Search Results (22)

Background: Rhegmatogenous retinal detachment (RRD), the most common type of retinal detachment, requires prompt surgery to reattach the retina and avoid permanent vision loss. While surgical treatment is adapted to each individual case, one frequent option is pars plana vitrectomy (PPV) with silicone oil (SO) tamponade. Despite achieving anatomical success (complete retinal attachment), concerns persist regarding potential microvascular alterations in the retina and choroid, with a negative impact on visual function. Optical coherence tomography angiography (OCTA) allows detailed, in-depth imaging of retinal and choroidal circulation, whereas microperimetry makes it possible to accurately assess macular function. This review aims to strengthen the existing evidence on vascular and functional alterations at the macular level after SO tamponade in cases of RRD. Methods: A narrative review was conducted using a structured approach, utilizing a PubMed search from January 2000 up to April 2025. Twenty-three studies on OCTA and microperimetry after SO tamponade for RRD were included. Data on vessel densities, choroidal vascular index (CVI), foveal avascular zone (FAZ) size, and retinal sensitivity were extracted and qualitatively analyzed. Results: Studies consistently reported a reduction in the vessel density within the superficial capillary plexus (SCP) under SO tamponade, with partial but incomplete reperfusion post-removal. Choroidal perfusion and CVI were also decreased, exhibiting a negative correlation with the duration of SO tamponade. Microperimetry demonstrated significant reductions in retinal sensitivity (~5–10 dB) during SO tamponade, which modestly improved (~1–2 dB) following removal but generally remaining below normal levels. Conclusions: SO tamponade causes substantial retinal and choroidal vascular impairment and measurable macular dysfunction, even after anatomical reattachment of the retina. It is recommended to perform early SO removal (~3–4 months) and implement routine monitoring by OCTA and microperimetry with the aim of optimizing patient outcomes. Future research should focus on investigating protective strategies and enhancing visual rehabilitation following RRD repair. Full article

Retina-like photoimaging devices with features such as a wide-field-of-view and high spatial resolution have wide application prospects in retinal prosthetics and remote sensing. However, the fabrication of flexible and conformal surfaces is hindered by the incompatible microfabrication processes of traditional rigid, silicon-based substrates. A kirigami strategy for hemispherical surface assembly is proposed to construct a MoS₂-based retina-like photodetector array. The device is first fabricated on a flat polyimide (PI) substrate and then tailored using a laser. By approximating the spherical surface using planar sectors, the laser-cut PI film can tightly adhere to the PDMS spherical shell without significant wrinkles. The responsivity and specific detectivity of our conformal photodetector can reach as high as 247.9 A/W and 6.16 × 10¹¹ Jones, respectively. The array integrates 180 pixels on a spherical crown with a radius of 11 mm, and a hollow letter “T” is successfully recognized. Comprehensive experimental results in this work reveal the utility of our device for photoelectric detection and imaging. We believe that our work provides a new methodology for the exploitation of 2D material-based retinal image sensors. Full article

This study evaluated the neuroprotective potential of peptain-1 conjugated to a cell-penetrating peptide (CPP-P1) in an ocular hypertension model of glaucoma. Brown Norway (BN) rats were subjected to intraocular pressure (IOP) elevation via intracameral injection of silicone oil (SO), with concurrent intravitreal injections of either CPP-P1 or a vehicle. Retinal cross-sections were analyzed for markers of neuroprotection, including cAMP response element-binding protein (CREB), phosphorylated CREB (p-CREB), growth-associated protein-43 (GAP43), synapsin-1 (SYN1), and superoxide dismutase 2 (SOD2). Hematoxylin and eosin staining was used to assess retinal-layer thickness. SO-treated rats exhibited significant reductions in the thickness of the inner nuclear layer (INL, 41%, p = 0.016), inner plexiform layer (IPL, 52%, p = 0.0002), and ganglion cell layer (GCL, 57%, p = 0.001). CPP-P1 treatment mitigated these reductions, preserving INL thickness by 32% (p = 0.059), IPL by 19% (p = 0.119), and GCL by 31% (p = 0.057). Increased levels of CREB (p = 0.17) and p-CREB (p = 0.04) were observed in IOP-elevated, CPP-P1-treated retinas compared to IOP-elevated, vehicle-treated retinas. Although overall GAP43 levels were low, there was a modest increase in expression within the IPL and GCL in SO- and CPP-P1-treated retinas (p = 0.15 and p = 0.09, respectively) compared to SO- and vehicle-treated retinas. SO injection reduced SYN1 expression in both IPL and GCL (p = 0.01), whereas CPP-P1 treatment significantly increased SYN1 levels in the IPL (p = 0.03) and GCL (p = 0.002). While SOD2 expression in the GCL was minimal across all groups, a trend toward increased expression was observed in CPP-P1-treated animals (p = 0.16). The SO model was replicated with SO removal after 7 days and monitored for 21 days followed by retinal flat-mount preparation to assess retinal ganglion cell (RGC) survival. A 42% loss in RGCs (p = 0.009) was observed in SO-injected eyes, which were reduced by approximately 37% (p = 0.03) with CPP-P1 treatment. These findings suggest that CPP-P1 is a promising neuroprotective agent that promotes retinal ganglion cell survival and the preservation of other retinal neurons, potentially through enhanced CREB signaling in a rat model of SO-induced ocular hypertension. Full article

In this study, we describe a case of graft dislocation into the vitreous cavity after Descemet stripping automated endothelial keratoplasty (DSAEK), and review the risk factors and complications of posterior dislocation. A 70-year-old female with disruption of the iris–lens diaphragm experienced DSAEK graft dislocation into the vitreous cavity during air re-bubbling at 1 week postoperatively. The corneal opacity hindered adequate visualization of the vitreous cavity for the immediate retrieval of the graft. Five days after re-bubbling, vitrectomy and corneal tissue removal was performed using a temporary Eckardt keratoprosthesis, and penetrating keratoplasty was subsequently performed. Two weeks after graft removal, a retinal detachment occurred. Silicon oil was used as a tamponade to reattach the retina. Three months after the last procedure, the retina was attached, and the cornea was clear. Posterior dislocation of DSAEK graft is a rare complication. A disrupted iris–lens diaphragm and previous vitrectomy are the main risk factors. Severe vision loss is more likely to occur when corneal tissue removal is delayed. In cases of delayed removal, it is advisable to take precautions to prevent possible retinal detachment. Full article

Background: Endotamponade of the vitreous body with silicone oil is a common procedure, being the basis of many vitreoretinal surgeries. However, emulsification may happen, which is a clinically relevant adverse event of silicone oil use. Methods: This review provides a thorough analysis of the emulsification process. It focuses on describing factors affecting this event as well as its possible subsequent complications. Results: The viscosity of silicone oil, the duration of emulsification, the status of the lens and many other factors have an influence on the onset and intensity of emulsification. This phenomenon carries several risks for operated eyes such as increased intraocular pressure, keratopathy or structural changes to the retina. Conclusions: The use of modern imaging techniques, especially optical coherence tomography, enables faster detection of the emulsification process. This allows for an adequate clinical response and more accurate follow-up of the patient. Full article

Neuromorphic Vision Sensors (NVSs) are emerging sensors that acquire visual information asynchronously when changes occur in the scene. Their advantages versus synchronous capturing (frame-based video) include a low power consumption, a high dynamic range, an extremely high temporal resolution, and lower data rates. Although the acquisition strategy already results in much lower data rates than conventional video, NVS data can be further compressed. For this purpose, we recently proposed Time Aggregation-based Lossless Video Encoding for Neuromorphic Vision Sensor Data (TALVEN), consisting in the time aggregation of NVS events in the form of pixel-based event histograms, arrangement of the data in a specific format, and lossless compression inspired by video encoding. In this paper, we still leverage time aggregation but, rather than performing encoding inspired by frame-based video coding, we encode an appropriate representation of the time-aggregated data via point-cloud compression (similar to another one of our previous works, where time aggregation was not used). The proposed strategy, Time-Aggregated Lossless Encoding of Events based on Point-Cloud Compression (TALEN-PCC), outperforms the originally proposed TALVEN encoding strategy for the content in the considered dataset. The gain in terms of the compression ratio is the highest for low-event rate and low-complexity scenes, whereas the improvement is minimal for high-complexity and high-event rate scenes. According to experiments on outdoor and indoor spike event data, TALEN-PCC achieves higher compression gains for time aggregation intervals of more than 5 ms. However, the compression gains are lower when compared to state-of-the-art approaches for time aggregation intervals of less than 5 ms. Full article

An ultrathin nano photodiode array fabricated in a flexible substrate can be an ideal therapeutic replacement for degenerated photoreceptor cells damaged by Age-related Macula Degeneration (AMD) and Retinitis Pigmentosa (RP), such as retinal infections. Silicon-based photodiode arrays have been attempted as artificial retinas. Considering the difficulties caused by hard silicon subretinal implants, researchers have diverted their attention towards organic photovoltaic cells-based subretinal implants. Indium-Tin Oxide (ITO) has been a favorite choice as an anode electrode. A mix of poly(3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyleste (P3HT: PCBM) has been utilized as an active layer in such nanomaterial-based subretinal implants. Though encouraging results have been obtained during the trial of such retinal implants, the need to replace ITO with a suitable transparent conductive electrode will be a suitable substitute. Further, conjugated polymers have been used as active layers in such photodiodes and have shown delamination in the retinal space over time despite their biocompatibility. This research attempted to fabricate and characterize Bulk Hetero Junction (BHJ) based Nano Photo Diode (NPD) utilizing Graphene–polyethylene terephthalate (G–PET)/semiconducting Single-Wall Carbon Nano Tubes (s-SWCNT): fullerene (C₆₀) blend/aluminium (Al) structure to determine the issues in the development of subretinal prosthesis. An effective design approach adopted in this analysis has resulted in developing an NPD with an Efficiency of 10.1% in a non-ITO-driven NPD structure. Additionally, the results show that the efficiency can be further improved by increasing active layer thickness. Full article

Pathological tissue on the surface of the retina that can be of different etiology and pathogenesis can cause changes in the retina that have a direct consequence on vision. Tissues of different etiology and pathogenesis have different morphological structures and also different macromolecule compositions usually characteristic of specific diseases. In this study, we evaluated and compared biochemical differences among samples of three different types of epiretinal proliferations: idiopathic epiretinal membrane (ERMi), membranes in proliferative vitreoretinopathy (PVRm), and proliferative diabetic retinopathy (PDRm). The membranes were analyzed by using synchrotron radiation-based Fourier transform infrared micro-spectroscopy (SR-FTIR). We used the SR-FTIR micro-spectroscopy setup, where measurements were set to achieve a high resolution that was capable of showing clear biochemical spectra in biological tissue. We were able to identify differences between PVRm, PDRm, and ERMi in protein and lipid structure; collagen content and collagen maturity; differences in proteoglycan presence; protein phosphorylation; and DNA expression. Collagen showed the strongest expression in PDRm, lower expression in ERMi, and very low expression in PVRm. We also demonstrated the presence of silicone oil (SO) or polydimethylsiloxane in the structure of PVRm after SO endotamponade. This finding suggests that SO, in addition to its many benefits as an important tool in vitreoretinal surgery, could be involved in PVRm formation. Full article

The vitreous humour is a gel-like structure that composes the majority of each eye. It functions to provide passage of light, be a viscoelastic dampener, and hold the retina in place. Vitreous liquefaction causes retinal detachment and retinal tears requiring pars plana vitrectomy for vitreous substitution. An ideal vitreous substitute should display similar mechanical, chemical, and rheological properties to the natural vitreous. Currently used vitreous substitutes such as silicone oil, perfluorocarbon liquids, and gases cannot be used long-term due to adverse effects such as poor retention time, cytotoxicity, and cataract formation. Long-term, experimental vitreous substitutes composed of natural, modified and synthetic polymers are currently being studied. This review discusses current long- and short-term vitreous substitutes and the disadvantages of these that have highlighted the need for an ideal vitreous substitute. The review subsequently focuses specifically on currently used polysaccharide- and synthetic polymer-based vitreous substitutes, which may be modified or functionalised, or employed as the derivative, and discusses experimental vitreous substitutes in these classes. The advantages and challenges associated with the use of polymeric substitutes are discussed. Innovative approaches to vitreous substitution, namely a novel foldable capsular vitreous body, are presented, as well as future perspectives related to the advancement of this field. Full article

(1) Background: We aimed to systematically review the current literature to evaluate if in patients with postoperative endophthalmitis treated with pars plana vitrectomy, silicone oil tamponade could provide a useful contribution to the control and eradication of infection and if it could influence anatomical recovery and functional outcome. (2) Randomized controlled trials, cross-sectional studies, case series, and case reports published in the English language in peer-reviewed journals were included. No restriction was placed based on the study location. We used medical subject headings (MeSH) and text words. We searched MEDLINE (OVID and PubMed), Google Scholar, ISI Web of Science (Thom-on-Reuters), and the Cochrane Library (Wiley) from January 1995 to the present. To ensure literature saturation, we scanned the reference lists of included studies or relevant reviews identified through the search. Risk of Bias was assessed using the Newcastle-Ottawa scale for longitudinal studies and Cochrane risk-of-bias tool for randomized trials. (3) Results: abstracts of 75 articles were selected for full-text reading; after full-text reading, 44 articles were taken into consideration in the systematic review. 5 out of 7 in vitro experimental studies demonstrated antimicrobial activity against different species of bacteria and fungi. The use of SO as endotamponade associated with PPV led to better visual acuity and a lower rate of retinal detachment and the need for additional surgery. (4) Conclusions: Silicone oil reduces the risk of postoperative retinal detachment, especially in case of undetected retinal breaks, produces compartmentalization of the eye, may lead to early visual recovery, allows laser photocoagulation, prevents severe postoperative hypotony and has antimicrobic activity due to an inhibitory effect for several species of pathogens. Concerns regarding possible toxic effects on the retina and optic disc, compartmentalization and impaired washout of pathogen toxins have been reported. It may also influence intravitreal antibiotic distribution and clearance. Full article

Silicone oils (SO) are used as long-term intraocular tamponades and have an irreplaceable role in vitreoretinal surgery. They can, however, be associated with multiple and potentially severe complications, involving different ocular tissues, in particular retina and cornea. Recent advances in ophthalmic imaging have allowed the precise characterization of retinal and corneal microstructural changes, at a subclinical level. This detailed analysis of SO-related retinal and corneal changes has improved our understanding of their pathogenesis and offer the potential for optimized monitoring and management of patients with SO-filled eyes. This review aims to provide clinicians and ophthalmic scientists with an updated and comprehensive overview of the corneal and retinal changes associated with SO tamponade. Full article

Purpose: The development of primary human retinal pigmented epithelium (hRPE) for clinical transplantation purposes on biodegradable scaffolds is indispensable. We hereby report the results of the subretinal implantation of hRPE cells on nanofibrous membranes in minipigs. Methods: The hRPEs were collected from human cadaver donor eyes and cultivated on ultrathin nanofibrous carriers prepared via the electrospinning of poly(L-lactide-co-DL-lactide) (PDLLA). “Libechov” minipigs (12–36 months old) were used in the study, supported by preoperative tacrolimus immunosuppressive therapy. The subretinal implantation of the hRPE-nanofibrous carrier was conducted using general anesthesia via a custom-made injector during standard three-port 23-gauge vitrectomy, followed by silicone oil endotamponade. The observational period lasted 1, 2, 6 and 8 weeks, and included in vivo optical coherence tomography (OCT) of the retina, as well as post mortem immunohistochemistry using the following antibodies: HNAA and STEM121 (human cell markers); Bestrophin and CRALBP (hRPE cell markers); peanut agglutining (PNA) (cone photoreceptor marker); PKCα (rod bipolar marker); Vimentin, GFAP (macroglial markers); and Iba1 (microglial marker). Results: The hRPEs assumed cobblestone morphology, persistent pigmentation and measurable trans-epithelial electrical resistance on the nanofibrous PDLLA carrier. The surgical delivery of the implants in the subretinal space of the immunosuppressed minipigs was successfully achieved and monitored by fundus imaging and OCT. The implanted hRPEs were positive for HNAA and STEM121 and were located between the minipig’s neuroretina and RPE layers at week 2 post-implantation, which was gradually attenuated until week 8. The neuroretina over the implants showed rosette or hypertrophic reaction at week 6. The implanted cells expressed the typical RPE marker bestrophin throughout the whole observation period, and a gradual diminishing of the CRALBP expression in the area of implantation at week 8 post-implantation was observed. The transplanted hRPEs appeared not to form a confluent layer and were less capable of keeping the inner and outer retinal segments intact. The cone photoreceptors adjacent to the implant scaffold were unchanged initially, but underwent a gradual change in structure after hRPE implantation; the retina above and below the implant appeared relatively healthy. The glial reaction of the transplanted and host retina showed Vimentin and GFAP positivity from week 1 onward. Microglial activation appeared in the retinal area of the transplant early after the surgery, which seemed to move into the transplant area over time. Conclusions: The differentiated hRPEs can serve as an alternative cell source for RPE replacement in animal studies. These cells can be cultivated on nanofibrous PDLLA and implanted subretinally into minipigs using standard 23-gauge vitrectomy and implantation injector. The hRPE-laden scaffolds demonstrated relatively good incorporation into the host retina over an eight-week observation period, with some indication of a gliotic scar formation, and a likely neuroinflammatory response in the transplanted area despite the use of immunosuppression. Full article

This study aimed to evaluate and compare the retinal and choroidal thickness and vessel density (VD) changes between silicone oil (SO) tamponade and after SO removal using swept-source optical coherence tomography (SS-OCT) and OCT angiography (OCTA). Thirty patients who underwent pars plana vitrectomy for retinal detachment (RD) with SO tamponade were included. SS-OCT and OCTA were conducted before RD surgery, during SO tamponade, and after SO removal. A 3-dimensional volumetric wide scan protocol was used for the analysis. The segmented retina, choroidal thickness map, and peripapillary thickness were then measured. For the OCTA analysis, 4.5 × 4.5 mm scans were used. Superficial and deep capillary plexus VDs in unaffected fellow eyes and eyes after SO removal were compared. During the SO tamponade period, the thickness of the parafoveal total retina, ganglion cell-inner plexiform layer, and peripapillary retinal nerve fiber layer (ppRNFL) were significantly thinner than those of unaffected fellow eyes (p < 0.05). The parafoveal layer thickness thinning recovered up to three to six months after SO removal. Moreover, six months after SO removal, the parafoveal thickness was not significantly different compared to that of unaffected fellow eyes (p > 0.05). However, the ppRNFL thickness was significantly decreased during SO tamponade and remained unrecovered six months after SO removal. There was no significant difference in the VD on the OCTA. Thus, SO tamponade and removal for RD resulted in a change in the retinal and peripapillary thickness. This may be due to the mechanical pressure effect of SO. Full article

The temperature of the vitreous has been reported to vary during cataract and vitreous surgery. We measured intraocular temperature at four intraocular sites; the anterior chamber (AC), just behind the crystalline lens, mid-vitreous, and just anterior to the optic disc (OD) at the beginning of vitrectomy with a thermoprobe in 48 eyes. The temperatures were compared in three groups; eyes that underwent vitrectomy for the first time (Group V, n = 30), eyes that had previous vitrectomy and the vitreous cavity had been filled with balanced salt solution (BSS; Group A, n = 12), and eyes that had previous vitrectomy and the vitreous cavity was filled with silicone oil (Group S, n = 6). There was a gradient in the temperature in all groups, i.e., it was lowest in the AC, and it increased at points closer to the retina. The intraocular temperature was significantly correlated with the type of fluid in the vitreous cavity. The mean intraocular temperatures were not significantly different in Groups V and A, but they were significantly higher in Group S. Clinicians should be aware of the differences in the temperature at the different intraocular sites because the temperatures may affect the physiology of the retina and the recovery process. Full article

The aim of this study was to report on the anatomical and functional results of surgical management of seven cases of endophthalmitis related to a single day of intravitreal aflibercept injections. Patients with signs of endophthalmitis who underwent aflibercept injections (seven eyes) performed on the same day were retrospectively evaluated. The data of visual acuity and optical coherence tomography (OCT) within nine months of the follow-up and the treatment and results of microbiological cultures are reported. Four of the total seven cases had a positive bacterial culture outcome (Streptococcus mitis). All patients underwent vitrectomy combined with phacoemulsification when the eyes were not pseudophakic, vancomycin infusion, and silicone oil tamponade within 24 h; additionally, systemic antibiotics were administered intravenously. The final best-corrected visual acuity (BCVA) after the treatment was finger counting or light perception in all cases, and all eyes were saved with disruption of the inner retinal layers and stabilization of the retina in regard to changes related to the wet age-related macular degeneration (AMD). Although the retinal anatomy was mostly preserved, most of the patients affected by Streptococcus mitis-induced endophthalmitis did not regain baseline vision after the therapy. Full article