Biodegradable nanofibrillated microcellular PBS/PLA foams for selective oil absorption.

To address the challenges posed by spilled oil and oily wastewater, the development of clean oil-adsorption materials is crucial. However, traditional oil-adsorption materials suffer from the issue of secondary pollution. Herein, fully biodegradable nanofibrillated poly(butylene succinate)/poly(lactic acid) (PBS/PLA) foams with outstanding selective oil-adsorption performance were successfully fabricated via an eco-friendly supercritical CO2 foaming technology. The PBS/PLA composites, featuring nanofibrils with a diameter of approximately 100 nm, were prepared through a hot-stretching method subsequent to extrusion. Substantial improvements were observed in the crystallization rate and rheological properties of the fibrillated PBS/PLA composites. Furthermore, PLA nanofibrils enhanced foamability of the composite, achieving an impressive expansion ratio of up to 38.0, resulting in an outstanding oil-absorption performance (19.2-50.4 g/g) of the F-1 %-95 foam. Additionally, 20 adsorption-desorption cycles illustrated the prepared F-1 %-95 foam displayed recyclable oil-absorption characteristics. This work provides an eco-friendly strategy for preparing fully biodegradable foams intended for application as oil-adsorption materials.

Super toughened blends of poly(lactic acid) and poly(butylene adipate-co-terephthalate) injection-molded foams via enhancing interfacial compatibility and cellular structure.

Biodegradable poly(lactic acid) (PLA) foams have drawn increasing attention due to environmental challenges and petroleum crisis. However, it still remains a challenge to prepare PLA foams with fine cellular structures and high impact property, which significantly hinders its widespread application. Herein, phase interface-enhanced PLA/ poly(butylene adipate-co-terephthalate) (PBAT) blend foam, modified by a reactive compatibilizer through a simple reactive extrusion, was produced via a core-back foam injection molding technique. The obtained PLA blend foams displayed an impact strength as high as 49.1 kJ/m2, which was 9.3 and 6.4 times that of the unmodified PLA/PBAT blend and its corresponding foam, respectively. It proved that the interfacial adhesion and cell size both strongly affected the impact strength of injection-molded PLA/PBAT foams, and two major conclusions were proposed. First, enhancing interfacial adhesion could cause a brittle-tough transition of PLA/PBAT foams. Additionally, for foams with high interfacial adhesion, small cell size (<12 µm) was more favorable for the stretching of cells and extension of the whitened region in comparison with big cell size (cell size >60 µm), leading to the drastic toughening of PLA blends. This study provides a feasible, industrially scalable and practical strategy to prepare super toughened and fully biodegradable PLA materials.

The Synergistic Effects between Sulfobetaine and Hydrophobically Modified Polyacrylamide on Properties Related to Enhanced Oil Recovery.

In order to explore the mechanism responsible for the interactions in the surfactant-polymer composite flooding and broaden the application range of the binary system in heterogeneous oil reservoirs, in this paper, the influences of different surfactants on the viscosity of two polymers with similar molecular weights, partially hydrolyzed polyacrylamide (HPAM) and hydrophobically modified polyacrylamide (HMPAM), were studied at different reservoir environments. In addition, the relationship between the surfactant-polymer synergistic effects and oil displacement efficiency was also investigated. The experimental results show that for HPAM, surfactants mainly act as an electrolyte to reduce its viscosity. For HMPAM, SDBS and TX-100 will form aggregates with the hydrophobic blocks of polymer molecules, reducing the bulk viscosity. However, zwitterionic surfactant aralkyl substituted alkyl sulfobetaine BSB molecules can build "bridges" between different polymer molecules through hydrogen bonding and electrostatic interaction. After forming aggregates with HMPAM molecules, the viscosity will increase. The presence of two polymers all weakened the surfactant oil-water interfacial membrane strength to a certain extent, but had little effect on the interfacial tension. The synergistic effect of the "bridge" between HMPAM and BSB under macroscopic conditions also occurs in the microscopic pores of the core, which has a beneficial effect on improving oil recovery.

Dynamic Interfacial Tensions of Surfactant and Polymer Solutions Related to High-Temperature and High-Salinity Reservoir.

Betaine is a new surfactant with good application prospects in high-temperature and high-salinity reservoirs. The interfacial properties of two kinds of betaine mixtures with a good synergistic effect were evaluated in this paper. On this basis, the effects of temperature-resistant, salt-resistant polymers with different contents of 2-acrylamide-2-methylpropanesulfonic acid (AMPS) on dynamic interfacial tensions (IFTs) against n-alkanes and crude oil were studied. The experimental results show that the IFTs between betaine ASB and n-alkanes can be reduced to ultra-low values by compounding with anionic surfactant petroleum sulfonate (PS) and extended anionic surfactant alkoxyethylene carboxylate (AEC), respectively. ASB@AEC is very oil-soluble with nmin value ≥14, and ASB@PS is relatively water-soluble with nmin value of 10. The water solubility of both ASB@PS and ASB@AEC is enhanced by the addition of water-soluble polymers. The HLB of the ASB@AEC solution becomes better against crude oil after the addition of polymers, and the IFT decreases to an ultra-low value as a result. On the contrary, the antagonistic effect in reducing the IFT can be observed for ASB@PS in the same case. In a word, polymers affect the IFTs of surfactant solutions by regulating the HLB.

Improved thermal insulation and compressive property of bimodal poly (lactic acid)/cellulose nanocomposite foams.

In this work, an innovative PLA/CNF nanocomposite foam with a bimodal cell structure is prepared by a simple one-step depressurization foaming process using only supercritical carbon dioxide (ScCO2) as the foaming agent. Only at a specific foaming temperature, PLA/CNF nanocomposites foam with a bimodal cell structure could be obtained. According to the different crystallization kinetics and nucleation efficiency of samples, it was inferred that the crystallization rate and phase interface would affect the cell structure. The prepared PLA/CNF nanocomposite foam with a bimodal cell structure had an expansion ratio as high as 20 times and thermal conductivity of 0.041 w m-1 k-1, which exhibited low density and excellent thermal-insulation property. Meanwhile, the PLA/CNF nanocomposite foam exhibited excellent compression performance due to the presence of CNFs, which showed promising application in packaging and construction materials.

PEELED INTERNAL LIMITING MEMBRANE REPOSITION FOR IDIOPATHIC MACULAR HOLES: A Pilot Randomized Controlled Trial.

PURPOSE: To compare the functional and anatomical outcomes of peeled internal limiting membrane reposition and traditional internal limiting membrane peeling for the treatment of idiopathic macular hole. METHODS: This is a randomized, single-center, and double-blinded, pilot, controlled trial. RESULTS: Of the 30 patients enrolled, 27 (13 in Group 1 and 14 in Group 2) were included in the primary analysis (22 women [81.5%]; mean [SD] age, 61.7 [6.8] years). The BCVA was 0.23 ± 0.18 logMAR in the reposition group and 0.44 ± 0.24 logMAR in the peeling group at 6 months postoperatively (P = 0.02). The primary MH closure rate is 86.7% in the reposition group and 93.3% in the peeling group (P = 0.60). The range of the inner retinal dimpling was significantly lower in the reposition group at 6 months postoperatively (P < 0.0001). The thickness of the full parafovea (P = 0.0092), inner parafovea (P = 0.0007), inner perifovea (P = 0.0044), and outer fovea (P = 0.0392) was significantly greater in the reposition group than that in the peeling group at 6 months postoperatively. The sensitivity threshold and mfERG P1 wave amplitude density in rings one, four, and five were higher in the reposition group than in the peeling group at 6 months postoperatively. CONCLUSION: Our findings suggest that the novel technique of peeled internal limiting membrane reposition has advantages over the traditional internal limiting membrane peeling in better microstructural outcomes of inner retina and functional recoveries. Furthermore, larger RCT studies are warranted.

Early-Stage Geopolymerization Process of Metakaolin-Based Geopolymer.

The geopolymerization of aluminosilicate materials in alkaline environments is a complex physicochemical process that greatly influences the microstructure and engineering performances. This work aims to reveal the geopolymerization process of metakaolin-based geopolymer (MKG) in the first 5 d. Physicochemical characteristics of different evolution stages are disposed of in chronological order. The evolutions of electrical resistivity, dehydration process, volume deformation, and ionic concentration are comprehensively analyzed. Results show that chemical dissolution produces large dismantled fragments rather than small free monomers. The formation of a solid matrix follows the "spatial filling rule", which means that gels grow by locking swelling fragments to form a framework, then densely filling residual space. Based on chemical models, early geopolymerization of MKG can be divided into six stages from the physicochemical perspective as dismantling, locking fixation, free filling, limited filling, second dissolution, and local mending. Those findings expand the understanding of the phase evolution of the early geopolymerization process; thus, the microstructure of MKG can be better manipulated, and its engineering performances can be improved.

Fabrication of super-hydrophilic and highly open-porous poly (lactic acid) scaffolds using supercritical carbon dioxide foaming.

Porous poly (lactic acid) (PLA)-based scaffolds have been widely used as a promising product in tissue engineering. However, it is still a challenge to prepare the PLA-based scaffolds with high expansion ratio, good hydrophilicity, and excellent cytocompatibility by a green and cost-effective fabrication approach. Herein, we prepared porous PLA-based scaffolds using carbon dioxide (CO2) as the physical foaming agent. To improve the hydrophilicity and foaming behavior of PLA, poly (ethylene glycol) (PEG) was selected as a good additive to blend with PLA. It revealed that the introduction of PEG could improve the foaming behavior of PLA and promote the formation of opening cells via reducing the matrix strength of PLA. The obtained 3D PLA/PEG scaffolds exhibited high expansion ratio (9.1), high open-cell content (95.2%), and super-hydrophilicity (water contact angle 0°). Additionally, the mouse fibroblast NIH/3T3 cells with live/dead cell fluorescence staining assay was utilized to examine the biocompatibility of PLA/PEG scaffolds. The result demonstrated that the proliferation ratio of NIH/3 T3 cells on the surface of PLA/PEG scaffolds was higher than that of PLA scaffolds, indicating that the highly interconnected cell structure was conducive to cell adhesion and attachment. Consequently, such hydrophilic open-cell structure obtained by adding PEG into PLA possesses great potential for use in tissue engineering.

Promoted formation of stereocomplex in enantiomeric poly(lactic acid)s induced by cellulose nanofibers.

Stereocomplex (SC) crystallization between enantiomeric poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA) is believed to yield poly(lactic acid) (PLA) with superior physiochemical properties. However, homocrystallization (HC) crystallites are inevitably generated in the PLLA/PDLA blends. Herein, we report a simple approach to fabricate PLLA/PDLA racemic blends with high contents of SC crystallites by introducing cellulose nanofibers (CNFs). The isothermal crystallization results revealed that the half-crystallization time of the PLLA/PDLA blend was significantly decreased by adding CNFs. Additionally, with the incorporation of 3 wt% modified CNFs, the PLLA/PDLA blend was overwhelmingly crystallized into SC crystallites with no HC crystallite formation. Based on Fourier transform infrared spectroscopy findings, it was speculated that the preferred SC crystallization of PLLA/PDLA/CNF was caused by enhanced interchain molecular interactions between CNFs and PLA. This work presents a feasible and efficient method to fabricate PLA with exclusively SC crystallites, which possesses great potential for producing high-performance PLA materials.

Retinal vein occlusion with cerebral infarction in a preterm neonate: a case report.

BACKGROUND: Retinal vein occlusion (RVO) is a common disease that causes blindness in elderly patients, and cerebral infarction is also a severe disorder impairing the health of individuals. Both diseases are not common in neonates and are related to thrombosis. To date, only one case of simultaneous occurrence of RVO with intracranial haemorrhage in a full-term neonate has been reported. CASE PRESENTATION: A preterm neonate was diagnosed with cerebral infarction and RVO. Retinal haemorrhage and macular oedema were detected in the left eye after the onset of ipsilateral stroke. Although the retinal conditions in this case resolved spontaneously without ocular treatment, the long-term effect on visual function is still unknown. CONCLUSIONS: Given that ocular fundus examinations are rarely performed in paediatric stroke patients, a screening fundus examination in these newborns with stroke might be worth considering.

A green fabrication method of poly (lactic acid) perforated membrane via tuned crystallization and gas diffusion process.

Poly (lactic acid) (PLA) perforated membrane is typically obtained through the solvent-volatilization-induced or non-solvent-induced phase separation (NIPS) method. However, the residual organic solvents would unavoidably limit the application of PLA perforated membrane in biomedical and high-end water purification fields. Herein, an innovative solution-free method was proposed for preparing the PLA perforated membrane via a simple and environmentally friendly way. We have successfully fabricated the PLA perforated membrane using a physical foaming technique with CO2 as the blowing agent. By tuning the primary film thickness, saturation pressure, and foaming temperature, PLA perforated membrane's cell morphology could be accordingly adjusted. The PLA perforated membrane with a highly-ordered straight pore channel and high open cell content (OCC) approximately 72% was obtained under a mild condition. The formation mechanism of the PLA perforated membrane was discussed via the interaction of crystallization behavior and gas diffusion process. This green and solvent-free PLA perforated membrane possesses great potential for use in areas like the tissue engineering and high-end water purification.

Early detection of ocular abnormalities in a Chinese multicentre neonatal eye screening programme-1-year result.

PURPOSE: Early detection of ocular abnormalities in newborns is essential for timely diagnosis and treatment. This study aimed to assess the 1-year result of a multicentre prospective neonatal eye examination programme with wide-field digital imaging system in China. METHODS: A multicentre collaborative prospective study group for neonatal eye screening was established in nine hospitals, including eight Maternal and Children's Hospitals, and one general hospital across China from July 2016 to June 2017. Ocular examinations were performed on newborns within 28 days after birth using a wide-field digital imaging system. Data were reviewed and analysed. The primary outcome was the prevalence of ocular abnormalities in neonates. RESULTS: We detected 13 514 (20.91%) abnormal cases in 64 632 newborns. The most frequent abnormality was retinal haemorrhage (RH; 11.83%). Most of mild RH resolved spontaneously. Among those who were beyond retinopathy of prematurity (ROP) screening criteria of China (gestational age ≥32 w and birthweight ≥2000 g), the total number of neonates with ocular abnormality was 12 218/62 799(19.45%). 59.44% of neonatal ocular abnormalities detected (accounting for 11.56% of all the screened population) needed further interference or observation. Among them, 258 patients (0.41% of all the screened population) needed immediate or timely intervention, including congenital cataract, retinal detachment, retinoblastoma and other ocular abnormalities. One thousand and ninety-eight patients (1.75% of all the screened neonates) should be followed up closely and needed further diagnosis or intervention if necessary, such as ROP or ROP-like retinopathy, familial exudative vitreoretinopathy and persistent hyperplasia of primary vitreous. Five thousand nine hundred and six patients (9.4%) with minor clinical significance needed short-term follow-up. CONCLUSIONS: This prospective multicentre study of newborn ocular examination showed a relatively high prevalence of ocular abnormalities. There are a relatively high percentage of congenital eye pathology that required further referral and treatment in those neonates who were not screened routinely. According to the benefits and risks associated with neonatal eye examinations, neonatal ocular screening programme can detect ocular abnormalities at the very early stage and may play a positive role in promoting paediatric eye health.

Study on a New Environmentally Friendly Synthetic Fluid for Preparing Synthetic-Based Drilling Fluid.

In view of the pollution problems related to using oil-based drilling fluids, we prepared a new environmentally friendly synthetic fluid, namely, NSF, for use in synthetic-based drilling fluid instead. We used heavy hydrocarbons from Daqing as raw material in our preparation and employed few-steps refining techniques, such as hydrodesulfurization, hydrodearomatization, and hydrogenation. After the treatment, the sulfur and aromatic hydrocarbon contents in the NSF were <0.5 mg/L, meeting international environmental standards. NSF is composed mainly of C12-C22 hydrocarbons, and is characterized by low impurity content, small specific gravity, and easy degradation. In addition, the LC50 value is >1,000,000 mg/L water-soluble fraction; therefore, its toxicity is <10% of that of diesel in oil-based drilling fluid and, as the flash point of NSF is about 134°C, the related fire hazard is low. The synthetic-based drilling fluid with NSF has the advantage of causing no swelling damage to the reservoir, and saves the cost of drilling fluid because it doesn't need to deal with the environmental problems (the sulfur and aromatic hydrocarbon contents were <0.5 mg/L) and field problems caused by the reaction between drilling fluid and reservoir, and greatly increases the ROP through reducing the drill pipe sticking and with C12-C22 hydrocarbons in synthetic-based fluid, and safely uses, and has stable drilling fluid performances which are flash point (134°C) and low fire hazard. We have therefore achieved our aim of preparing a high-quality and non-toxic synthetic fluid, of which the aromatic hydrocarbon and sulfur contents meet international standards. Using this synthetic-based drilling fluid therefore facilitates environment protection drilling.

Pathologic comparisons of enucleated eyes with retinoblastoma after superselective ophthalmic arterial chemotherapy with or without intravenous chemotherapy.

AIM: To describe and compare pathologic findings in eyes enucleated after superselective ophthalmic arterial chemotherapy (SOAC) or SOAC with intravenous chemotherapy (IVC) for retinoblastoma. METHODS: Medical records between January 1st, 2014 and June 30th, 2017 were retrospectively analyzed, and pathologic findings were recorded. This study included 36 eyes from 22 (61.1%) male and 14 (38.9%) female patients. Nineteen of 36 (52.8%) eyes received SOAC (mean=3, range=1-7) as primary treatment, and 17 of 36 (47.2%) eyes received SOAC (mean=3.7, range=1-10) after IVC (mean=6.1, range=2-11). Tumor extension including choroidal invasion (n=9, 25%), optic nerve invasion (n=5, 13.9%) and anterior segment invasion (n=5, 13.9%) were recorded. RESULTS: Histopathologic evidence of ischemic damage in the retina and choroid was found in 28 (77.8%) eyes. Thrombosed blood vessels were identified in 9 (25%) eyes, including orbital artery in the retrobulbar orbit (n=1), intrascleral vessels (n=4), and chorioretinal vessels (n=6). Fibrotic changes were found in extraocular muscles (n=5, 13.9%) and optic nerve (n=5, 13.9%). Varying degrees of scleral degeneration were found in all eyes. In statistical analysis, there was no significant difference in clinical and pathologic changes between SOAC group and SOAC with IVC group except for optic nerve invasion (P=0.047). CONCLUSION: SOAC for retinoblastoma can result in ocular toxicity, and SOAC with IVC do not increase the toxicity but reduced the incidence of optic nerve invasion.

Management of stage 3B Coats disease: presentation of a combined treatment modality and long-term follow-up.

PURPOSE: To present a combined treatment modality in the management of stage 3B Coats disease and to evaluate its efficacy in the long-term follow-up. METHODS: This study was a retrospective review of 29 eyes from 29 consecutive patients who had stage 3B Coats disease with total exudative retinal detachment (ERD). The combined treatment modality consisted of external drainage of subretinal fluid (SRF), followed by endolaser photocoagulation via a nonvitrectomy approach, and intravitreal ranibizumab injection. Final disease status, anatomic success, and final visual acuity were the main outcome measures. RESULTS: The treated eyes initially received one session of external drainage of SRF, followed by an average of 1.4 sessions (range, 1 to 3 sessions) of endolaser photocoagulation and intravitreal ranibizumab injection. With a median follow-up period of 40 months (range, 21-81 months), all eyes demonstrated no disease progression, including 6 eyes that required vitrectomy with silicone oil tamponade due to increasing ERD after initial treatment. No enucleation was required. At the final follow-up, anatomic success with retinal reattachment and no active disease was achieved in 24 of 29 eyes (82.8%). Fibrosis was observed in 22 eyes (75.9%) with a mean onset time of 9 months (range, 5-16 months); of these, 3 and 9 eyes developed tractional retinal detachment and epiretinal membrane, respectively. In 62.1% of the eyes, the final visual acuity was only light perception or no light perception. CONCLUSION: The combined treatment modality presented in this study is an effective way in the management of stage 3B Coats disease with total ERD.

Internal limiting membrane dragging and peeling: a modified technique for macular holes closure surgery.

AIM: To introduce a modified technique of internal limiting membrane (ILM) centripetal dragging and peeling to treat idiopathic macular hole (IMH) and to observe the ILM-retina adhesive forces. METHODS: Twenty-six consecutive patients with stage 3 to 4 IMH and followed up at least six months were enrolled. All patients underwent complete par plana vitrectomy, ILM dragging and peeling, fluid and gas exchange, 15% C3F8 tamponade and 2-week prone position. The best corrected visual acuity, macular hole evaluation by optical coherence tomography, and complications were evaluated. RESULTS: The mean diameter of IMH was 524±148 µm (range: 201-683 µm), with 21 cases (80.8%) greater than 400 µm. ILM dragging and peeling were successfully performed in all cases. Most of the ILM-retina adhesive forces are severe (42.3%, 11/26), followed by mild (38.5%, 10/26), and moderate (19.2%, 5/26). The mean follow-up duration was 21.2±6.1mo. The IMH was closed in 25 (96.3%) eyes. Visual acuity (logMAR) improved significantly from 1.2±0.6 preoperatively to 0.7±0.5 postoperatively (P<0.001). CONCLUSION: Preexisting ILM-retina adhesive force is found in IMH patients. With assistance of this force, this modified technique may help to release the IMH edges and improve the closure rate of large IMH.

Aqueous humour cytokines profiles in eyes with Coats disease and the association with the severity of the disease.

BACKGROUND: To investigate aqueous humour (AH) cytokine profiles in eyes with Coats disease and analyze the association between cytokine concentrations and the severity of the disease. METHODS: The study included 36 patients (36 eyes) with Coats disease and 15 control patients (15 eyes) with congenital cataract. AH samples were obtained preoperatively and the concentrations of 22 different cytokines were measured through Cytometric Bead Array technology. Clinical characteristics of Coats disease, including the extent of retinal exudation and exudative retinal detachment (ERD), were recorded for analysis. RESULTS: The concentrations of 8 cytokines (VEGF, IL-6, IL-8, MCP-1, MIP-1α, IP-10, VCAM-1 and ICAM-1) were significantly higher in the Coats disease group than in the control group (all P < 0.002). Except for VCAM-1 and ICAM-1, the concentration of the other cytokines listed above showed a significant increase from stage 2 to stage 3 (all P < 0.05). Meanwhile, the concentrations of VEGF, IL-8, MCP-1 and MIP-1α showed a significant and positive association with the extent of retinal exudation and ERD (all r > 0.4, P < 0.05). Among these, IL-8 showed a strong association with the extent of retinal exudation and ERD (all r > 0.7, P < 0.001). The concentrations of IL-1α, IL-1ß, IL-2, IL-4, IL-5, IL-10, IL-12, Fractalkine, RANTES, G-CSF and GM-CSF were very low in both groups. CONCLUSIONS: Various cytokines in the AH, including elevated VEGF, IL-6, IL-8, MCP-1, MIP-1α, IP-10, VCAM-1 and ICAM-1, may be involved in the pathogenesis and progression of Coats disease. Increasing severity of Coats disease is significantly associated with the AH concentrations of VEGF, IL-8, MCP-1 and MIP-1α. Further clinical treatment aimed to reduce vascular leakage and antagonize neovascularization and inflammation may be useful in preventing the progression of Coats disease.

Combined intra-arterial chemotherapy and intravitreal melphalan for the treatment of advanced unilateral retinoblastoma.

AIM: To evaluate the efficacy and safety of combined intra-arterial chemotherapy (IAC) and intravitreal melphalan (IVM) for the treatment of advanced unilateral retinoblastoma. METHODS: This retrospective study involved 30 consecutive eyes from 30 Chinese patients with advanced unilateral retinoblastoma. All patients were initially treated with IAC combined with IVM. The clinical status and complications were recorded at each visit. RESULTS: The International Intraocular Retinoblastoma Classification groups were D in 23 eyes and E in 7 eyes. All eyes showed severe cloud vitreous seeds at the first visit. The mean number of IAC cycles and intravitreal injections was 3.2 (range, 3-4) and 6 (range, 1-14), respectively. The median follow-up time was 29mo (range, 7-36mo). Treatment success with regression of the retinal tumor and vitreous seeds was achieved in 29 of 30 eyes (96.7%). Globe salvage was attained in 93.3% (28/30) eyes, and enucleation (n=2) was performed due to neovascular glaucoma and persistent vitreous hemorrhage. Complications included retinal pigment epithelium (RPE) atrophy (n=13; 43%), mild lens opacity (n=7; 23%), vitreous hemorrhage (n=5; 17%) and rhegmatogenous retinal detachment (n=1; 3%). No extraocular tumor extension or metastasis occurred. CONCLUSION: Combined IAC and IVM is effective and safe for the treatment of advanced unilateral retinoblastoma.

Reduction of circular RNA expression associated with human retinoblastoma.

This study investigated the profile of circular RNA (circRNA) expression and its epigenetic role associated with human retinoblastoma (RB). Twelve paired primary samples from un-treated RB patients (primary RB samples and corresponding adjacent normal retinal samples) and eight recurrent RB samples from RB patients having recurrence after treatment were collected. Ribosomal-RNA depleted sequencing was performed in four paired primary samples. Quantitative polymerase chain reaction was conducted to validate circRNA and mRNA expression in the other eight paired primary samples and in eight recurrent RB samples. Bioinformatic analysis was applied to predict the oncological signal pathways and the binding microRNA (miRNA) of circRNA. As a result, a total of 47640 circRNAs were identified by RNA-sequencing, with a lower abundance of circRNAs in primary RB samples relative to matched normal retinal samples [22366 (47%) versus 37161 (78%), P <0.001]. Among the 11887 overlapping circRNAs in both RB and normal retinal samples, 550 circRNAs were downregulated and seven were upregulated in primary RB samples compared to normal retinal samples. The host genes of the differentially expressed circRNAs were associated with chromatin modification. TET1-has_circ_0093996 (ten-eleven translocation-1), whose host gene TET1 participates in chromatin modifying, was downregulated in both primary and recurrent RB samples. Programmed cell death 4 （PDCD4) was also downregulated in both primary and recurrent RB samples. We used bioinformatic tools to construct a complete regulatory axis including TET1-has_circ_0093996-miR-183-PDCD4 that regulates RB pathogenesis. In conclusion, circRNA expression is downregulated in RB tumor, which suggests epigenetic regulation of RB pathogenesis by circRNAs.