 cell uptake of small and ultrasmall superparamagnetic iron oxide

PURPOSE

To investigate the cytotoxicity, cellular intake and magnetic field interaction of three superparamagnetic iron oxide (SPIO) and one ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles on ARPE-19 cells.

METHODS

Two FDA-approved SPIO nanoparticles (Endorem and Lumirem), one commercial SPIO(FluidMag-L) and one FDA-approved USPIO (Feraheme) were tested. Nanoparticle suspensions were diluted and prepared in high- (1000 Fe-ug/ml) and low- (100 Fe-ug/ml) dose suspensions. ARPE-19 cells were incubated in four 24-well plates and the medium changed every other day until cells attained 80% confluence. Nanoparticle cytotoxicity was evaluated using the XTT cytotoxicity assay. Cellular attraction was tested after digestion of the cells in collagenase A (1 mg/ml) overnight. A 3500 Gauss neodymium magnet was used to attract cells to the well walls. ARPE-19 cell ultrastructure was evaluated by transmission electron microscopy (TEM) to determine the specific locations of nanoparticles within the cell membranes.

RESULTS

Cytotoxicity assessment by the XTT assay revealed that ARPE-19 cells that were exposed to either concentration of Endorem, FLuidMag-L, Feraheme non-conjugated with protamine and heparin or Lumirem demonstrated no statistically significant toxicity. Cells exposed to Feraheme when conjugated with protamine and heparin presented severe toxicity in both concentrations. When a magnetic field was applied, all nanoparticle-containing samples, except Feraheme non-conjugated form, were promptly attracted. TEM and prussian blue staining examination revealed that Feraheme alone was not initially capable of cellular uptake. This issue was solved by conjugating Feraheme with protamine and heparin (although cytotoxicity was found on those samples). Endorem, FLuidMag-L, Feraheme conjugated form were found within the cytoplasm of ARPE-19 cells.

CONCLUSIONS

Ferahame when conjugated with protamine and heparin was cytotoxic at the higher and lower doses, as revealed by the XTT assay. Endorem and FluidMag-L were not toxic at the studied concentrations. Feraheme non-conjugated solutions and Lumirem solutions provided were harmless but were not internalized by ARPE-19 cells. All the studied nanoparticles were attracted to the magnetic field except Feraheme in the non-conjugated form.

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.

Morphologic features and viability analysis of human detached retinal pigment epithelium in age-related macular degeneration

PURPOSE

To evaluate the morphologic features and viability of human retinal pigment epithelium (RPE) cells captured from the pigment epithelium detachment (PED) region outside the choroidal neovascular membrane lesion in eyes with hemorrhagic age-related macular degeneration.

DESIGN

Prospective, observational case series.

METHODS

Five specimens of the RPE sheet were obtained from the PED region after choroidal neovascular membrane excision in 5 eyes of 5 patients during RPE transplantation for hemorrhagic age-related macular degeneration. The specimens were stained with hematoxylin and eosin and with periodic acid-Schiff. Immunohistochemistry analysis for RPE-65 and zonula occludens-1 also was performed. RPE cells from the PED region were cultured and passaged 5 times. Scanning and transmission electron microscopy were performed to analyze the specimens.

RESULTS

The RPE cells of the specimens contained brownish pigment and were autofluorescent in vitro. Periodic acid-Schiff staining revealed that the Bruch membrane below the RPE monolayer was not intact. The specimens demonstrated positive results for both zonula occludens-1 and RPE-65 staining. The RPE basement membrane in the specimen was observed by both scanning and transmission electron microscopy. Intercellular tight junctions among RPE cells of the specimen also were observed. RPE cells captured from the PED region were cultured successfully and were passaged 5 times.

CONCLUSIONS

The RPE sheet developed from the PED region outside the choroidal neovascular membrane lesion had tight intercellular junctions, a simple RPE basement membrane, and active cellular viability. This monolayer RPE sheet may be considered as a substitution for subfoveal RPE loss in eyes with hemorrhagic age-related macular degeneration.

Comparison of anatomic and functional results after retinotomy for retinal detachment in pediatric and adult patients

PURPOSE

We investigated characteristics and treatment outcomes of pediatric vs adult retinal detachment managed by retinotomy and retinectomy.


METHODS

This was a retrospective, nonrandomized, interventional study involving 20 pediatric patients and 25 adult patients operated with vitrectomy and retinectomy due to retinal detachment. Outcome measures included preoperative and postoperative visual acuity at 6 months and at final visit, postoperative proliferative vitreoretinopathy, silicone oil removal, final intraocular pressure (IOP), and final anatomic success, defined as complete retinal reattachment.


RESULTS

Reattachment was observed in 60% (12/20) of pediatric patients and 88% (22/25) of adults at final visit (p=0.041). Statistically significant improvement in visual acuity was observed in adults (p<0.001) but not in children (p=0.360) due to large proportion of anatomic failure. Children required a higher number of further reoperations (p=0.008). Postoperative proliferative vitreoretinopathy was significantly more frequent in pediatric eyes (p=0.003). 


CONCLUSIONS

The clinical features and prognosis for pediatric retinotomies and retinectomies are different from those for adults. When a decision to perform retinotomy in children is made, we can anticipate significantly lower anatomic success than in adults. Even though the overall visual acuity was worse in children than in adults, 25% of pediatric eyes achieved 5/50 or better vision.

Cell replacement and visual restoration by retinal sheet transplants

Retinal diseases such as age-related macular degeneration (ARMD) and retinitis pigmentosa (RP) affect millions of people. Replacing lost cells with new cells that connect with the still functional part of the host retina might repair a degenerating retina and restore eyesight to an unknown extent. A unique model, subretinal transplantation of freshly dissected sheets of fetal-derived retinal progenitor cells, combined with its retinal pigment epithelium (RPE), has demonstrated successful results in both animals and humans. Most other approaches are restricted to rescue endogenous retinal cells of the recipient in earlier disease stages by a 'nursing' role of the implanted cells and are not aimed at neural retinal cell replacement. Sheet transplants restore lost visual responses in several retinal degeneration models in the superior colliculus (SC) corresponding to the location of the transplant in the retina. They do not simply preserve visual performance - they increase visual responsiveness to light. Restoration of visual responses in the SC can be directly traced to neural cells in the transplant, demonstrating that synaptic connections between transplant and host contribute to the visual improvement. Transplant processes invade the inner plexiform layer of the host retina and form synapses with presumable host cells. In a Phase II trial of RP and ARMD patients, transplants of retina together with its RPE improved visual acuity. In summary, retinal progenitor sheet transplantation provides an excellent model to answer questions about how to repair and restore function of a degenerating retina. Supply of fetal donor tissue will always be limited but the model can set a standard and provide an informative base for optimal cell replacement therapies such as embryonic stem cell (ESC)-derived therapy.

A pedicled autologous choroid RPE patch: a technique to preserve perfusion

The aim of the study is to report a technique of a pedicled autologous choroid retinal pigment epithelium (RPE) patch that aims to preserve perfusion of the transplanted tissue. A case report of a patient with sudden vision deterioration due to submacular hemorrhage in age-related macular degeneration. The surgery involved a 180-degree peripheral retinectomy and the creation of a pedicled graft instead of an isolated one. Outcome measures included preoperative and postoperative visual acuity and optical coherence tomography scans at 1, 3, 6, 12 months and patch vascularization on postoperative indocyanine green angiography. Postoperatively the patch was positioned under the fovea with an intact pedicle. Indocyanine green angiography showed perfusion through the pedicle and patch vasculature on the third postoperative day. Best corrected visual acuity improved from 0.5/50 to 5/50 at 1 month and remained stable over 1 year follow-up. No choroidal neovascularization recurrence was observed. This case report demonstrates the feasibility of a pedicled RPE-choroid graft that is an alternative to a free isolated graft. Our modification of patch surgery, by demonstrating early perfusion, offers an advantage, similar to macular translocation, when photoreceptors are embedded in RPE and choroid with blood circulation immediately after the surgery.

Ophthalmic transplantology: posterior segment of the eye--part II

Background

Transplants of the retina are among the new strategies being used in the treatment of genetic and degenerative macular diseases. Moreover, various cell cultures are being tested to treat retinal disorders.

Material/Methods

Literature dated from 2004 to 2011 was comprehensively examined via Medline and PubMed searches for the following terms: auto-, homo-, heterologous transplantation, retina, stem cells, cultivated cells.

Results

Tissue and cell therapy of retinal diseases are reviewed, including full-thickness retina/retinal pigment epithelium (RPE)/choroid graft; full and partial thickness RPE/choroid complex grafts; RPE/Bruch membrane complex graft; and RPE, iris pigment epithelium and stem cell grafts. Recommendations for transplants, as well as the benefits and weaknesses of specific techniques in retina transplants, are discussed.

Conclusions

Auto- and allogenic transplants of a full or partial thickness retina/RPE/Bruch membrane/choroid complex represent an alternative treatment offered to patients with some macular diseases. Stem cell transplantation to reconstruct and regenerate the macula requires further biomolecular and animal research studies.

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.

Phase-stabilized optical frequency domain imaging at 1-µm for the measurement of blood flow in the human choroid

In optical frequency domain imaging (OFDI) the measurement of interference fringes is not exactly reproducible due to small instabilities in the swept-source laser, the interferometer and the data-acquisition hardware. The resulting variation in wavenumber sampling makes phase-resolved detection and the removal of fixed-pattern noise challenging in OFDI. In this paper this problem is solved by a new post-processing method in which interference fringes are resampled to the exact same wavenumber space using a simultaneously recorded calibration signal. This method is implemented in a high-speed (100 kHz) high-resolution (6.5 µm) OFDI system at 1-µm and is used for the removal of fixed-pattern noise artifacts and for phase-resolved blood flow measurements in the human choroid. The system performed close to the shot-noise limit (<1dB) with a sensitivity of 99.1 dB for a 1.7 mW sample arm power. Suppression of fixed-pattern noise artifacts is shown up to 39.0 dB which effectively removes all artifacts from the OFDI-images. The clinical potential of the system is shown by the detection of choroidal blood flow in a healthy volunteer and the detection of tissue reperfusion in a patient after a retinal pigment epithelium and choroid transplantation.

Retinal stimuli can be restored after autologous transplant of retinal pigment epithelium and choroid in pigment epithelium tears

PURPOSE

To evaluate the functional and anatomical outcome of patients undergoing autologous transplant of retinal pigment epithelium (RPE) and choroid after RPE tear secondary to age-related macular degeneration (AMD).

METHODS

Data from nine eyes of nine patients were analysed retrospectively. Examinations included fluorescein and indocyanine green angiography, fundus autofluorescence imaging, optical coherence tomography, microperimetry and determination of visual acuity (far and reading ability). Data regarding intraoperative and postoperative complications were recorded. Mean follow-up time was 18 months (range 4 months to 5 years).

RESULTS

After surgery, far visual acuity improved or remained stable (±3 lines) in three of nine eyes and for the near visual acuity in three of nine eyes. Visual acuity decreased postoperatively at the last follow-up in four eyes mainly because of postoperative complications, i.e. retinal detachment due to proliferative vitreoretinopathy, retinal artery occlusion, pucker and fibrosis of the graft. In one case, retinal stimuli were restored over the scotoma as seen in microperimetry.

CONCLUSION

Autologous transplant of RPE and choroid is a therapy option for RPE tears. Retinal stimuli can be restored in selected cases. Numerous intra- and postoperative complications compromise the functional prognosis and outcome.