The potential of marine resources for retinal diseases: a systematic review of the molecular mechanisms

We rely on vision more than on any other sense to obtain information about our environment. Hence, the loss or even impairment of vision profoundly affects our quality of life. Diet or food components have already demonstrated beneficial effects on the development of retinal diseases. Recently, there has been a growing interest in resources from marine animals and plants for the prevention of retinal diseases through nutrition. Especially fish intake and omega-3 fatty acids have already led to promising results, including associations with a reduced incidence of retinal diseases. However, the underlying molecular mechanisms are insufficiently explained. The aim of this review was to summarize the known mechanistic effects of marine resources on the pathophysiological processes in retinal diseases. We performed a systematic literature review following the PRISMA guidelines and identified 107 studies investigating marine resources in the context of retinal diseases. Of these, 46 studies described the underlying mechanisms including anti-inflammatory, antioxidant, antiangiogenic/vasoprotective, cytoprotective, metabolic, and retinal function effects, which we critically summarize. We further discuss perspectives on the use of marine resources for human nutrition to prevent retinal diseases with a particular focus on regulatory aspects, health claims, safety, and bioavailability.

Intravitreal injection of povidone-iodine for the treatment of vancomycin-resistant Enterococcus faecalis endophthalmitis in rabbit eyes

The aim of this study was to investigate the efficacy of intravitreal povidone-iodine (PI) in the treatment of vancomycin-resistant Enterococcus faecalis (VRE) endophthalmitis. Fifty New Zealand white rabbits were divided into 5 groups (n = 10 in each group). After the induction of endophthalmitis using VRE (minimum inhibitory concentration [MIC] ≥ 40 μg/mL) in the right eye, Group A, B, C, and D received intravitreal injections of 0.1% PI, 0.3% PI, 0.05% vancomycin, and 0.5% vancomycin, respectively. Eyes in Group E were used as controls. Fundus photography, vitreous culture, electroretinography (ERG), and histologic examinations of the retina were conducted on day 14. A marked improvement in endophthalmitis was observed in Group A, B, C and D, compared to Group E. Fundus photographs showed mild vitreous opacities in Group A and B, and moderate vitreous opacity in Group C. All eyes in Group D had a clear vitreous. In vitreous culture, bacterial growth was found in 6 eyes (100, 200, 200, 400, 500, and 500 colony-forming units) in Group C, but not in Groups A, B, or D. ERG and histological examination also indicated intraocular damage in Group C. Our results show that intravitreal injection of PI, even at low concentrations, was effective for treatment of VRE endophthalmitis, although some vitreous opacity remained. Intravitreal vancomycin injection was also useful to treat resistant strains, if used at a higher concentration within the safety threshold.

SQUARE GRID DEFORMATION ANALYSIS OF THE MACULA AND POSTOPERATIVE METAMORPHOPSIA AFTER MACULAR HOLE SURGERY

PURPOSE

To investigate the correlation between postoperative metamorphopsia and macular deformation after macular hole surgery.

METHODS

This study included 28 eyes of 28 patients who underwent vitrectomy and internal limiting membrane removal for an idiopathic macular hole. The retinal vasculatures were compared between preoperative and postoperative photographs, and postoperative deformation of the macula was assessed as deformation of the square grid. The displacement of each node was measured, and deformation of the grid was calculated as differences in the coordinates of the adjacent nodes. These parameters were analyzed to find correlation with metamorphopsia measured using the M-charts after 6 postoperative months.

RESULTS

The average deformations in the vertical and horizontal lines of the grid were 94.29 μm and 49.72 μm, respectively. Perifoveal deformation was significantly greater than parafoveal deformation (P = 0.001∼0.019). The multiple regression analysis demonstrated that the vertical M-score correlated with superior perifoveal deformation of the vertical line on the fovea (P = 0.036), and the horizontal M-score correlated with temporal perifoveal deformation of the horizontal line on the fovea (P = 0.032).

CONCLUSION

The parafoveal tissue was displaced with the fovea concurrently after internal limiting membrane removal in macular hole surgery causing perifoveal deformation, which correlated with postoperative metamorphopsia.

Enterococcus faecalis Endophthalmitis: Clinical Settings, Antibiotic Susceptibility, and Management Outcomes

Enterococcus faecalis is known to cause severe acute endophthalmitis and often leads to poor visual outcomes in most ophthalmic infections. This retrospective study is to report the clinical settings, antimicrobial susceptibility patterns, and visual outcome of E. faecalis endophthalmitis at a tertiary referral institution in Taoyuan, Taiwan. E. faecalis endophthalmitis was diagnosed in 37 eyes of 37 patients. Post-cataract surgery was the most common cause (n = 27, 73%), followed by bleb-associated (n = 3, 8%), endogenous (n = 2, 5%), corneal ulcer-related (n = 2, 5%), post-vitrectomy (n = 1, 3%), post-pterygium excision (n = 1, 3%), and trauma (n = 1, 3%). Visual acuities upon presentation ranged from counting fingers to no light perception. Pars plana vitrectomy with intravitreal antibiotics were performed in 23 eyes (76%) as primary or secondary treatment. All isolates (37/37, 100%) were sensitive to vancomycin, penicillin, ampicillin, and teicoplanin. Six of 22 eyes (27%) were resistant to high-level gentamicin (minimum inhibitory concentration > 500 mg/L). Final visual acuities were better than 20/400 in 11 eyes (30%), 5/200 to hand motions in 4 eyes (11%), and light perception to no light perception in 22 eyes (59%). Three eyes were treated with evisceration. Compared with non-cataract subgroups, the post-cataract subgroup showed a significant difference of better visual prognosis (p = 0.016).

Emerging Enterococcus isolates in postoperative endophthalmitis by selection pressure of fluoroquinolones: an 11-year multicenter and experimental study

Postoperative endophthalmitis (PE) is the devastating complication that frequently results in vision loss. Recently, enterococcus have emerged as a major cause of PE in several countries and resulted in poor visual outcome. However, the reason remains elusive. We investigate whether selection pressure of fluoroquinolone exerts effects on microorganism profiles isolated from PE. Medical records of patients who were diagnosed with PE at eight resident training institutions between January 2004 and December 2015 were reviewed. The most common isolate was Enterococcus faecalis (28.0%), followed by Staphylococcus epidermidis (18.6%) and other coagulase negative Staphylococci (7.6%). However, the rates of E. faecalis isolated from conjunctival microbes were 6.2% (16/257) and their resistance to fluoroquinolones was higher than those of S. epidermidis. In vitro and in vivo co-culture models of E. faecalis and S. epidermidis were established for survival assays after administration of fourth-generation fluoroquinolone. In in vitro co-culture model, the survival assay of E. faecalis and S. epidermidis against the treatment of moxifloxacin showed that E. faecalis survived significantly better than S. epidermidis in the presence of moxifloxacin 1 µg/mL and more. In in vivo co-culture model, E. faecalis survived significantly better than S. epidermidis after topical treatment of moxifloxacin (5 mg/mL). E. faecalis has been the most common causative strain of PE in Korea. We suggest that the increase of E. faecalis in PE could be associated with the selection pressure of fourth-generation fluoroquinolone.

Summary:Enterococcus spp. have emerged as a leading causative strain of postoperative endophthalmitis in 11-year clinical data. We suggest that the increase of Enterococcus spp. is associated with the selection pressure of fourth-generation fluoroquinolone.

A Metabolic Landscape for Maintaining Retina Integrity and Function

Neurons have high metabolic demands that are almost exclusively met by glucose supplied from the bloodstream. Glucose is utilized in complex metabolic interactions between neurons and glia cells, described by the astrocyte-neuron lactate shuttle (ANLS) hypothesis. The neural retina faces similar energy demands to the rest of the brain, with additional high anabolic needs to support continuous renewal of photoreceptor outer segments. This demand is met by a fascinating variation of the ANLS in which photoreceptors are the central part of a metabolic landscape, using glucose and supplying surrounding cells with metabolic intermediates. In this review we summarize recent evidence on how neurons, in particular photoreceptors, meet their energy and biosynthetic requirements by comprising a metabolic landscape of interdependent cells.

Genomic and phenotypic diversity of Enterococcus faecalis isolated from endophthalmitis

Enterococcus faecalis are hospital-associated opportunistic pathogens and also causative agents of post-operative endophthalmitis. Patients with enterococcal endophthalmitis often have poor visual outcomes, despite appropriate antibiotic therapy. Here we investigated the genomic and phenotypic characteristics of E. faecalis isolates collected from 13 patients treated at the University of Pittsburgh Medical Center Eye Center over 19 years. Comparative genomic analysis indicated that patients were infected with E. faecalis belonging to diverse multi-locus sequence types (STs) and resembled E. faecalis sampled from clinical, commensal, and environmental sources. We identified known E. faecalis virulence factors and antibiotic resistance genes in each genome, including genes conferring resistance to aminoglycosides, erythromycin, and tetracyclines. We assessed all isolates for their cytolysin production, biofilm formation, and antibiotic susceptibility, and observed phenotypic differences between isolates. Fluoroquinolone and cephalosporin susceptibilities were particularly variable between isolates, as were biofilm formation and cytolysin production. In addition, we found evidence of E. faecalis adaptation during recurrent endophthalmitis by identifying genetic variants that arose in sequential isolates sampled over eight months from the same patient. We identified a mutation in the DNA mismatch repair gene mutS that was associated with an increased rate of spontaneous mutation in the final isolate from the patient. Overall this study documents the genomic and phenotypic variability among E. faecalis causing endophthalmitis, as well as possible adaptive mechanisms underlying bacterial persistence during recurrent ocular infection.

Effect of Dexamethasone Implant on Subfoveal Choroidal Thickness in Early Period in Vitrectomized Eyes with Diabetic Macular Edema

Aim

To investigate the change in subfoveal choroidal thickness (SFCT) in vitrectomized eyes with intravitreal dexamethasone (IVD) implant injection for the treatment of diabetic macular edema (DME).

Method

In this prospective and controlled study, the vitrectomized eyes of diabetic patients were included. The study group (Group 1) was formed by diabetic vitrectomized eyes with DME. The control group (Group 2) was formed by diabetic vitrectomized eyes without DME. Only one intravitreal IVD implant was injected into the eyes in Group 1. In the first, second, and fourth months, choroidal layers were measured by optical coherence tomography and complete ophthalmologic examinations were performed for all cases.

Results

Ninety-six eyes of 96 cases were included in the study. There were 48 eyes of 48 different patients in each group. After IVD injection, statistically significant improvement was observed in the best corrected visual acuity in Group 1. The mean SFCT in eyes with DME was statistically significantly thinner (p < 0.01) and thinness became more pronounced during the four-month follow-up period after IVD implant injection (p < 0.01).

Conclusion

In the presence of DME in vitrectomized eyes, the thinness of the SFCT may become evident after dexamethasone implant injection.

Effect of selectively knocking down key metabolic genes in Müller glia on photoreceptor health

The importance of Müller glia for retinal homeostasis suggests that they may have vulnerabilities that lead to retinal disease. Here, we studied the effect of selectively knocking down key metabolic genes in Müller glia on photoreceptor health. Immunostaining indicated that murine Müller glia expressed insulin receptor (IR), hexokinase 2 (HK2) and phosphoglycerate dehydrogenase (PHGDH) but very little pyruvate dehydrogenase E1 alpha 1 (PDH-E1α) and lactate dehydrogenase A (LDH-A). We crossed Müller glial cell-CreER (MC-CreER) mice with transgenic mice carrying a floxed IR, HK2, PDH-E1α, LDH-A, or PHGDH gene to study the effect of selectively knocking down key metabolic genes in Müller glia cells on retinal health. Selectively knocking down IR, HK2, or PHGDH led to photoreceptor degeneration and reduced electroretinographic responses. Supplementing exogenous l-serine prevented photoreceptor degeneration and improved retinal function in MC-PHGDH knockdown mice. We unexpectedly found that the levels of retinal serine and glycine were not reduced but, on the contrary, highly increased in MC-PHGDH knockdown mice. Moreover, dietary serine supplementation, while rescuing the retinal phenotypes caused by genetic deletion of PHGDH in Müller glial cells, restored retinal serine and glycine homeostasis probably through regulation of serine transport. No retinal abnormalities were observed in MC-CreER mice crossed with PDH-E1α- or LDH-A-floxed mice despite Cre expression. Our findings suggest that Müller glia do not complete glycolysis but use glucose to produce serine to support photoreceptors. Supplementation with exogenous serine is effective in preventing photoreceptor degeneration caused by PHGDH deficiency in Müller glia.

Replacement of polyps with type 1 macular neovascularization in polypoidal choroidal vasculopathy imaged with swept source OCT angiography

Purpose

To investigate the morphological changes of polyps in eyes with polypoidal choroidal vasculopathy (PCV) after treatment with vascular endothelial growth factor (VEGF) inhibitors using swept source optical coherence tomography angiography (SS-OCTA).

Observations

Following anti-VEGF therapy, polyps were found to evolve into typical type 1 macular neovascularization (MNV) in five eyes. In all of these five eyes, a polypoidal lesion was detected adjacent to a serous or hemorrhagic retinal pigment epithelial detachment (PED).

Conclusions and importance

Polypoidal lesions in PCV can evolve into typical type 1 MNV. This morphological evolution suggests that these polyps are clusters of tangled vessels that can proliferate into a more typical neovascular pattern, and this evolution may be facilitated by being adjacent to a PED. Since this morphological appearance could be associated with a better prognosis, SS-OCTA might be helpful in identifying cases of transformed polyps that may be associated with a decreased risk for vision loss.

HUMAN AMNIOTIC MEMBRANE TO TREAT MACULAR HOLES THAT FAILED TO CLOSE, SULFUR HEXAFLUORIDE ENDOTAMPONADE VERSUS AIR ENDOTAMPONADE: A Prospective Comparative Study

BACKGROUND/PURPOSE

To determinate the efficacy of the human amniotic membrane plugs with sulfur hexafluoride versus human amniotic membrane plug with air as endotamponade to treat macular holes that failed to close after vitrectomy plus internal limiting membrane peeling. Multimodal imaging was focused to evaluate preoperative features and postoperative changes.

METHODS

Prospective interventional comparative study. Twenty eyes of 20 patients affected with macular hole that failed to close were divided into 2 groups: 10 eyes received an amniotic membrane plug with 20% sulfur hexafluoride tamponade and 10 eyes received an amniotic membrane plug with air tamponade. All eyes were studied using multimodal advanced diagnostic tools, such as spectral-domain optical coherence tomography, optical coherence tomography angiography, microperimetry, and adaptive optics to investigate the postoperative results.

RESULTS

In both groups, all macular holes were found successfully closed after 12 months. Mean preoperative best-corrected visual acuity was 20/400 in the SF6 group and 20/250 in air group. Final mean best-corrected visual acuity was 20/63 in both groups. The superficial capillary plexus, studied using optical coherence tomography angiography, showed a statistically significant difference between the treated and the fellow eyes. Adaptive optics images revealed the presence of a photoreceptor cell mosaic in the area of the amniotic membrane plug.

CONCLUSION

The human amniotic membrane combined with air endotamponade demonstrated its effectiveness to seal macular holes that failed to close after vitrectomy plus internal limiting membrane peeling. Advanced multimodal diagnostic imaging helped us to better understand the modifications associated with the use of the amniotic membrane in these cases.

Retinal glial remodeling by FGF21 preserves retinal function during photoreceptor degeneration

The group of retinal degenerations, retinitis pigmentosa (RP), comprises more than 150 genetic abnormalities affecting photoreceptors. Finding degenerative pathways common to all genetic abnormalities may allow general treatment such as neuroprotection. Neuroprotection may include enhancing the function of cells that directly support photoreceptors, retinal pigment epithelial cells, and Müller glia. Treatment with fibroblast growth factor 21 (FGF21), a neuroprotectant, from postnatal week 4-10, during rod and cone loss in P23H mice (an RP model) with retinal degeneration, preserved photoreceptor function and normalized Müller glial cell morphology. Single-cell transcriptomics of retinal cells showed that FGF21 receptor Fgfr1 was specifically expressed in Müller glia/astrocytes. Of all retinal cells, FGF21 predominantly affected genes in Müller glia/astrocytes with increased expression of axon development and synapse formation pathway genes. Therefore, enhancing retinal glial axon and synapse formation with neurons may preserve retinal function in RP and may suggest a general therapeutic approach for retinal degenerative diseases.

Timing of Complete Polypoidal Regression after Intravitreous Aflibercept Treatments in Polypoidal Choroidal Vasculopathy

PURPOSE

To understand timing of complete polypoidal regression on indocyanine green angiography (ICGA) after aflibercept injections for polypoidal choroidal vasculopathy (PCV).

DESIGN

Multicenter prospective study.

PARTICIPANTS

Adults with treatment-naïve PCV.

METHODS

After institutional review board approval, participants were enrolled and followed up for 1 year, from Apr 1, 2016, through Dec 30, 2018, at 2 university-based centers in Thailand. Diagnosis of PCV was based on the Efficacy and Safety of Verteporfin Photodynamic Therapy in Combination with Ranibizumab or Alone versus Ranibizumab Monotherapy in Patients with Symptomatic Macular Polypoidal Choroidal Vasculopathy criteria. Eligible eyes received fixed-dose aflibercept injections (3 monthly then every 8 weeks), or monthly if fluid persisted on OCT. Photodynamic therapy (PDT) was administered when fluid persisted despite 6 consecutive injections. Indocyanine green angiography was performed at baseline and then every 8 weeks. The 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) was administered at baseline, 6 months, and 1 year. Two retina specialists reviewed posttreatment ICGA, categorized into: complete regression (complete disappearance of polypoidal lesions), partial regression (reduced in size or number), or no regression. Disagreements were resolved through open adjudication.

MAIN OUTCOME MEASURES

Timing of complete regression over 1 year.

RESULTS

Final analysis included 40 eyes (39 participants; 100% Thai, 59% women; mean age±standard deviation, 64 ± 8.3 years). At baseline, 90% had 5 or more polypoidal lesions. Ninety-five percent received aflibercept monotherapy, and 5% received rescue PDT per protocol. Polypoidal statuses at 1 year were 55% complete, 40% partial, and 5% no regression. Cumulative rates of complete regression at 2, 4, 6, and 12 months were 28%, 33%, 43%, and 55%. Of 22 eyes with complete regression at 1 year, complete regression was identified first at 2, 4, 6, 8, 10, 12 months in 50%, 9%, 18%, 5%, 9%, and 9%, respectively. Cumulative rates of complete regression among these eyes at 2, 6, and 12 months were 50%, 77%, and 100%, respectively. Median duration of complete regression was 3 months (interquartile range, 2-6 months). Median visual acuity improved from 20/125 (Snellen equivalent) to 20/50; median NEI VFQ-25 scores improved from 80 to 93 from baseline to 1 year.

CONCLUSIONS

Complete polypoidal regression could occur as early as 2 months after aflibercept injections. Most PCV eyes with complete polypoidal regression at 1 year already showed complete regression within the first 6 months. These findings support consideration of aflibercept for PCV to achieve both anatomic and visual outcomes.

Acute Infectious Endophthalmitis After Cataract Surgery: Epidemiological Characteristics, Risk Factors and Incidence Trends, 2008-2019

Objective

Intended to investigate the epidemiological characteristics, risk factors and incidence trend of endophthalmitis after cataract surgery in recent 12 years.

Methods

A retrospective study was conducted on the patients who underwent cataract surgery in Qingdao Eye Hospital from January 1, 2008, to December 31, 2019, including age, sex, history of diabetes, intraoperative operation and complications. In addition, the related risk factors and incidence trend of acute infective endophthalmitis were analyzed. The incidence of endophthalmitis and its related factors were analyzed by univariate and multivariate logistic regression analysis.

Results

A total of 55,612 cases of cataract surgery were performed in our hospital in 12 years, and 42 cases of acute infective endophthalmitis occurred (the incidence rate was 0.076%). The average occurrence time was 10.57 days ± 11.17, with eye pain as the main complaint and anterior chamber fibrin exudation as the main clinical manifestation. In addition, there were eight cases of anterior chamber hypopyon and 18 cases of vitreous reaction, the results of anterior aqueous humor or vitreous fluid culture in 10 patients were positive. Univariate analysis showed that intraoperative rupture of posterior capsule, non-use of antibiotics and non-use of behind-the-lens washout were the risk factors of infectious endophthalmitis after cataract surgery (P=0.032, P=0.000, P=0.000). Besides, multivariate logistic regression analysis showed that intraoperative rupture of posterior capsule was the main risk factor.

Conclusion

The occurrence of endophthalmitis after cataract surgery is mainly related to intraoperative rupture of posterior capsule, absence of antibiotics and behind-the-lens washout. In addition, the incidence of endophthalmitis after cataract surgery decreased during the past 12 years.

Ultrastructural study of closed macular hole- preliminary application of a novel high magnification module combining with OCT

Background

As a novel high magnification module (HMM) combining with OCT (OCT-HMM) is able to detect the microstructure of retina, we apply it to explore the ultrastructure of the macula after closure of the idiopathic macular hole (IMH) by surgery.

Methods

This is an observational case series study in which patients with full-thickness IMHs who had undergone successful macular closure by vitrectomy and internal limiting membrane peeling and healthy subjects were recruited. After comprehensive ophthalmic examinations, the images of macular area were obtained and collected by professional operators using OCT-HMM. Then images were independently analyzed by 4 masked vitreoretinal specialists.

Results

A total of 24 IMH eyes and 42 healthy eyes were examined. HMM images were obtained in 10 IMH eyes. Among them, 4 eyes whose macula closed completely with recovery of photoreceptor layer presented a dark arc nasal to the fovea, oriented to the optic, and the notch of arc faced temporally. Six eyes in which the macula closed incompletely with photoreceptor cells loss revealed a dark ring with uneven bright spots inside. The other 14 eyes failed to obtain clear images by OCT-HMM. The contra lateral eyes of the patients and the healthy subjects’ eyes succeeded to obtain the HMM images which displayed evenly grey background thickly covered with tiny bright dots that was in similar size and evenly and widely distributed and there no dark arc or ring. OCT B-scan and IR images could be acquired in all of the IMH and healthy eyes.

Conclusion

The preliminary application of HMM has supplied us a brand-new insight into the microstructure of closed IMH. A dark arc sign could be detected with OCT-HMM in the macula which was functionally closed after surgery that was probably the healing mark on a microstructure photoreceptors level. Its existence and shape indicated that the functional closure followed by a retinal displacement mainly horizontally from temporal side to nasal side but not symmetric centripetally.

Metabolism in the Zebrafish Retina

Retinal photoreceptors are amongst the most metabolically active cells in the body, consuming more glucose as a metabolic substrate than even the brain. This ensures that there is sufficient energy to establish and maintain photoreceptor functions during and after their differentiation. Such high dependence on glucose metabolism is conserved across vertebrates, including zebrafish from early larval through to adult retinal stages. As the zebrafish retina develops rapidly, reaching an adult-like structure by 72 hours post fertilisation, zebrafish larvae can be used to study metabolism not only during retinogenesis, but also in functionally mature retinae. The interplay between rod and cone photoreceptors and the neighbouring retinal pigment epithelium (RPE) cells establishes a metabolic ecosystem that provides essential control of their individual functions, overall maintaining healthy vision. The RPE facilitates efficient supply of glucose from the choroidal vasculature to the photoreceptors, which produce metabolic products that in turn fuel RPE metabolism. Many inherited retinal diseases (IRDs) result in photoreceptor degeneration, either directly arising from photoreceptor-specific mutations or secondary to RPE loss, leading to sight loss. Evidence from a number of vertebrate studies suggests that the imbalance of the metabolic ecosystem in the outer retina contributes to metabolic failure and disease pathogenesis. The use of larval zebrafish mutants with disease-specific mutations that mirror those seen in human patients allows us to uncover mechanisms of such dysregulation and disease pathology with progression from embryonic to adult stages, as well as providing a means of testing novel therapeutic approaches.

Two-year results of a treat and extend regimen with aflibercept in Caucasian patients with aneurysmal type 1 neovascularization

INTRODUCTION

There are a few reports investigating the treatment of aneurysmal type 1 neovascularization (AT1) in Caucasian patients. The aim of this study is to evaluate the 2-year results of a treat and extend regimen with aflibercept in Caucasian patients with AT1.

METHODS

We conducted an observational retrospective study in 28 eyes of 26 patients with naïve AT1 treated with a treat an extend regimen of intravitreal aflibercept. Best corrected visual acuity (BCVA), central macular thickness (CMT), pigment epithelium detachment (PED) height, presence of dry macula, and regression rate of polypoidal lesions were assessed at baseline and at 12 and 24 months.

RESULTS

BCVA was significantly increased by 9.03 ± 16 letters (p < 0.01) and 9.2 ± 16.87 letters (p < 0.01) after the 12 and 24 months follow-up. A significant decrease of CMT was found at 12 and 24 months (p < 0.01). Nevertheless, significant changes in PED height were not observed (0.1 < p > 0.05). At 12 and 24 months of follow-up, dry macula was achieved in a total of 10 eyes (35.71%) and 15 eyes (53.57%). The regression rate of polypoidal lesions was 25% (7 eyes) and 35.71% (10 eyes) after 12 and 24 months. The mean number of intravitreal injections was 7.81 ± 3.20 the first year and 6.11 ± 3.49 the second year.

CONCLUSION

To the best of our knowledge, treat and extend regimen with intravitreal aflibercept in Caucasian patients may be effective for improving BCVA, CMT, wet macula, and regression rate of polypoidal lesions.

Sodium iodate induces ferroptosis in human retinal pigment epithelium ARPE-19 cells

Sodium iodate (SI) is a widely used oxidant for generating retinal degeneration models by inducing the death of retinal pigment epithelium (RPE) cells. However, the mechanism of RPE cell death induced by SI remains unclear. In this study, we investigated the necrotic features of cultured human retinal pigment epithelium (ARPE-19) cells treated with SI and found that apoptosis or necroptosis was not the major death pathway. Instead, the death process was accompanied by significant elevation of intracellular labile iron level, ROS, and lipid peroxides which recapitulated the key features of ferroptosis. Ferroptosis inhibitors deferoxamine mesylate (DFO) and ferrostatin-1(Fer-1) partially prevented SI-induced cell death. Further studies revealed that SI treatment did not alter GPX4 (glutathione peroxidase 4) expression, but led to the depletion of reduced thiol groups, mainly intracellular GSH (reduced glutathione) and cysteine. The study on iron trafficking demonstrated that iron influx was not altered by SI treatment but iron efflux increased, indicating that the increase in labile iron was likely due to the release of sequestered iron. This hypothesis was verified by showing that SI directly promoted the release of labile iron from a cell-free lysate. We propose that SI depletes GSH, increases ROS, releases labile iron, and boosts lipid damage, which in turn results in ferroptosis in ARPE-19 cells.

Metabolic Analysis of Vitreous/Lens and Retina in Wild Type and Retinal Degeneration Mice

Photoreceptors are the light-sensing cells of the retina and the major cell type affected in most inherited retinal degenerations. Different metabolic pathways sustain their high energetic demand in physiological conditions, particularly aerobic glycolysis. The principal metabolome of the mature retina has been studied, but only limited information is available on metabolic adaptations in response to key developmental events, such as eye opening. Moreover, dynamic metabolic changes due to retinal degeneration are not well understood. Here, we aimed to explore and map the ocular metabolic dynamics induced by eye opening in healthy (wild type) or Pde6b-mutant (retinal degeneration 1, Rd1) mice, in which photoreceptors degenerate shortly after eye opening. To unravel metabolic differences emerging before and after eye opening under physiological and pathophysiological conditions, we performed nuclear magnetic resonance (NMR) spectroscopy-based metabolome analysis of wild type and Rd1 retina and vitreous/lens. We show that eye opening is accompanied by changes in the concentration of selected metabolites in the retina and by alterations in the vitreous/lens composition only in the retinal degeneration context. As such, we identify NAcetylaspartate as a potential novel vitreous/lens marker reflecting progressive retinal degeneration. Thus, our data can help elucidating mechanisms underlying key events in retinal physiology and reveal changes occurring in pathology, while highlighting the importance of the vitreous/lens in the characterization of retinal diseases.

Photoreceptor metabolic reprogramming: current understanding and therapeutic implications

Acquired and inherited retinal disorders are responsible for vision loss in an increasing proportion of individuals worldwide. Photoreceptor (PR) death is central to the vision loss individuals experience in these various retinal diseases. Unfortunately, there is a lack of treatment options to prevent PR loss, so an urgent unmet need exists for therapies that improve PR survival and ultimately, vision. The retina is one of the most energy demanding tissues in the body, and this is driven in large part by the metabolic needs of PRs. Recent studies suggest that disruption of nutrient availability and regulation of cell metabolism may be a unifying mechanism in PR death. Understanding retinal cell metabolism and how it is altered in disease has been identified as a priority area of research. The focus of this review is on the recent advances in the understanding of PR metabolism and how it is critical to reduction-oxidation (redox) balance, the outer retinal metabolic ecosystem, and retinal disease. The importance of these metabolic processes is just beginning to be realized and unraveling the metabolic and redox pathways integral to PR health may identify novel targets for neuroprotective strategies that prevent blindness in the heterogenous group of retinal disorders.

Outcomes of a 2-year treat-and-extend regimen with aflibercept for diabetic macular edema

This prospective, open-label, single-arm, non-randomized clinical trial, assessed the efficacy of a 2-year treat-and-extend (T&E) regimen involving intravitreal aflibercept injection (IAI), with the longest treatment interval set to 16 weeks, and adjunct focal/grid laser in diabetic macula edema (DME) patients. We examined 40 eyes (40 adults) with fovea-involving DME from 8 Japanese centers between April 2015 and February 2017. Participants received IAI with an induction period featuring monthly injections and a subsequent T&E period featuring 8–16-week injection interval, adjusted based on optical coherence tomography findings. The primary endpoints were mean changes in the best-corrected visual acuity (BCVA) and central subfield macular thickness (CST) from baseline. Thirty patients (75%) completed the 2-year follow-up. The mean BCVA and CST changed from 60.5 ± 15.6 letters and 499.2 ± 105.6 µm at baseline to 66.6 ± 17.1 letters (P = 0.217) and 315.2 ± 79.0 µm (P < 0.001), respectively, after 2 years. The treatment interval was extended to 12 and 16 weeks in 6.7% and 66.7% of patients, respectively, at the end of 2 years. The T&E aflibercept regimen with the longest treatment interval set to 16 weeks, with adjunct focal/grid laser may be a rational 2-year treatment strategy for DME.

One-year outcomes of fixed-dosing Aflibercept therapy for pre treated and naive polypoidal choroidal vasculopathy patient

BACKGROUND

Polypoidal choroidal vasculopathy (PCV) is a type of age-related macular degeneration that can cause permanent vision loss. The purpose of this paper was to report the one-year outcomes of fixed-dosing aflibercept therapy for the treatment of PCV.

METHODS

This was a prospective, single-arm, interventional case series study of 25 PCV patients; 12 pre-treated and 13 treatment-naïve patients. The patients were treated and monitored for 12 months. Each patient was administered with an aflibercept (2.0 mg) injection every month for the first 3 months (the loading phase), and thereafter, once every 2 months. At every follow-up visit, best-corrected visual acuity (BCVA) test, fundus examination, and optical coherence tomography for measuring the central subfield macular thickness (CSMT) were performed. Fluorescein and indocyanine green angiography were conducted at baseline and at 4 and 12 months.

RESULTS

After 12 months of aflibercept therapy, the mean BCVA of the patients significantly improved from 65.48 letters at baseline to 69.91 letters (p=0.001), and the CSMT significantly decreased from 406.92 um at baseline to 276.12 um (p< 0.001). Additionally, ten patients (40%) showed complete polyp regression. The treatment-naïve patients showed a statistically significant improvement in BCVA from 66.58 letters at baseline to 76.36 letters at 12 months, and a significant decrease in CSMT, from 462 to 243 um. In the pre-treated group, there was no change in BCVA (64.46 letters), and the decrease in CSMT from 356.08 to 303.69 um was not statistically significant.

CONCLUSIONS

The fixed-dosing aflibercept regimen is effective for treating patients with PCV and is more effective in treatment-naïve patients than in pre-treated patients.

TRIAL REGISTRATION

Clinical Research Information Service (CRiS), Republic of Korea. Identifer: KCT0005798, Registered: Jan 20, 2021. Retrospectively registered, URL: https://cris.nih.go.kr/cris/en/search/search_result_st01.jsp?seq=18546.

Treat-and-extend therapy with aflibercept for diabetic macular edema: a prospective clinical trial

PURPOSE

To investigate the efficacy and safety of a treat-and-extend (T&E) regimen using aflibercept (Eylea) for diabetic macular edema (DME).

STUDY DESIGN

Prospective, open-label, multicenter, single-arm, nonblinded clinical study.

METHODS

Forty eyes of 40 patients with DME received a T&E regimen of intravitreal aflibercept injection (IAI) with the longest treatment interval set to 16 weeks and adjunct focal/grid laser for 1 year. An intent-to-treat analysis was performed using the same last-observation-carried-forward method. A per-protocol analysis was also performed for patients who completed a 1-year T&E regimen. The primary endpoints were mean changes in best-corrected visual acuity (BCVA) and central subfield macular thickness (CST) from baseline. Secondary endpoints included IAI-interval extension and resultant IAI numbers and the association between an early response to IAI and final BCVA gain at 1 year.

RESULTS

Thirty-one patients (77.5%) completed the 1-year aflibercept T&E regimen. In these per-protocol participants, the mean CST improvement/reduction was 187.3 ± 145.0 µm (P < .001), but the mean BCVA gain was limited to 4.3 ± 12.2 letters (P = .782). Subanalysis revealed that eyes that gained ≥ 4 letters (median at week 12) after the initial 3 consecutive IAIs (induction phase) achieved greater vision improvement (13.8 ± 9.5 letters) than did the residual eyes (- 4.3 ± 9.2 letters) at 1 year (P < .001). Treatment intervals were extended to 12 and 16 weeks in 16.1% (5/31) and 45.2% (14/31) of the patients, respectively. The mean IAI number was 7.0 ± 1.1.

CONCLUSIONS

The results of this study suggest that although the BCVA improvement might be somewhat less than that of frequent treatment, a T&E aflibercept regimen with the longest treatment interval set to 16 weeks is a realizable rational strategy for DME treatment over 1 year.

Systematic review with network meta-analysis of antivascular endothelial growth factor use in managing polypoidal choroidal vasculopathy

Polypoidal choroidal vasculopathy (PCV) is a vision-threatening disease common in Asian populations. However, the optimal treatment for PCV remains under debate. We searched the databases with optimal searching strategy. The study included randomized clinical trials and prospective studies that recruited patients with active PCV who had received interventions, including PDT, anti-VEGF, or a combination of PDT and anti-VEGF. The Grading of Recommendations Assessment, Development, and Evaluation methodology was used for rating the quality of evidence. Our study included 11 studies involving 1277 patients. The network meta-analysis of RCTs revealed the anti-VEGF group, early combination group, and late combination group had significant BCVA changes compared with the PDT group. Early combination therapy led to a significant decrease in CRT compared with PDT, anti-VEGF, and late combination therapy. Additionally, the early combination group had a significantly higher complete polyp regression rate than the anti-VEGF group. No significant differences were detected in the analysis of the number of anti-VEGF injections and safety profile. This network meta-analysis revealed that early combination therapy exhibited better efficacy related to anatomical outcomes than other therapies. Nonetheless, no significant differences related to BCVA change could be detected between anti-VEGF and late combination therapy.

One-year Results of Aflibercept Treatment for Polypoidal Choroidal Vasculopathy with Good Visual Acuity

PURPOSE

To evaluate the one-year efficacy of intravitreal aflibercept injection in polypoidal choroidal vasculopathy (PCV) with best-corrected visual acuity (BCVA) of 20 / 40 or better.

METHODS

This was a multicenter retrospective study. The medical records of patients diagnosed with treatment-naïve PCV were retrospectively reviewed. Patients with an initial BCVA of 20 / 40 or better and who had undergone intravitreal aflibercept injection were included. Patients were treated with three consecutive monthly injections, followed by pro re nata regimen according to the clinician's discretion at variable interval visits. The proportions of eyes for which BCVA was maintained (≤ 0.2 logarithm of the minimum angle of resolution change) or improved at 12 months were evaluated. The changes of BCVA, central subfield macular thickness (CSMT), pigment epithelial detachment, and subretinal fluid also were assessed.

RESULTS

A total of 86 eyes were included. The mean number of injections for 12 months of treatment was 5.4 ± 1.7. BCVA was maintained or improved in 94.2% (81 / 86) of cases. Mean BCVA (logarithm of the minimum angle of resolution) had changed from the baseline (0.23 ± 0.09) at 3 months (0.21 ± 0.14), 6 months (0.24 ± 0.22), and 12 months (0.20 ± 0.18), but with no statistical significance. CSMT had improved significantly from the baseline (336.1 ± 97.3 μm) at 3 months (223.6 ± 47.22 μm), 6 months (239.6 ± 64.2 μm), and 12 months (223.8 ± 47.9 μm). Pigment epithelial detachment was observed in 93% of cases at the baseline, 72.1% at 3 months, and 69.8% at 12 months, showing a significant decrease at all observation points. Subretinal fluid was observed in 91.9% of cases at the baseline, 20.9% at 3 months, and 29.1% at 12 months, showing a significant decrease at all observation points.

CONCLUSIONS

In cases of PCV with good visual acuity, intravitreal aflibercept injections decreased CSMT and were effective in maintaining visual acuity.

Retinal vessel oximetry in children with inherited retinal diseases

BACKGROUND

Retinal vessel oximetry (RO) has been used to show altered metabolic function in patients with inherited retinal diseases (IRDs). The aim of this study was to investigate RO parameters of children with IRDs and presumed IRD carriers (pIRDc) and to compare them to controls.

METHODS

In this cross-sectional cohort study, 142 eyes from 71 Caucasian subjects were included: 40 eyes with IRDs, 26 eyes with pIRDc and 76 control eyes. The oxygen saturation was measured with the Retinal Vessel Analyser (IMEDOS Systems UG, Jena, Germany). Mean oxygen saturations in the peripapillary retinal arterioles (A-SO₂ ; %) and venules (V-SO₂ ; %) were estimated, and their difference (A-V SO₂ ; %) was calculated. In addition, we evaluated the mean diameter in all major retinal arterioles (D-A; μm) and venules (D-V; μm). anova-based linear mixed-effects models were calculated with SPSS^® .

RESULTS

In general, children suffering from IRDs differed from controls when the A-SO₂ and A-V SO₂ were taken into account: both the A-SO₂ and the A-V SO₂ were significantly increased (p = 0.012). In subgroup analyses, children suffering from rod-cone dystrophy (RCD) presented an A-SO₂ increase (99.12 ± 8.24%) when compared to controls (91.33 ± 10.34%, p = 0.014) and pIRDc (92.37 ± 6.57%, p = 0.065). For V-SO₂ significant changes in RCD (67.42 ± 9.19%) were found in comparison with controls (58.24 ± 11.74%, p < 0.041), pIRDc (56.67 ± 7.16%, p = 0.007), cone-rod dystrophies (CRD, 52.17 ± 5.32%, p < 0.001) and inherited macular dystrophies (IMD, 55.74 ± 6.96%, p = 0.004), In addition, A-V SO₂ was decreased in RCD (31.69 ± 3.92%) when measured against CRD (41.9 ± 8.87%, p = 0.017) or IMD (39.52 ± 8.95%, p = 0.059).

CONCLUSION

In general, we found that children with IRDs presented early metabolic changes. Within IRDs, children with RCD showed more affected metabolic changes. Thus, RO may support early screening to rule out IRDs in children, and more precisely may help to differentiate those suffering from RCD.

Managing Diabetic Macular Edema in Clinical Practice: Systematic Review and Meta-Analysis of Current Strategies and Treatment Options

Purpose

This meta-analysis aims to summarize 12-month best-corrected visual acuity (BCVA) outcomes in response to anti-vascular endothelial growth factor (VEGF) therapy and dexamethasone implant for the treatment of diabetic macular edema (DME) and to identify factors affecting treatment response using evidence generated from meta-regression.

Methods

A systematic review of electronic databases was conducted to identify randomized controlled trials (RCTs) and real-life/observational studies that reported 12-month changes in BCVA in patients with DME on anti-VEGF or dexamethasone implant treatment in monotherapy. Study factors that were analyzed are baseline patient characteristics, study type, drug employed, number of injections and 12-month change in BCVA. Data were pooled in a random-effects meta-analysis with BCVA change as the main outcome. Meta-regression was conducted to assess the impact of multiple covariates.

Results

One-hundred-five heterogeneous study populations (45,032 eyes) were identified and included in the analysis. The use of anti-VEGFs and dexamethasone implant induced an overall increase of +8.13 ETDRS letters in BCVA at 12 months of follow-up. Meta-regression provided evidence that mean BCVA change using anti-VEGFs was not statistically higher for RCTs (p=0.35) compared to observational studies. Dexamethasone implant showed a trend for better results in observational studies over RCTs. Populations following a fixed aflibercept regimen performed better than those following a reactive treatment regimen. Mean BCVA gain was higher in younger populations (p<0.001), with lower baseline BCVA (p<0.0001) and longer diabetes duration (p<0.0001), receiving a higher number of injections (p<0.0001).

Conclusion

Intravitreal therapy with anti-VEGFs or dexamethasone implant produces a significant improvement in BCVA at 12 months in patients with DME. Meta-regression identified the modifiable covariates that can be targeted in order to maximize functional results.

Efficacy and safety of intravitreal aflibercept for polypoidal choroidal vasculopathy: 96-week outcomes in the Japanese subgroup of the PLANET study

PURPOSE

To evaluate the efficacy and safety of intravitreal aflibercept (IVT-AFL) versus IVT-AFL plus rescue photodynamic therapy (IVT-AFL + rPDT) in the subgroup of Japanese patients with polypoidal choroidal vasculopathy (PCV) enrolled in the PLANET study.

STUDY DESIGN

A 96-week, double-masked, sham-controlled phase-3b/4 randomized clinical trial conducted at multiple centers from May 2014 to August 2016.

PATIENTS AND METHODS

Patients with PCV (BCVA 73-24 ETDRS letters [20/40-20/320 Snellen]) received 3 initial monthly doses of IVT-AFL 2 mg. At week 12, the patients were randomly assigned 1:1 to IVT-AFL + sham PDT or IVT-AFL + rPDT. Patients not requiring rescue received IVT-AFL every 8 weeks; those requiring rescue received IVT-AFL monthly plus sham/active PDT. Following week 52, the treatment intervals could be extended > 8 weeks.

RESULTS

The baseline demographics for the 159 Japanese patients were balanced. At week 96, the mean BCVA change was + 9.7 (IVT-AFL) versus + 9.5 letters (IVT-AFL + rPDT) (least-squares mean difference of - 0.3; 95% CI, - 3.7 to 3.1); the mean central subfield thickness reduction was - 148.0 µm versus - 145.9 µm. Overall, 17.1% of the patients required rescue PDT. At week 96, 25.0% (IVT-AFL) and 37.9% (IVT-AFL + rPDT) of the patients had complete polyp regression; 84.1% (IVT-AFL) and 88.4% (IVT-AFL + rPDT) of the patients had no evidence of active polyps. The mean number of injections (weeks 52-96) were 4.6 (IVT-AFL) and 4.5 (IVT-AFL + rPDT). Overall, 36.0% (IVT-AFL) and 33.8% (IVT-AFL + rPDT) of the patients experienced ocular treatment-emergent adverse events.

CONCLUSION

IVT-AFL monotherapy was efficacious for the treatment of Japanese patients with PCV, and the addition of rescue PDT did not show additional benefits.

Regenerative Approaches and Future Trends for the Treatment of Corneal Burn Injuries

Ocular chemical and thermal burns are frequent causes of hospitalization and require immediate interventions and care. Various surgical and pharmacological treatment strategies are employed according to damage severity. Controlling inflammation and neovascularization while promoting normal ocular surface anatomy and function restoration is the principal aim. In the most severe cases, when epithelial healing is severely affected, reconstruction of the ocular surface may be a valid option, which, however, requires expertise, adequate instruments, and qualified donors. Numerous endogenous and exogenous strategies have been considered for corneal repair. Among these, stem cells and their derivatives have offered numerous attractive possibilities in finding an effective way in stimulating corneal regeneration. Limbal epithelial stem cells and mesenchymal cells from the ocular tissue as well as from various sources have demonstrated their effectiveness in dampening neovascularization, scarring, and inflammation, while promoting epithelialization of the injured cornea. Moreover, a plethora of cytokines and growth factors, and extracellular vesicles, which constitute the secretome of these cells, work in concert to enhance wound healing. In this review, we provide an update on the recent potential therapeutic avenues and clinical applications of stem cells and their products in corneal regeneration after burn injury, as well as current imaging strategies for monitoring therapeutic efficacy and damage resolution.

Seasonal variation in acute post-cataract surgery endophthalmitis incidences in South Korea

PURPOSE

Previous studies have reported conflicting results on the influence of seasons on post-cataract surgery endophthalmitis incidences. This study aimed to investigate the seasonality associated with the incidence of postoperative endophthalmitis, and to evaluate its association with climate variables in South Korea.

SETTING

South Korea.

DESIGN

Retrospective cohort study.

METHODS

The postoperative endophthalmitis incidences were identified using the Health Insurance Review and Assessment Service claim data from July 2014 to June 2017. The monthly climate data were obtained from the Korea Meteorological Administration. The incidences of endophthalmitis were analyzed by the month of the year, and by the season. The association between postoperative endophthalmitis and the climatic variables, including mean temperature, relative humidity, precipitation, and hours of sunshine, was investigated.

RESULTS

The incidences were the highest in July, and they were the most prevalent during the summer months, although fewer cataract surgeries were performed in the summer months than during the rest of the year. The postoperative endophthalmitis incidences tended to increase with increasing relative humidity and increasing precipitation.

CONCLUSIONS

The incidences of post-cataract surgery endophthalmitis peaked during the hot and humid months. Understanding the seasonal and climatic influences on postoperative infection might help in risk stratification and outcome improvisation after the cataract surgery is performed.

Luteolin delays photoreceptor degeneration in a mouse model of retinitis pigmentosa

Luteolin is neuroprotective for retinal ganglion cells and retinal pigment epithelial cells after oxidative injury, whereby it can inhibit microglial neurotoxicity. Therefore, luteolin holds the potential to be useful for treatment of retinal diseases. The purpose of this study was to investigate whether luteolin exhibits neuroprotective effects on rod cells in rd10 mice, a slow photoreceptor-degenerative model of retinitis pigmentosa. Luteolin (100 mg/kg) intraperitoneally injected daily from postnatal day 14 (P14) to P25 significantly enhanced the visual performance and retinal light responses of rd10 mice at P25. Moreover, it increased the survival of photoreceptors and improved retinal structure. Mechanistically, luteolin treatment attenuated increases in reactive oxygen species, photoreceptor apoptosis, and reactive gliosis; increased mRNA levels of anti-inflammatory cytokines while lowering that of pro-inflammatory and chemoattractant cytokines; and lowered the ratio of phospho-JNK/JNK. Application of the JNK inhibitor SP600125 exerted a similar protective effect to luteolin, suggesting that luteolin delays photoreceptor degeneration and functional deterioration in rd10 mice through regulation of retinal oxidation and inflammation by inhibiting the JNK pathway. Therefore, luteolin may be useful as a supplementary treatment for retinitis pigmentosa. This study was approved by the Qualified Ethics Committee of Jinan University, China (approval No. IACUC-20181217-02) on December 17, 2018.

Basolateral activation with TLR agonists induces polarized cytokine release and reduces barrier function in RPE in vitro

PURPOSE

Systemic inflammation may be of importance in the development of AMD. RPE cells can recognize danger signals with toll-like receptors (TLR) and may react in a pro-inflammatory manner. In this study, we evaluated the basal and apical secretions of TNFα, IL-6, and IL-1β in primary RPE cells and RPE/choroid explant cells under basolateral stimulation of TLR2, 3, and 4; the effects on barrier function; and their influence on neuronal cell viability.

METHODS

RPE/choroid tissue explants were prepared from porcine eyes and cultivated in modified Ussing chambers; primary porcine RPE cells on transwell plates. Cells were basally stimulated with agonists Pam2CSK4 (Pam; TLR2), polyinosinic/polycytidylic acid (Poly I:C; TLR3), and lipopolysaccharide (LPS; TLR4) for 24 h. Supernatants were evaluated with ELISA for cytokines TNFα, IL-6, and IL-1β. Apical supernatants were applied to SHSY-5Y cells, and cell viability was evaluated in MTT assay. Barrier function was tested by measuring transepithelial electrical resistance (TER) and occludin immunostaining.

RESULTS

None of the tested TLR agonists was toxic on RPE cells after 24 h of exposure. Unstimulated RPE cells secreted hardly any cytokines. Pam induced IL-6, IL-1ß, and TNFα on the basal and apical sides at all concentrations tested. Poly I:C induced IL-6 and TNFα primarily at the basal side at lower but on both sides at higher concentrations. LPS induced IL-6, IL-1ß, and TNFα apically and basally at all concentrations tested. In the RPE/choroid, a strong difference between apical and basal secretions could be found. IL-6 was constitutively secreted basally, but not apically, but was induced by all agonists on both sides. IL-1ß and TNFα alpha were strongly induced on the basal side by all agonists. TER was reduced by all agonists, with Pam and LPS being effective in all concentrations tested. Occludin expression was unaltered, but the distribution was influenced by the agonists, with a less distinct localization at the cell borders after treatment. None of the agonists or supernatants of treated RPE and RPE/choroid organ cultures exerted any effect on viability of SHSY-5Y cells.

CONCLUSIONS

Danger signals activating TLRs can induce polarized cytokine expression and contribute to the loss of barrier function in the RPE.

The ocular surface bacterial contamination and its management in the prophylaxis of post cataract surgery endophthalmitis

Objective: To investigate the recent pieces of evidence regarding the bacterial ocular surface contamination and its treatment in the prophylaxis of post-cataract surgery endophthalmitis. Methods: We conducted a literature research on the topic of interest and selected the most relevant data. Results: The studies reported a relatively high rate of positive conjunctival culture and the most frequently isolated organism was Coagulase negative Staphylococcus, which is also the most common etiological agent of the postoperative endophthalmitis. The bacterial ocular surface load is influenced by age, climate, associated diseases, topical and systemic medication. The use of povidone-iodine alone or in association with levofloxacin eyedrops as prophylactic method is effective in reducing the conjunctival bacterial contamination and consequently decreases the incidence of postoperative endophthalmitis. Conclusions: Based on the current pieces of evidence, adequate treatment of the bacterial ocular surface contamination prior to cataract surgery seems to be effective in preventing endophthalmitis after cataract surgery. Abbreviations: EU = European Union, Spp. = Species, HIV = Human Immunodeficiency Virus.

Rod photoreceptor clearance due to misfolded rhodopsin is linked to a DAMP-immune checkpoint switch

Chronic endoplasmic reticulum stress resulting from misfolding of the visual pigment rhodopsin (RHO) can lead to loss of rod photoreceptors, which initiates retinitis pigmentosa, characterized initially by diminished nighttime and peripheral vision. Cone photoreceptors depend on rods for glucose transport, which the neurons use for assembly of visual pigment-rich structures; as such, loss of rods also leads to a secondary loss of cone function, diminishing high-resolution color vision utilized for tasks including reading, driving, and facial recognition. If dysfunctional rods could be maintained to continue to serve this secondary cone preservation function, it might benefit patients with retinitis pigmentosa, but the mechanisms by which rods are removed are not fully established. Using pigs expressing mutant RHO, we find that induction of a danger-associated molecular pattern (DAMP) "eat me" signal on the surface of mutant rods is correlated with targeting the live cells for (PrCR) by retinal myeloid cells. Glucocorticoid therapy leads to replacement of this DAMP with a "don't eat me" immune checkpoint on the rod surface and inhibition of PrCR. Surviving rods then continue to promote glucose transport to cones, maintaining their viability.

Two-year outcomes of the treat-and-extend regimen using aflibercept for treating diabetic macular oedema

This study was performed to investigate the efficacy of the treat-and-extend regimen using aflibercept for treating diabetic macular oedema (DME). This prospective, multicentre, interventional, single-arm, 104-week clinical trial included 48 patients with DME visual impairment. The patients’ eyes received five consecutive intravitreal injections (2 mg aflibercept) every four weeks with two-week adjustments based on central subfield macular thickness (CSMT) changes. Injections were deferred when CSMT was stable. The number of injections, best-corrected visual acuity (BCVA), CSMT, and diabetic retinopathy severity scale scores were analysed. Compared to baseline, BCVA improved by + 9.1 letters at 52 weeks and was maintained with + 9.4-letter gain at 104 weeks (P < 0.001). Between baseline and 104 weeks, CSMT decreased from 489 to 298 μm (P < 0.001) and eyes with vision ≥ 20/40 increased from 17.4 to 43.5% (P = 0.007). The mean number of injections decreased from 8.5 in year one to 3.9 in year two. The injection interval was extended to ≥ 12 weeks in 56.5% of patients. The treat-and-extend regimen of aflibercept in DME showed 2-year efficacy comparable to that of fixed dosing regimens. The flexible dosing of this regimen reduced the number of injections in year two while maintaining efficacy.

Novel Method of Plugging the Hole: Anatomical and Functional Outcomes of Human Amniotic Membrane-Assisted Macular Hole Surgery

Purpose:

To describe the surgical outcomes of macular holes (MHs) by inserting a human amniotic membrane (hAM) plug.

Methods:

In this retrospective, interventional, comparative case series, 10 patients who had undergone hAM plugging for a MH were included in the study. Seven patients had idiopathic full-thickness MHs, 1 patient had traumatic MH, and 1 patient each had a MH-induced retinal detachment and combined retinal detachment. The control group included 10 cases with similar configuration and duration of MHs treated with the inverted peeling of the internal limiting membrane technique. All patients underwent a standard 3-port, 25-gauge transconjunctival pars plana vitrectomy and hAM plug transplantation in the subretinal space under the MH. The anatomic and functional outcomes were assessed at 4 weeks postsurgery.

Results:

At the 4-week follow-up visit, all the MHs in the hAM plug group achieved hole closure, whereas 80% of the eyes in the control group were able to achieve hole closure. Improvement of 0.1 logMAR vision was noted in 8 of the 10 patients. At the 4-week follow-up visit, the external limiting membrane and ellipsoid zone layer continuity over the hAM was defined only in one case. No significant difference was found between the hAM plug group and controls in visual and anatomical responses. No complications following hAM transplantation such as rejection, endophthalmitis, or hypotony were noted following surgery.

Conclusion:

Subretinal hAM graft transplantation can be a useful option in the repair of primary or refractory MHs not only for achieving anatomic closure but also for the accompanying visual improvement.

Adipose-Derived Stem Cells: Current Applications and Future Directions in the Regeneration of Multiple Tissues

Adipose-derived stem cells (ADSCs) can maintain self-renewal and enhanced multidifferentiation potential through the release of a variety of paracrine factors and extracellular vesicles, allowing them to repair damaged organs and tissues. Consequently, considerable attention has increasingly been paid to their application in tissue engineering and organ regeneration. Here, we provide a comprehensive overview of the current status of ADSC preparation, including harvesting, isolation, and identification. The advances in preclinical and clinical evidence-based ADSC therapy for bone, cartilage, myocardium, liver, and nervous system regeneration as well as skin wound healing are also summarized. Notably, the perspectives, potential challenges, and future directions for ADSC-related researches are discussed. We hope that this review can provide comprehensive and standardized guidelines for the safe and effective application of ADSCs to achieve predictable and desired therapeutic effects.

The Genus Ochrobactrum as Major Opportunistic Pathogens

Ochrobactrum species are non-enteric, Gram-negative organisms that are closely related to the genus Brucella. Since the designation of the genus in 1988, several distinct species have now been characterised and implicated as opportunistic pathogens in multiple outbreaks. Here, we examine the genus, its members, diagnostic tools used for identification, data from recent Ochrobactrum whole genome sequencing and the pathogenicity associated with reported Ochrobactrum infections. This review identified 128 instances of Ochrobactrum spp. infections that have been discussed in the literature. These findings indicate that infection review programs should consider investigation of possible Ochrobactrum spp. outbreaks if these bacteria are clinically isolated in more than one patient and that Ochrobactrum spp. are more important pathogens than previously thought.

Multifunctional Monoclonal Antibody Targeting Pseudomonas aeruginosa Keratitis in Mice

A worrisome trend in the study and treatment of infectious disease noted in recent years is the increase in multidrug resistant strains of bacteria concurrent with a scarcity of new antimicrobial agents to counteract this rise. This is particularly true amongst bacteria within the Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species (ESKAPE) designation. P. aeruginosa is one of the most common causes of bacterial keratitis. Therefore, it is of vital importance to characterize new antimicrobial agents with anti-Pseudomonal activity for use with the ocular surface. MEDI3902 is a multifunctional antibody that targets the P. aeruginosa persistence factor Psl exopolysaccharide, and the type 3 secretion protein PcrV. We initially assessed this antibody for ocular surface toxicity. The antimicrobial activity of the antibody was then tested by treating mice with established P. aeruginosa keratitis with both topical and intravenous treatment modalities. MEDI3902, was shown to be non-toxic to the ocular surface of mice when given topically. It was also effective compared to the control antibody at preventing P. aeruginosa keratitis with a one-time treatment at the time of infection. Both topical and intravenous administration of MEDI3902 has been proved significant in treating established keratitis infections as well, speeding the resolution of infection significantly more than that of the control IgG. We report the first use of a topical immunotherapeutic multifunctional agent targeting Psl and type 3 secretion on the ocular surface as an antimicrobial agent. While MEDI3902 has been shown to prevent Pseudomonas biofilm formation in keratitis models when given prophylactically intravitally, we show that MEDI3902 has the capability to also treat an active infection when given intravenously to mice with Pseudomonas keratitis. Our data indicate antibodies are well tolerated and nontoxic on the ocular surface. They reduce infection in mice treated concurrently at inoculation and reduced the signs of cornea pathology in mice with established infection. Taken together, these data indicate treatment with monoclonal antibodies directed against Psl and PcrV may be clinically effective in the treatment of P. aeruginosa keratitis and suggest that the design of further antibodies to be an additional tool in the treatment of bacterial keratitis.

Human amniotic membrane plug to promote failed macular hole closure

The failed macular hole is a full-thickness defect involving the fovea that fails to close despite 1 or more surgeries. While many surgical options have been proposed to manage it, none of these guarantee complete anatomical success and satisfactory visual recovery. We report postoperative outcomes on 36 patients affected by failed macular hole, treated with a human amniotic membrane plug transplant. Follow-ups were performed with a standard ophthalmological examination and with advanced multimodal diagnostic imaging. Anatomical closure was achieved at 3 months in all patients. Mean best-corrected visual acuity improved statistically significantly at 6 months (p < 0.05). Through microperimetric tests, we assessed a partial recovery of the macular sensitivity on the edges of the plug. Analyzing SD-OCT images, we reported a tissutal ingrowth above the plug, and its segmentation into layers, mimicking normal retinal architecture. OCT-Angiography images non invasively analysed the retinal parafoveal capillary microvasculature; the elaboration of Adaptive Optics images showed the presence of photoreceptors at the edges of the plug. This work demonstrates not only the complete anatomical success of our technique, but also remarkable functional results, and opens the door to a greater understanding of modifications induced by the presence of a human amniotic membrane plug.

Esculin and ferric citrate-incorporated sturgeon skin gelatine as an antioxidant film for food packaging to prevent Enterococcus faecalis contamination

Herein, a sturgeon skin gelatine film combined with esculin and ferric citrate was developed as an edible food packaging material to prevent Enterococcus faecalis (E. faecalis) contamination. E. faecalis is able to hydrolyse esculin in the film, and then the hydrolysed product, esculetin, combines with ferric citrate to form a brown-black phenol iron complex. This phenomenon can be observed easily after 48 h of contamination under visible light, and it can be determined under 365 nm ultraviolet light with high sensitivity. With the addition of esculin and ferric citrate, the film showed better mechanical properties and water vapour permeability than those of the unmodified gelatine. When an increased amount of esculin was added, an increase in thermal stability, antioxidant activity, and antioxidant stability of the film was observed. These physicochemical characteristics are beneficial for developing a packaging material for food storage that mitigates foodborne illness caused by E. faecalis.

Selective knockdown of hexokinase 2 in rods leads to age-related photoreceptor degeneration and retinal metabolic remodeling

Photoreceptors, the primary site of phototransduction in the retina, require energy and metabolites to constantly renew their outer segments. They preferentially consume most glucose through aerobic glycolysis despite possessing abundant mitochondria and enzymes for oxidative phosphorylation (OXPHOS). Exactly how photoreceptors balance aerobic glycolysis and mitochondrial OXPHOS to regulate their survival is still unclear. We crossed rhodopsin-Cre mice with hexokinase 2 (HK2)-floxed mice to study the effect of knocking down HK2, the first rate-limiting enzyme in glycolysis, on retinal health and metabolic remodeling. Immunohistochemistry and Western blots were performed to study changes in photoreceptor-specific proteins and key enzymes in glycolysis and the tricarboxylic acid (TCA) cycle. Changes in retinal structure and function were studied by optical coherence tomography and electroretinography. Mass spectrometry was performed to profile changes in ¹³C-glucose-derived metabolites in glycolysis and the TCA cycle. We found that knocking down HK2 in rods led to age-related photoreceptor degeneration, evidenced by reduced expression of photoreceptor-specific proteins, age-related reductions of the outer nuclear layer, photoreceptor inner and outer segments and impaired electroretinographic responses. Loss of HK2 in rods led to upregulation of HK1, phosphorylation of pyruvate kinase muscle isozyme 2, mitochondrial stress proteins and enzymes in the TCA cycle. Mass spectrometry found that the deletion of HK2 in rods resulted in accumulation of ¹³C-glucose along with decreased pyruvate and increased metabolites in the TCA cycle. Our data suggest that HK2-mediated aerobic glycolysis is indispensable for the maintenance of photoreceptor structure and function and that long-term inhibition of glycolysis leads to photoreceptor degeneration.

One-Year Results of a Treat-and-Extend Regimen of Intravitreal Aflibercept for Polypoidal Choroidal Vasculopathy

Introduction

To evaluate 1-year outcomes of intravitreal aflibercept (IVA) using a treat-and-extend (TAE) regimen for polypoidal choroidal vasculopathy (PCV) and identify the factors for patients whose treatment intervals could be extended.

Methods

Fifty-one eyes of treatment-naïve PCV patients treated with IVA using a TAE regimen for at least 1 year were examined retrospectively. All patients received at least three IVA injections every 5 weeks, and the intervals were then extended by 2-week adjustments up to 13 weeks. When retinal exudation recurred, the patient was treated with the same regimen, but with a shortened interval of 5 weeks.

The main outcome measures were changes in best-corrected visual acuity (BCVA) and central retinal thickness (CRT) as well as the treatment interval at 1 year.

Results

The mean logarithm of the minimum angle of resolution BCVA improved from 0.24 ± 0.32 at baseline to 0.18 ± 0.31 at 12 months (p = 0.048). The mean CRT decreased from 350.3 ± 147.7 µm at baseline to 215.3 ± 75.0 µm at 4 months (p < 0.001), after which it was maintained at this level. At 12 months, the administration interval was 5 weeks in eight eyes (15.7%), 7 weeks in six eyes (11.8%), 9 weeks in two eyes (3.9%), 11 weeks in four eyes (7.8%), and 13 weeks in 31 eyes (60.8%). Female sex, a thinner CRT at 6 months, and absence of polypoidal lesions at 12 months were significant factors related to patients whose treatment intervals could be extended without recurrence to 13 weeks.

Conclusion

IVA using a TAE regimen improved visual and anatomical outcomes in eyes with PCV at 1 year using a protocol to adjust the injection intervals specifically for each patient so as to obtain no retinal exudation.

Eucalyptol Inhibits Amyloid-β-Induced Barrier Dysfunction in Glucose-Exposed Retinal Pigment Epithelial Cells and Diabetic Eyes

Hyperglycemia elicits tight junction disruption and blood-retinal barrier breakdown, resulting in diabetes-associated vison loss. Eucalyptol is a natural compound found in eucalyptus oil with diverse bioactivities. This study evaluated that eucalyptol ameliorated tight junctions and retinal barrier function in glucose/amyloid-β (Aβ)-exposed human retinal pigment epithelial (RPE) cells and in db/db mouse eyes. RPE cells were cultured in media containing 33 mM glucose or 5 μM Aβ for 4 days in the presence of 1–20 μM eucalyptol. The in vivo animal study employed db/db mice orally administrated with 10 mg/kg eucalyptol. Nontoxic eucalyptol inhibited the Aβ induction in glucose-loaded RPE cells and diabetic mouse eyes. Eucalyptol reversed the induction of tight junction-associated proteins of ZO-1, occludin-1 and matrix metalloproteinases in glucose- or Aβ-exposed RPE cells and in diabetic eyes, accompanying inhibition of RPE detachment from Bruch’s membrane. Adding eucalyptol to glucose- or Aβ-loaded RPE cells, and diabetic mouse eyes reciprocally reversed induction/activation of apoptosis-related bcl-2, bax, cytochrome C/Apaf-1 and caspases. Eucalyptol attenuated the generation of reactive oxygen species and the induction of receptor for advanced glycation end products in Aβ-exposed RPE cells and diabetic eyes. Eucalyptol may ameliorate RPE barrier dysfunction in diabetic eyes through counteracting Aβ-mediated oxidative stress-induced RPE cell apoptosis.

Metabolic Features of Mouse and Human Retinas: Rods versus Cones, Macula versus Periphery, Retina versus RPE

Photoreceptors, especially cones, which are enriched in the human macula, have high energy demands, making them vulnerable to metabolic stress. Metabolic dysfunction of photoreceptors and their supporting retinal pigment epithelium (RPE) is an important underlying cause of degenerative retinal diseases. However, how cones and the macula support their exorbitant metabolic demand and communicate with RPE is unclear. By profiling metabolite uptake and release and analyzing metabolic genes, we have found cone-rich retinas and human macula share specific metabolic features with upregulated pathways in pyruvate metabolism, mitochondrial TCA cycle, and lipid synthesis. Human neural retina and RPE have distinct but complementary metabolic features. Retinal metabolism centers on NADH production and neurotransmitter biosynthesis. The retina needs aspartate to sustain its aerobic glycolysis and mitochondrial metabolism. RPE metabolism is directed toward NADPH production and biosynthesis of acetyl-rich metabolites, serine, and others. RPE consumes multiple nutrients, including proline, to produce metabolites for the retina.

Inhibition of Mitochondrial Respiration Impairs Nutrient Consumption and Metabolite Transport in Human Retinal Pigment Epithelium

Mitochondrial respiration in mammalian cells not only generates ATP to meet their own energy needs but also couples with biosynthetic pathways to produce metabolites that can be exported to support neighboring cells. However, how defects in mitochondrial respiration influence these biosynthetic and exporting pathways remains poorly understood. Mitochondrial dysfunction in retinal pigment epithelium (RPE) cells is an emerging contributor to the death of their neighboring photoreceptors in degenerative retinal diseases including age-related macular degeneration. In this study, we used targeted-metabolomics and ¹³C tracing to investigate how inhibition of mitochondrial respiration influences the intracellular and extracellular metabolome. We found inhibition of mitochondrial respiration strikingly influenced both the intracellular and extracellular metabolome in primary RPE cells. Intriguingly, the extracellular metabolic changes sensitively reflected the intracellular changes. These changes included substantially enhanced glucose consumption and lactate production; reduced release of pyruvate, citrate, and ketone bodies; and massive accumulation of multiple amino acids and nucleosides. In conclusion, these findings reveal a metabolic signature of nutrient consumption and release in mitochondrial dysfunction in RPE cells. Testing medium metabolites provides a sensitive and noninvasive method to assess mitochondrial function in nutrient utilization and transport.