2020

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Kegeles E, Naumov A, Karpulevich EA, Volchkov P, Baranov P. Convolutional Neural Networks Can Predict Retinal Differentiation in Retinal Organoids. Front Cell Neurosci 2020;14:171.Abstract
We have developed a deep learning-based computer algorithm to recognize and predict retinal differentiation in stem cell-derived organoids based on bright-field imaging. The three-dimensional "organoid" approach for the differentiation of pluripotent stem cells (PSC) into retinal and other neural tissues has become a major strategy to recapitulate development. We decided to develop a universal, robust, and non-invasive method to assess retinal differentiation that would not require chemical probes or reporter gene expression. We hypothesized that basic-contrast bright-field (BF) images contain sufficient information on tissue specification, and it is possible to extract this data using convolutional neural networks (CNNs). Retina-specific Rx-green fluorescent protein mouse embryonic reporter stem cells have been used for all of the differentiation experiments in this work. The BF images of organoids have been taken on day 5 and fluorescent on day 9. To train the CNN, we utilized a transfer learning approach: ImageNet pre-trained ResNet50v2, VGG19, Xception, and DenseNet121 CNNs had been trained on labeled BF images of the organoids, divided into two categories (retina and non-retina), based on the fluorescent reporter gene expression. The best-performing classifier with ResNet50v2 architecture showed a receiver operating characteristic-area under the curve score of 0.91 on a test dataset. A comparison of the best-performing CNN with the human-based classifier showed that the CNN algorithm performs better than the expert in predicting organoid fate (84% vs. 67 ± 6% of correct predictions, respectively), confirming our original hypothesis. Overall, we have demonstrated that the computer algorithm can successfully recognize and predict retinal differentiation in organoids before the onset of reporter gene expression. This is the first demonstration of CNN's ability to classify stem cell-derived tissue .
Kempen JH, Van Natta ML, Friedman DS, Altaweel MM, Ansari H, Dunn JP, Elner SG, Holbrook JT, Lim LL, Sugar EA, Jabs DA, and Group MUST (MUST) TF-up SR. Incidence and Outcome of Uveitic Glaucoma in Eyes With Intermediate, Posterior, or Panuveitis Followed up to 10 Years After Randomization to Fluocinolone Acetonide Implant or Systemic Therapy. Am J Ophthalmol 2020;219:303-316.Abstract
PURPOSE: To evaluate long-term risk and outcomes of glaucoma in eyes with intermediate, posterior, and panuveitis managed with systemic or fluocinolone acetonide (0.59 mg, "implant") therapy. DESIGN: Prospective Follow-up of the Multicenter Uveitis Steroid Treatment (MUST) Clinical Trial Cohort. METHODS: Patients with intermediate, posterior, or panuveitis randomized to implant or systemic therapy (corticosteroid plus immunosuppression in >90%) were followed prospectively for glaucoma incidence and outcome. RESULTS: Among 405 uveitic at-risk eyes of 232 patients (median follow-up = 6.9 years), 40% (79/196) of eyes assigned and treated with implant and 8% (17/209) of eyes assigned and treated with systemic therapy (censoring eyes receiving an implant on implantation) developed glaucoma (hazard ratio [HR] = 5.9, 95% confidence interval [CI] 3.2, 10.8; P < .001). Adjustment for intraocular pressure (IOP) elevation during follow-up only partially mitigated the association of implant treatment with glaucoma incidence: HR = 3.1 (95% CI 1.6, 6.0); P = .001. Among 112 eyes of 83 patients developing glaucoma, the 5-year cumulative incidence following diagnosis of sustained (2 or more consecutive visits) worsening of mean deviation by ≥6 dB was 20% (95% CI 12%, 33%); 5-year cumulative incidence of sustained worsening of cup-to-disc ratio by ≥0.2 was 26% (95% CI 17%, 39%). CONCLUSIONS: The implant has substantially higher risk of glaucoma than systemic therapy, a difference not entirely explained by posttreatment IOP elevation. Management of IOP elevation was effective in preventing worsening of glaucoma for the large majority of cases, but even under expert clinical management, some glaucoma worsened. Uveitis cases should be monitored carefully for IOP elevation and glaucoma indefinitely.
Kempen JH, Abashawl A, Suga HK, Nigussie Difabachew M, Kempen CJ, Tesfaye Debele M, Menkir AA, Assefa MT, Asfaw EH, Habtegabriel LB, Sitotaw Addisie Y, Nilles EJ, Longenecker JC. SARS-CoV-2 Serosurvey in Addis Ababa, Ethiopia. Am J Trop Med Hyg 2020;103(5):2022-2023.Abstract
In a serosurvey of asymptomatic people from the general population recruited from a clinical laboratory in May 2020 in Addis Ababa, Ethiopia, three of 99 persons tested positive for SARS-CoV-2 IgG (3.0%, 95% binomial exact confidence interval: 0.6-8.6%). Taking into account pretest probability and the sampling scheme, the range of plausible population prevalence values was approximately 1.0-8.4%. These results suggest that a larger number of people have been infected than the counts detected by surveillance to date; nevertheless, the results suggest the large majority of the general population in Addis Ababa currently is susceptible to COVID-19.
Khalil IA, Saleh B, Ibrahim DM, Jumelle C, Yung A, Dana R, Annabi N. Ciprofloxacin-loaded bioadhesive hydrogels for ocular applications. Biomater Sci 2020;8(18):5196-5209.Abstract
The management of corneal infections often requires complex therapeutic regimens involving the prolonged and high-frequency application of antibiotics that provide many challenges to patients and impact compliance with the therapeutic regimens. In the context of severe injuries that lead to tissue defects (e.g. corneal lacerations) topical drug regimens are inadequate and suturing is often indicated. There is thus an unmet need for interventions that can provide tissue closure while concurrently preventing or treating infection. In this study, we describe the development of an antibacterial bioadhesive hydrogel loaded with micelles containing ciprofloxacin (CPX) for the management of corneal injuries at risk of infection. The in vitro release profile showed that the hydrogel system can release CPX, a broad-spectrum antibacterial drug, for up to 24 h. Moreover, the developed CPX-loaded hydrogels exhibited excellent antibacterial properties against Staphylococcus aureus and Pseudomonas aeruginosa, two bacterial strains responsible for the most ocular infections. Physical characterization, as well as adhesion and cytocompatibility tests, were performed to assess the effect of CPX loading in the developed hydrogel. Results showed that CPX loading did not affect stiffness, adhesive properties, or cytocompatibility of hydrogels. The efficiency of the antibacterial hydrogel was assessed using an ex vivo model of infectious pig corneal injury. Corneal tissues treated with the antibacterial hydrogel showed a significant decrease in bacterial colony-forming units (CFU) and a higher corneal epithelial viability after 24 h as compared to non-treated corneas and corneas treated with hydrogel without CPX. These results suggest that the developed adhesive hydrogel system presents a promising suture-free solution to seal corneal wounds while preventing infection.
Kim S, Bispo PJM, Tanner EEL, Mitragotri S, E Silva RN, Gipson I, Chodosh J, Behlau I, Paschalis EI, Gilmore MS, Dohlman CH. The Search for Antifungal Prophylaxis After Artificial Corneal Surgery-An In Vitro Study. Cornea 2020;39(12):1547-1555.Abstract
PURPOSE: To evaluate the antifungal properties of topical antibiotics (already being used successfully to prevent bacterial endophthalmitis) and some promising antiseptics for antifungal prophylaxis in the setting of artificial corneal implantation. METHODS: Several commonly used antibiotics for antimicrobial prophylaxis after artificial corneal implantation, in addition to antiseptics [benzalkonium chloride (BAK), povidone-iodine (PI), and some ionic liquids (ILs)], were tested in vitro against Candida albicans, Fusarium solani, and Aspergillus fumigatus. The time-kill activity was determined. Toxicity was assayed in vitro on human corneal epithelial cultures using trypan blue. Adhesion and tissue invasion experiments were also carried out on porcine corneas and commonly used contact lenses, with or without gamma irradiation, and by analysis with fluorescence microscopy. RESULTS: Polymyxin B (PMB)/trimethoprim/BAK (Polytrim), PMB alone, gatifloxacin with BAK (Zymaxid), and same-concentration BAK alone exhibited antifungal activity in vitro. Moxifloxacin (MOX) or gatifloxacin without BAK-as well as trimethoprim, vancomycin, and chloramphenicol-had no effect. 1% PI and ILs had the highest efficacy/toxicity ratios (>1), and Polytrim was species dependent. Subfungicidal concentrations of Polytrim reduced adhesion of C. albicans to Kontur contact lenses. Gamma-irradiated corneas showed enhanced resistance to fungal invasion. CONCLUSIONS: Of antibiotic preparations already in use for bacterial prophylaxis after KPro surgery, Polytrim is a commonly used antibiotic with antifungal effects mediated by both PMB and BAK and may be sufficient for prophylaxis. PI as a 1% solution seems to be promising as a long-term antifungal agent. Choline-undecanoate IL is effective and virtually nontoxic and warrants further development.
Kitamoto K, Taketani Y, Fujii W, Inamochi A, Toyono T, Miyai T, Yamagami S, Kuroda M, Usui T, Ouchi Y. Generation of mouse model of TGFBI-R124C corneal dystrophy using CRISPR/Cas9-mediated homology-directed repair. Sci Rep 2020;10(1):2000.Abstract
Mutations in transforming growth factor-beta-induced (TGFBI) gene cause clinically distinct types of corneal dystrophies. To delineate the mechanisms driving these dystrophies, we focused on the R124C mutation in TGFBI that causes lattice corneal dystrophy type1 (LCD1) and generated novel transgenic mice harbouring a single amino acid substitution of arginine 124 with cysteine in TGFBI via ssODN-mediated base-pair substitution using CRISPR/Cas9 technology. Eighty percent of homozygous and 9.1% of heterozygous TGFBI-R124C mice developed a corneal opacity at 40 weeks of age. Hematoxylin and eosin and Masson trichrome staining showed eosinophilic deposits in subepithelial corneal stroma that stained negative for Congo-red. Although amyloid deposition was not observed in TGFBI-R124C mice, irregular amorphous deposits were clearly observed via transmission electron microscopy near the basement membrane. Interestingly, we found that the corneal deposition of TGFBI protein (TGFBIp) was significantly increased in homozygous TGFBI-R124C mice, suggesting a pathogenic role for the mutant protein accumulation. Furthermore, as observed in the LCD1 patients, corneal epithelial wound healing was significantly delayed in TGFBI-R124C mice. In conclusion, our novel mouse model of TGFBI-R124C corneal dystrophy reproduces features of the human disease. This mouse model will help delineate the pathogenic mechanisms of human corneal dystrophy.
Koo EH, Pineda R, Afshari N, Eghrari A. Learning Descemet Membrane Endothelial Keratoplasty: A Survey of U.S. Corneal Surgeons. Cornea 2020;39(5):590-593.Abstract
PURPOSE: The transition to Descemet membrane endothelial keratoplasty (DMEK) is frequently challenging, requiring the adoption of new techniques, skills, and methods. We sought to draw on surgeons' initial experiences with DMEK to characterize the learning curve associated with this procedure and identify factors that could be linked to the frequency of primary graft failure (PGF) in the first 10 cases. METHODS: We invited corneal surgeons based in the United States who started performing the DMEK procedure within the past 2 years to answer a 12-question survey using an online survey platform. We analyzed quantitative and qualitative data. A Fisher exact test was used to determine whether preoperative approaches to preparation were associated with decreased PGF rates. RESULTS: A total of 100 US-based corneal surgeons replied from 34 of 50 states. Of these, 68% reported that DMEK comprised a majority of their endothelial keratoplasty cases. Approximately half of surgeons (52%) had performed more than 20 DMEK cases by the time of the survey, and 51% felt equally comfortable performing DMEK relative to Descemet stripping endothelial keratoplasty. Among the respondents, 37% answered that they had experienced PGF in the first 10 cases. Scrubbing in with an experienced colleague before surgery was associated with a decreased likelihood of at least one case of PGF (31%, P = 0.049), but not participation in a wet lab with an experienced instructor or mentor (38%, P = 0.50), nor having an eye bank representative present in the operating room (43%, P = 0.886). CONCLUSIONS: The collective experience of 100 surgeons beginning DMEK confirms the importance of mentorship and that the accompaniment of an experienced colleague during the learning curve is associated with lower rates of PGF.
Koulouri I, Hellwinkel O, Altenähr S, Spitzer M, Fritz S, Feuerstacke J, Filev F. A new storage solution for the hypothermic preservation of corneal grafts: an experimental study. Cell Tissue Bank 2020;21(3):507-521.Abstract
In this experimental study we used for the first time Tiprotec as a solution for corneal preservation and cold storage. We compared the resultant endothelial cell morphology and viability with this obtained after preservation of the ex-vivo corneas with both usual standard techniques: conventional cold storage (using Eusol-C) and organ culture. This prospective, in vitro, 3-armed parallel study was performed with the use of 90 porcine corneas (examined for their endothelial quality and transparency) randomly selected for preservation in three storage methods (each 30 corneas): organ culture, standard cold storage (Eusol-C) and experimental cold storage (Tiprotec) Endothelium cell quantity and quality as well as corneal opacification were assessed. The degree of endothelial transparency was significantly reduced over time with all preservation media, without any significant difference among the three groups at any point of time. A reduction in endothelial cell density was also observed with all three preservation media after 30 days of storage without statistically significant differences between groups. The number of hexagonal and pentagonal endothelium cells was significantly reduced overtime in all media with significantly more hexagonal and pentagonal in the organ culture group compared to the cold storage groups. We could show that the cryopreservation medium Tiprotec, used until now for the preservation of vascular grafts, was of similar quality compared to the medium Eusol-C for the hypothermic storage of corneal tissue for an extended period of time up to 30 days. In comparison to organic culture with culture medium KII, both Tiprotec and Eusol-C were found less effective in preserving endothelial cell quality, as assessed by the morphometric analysis, and viability, as assessed by the degree of vacuolization at least up to the 30th day of storage. However, both, Tiprotec- and Eusol-C-preserved corneas demonstrated a certain capacity to recover after their submission in organ culture.
Kras A, Celi LA, Miller JB. Accelerating ophthalmic artificial intelligence research: the role of an open access data repository. Curr Opin Ophthalmol 2020;31(5):337-350.Abstract
PURPOSE OF REVIEW: Artificial intelligence has already provided multiple clinically relevant applications in ophthalmology. Yet, the explosion of nonstandardized reporting of high-performing algorithms are rendered useless without robust and streamlined implementation guidelines. The development of protocols and checklists will accelerate the translation of research publications to impact on patient care. RECENT FINDINGS: Beyond technological scepticism, we lack uniformity in analysing algorithmic performance generalizability, and benchmarking impacts across clinical settings. No regulatory guardrails have been set to minimize bias or optimize interpretability; no consensus clinical acceptability thresholds or systematized postdeployment monitoring has been set. Moreover, stakeholders with misaligned incentives deepen the landscape complexity especially when it comes to the requisite data integration and harmonization to advance the field. Therefore, despite increasing algorithmic accuracy and commoditization, the infamous 'implementation gap' persists. Open clinical data repositories have been shown to rapidly accelerate research, minimize redundancies and disseminate the expertise and knowledge required to overcome existing barriers. Drawing upon the longstanding success of existing governance frameworks and robust data use and sharing agreements, the ophthalmic community has tremendous opportunity in ushering artificial intelligence into medicine. By collaboratively building a powerful resource of open, anonymized multimodal ophthalmic data, the next generation of clinicians can advance data-driven eye care in unprecedented ways. SUMMARY: This piece demonstrates that with readily accessible data, immense progress can be achieved clinically and methodologically to realize artificial intelligence's impact on clinical care. Exponentially progressive network effects can be seen by consolidating, curating and distributing data amongst both clinicians and data scientists.
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Lally DR, Kasetty MA. CLOSURE OF SMALL MACULAR HOLES USING VITRECTOMY SURGERY WITH INTERNAL LIMITING MEMBRANE PEELING WITHOUT THE USE OF INTRAOCULAR GAS TAMPONADE: BROADENING THE UNDERSTANDING OF THE MACULAR HOLE PATHOPHYSIOLOGY. Retin Cases Brief Rep 2020;14(2):104-109.Abstract
PURPOSE: To determine whether small macular hole closure can be achieved with 25-G vitrectomy surgery with internal limiting membrane peeling without the use of intraocular gas tamponade or facedown positioning. METHODS: 25-G vitrectomy surgery with internal limiting membrane peeling without the use of intraocular gas tamponade or positioning was performed on 20 eyes with a small (<400-µm diameter), full-thickness macular hole. RESULTS: In 17 of 20 eyes (85%), the hole had closed. Three holes had closed by Postoperative Day 1, 13 holes by Postoperative Week 1, 16 holes by Postoperative Week 2, and 17 holes by Postoperative Week 6. At Postoperative Month 1, vision improved in 16 of 17 eyes in which the macular hole had closed. One hole that had not closed at the first postoperative week and two holes that had not closed at the third postoperative week required follow-up surgery with intraocular gas tamponade and facedown positioning, after which the hole closed. The mean preoperative visual acuity was 0.626 logMAR (20/85), and the mean postoperative visual acuity after 1 month was 0.392 logMAR (20/50) (P < 0.001). CONCLUSION: Vitrectomy surgery with internal limiting membrane peeling without the use of gas tamponade or positioning can achieve closure of small macular holes.
Lambert SR, VanderVeen DK, Kim SJ. Reply. Ophthalmology 2020;127(1):e6-e7.
Lambert SR, VanderVeen DK, Aakalu VK, Kim SJ. Reply. Ophthalmology 2020;127(1):e8-e9.
Lee J-J, Ishihara K, Notomi S, Efstathiou NE, Ueta T, Maidana D, Chen XH, Iesato Y, Caligiana A, Vavvas DG. Lysosome-associated membrane protein-2 deficiency increases the risk of reactive oxygen species-induced ferroptosis in retinal pigment epithelial cells. Biochem Biophys Res Commun 2020;521(2):414-419.Abstract
Lysosome-associated membrane protein-2 (LAMP2), is a highly glycosylated lysosomal membrane protein involved in chaperone mediated autophagy. Mutations of LAMP2 cause the classic triad of myopathy, cardiomyopathy and encephalopathy of Danon disease (DD). Additionally, retinopathy has also been observed in young DD patients, leading to vision loss. Emerging evidence show LAMP2-deficiency to be involved in oxidative stress (ROS) but the mechanism remains obscure. In the present study, we found that tert-butyl hydroperoxide or antimycin A induced more cell death in LAMP2 knockdown (LAMP2-KD) than in control ARPE-19 cells. Mechanistically, LAMP2-KD reduced the concentration of cytosolic cysteine, resulting in low glutathione (GSH), inferior antioxidant capability and mitochondrial lipid peroxidation. ROS induced RPE cell death through ferroptosis. Inhibition of glutathione peroxidase 4 (GPx4) increased lethality in LAMP2-KD cells compared to controls. Cysteine and glutamine supplementation restored GSH and prevented ROS-induced cell death of LAMP2-KD RPE cells.
Lee JS, Mukherjee S, Lee JY, Saha A, Chodosh J, Painter DF, Rajaiya J. Entry of Epidemic Keratoconjunctivitis-Associated Human Adenovirus Type 37 in Human Corneal Epithelial Cells. Invest Ophthalmol Vis Sci 2020;61(10):50.Abstract
Purpose: Ocular infection by human adenovirus species D type 37 (HAdV-D37) causes epidemic keratoconjunctivitis, a severe, hyperacute condition. The corneal component of epidemic keratoconjunctivitis begins upon infection of corneal epithelium, and the mechanism of viral entry dictates subsequent proinflammatory gene expression. Therefore, it is important to understand the specific pathways of adenoviral entry in these cells. Methods: Transmission electron microscopy of primary and tert-immortalized human corneal epithelial cells infected with HAdV-D37 was performed to identify the means of viral entry. Confocal microscopy was used to determine intracellular trafficking. The results of targeted small interfering RNA and specific chemical inhibitors were analyzed by quantitative PCR, and Western blot. Results: By transmission electron microscopy, HAdV-D37 was seen to enter by both clathrin-coated pits and macropinocytosis; however, entry was both pH and dynamin 2 independent. Small interfering RNA against clathrin, AP2A1, and lysosome-associated membrane protein 1, but not early endosome antigen 1, decreased early viral gene expression. Ethyl-isopropyl amiloride, which blocks micropinocytosis, did not affect HAdV-D37 entry, but IPA, an inhibitor of p21-activated kinase, and important to actin polymerization, decreased viral entry in a dose-dependent manner. Conclusions: HAdV-D37 enters human corneal epithelial cells by a noncanonical clathrin-mediated pathway involving lysosome-associated membrane protein 1 and PAK1, independent of pH, dynamin, and early endosome antigen 1. We showed earlier that HAdV-D37 enters human keratocytes through caveolae. Therefore, epidemic keratoconjunctivitis-associated viruses enter different corneal cell types via disparate pathways, which could account for a relative paucity of proinflammatory gene expression upon infection of corneal epithelial cells compared with keratocytes, as seen in prior studies.
Lei F, Cui N, Zhou C, Chodosh J, Vavvas DG, Paschalis EI. CSF1R inhibition by a small-molecule inhibitor is not microglia specific; affecting hematopoiesis and the function of macrophages. Proc Natl Acad Sci U S A 2020;117(38):23336-23338.Abstract
Colony-stimulating factor 1 receptor (CSF1R) inhibition has been proposed as a method for microglia depletion, with the assumption that it does not affect peripheral immune cells. Here, we show that CSF1R inhibition by PLX5622 indeed affects the myeloid and lymphoid compartments, causes long-term changes in bone marrow-derived macrophages by suppressing interleukin 1β, CD68, and phagocytosis but not CD208, following exposure to endotoxin, and also reduces the population of resident and interstitial macrophages of peritoneum, lung, and liver but not spleen. Thus, small-molecule CSF1R inhibition is not restricted to microglia, causing strong effects on circulating and tissue macrophages that perdure long after cessation of the treatment. Given that peripheral monocytes repopulate the central nervous system after CSF1R inhibition, these changes have practical implications for relevant experimental data.
Levy JM, Yeh W-H, Pendse N, Davis JR, Hennessey E, Butcher R, Koblan LW, Comander J, Liu Q, Liu DR. Cytosine and adenine base editing of the brain, liver, retina, heart and skeletal muscle of mice via adeno-associated viruses. Nat Biomed Eng 2020;4(1):97-110.Abstract
The success of base editors for the study and treatment of genetic diseases depends on the ability to deliver them in vivo to the relevant cell types. Delivery via adeno-associated viruses (AAVs) is limited by AAV packaging capacity, which precludes the use of full-length base editors. Here, we report the application of dual AAVs for the delivery of split cytosine and adenine base editors that are then reconstituted by trans-splicing inteins. Optimized dual AAVs enable in vivo base editing at therapeutically relevant efficiencies and dosages in the mouse brain (up to 59% of unsorted cortical tissue), liver (38%), retina (38%), heart (20%) and skeletal muscle (9%). We also show that base editing corrects, in mouse brain tissue, a mutation that causes Niemann-Pick disease type C (a neurodegenerative ataxia), slowing down neurodegeneration and increasing lifespan. The optimized delivery vectors should facilitate the efficient introduction of targeted point mutations into multiple tissues of therapeutic interest.
Li LH, Lee JC-Y, Leung HH, Lam WC, Fu Z, Lo ACY. Lutein Supplementation for Eye Diseases. Nutrients 2020;12(6)Abstract
Lutein is one of the few xanthophyll carotenoids that is found in high concentration in the macula of human retina. As synthesis of lutein within the human body is impossible, lutein can only be obtained from diet. It is a natural substance abundant in egg yolk and dark green leafy vegetables. Many basic and clinical studies have reported lutein's anti-oxidative and anti-inflammatory properties in the eye, suggesting its beneficial effects on protection and alleviation of ocular diseases such as age-related macular degeneration, diabetic retinopathy, retinopathy of prematurity, myopia, and cataract. Most importantly, lutein is categorized as Generally Regarded as Safe (GRAS), posing minimal side-effects upon long term consumption. In this review, we will discuss the chemical structure and properties of lutein as well as its application and safety as a nutritional supplement. Finally, the effects of lutein consumption on the aforementioned eye diseases will be reviewed.
Li Y, He X, Kawaguchi R, Zhang Y, Wang Q, Monavarfeshani A, Yang Z, Chen B, Shi Z, Meng H, Zhou S, Zhu J, Jacobi A, Swarup V, Popovich PG, Geschwind DH, He Z. Microglia-organized scar-free spinal cord repair in neonatal mice. Nature 2020;587(7835):613-618.Abstract
Spinal cord injury in mammals is thought to trigger scar formation with little regeneration of axons. Here we show that a crush injury to the spinal cord in neonatal mice leads to scar-free healing that permits the growth of long projecting axons through the lesion. Depletion of microglia in neonatal mice disrupts this healing process and stalls the regrowth of axons, suggesting that microglia are critical for orchestrating the injury response. Using single-cell RNA sequencing and functional analyses, we find that neonatal microglia are transiently activated and have at least two key roles in scar-free healing. First, they transiently secrete fibronectin and its binding proteins to form bridges of extracellular matrix that ligate the severed ends of the spinal cord. Second, neonatal-but not adult-microglia express several extracellular and intracellular peptidase inhibitors, as well as other molecules that are involved in resolving inflammation. We transplanted either neonatal microglia or adult microglia treated with peptidase inhibitors into spinal cord lesions of adult mice, and found that both types of microglia significantly improved healing and axon regrowth. Together, our results reveal the cellular and molecular basis of the nearly complete recovery of neonatal mice after spinal cord injury, and suggest strategies that could be used to facilitate scar-free healing in the adult mammalian nervous system.
Liebman DL, McKay KM, Haviland MJ, Moustafa GA, Borkar DS, Kloek CE. Quantifying the educational benefit of additional cataract surgery cases in ophthalmology residency. J Cataract Refract Surg 2020;46(11):1495-1500.Abstract
PURPOSE: To quantify the resident learning curve for cataract surgery using operative time as an indicator of surgical competency, to identify the case threshold at which marginal additional educational benefit became equivocal, and to characterize heterogeneity in residents' pathways to surgical competency. SETTING: Academic medical center. DESIGN: Large-scale retrospective consecutive case series. METHODS: All cataract surgery cases performed by resident physicians as primary surgeon at Massachusetts Eye and Ear from July 1, 2010, through June 30, 2015, were reviewed. Data were abstracted from Accreditation Council for Graduate Medical Education case logs and operative time measurements. A linear mixed-methods analysis was conducted to model changes in residents' cataract surgery operative times as a function of sequential case number, with resident identity included as a random effect in the model to normalize between-resident variability. RESULTS: A total of 2096 cases were analyzed. A marked progressive decrease in operative time was noted for resident cases 1 to 39 (mean change -0.17 minutes per additional case, 95% CI, -0.21 to -0.12; P < .001). A modest, steady reduction in operative time was subsequently noted for case numbers 40 to 149 (mean change -0.05 minutes per additional case, 95% CI, -0.07 to -0.04; P < .001). No statistically significant improvement was found in operative times beyond the 150th case. CONCLUSIONS: Residents derived educational benefit from performing a greater number of cataract procedures than current minimum requirements. However, cases far in excess of this threshold might have diminishing educational return in residency. Educational resources currently used for these cases might be more appropriately devoted to other training priorities.
Liou VD, Yoon MK. Advances in steroid sparing medical management of active thyroid eye disease. Semin Ophthalmol 2020;:1-8.Abstract
Thyroid eye disease (TED) is an autoimmune inflammatory disease of the orbit and the most common extrathyroidal manifestation of Graves disease. The release of pro-inflammatory cytokines is associated with inflammation of the ocular surface and lacrimal gland along with periorbital skin erythema and edema. Resultant tissue remodeling, fibrosis, and fat deposition can impart permanent physical changes to the ocular adnexa with effects on function and cosmesis. These changes occur in the active phase of disease, and it is during this time that steroids are often relied on to help alleviate symptoms. Due to the common and predictable side effects of long-term and high-dose steroid use, there has been a continuous effort to find alternative steroid-sparing medical management options for TED. This review highlights the various research studies that support the use of these medications.

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