May 2020

Akbari A, Jabbari N, Sharifi R, Ahmadi M, Vahhabi A, Seyedzadeh SJ, Nawaz M, Szafert S, Mahmoodi M, Jabbari E, Asghari R, Rezaie J. Free and hydrogel encapsulated exosome-based therapies in regenerative medicine. Life Sci 2020;249:117447.Abstract
Over the last few decades, mesenchymal stem cells-derived exosomes (MSCs-Ex) have attracted a lot of attention as a therapeutic tool in regenerative medicine. Exosomes are extracellular vehicles (EVs) that play important roles in cell-cell communication through various processes such as stress response, senescence, angiogenesis, and cell differentiation. Success in the field of regenerative medicine sparked exploration of the potential use of exosomes as key therapeutic effectors of MSCs to promote tissue regeneration. Various approaches including direct injection, intravenous injection, intraperitoneal injection, oral administration, and hydrogel-based encapsulation have been exploited to deliver exosomes to target tissues in different disease models. Despite significant advances in exosome therapy, it is unclear which approach is more effective for administering exosomes. Herein, we critically review the emerging progress in the applications of exosomes in the form of free or association with hydrogels as therapeutic agents for applications in regenerative medicine.
Almeida LM, Lebreton F, Gaca A, Bispo PM, Saavedra JT, Calumby RN, Grillo LM, Nascimento TG, Filsner PH, Moreno AM, Gilmore MS. Transferable Resistance Gene in Enterococcus faecalis from Swine in Brazil. Antimicrob Agents Chemother 2020;64(6)Abstract
OptrA is an ATP-binding cassette (ABC)-F protein that confers resistance to oxazolidinones and phenicols and can be either plasmid-encoded or chromosomally encoded. Here, we isolated 13 strains possessing a linezolid MIC of ≥4 mg/liter from nursery pigs in swine herds located across Brazil. Genome sequence comparison showed that these strains possess in different genetic contexts occurring in 5 different sequence type backgrounds. The gene invariably occurred in association with an regulator and a gene encoding a hypothetical protein. In some contexts, this genetic island was able to excise and form a covalently closed circle within the cell; this circle appeared to occur in high abundance and to be transmissible by coresident plasmids.
Aminkhani A, Sharifi S, Ekhtiyari S. Achillea filipendulina Lam.: Chemical Constituents and Antimicrobial Activities of Essential Oil of Stem, Leaf, and Flower. Chem Biodivers 2020;17(5):e2000133.Abstract
In this study, we extracted the essential oils of the stem, leaf, and flower of Achillea filipendulina, analyzed them, and studied their antibacterial properties. Of 16, 53, and 35 compounds identified in the stem, leaf, and flowers, respectively, only five are present in all three segments of the plant. The essential oil of the stem was mainly composed of neryl acetate, spathulenol, carvacrol, santolina alcohol, and trans-caryophyllene oxide. However, the main identified components of leaf were 1,8-cineole, camphor, ascaridole, trans-isoascaridole, and piperitone oxide and the main components of the flower oil were ascaridole, trans-isoascaridole, 1,8-cineole, p-cymene, and camphor. The extracted oil from different segments demonstrated varying antibacterial properties against both Gram-positive and Gram-negative bacteria, demonstrated by disk, minimum inhibitory concentration, and minimum bactericidal concentration methods. These suggest that the application of all segments of aerial parts of A. filipendulina may have a better therapeutic effect in fighting pathogenic systems.
Anchouche S, Yin J. Severe vernal keratoconjunctivitis complicated by anaesthetic abuse. Can J Ophthalmol 2020;
Baumal CR, Sarraf D, Bryant T, Gui W, Muakkassa N, Pichi F, Querques G, Choudhry N, Teke MY, Govetto A, Invernizzi A, Eliott D, Gaudric A, Cunha de Souza E, Naysan J, Lembo A, Lee GC, Freund BK. Henle fibre layer haemorrhage: clinical features and pathogenesis. Br J Ophthalmol 2020;Abstract
BACKGROUND: To describe the clinical presentation and characteristic imaging features of deep retinal haemorrhages primarily located in the Henle fibre layer (HFL) of the macula. The spectrum of aetiologies and a comprehensive theory of pathogenesis are presented. METHODS: This is a retrospective, multicentre case series evaluating eyes with retinal haemorrhage in HFL. Clinical features, underlying aetiology, systemic and ocular risk factors, visual acuity, and multimodal imaging including fundus photography and cross-sectional and en face optical coherence tomography (OCT) are presented. RESULTS: Retinal haemorrhages localised to HFL in 33 eyes from 23 patients were secondary to acute blunt trauma to the head (n=2), eye (n=1) and trunk (n=1), ruptured intracranial aneurysm (Terson's syndrome, n=3), general anaesthesia (n=1), epidural anaesthesia (n=1), hypertension with anaemia (n=1), decompression retinopathy (n=1), postvitrectomy with intraocular gas (n=1), retinal vein occlusion (n=7), myopic degeneration (n=2), macular telangiectasia type 2 (n=1), and polypoidal choroidal vasculopathy (n=1). Defining clinical features included deep retinal haemorrhage with feathery margin and petaloid pattern radiating from the fovea. OCT demonstrated characteristic hyper-reflectivity from the haemorrhage delineated by obliquely oriented fibres in the Henle layer. Spontaneous resolution of HFL haemorrhage occurred after 3 months in 15 patients with follow-up. CONCLUSION: The characteristic petaloid-shaped, deep intraretinal haemorrhage with a feathery margin localised to HFL is associated with various disorders. The terminology 'Henle fiber layer hemorrhage (HH)' is proposed to describe the clinical and OCT findings, which may result from abnormal retinal venous pressure from systemic or local retinovascular disorders affecting the deep capillary plexus or from choroidal vascular abnormalities.
Begaj T, Lorenzo M, Miller JB. A Young Man With Peripheral Vision Loss. JAMA Ophthalmol 2020;
Caton MT, Zamani AA, Du R, Prasad S. Optic Neuropathy Due to Compression by an Ectatic Internal Carotid Artery Within the Orbital Apex. J Neuroophthalmol 2020;Abstract
Neurovascular compression is a rare but potentially treatable cause of optic neuropathy. Although incidental contact of the cisternal optic nerve and internal carotid artery (ICA) is common, compressive optic neuropathy occurring within the orbital apex has not been comprehensively described. We report a case of intra-orbital and intracanalicular optic nerve compression due to an ectatic ICA in a patient with congenital absence of the contralateral ICA. This report describes the complementary roles of advanced neuroimaging and neuro-ophthalmologic examination in rendering the diagnosis.
Chilambi GS, Nordstrom HR, Evans DR, Ferrolino JA, Hayden RT, Marón GM, Vo AN, Gilmore MS, Wolf J, Rosch JW, Van Tyne D. Evolution of vancomycin-resistant during colonization and infection in immunocompromised pediatric patients. Proc Natl Acad Sci U S A 2020;117(21):11703-11714.Abstract
Patients with hematological malignancies or undergoing hematopoietic stem cell transplantation are vulnerable to colonization and infection with multidrug-resistant organisms, including vancomycin-resistant (VREfm). Over a 10-y period, we collected and sequenced the genomes of 110 VREfm isolates from gastrointestinal and blood cultures of 24 pediatric patients undergoing chemotherapy or hematopoietic stem cell transplantation for hematological malignancy at St. Jude Children's Research Hospital. We used patient-specific reference genomes to identify variants that arose over time in subsequent gastrointestinal and blood isolates from each patient and analyzed these variants for insight into how VREfm adapted during colonization and bloodstream infection within each patient. Variants were enriched in genes involved in carbohydrate metabolism, and phenotypic analysis identified associated differences in carbohydrate utilization among isolates. In particular, a Y585C mutation in the sorbitol operon transcriptional regulator was associated with increased bacterial growth in the presence of sorbitol. We also found differences in biofilm-formation capability between isolates and observed that increased biofilm formation correlated with mutations in the putative capsular polysaccharide () biosynthetic locus, with different mutations arising independently in distinct genetic backgrounds. Isolates with mutations showed improved survival following exposure to lysozyme, suggesting a possible reason for the selection of capsule-lacking bacteria. Finally, we observed mutations conferring increased tolerance of linezolid and daptomycin in patients who were treated with these antibiotics. Overall, this study documents known and previously undescribed ways that VREfm evolve during intestinal colonization and subsequent bloodstream infection in immunocompromised pediatric patients.
Corral-Serrano JC, Lamers IJC, van Reeuwijk J, Duijkers L, Hoogendoorn ADM, Yildirim A, Argyrou N, Ruigrok RAA, Letteboer SJF, Butcher R, van Essen MD, Sakami S, van Beersum SEC, Palczewski K, Cheetham ME, Liu Q, Boldt K, Wolfrum U, Ueffing M, Garanto A, Roepman R, Collin RWJ. PCARE and WASF3 regulate ciliary F-actin assembly that is required for the initiation of photoreceptor outer segment disk formation. Proc Natl Acad Sci U S A 2020;117(18):9922-9931.Abstract
The outer segments (OS) of rod and cone photoreceptor cells are specialized sensory cilia that contain hundreds of opsin-loaded stacked membrane disks that enable phototransduction. The biogenesis of these disks is initiated at the OS base, but the driving force has been debated. Here, we studied the function of the protein encoded by the photoreceptor-specific gene , which is mutated in inherited retinal dystrophy (RP54). We demonstrate that C2orf71/PCARE (photoreceptor cilium actin regulator) can interact with the Arp2/3 complex activator WASF3, and efficiently recruits it to the primary cilium. Ectopic coexpression of PCARE and WASF3 in ciliated cells results in the remarkable expansion of the ciliary tip. This process was disrupted by small interfering RNA (siRNA)-based down-regulation of an actin regulator, by pharmacological inhibition of actin polymerization, and by the expression of PCARE harboring a retinal dystrophy-associated missense mutation. Using human retinal organoids and mouse retina, we observed that a similar actin dynamics-driven process is operational at the base of the photoreceptor OS where the PCARE module and actin colocalize, but which is abrogated in mice. The observation that several proteins involved in retinal ciliopathies are translocated to these expansions renders it a potential common denominator in the pathomechanisms of these hereditary disorders. Together, our work suggests that PCARE is an actin-associated protein that interacts with WASF3 to regulate the actin-driven expansion of the ciliary membrane at the initiation of new outer segment disk formation.
Dockery DM, Rowe SG, Murphy MA, Krzystolik MG. The Ocular Manifestations and Transmission of COVID-19: Recommendations for Prevention. J Emerg Med 2020;Abstract
BACKGROUND: Coronavirus disease-2019 (COVID-19), caused by a novel coronavirus termed severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has been linked to ocular signs and symptoms in several case reports. Research has demonstrated that SARS-CoV-2 is spread primarily through close contact via respiratory droplets, but there is the possibility for ocular transmission, with the conjunctiva as a conduit as well as a source of infection. DISCUSSION: Ocular manifestations of SARS-CoV-2 include follicular conjunctivitis, and have been repeatedly noted as an initial or subsequent symptom of COVID-19-positive patients. Particularly in patients with ocular manifestations, there is evidence that the virus may present in tears, based on the detection of SARS-CoV-2 in conjunctival swab samples via reverse transcription polymerase chain reaction. The virus may therefore be transmittable from the ocular surface to a new host via contact with the ocular mucosa, tears, or subsequent fomites. CONCLUSIONS: All health care professionals should ask patients about ocular symptoms consistent with SARS-CoV-2, and use eye protection such as goggles or face shields as part of the standard personal protective equipment for high-risk patients in addition to wearing of masks by both the patient and provider, and should consider tears to be potentially infectious.
Fan N-W, Dohlman TH, Foulsham W, McSoley M, Singh RB, Chen Y, Dana R. The role of Th17 immunity in chronic ocular surface disorders. Ocul Surf 2020;Abstract
Th17 cells have been implicated in the pathogenesis of numerous inflammatory and autoimmune conditions. At the ocular surface, Th17 cells have been identified as key effector cells in chronic ocular surface disease. Evidence from murine studies indicates that following differentiation and expansion, Th17 cells migrate from the lymphoid tissues to the eye, where they release inflammatory cytokines including, but not limited to, their hallmark cytokine IL-17A. As the acute phase subsides, a population of long-lived memory Th17 cells persist, which predispose hosts both to chronic inflammation and severe exacerbations of disease; of great interest is the small subset of Th17/1 cells that secrete both IL-17A and IFN-γ in acute-on-chronic disease exacerbation. Over the past decade, substantial progress has been made in deciphering how Th17 cells interact with the immune and neuroimmune pathways that mediate chronic ocular surface disease. Here, we review (i) the evidence for Th17 immunity in chronic ocular surface disease, (ii) regulatory mechanisms that constrain the Th17 immune response, and (iii) novel therapeutic strategies targeting Th17 cells.
Farinha C, Cachulo ML, Coimbra R, Alves D, Nunes S, Pires I, Marques JP, Costa J, Martins A, Sobral I, Barreto P, Laíns I, Figueira J, Ribeiro L, Cunha-Vaz J, Silva R. Age-Related Macular Degeneration Staging by Color Fundus Photography vs. Multimodal Imaging-Epidemiological Implications (). J Clin Med 2020;9(5)Abstract
Epidemiology of age-related macular degeneration (AMD) is based on staging systems relying on color fundus photography (CFP). We aim to compare AMD staging using CFP to multimodal imaging with optical coherence tomography (OCT), infra-red (IR), and fundus autofluorescence (FAF), in a large cohort from the Epidemiologic AMD Coimbra Eye Study. All imaging exams from the participants of this population-based study were classified by a central reading center. CFP images were graded according to the International Classification and Grading System for AMD and staged with Rotterdam classification. Afterward, CFP images were reviewed with OCT, IR, and FAF and stage update was performed if necessary. Early and late AMD prevalence was compared in a total of 1616 included subjects. In CFP-based grading, the prevalence was 14.11% for early AMD ( = 228) and 1.05% ( = 17) for late AMD, nine cases (0.56%) had neovascular AMD (nAMD) and eight (0.50%) geographic atrophy (GA). Using multimodal grading, the prevalence increased to 14.60% for early AMD ( = 236) and 1.61% ( = 26) for late AMD, with 14 cases (0.87%) of nAMD and 12 (0.74%) of GA. AMD staging was more accurate with the multimodal approach and this was especially relevant for late AMD. We propose that multimodal imaging should be adopted in the future to better estimate and compare epidemiological data in different populations.
Feldstein IT, Peli E. Pedestrians Accept Shorter Distances to Light Vehicles Than Dark Ones When Crossing the Street. Perception 2020;49(5):558-566.Abstract
Does the brightness of an approaching vehicle affect a pedestrian's crossing decision? Thirty participants indicated their street-crossing intentions when facing approaching light or dark vehicles. The experiment was conducted in a real daylight environment and, additionally, in a corresponding virtual one. A real road with actual cars provides high face validity, while a virtual environment ensures the scenario's precise reproducibility and repeatability for each participant. In both settings, participants judged dark vehicles to be a more imminent threat-either closer or moving faster-when compared with light ones. Secondary results showed that participants accepted a significantly shorter time-to-contact when crossing the street in the virtual setting than on the real road.
Freitag SK, Tanking T. A Nomenclature to Describe the Sequence of Visual Field Defects in Progressive Thyroid Eye Disease-Compressive Optic Neuropathy (An American Ophthalmological Society Thesis). Am J Ophthalmol 2020;213:293-305.Abstract
PURPOSE: To create a novel nomenclature to characterize the longitudinal sequence of visual field (VF) defects in patients with progression of thyroid eye disease-compressive optic neuropathy (TED-CON). METHODS: A retrospective review of records from 1 institution identified patients with progressive Humphrey VF defects secondary to TED-CON. The VF defects were analyzed by 2 independent reviewers and classified into 1 of 10 categories, divided into 3 stages that reflect the observed progression pattern, plus a miscellaneous category (stage X). Stage 1 VF defects are the earliest detectable and involve the inferior visual field with 3 levels of severity. Stage 2 VF defects include 2 distinguishable levels of severity and occur as the inferior defects advance above the horizontal midline to involve the superior VF. Stage 3 involves progression of stage 2 VF defects to complete loss of inferior and superior hemifields. RESULTS: Of 234 VFs in 37 eyes of 23 subjects, inferior defects were most common, including stage 1a (small inferior paracentral defect) in 22 of 234 VFs (9.4%), stage 1b (large inferior paracentral defect) in 112 of 234 VFs (47.9%), and stage 1c (inferior altitudinal defect) in 11 of 234 VFs (4.7%). Stage 2a (inferior altitudinal with superior advancement above the horizontal meridian) occurred in 41 of 234 VFs (17.5%), stage 2b (inferior altitudinal with superior arcuate) occurred in 6 of 234 VFs (2.6%), and stage 3 (total loss) occurred in 5 of 234 VFs (2.1%). The longitudinal sequence of VF defects from the 37 eyes of 23 patients was analyzed. Thirty-one of 37 eyes (83.8%) demonstrated a predictable progression pattern from least to more severe: stage 1a, stage 1b, stage 1c, stage 2a, stage 2b, and stage 3. A reverse order of VF defect progression was noted in 15 eyes with improving TED-CON. A minority of progression patterns (16.2%) originated from stage X (central/paracentral, enlarged blind spot, and scatter). CONCLUSIONS: Humphrey VF defects resulting from TED-CON are most often inferior, often have a predictable pattern of progression, and can be categorized into a novel descriptive nomenclature system. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.
Hall LN, Shanbhag SS, Rashad R, Chodosh J, Saeed HN. The effects of systemic cyclosporine in acute Stevens-Johnson syndrome/toxic epidermal necrolysis on ocular disease. Ocul Surf 2020;Abstract
PURPOSE: To evaluate the effect of systemic cyclosporine (CsA) on ocular disease in Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) patients. METHODS: In this retrospective, comparative cohort study at a single center, patients with a diagnosis of SJS/TEN and with at least 3 months of follow up were divided into two groups: those who received systemic CsA and those who did not receive systemic CsA. Best-corrected visual acuity (BCVA) and chronic ocular surface complications score (COCS) at final follow-up were compared between the two groups. RESULTS: The median age and follow-up period of patients was 29 years (range, 1.5-71 years) and 16.8 months (range, 3.67-91.58 months), respectively. BCVA, COCS, meibomian gland dysfunction, limbal stem cell deficiency, and the need for mucous membrane grafting and scleral lenses were not significantly different between patients who received systemic CsA as compared to patients who did not receive systemic CsA. CONCLUSIONS: In this small cohort of patients with SJS/TEN, we could identify no association between the use of systemic CsA as a component of their initial therapy and chronic ocular complications.
Han X, Yang S, Kam WR, Sullivan DA, Liu Y. The carbonic anhydrase inhibitor dorzolamide stimulates the differentiation of human meibomian gland epithelial cells. Curr Eye Res 2020;Abstract
PURPOSE: Clinical studies have indicated that the long-term use of topical antiglaucoma drugs, such as carbonic anhydrase inhibitors (CAIs), may lead to meibomian gland dysfunction (MGD). We hypothesize that these adverse effects involve a direct influence on human MG epithelial cells (HMGECs). The purpose our present investigation was to test our hypothesis and determine whether exposure to dorzolamide, a CAI, impacts the proliferation, intracellular signaling and differentiation of HMGECs. : We cultured immortalized (i) HMGECs with vehicle or various concentrations of dorzolamide for 6 days. Cells were enumerated with a hemocytometer, and examined for their morphology, Akt signaling activity, accumulation of neutral lipids, phospholipids and lysosomes, and the expression of protein biomarkers for lipogenesis regulation, lysosomes and autophagosomes. : Our results show that a high, 500 µg/ml concentration of dorzolamide causes a significant decrease in Akt signaling and the proliferation of iHMGECs. However, the high dose of dorzolamide also promotes the differentiation of iHMGECs. This response features increases in the number of lysosomes, the accumulation of phospholipids, and the expression of the light chain 3A biomarker for autophagosomes. In contrast, the therapeutic amount (50 µg/ml) of dorzolamide has no impact on the proliferative or differentiative abilities of iHMGECs. : Our results support our hypothesis and demonstrate that the CAI dorzolamide does exert a direct influence on the proliferation and differentiation of iHMGECs. However, this effect is elicited only by a high, and not a therapeutic, amount of dorzolamide.
Hughes S, Gumas J, Lee R, Rumano M, Berger N, Gautam AK, Sfyroera G, Chan AL, Gnanaguru G, Connor KM, Kim BJ, Dunaief JL, Ricklin D, Hajishengallis G, Yancopoulou D, Reis ES, Mastellos DC, Lambris JD. Prolonged intraocular residence and retinal tissue distribution of a fourth-generation compstatin-based C3 inhibitor in non-human primates. Clin Immunol 2020;214:108391.Abstract
Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss among the elderly population. Genetic studies in susceptible individuals have linked this ocular disease to deregulated complement activity that culminates in increased C3 turnover, retinal inflammation and photoreceptor loss. Therapeutic targeting of C3 has therefore emerged as a promising strategy for broadly intercepting the detrimental proinflammatory consequences of complement activation in the retinal tissue. In this regard, a PEGylated second-generation derivative of the compstatin family of C3-targeted inhibitors is currently in late-stage clinical development as a treatment option for geographic atrophy, an advanced form of AMD which lacks approved therapy. While efficacy has been strongly suggested in phase 2 clinical trials, crucial aspects still remain to be defined with regard to the ocular bioavailability, tissue distribution and residence, and dosing frequency of such inhibitors in AMD patients. Here we report the intraocular distribution and pharmacokinetic profile of the fourth-generation compstatin analog, Cp40-KKK in cynomolgus monkeys following a single intravitreal injection. Using a sensitive surface plasmon resonance (SPR)-based competition assay and ELISA, we have quantified both the amount of inhibitor and the concentration of C3 retained in the vitreous of Cp40-KKK-injected animals. Cp40-KKK displays prolonged intraocular residence, being detected at C3-saturating levels for over 3 months after a single intravitreal injection. Moreover, we have probed the distribution of Cp40-KKK within the ocular tissue by means of immunohistochemistry and highly specific anti-Cp40-KKK antibodies. Both C3 and Cp40-KKK were detected in the retinal tissue of inhibitor-injected animals, with prominent co-localization in the choroid one-month post intravitreal injection. These results attest to the high retinal tissue penetrance and target-driven distribution of Cp40-KKK. Given its subnanomolar binding affinity and prolonged ocular residence, Cp40-KKK constitutes a promising drug candidate for ocular pathologies underpinned by deregulated C3 activation.
Jakobiec FA, Eagle RC, Selig M, Ma L, Shields C. Clinical Implications of Goblet Cells in Dacryoadenosis and Normal Human Lacrimal Glands. Am J Ophthalmol 2020;213:267-282.Abstract
PURPOSE: The purpose of this study was to investigate an enlarged dacryoadenotic lacrimal gland and normal lacrimal glands for the presence of goblet cells (mucocytes). DESIGN: Retrospective clinicopathologic series. METHODS: An enlarged lacrimal gland (dacryoadenosis) without obvious histopathologic alterations was extensively evaluated histochemically, immunohistochemically, and ultrastructurally to detect the presence of goblet cells and to compare the findings with those in five normal lacrimal glands. RESULTS: Granular, zymogen-rich pyramidal acinar cells in normal glands predominated over a previously not reported subpopulation of nongranular, pale-staining cells in both dacryoadenotic and normal lacrimal glands. These cells histochemically stained positively with mucicarmine and Alcian blue. Immunohistochemical and electron microscopic evaluations established that there was a displacement or replacement of cytoplasmic gross cystic disease fluid protein-15 and CK 7-positive tonofilaments in the pale acinar cells by myriad mucus granules. The goblet cells constituted approximately 2% of the normal acinar cells and 5% of dacryoadenotic acinar cells. A depletion of myoepithelial cells and ectopic intra-acinar ductular cells were also observed in dacryoadenosis. CONCLUSION: Dacryoadenosis is caused by an increase in the number of acini without individual acinar cell hyperplasia. A normal cytologic feature of the lacrimal gland is the presence of acinar goblet cells that had been long overlooked; they are increased in number in dacryoadenosis. Intra-acinar ductular cells and the scattered loss of myoepithelial cells are other abnormalities in dacryoadenosis. The presence of lacrimal gland goblet cells may have physiologic implications for the precorneal tear film and its derangements as well as for the histogenesis of mucus-producing carcinomas.
Jumelle C, Gholizadeh S, Annabi N, Dana R. Advances and limitations of drug delivery systems formulated as eye drops. J Control Release 2020;321:1-22.Abstract
Topical instillation of eye drops remains the most common and easiest route of ocular drug administration, representing the treatment of choice for many ocular diseases. Nevertheless, low ocular bioavailability of topically applied drug molecules can considerably limit their efficacy. Over the last several decades, numerous drug delivery systems (DDS) have been developed in order to improve drug bioavailability on the ocular surfaces. This review systematically covers the most recent advances of DDS applicable by topical instillation, that have shown better performance in in vivo models compared to standard eye drop formulations. These delivery systems are based on in situ forming gels, nanoparticles and combinations of both. Most of the DDS have been developed using natural or synthetic polymers. Polymers offer many advantageous properties for designing advanced DDS including biocompatibility, gelation properties and/or mucoadhesiveness. However, despite the high number of studies published over the last decade, there are several limitations for clinical translation of DDS. This review article focuses on the recent advances for the development of ocular drug delivery systems. In addtion, the potential challenges for commercialization of new DDS are presented.
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.