With the advancement of computational power, refinement of learning algorithms and architectures, and availability of big data, artificial intelligence (AI) technology, particularly with machine learning and deep learning, is paving the way for 'intelligent' healthcare systems. AI-related research in ophthalmology previously focused on the screening and diagnosis of posterior segment diseases, particularly diabetic retinopathy, age-related macular degeneration and glaucoma. There is now emerging evidence demonstrating the application of AI to the diagnosis and management of a variety of anterior segment conditions. In this review, we provide an overview of AI applications to the anterior segment addressing keratoconus, infectious keratitis, refractive surgery, corneal transplant, adult and paediatric cataracts, angle-closure glaucoma and iris tumour, and highlight important clinical considerations for adoption of AI technologies, potential integration with telemedicine and future directions.
PURPOSE: To provide a summary of the neuro-ophthalmic manifestations of coronavirus disease 19 (COVID-19) documented in the literature thus far. METHODS: The PubMed and Google Scholar databases were searched using the keywords: Neuro-Ophthalmology, COVID-19, SARS-CoV-2, and coronavirus. A manual search through reference lists of relevant articles was also performed. RESULTS/CONCLUSIONS: The literature on COVID-associated neuro-ophthalmic disease continues to grow. Afferent neuro-ophthalmic complications associated with COVID-19 include optic neuritis, papillophlebitis, papilledema, visual disturbance associated with posterior reversible encephalopathy syndrome, and vision loss caused by stroke. Efferent neuro-ophthalmic complications associated with COVID-19 include cranial neuropathies, Miller Fisher syndrome, Adie's pupils, ocular myasthenia gravis, nystagmus and eye movement disorders. Proposed mechanisms of neurologic disease include immunologic upregulation, vasodilation and vascular permeability, endothelial dysfunction, coagulopathy, and direct viral neurotropism. When patients present to medical centers with new onset neuro-ophthalmic conditions during the pandemic, COVID-19 infection should be kept on the differential.
AIMS/HYPOTHESIS: Proliferative diabetic retinopathy (PDR) with retinal neovascularisation (NV) is a leading cause of vision loss. This study identified a set of metabolites that were altered in the vitreous humour of PDR patients compared with non-diabetic control participants. We corroborated changes in vitreous metabolites identified in prior studies and identified novel dysregulated metabolites that may lead to treatment strategies for PDR. METHODS: We analysed metabolites in vitreous samples from 43 PDR patients and 21 non-diabetic epiretinal membrane control patients from Japan (age 27-80 years) via ultra-high-performance liquid chromatography-mass spectrometry. We then investigated the association of a novel metabolite (creatine) with retinal NV in mouse oxygen-induced retinopathy (OIR). Creatine or vehicle was administered from postnatal day (P)12 to P16 (during induced NV) via oral gavage. P17 retinas were quantified for NV and vaso-obliteration. RESULTS: We identified 158 metabolites in vitreous samples that were altered in PDR patients vs control participants. We corroborated increases in pyruvate, lactate, proline and allantoin in PDR, which were identified in prior studies. We also found changes in metabolites not previously identified, including creatine. In human vitreous humour, creatine levels were decreased in PDR patients compared with epiretinal membrane control participants (false-discovery rate <0.001). We validated that lower creatine levels were associated with vascular proliferation in mouse retina in the OIR model (p = 0.027) using retinal metabolomics. Oral creatine supplementation reduced NV compared with vehicle (P12 to P16) in OIR (p = 0.0024). CONCLUSIONS/INTERPRETATION: These results suggest that metabolites from vitreous humour may reflect changes in metabolism that can be used to find pathways influencing retinopathy. Creatine supplementation could be useful to suppress NV in PDR. Graphical abstract.
Photoreceptor degeneration caused by genetic defects leads to retinitis pigmentosa, a rare disease typically diagnosed in adolescents and young adults. In most cases, rod loss occurs first, followed by cone loss as well as altered function in cells connected to photoreceptors directly or indirectly. There remains a gap in our understanding of retinal cellular responses to photoreceptor abnormalities. Here, we utilized single-cell transcriptomics to investigate cellular responses in each major retinal cell type in retinitis pigmentosa model (P23H) mice vs. wild-type littermate mice. We found a significant decrease in the expression of genes associated with phototransduction, the inner/outer segment, photoreceptor cell cilium, and photoreceptor development in both rod and cone clusters, in line with the structural changes seen with immunohistochemistry. Accompanying this loss was a significant decrease in the expression of genes involved in metabolic pathways and energy production in both rods and cones. We found that in the Müller glia/astrocyte cluster, there was a significant increase in gene expression in pathways involving photoreceptor maintenance, while concomitant decreases were observed in rods and cones. Additionally, the expression of genes involved in mitochondrial localization and transport was increased in the Müller glia/astrocyte cluster. The Müller glial compensatory increase in the expression of genes downregulated in photoreceptors suggests that Müller glia adapt their transcriptome to support photoreceptors and could be thought of as general therapeutic targets to protect against retinal degeneration.
PURPOSE: To evaluate the long-term outcomes of uveitic macular edema (ME). DESIGN: Longitudinal follow-up of a cohort of participants in a randomized clinical trial. PARTICIPANTS: A total of 248 eyes of 177 participants with uveitic ME enrolled in the Multicenter Uveitis Steroid Treatment (MUST) Trial and Follow-up Study. METHODS: OCT measurements, taken at baseline and annually, were graded by reading center graders masked to clinical data. Macular edema was defined as a center macular thickness (CMT) ≥240 μm on time-domain OCT or time-domain OCT equivalent. Resolution of ME was defined as normalization of macular thickness on OCT. Relapse of ME was defined as increase in macular thickness to ≥240 μm in an eye that previously had resolution. Visual acuity was measured at each visit with logarithmic visual acuity charts. MAIN OUTCOME MEASURES: Resolution and relapse of ME. Visual acuity. RESULTS: Among 227 eyes with ME followed ≥1 year, the cumulative percent of eyes with ME resolving at any point during 7 years was 94% (95% confidence interval [CI], 89-97). Epiretinal membranes on OCT were associated with a lower likelihood of ME resolution (hazard ratio [HR], 0.74; 95% CI, 0.55-1.01; P = 0.05). Among 177 eyes with resolved ME, the cumulative percent with relapse within 7 years was 43% (95% CI, 32-51). Eyes in which ME resolved gained a mean of 6.24 letters (95% CI, 4.40-8.09; P < 0.001) compared with eyes that remained free from ME during the 1-year follow-up intervals, whereas eyes in which ME did not resolve experienced no gain in vision (mean change -1.30 letters; 95% CI, -2.70 to 0.09; P = 0.065), and eyes that developed ME during the year (incident or relapsed) experienced a mean loss of -8.65 letters (95% CI, -11.5 to -5.84, P < 0.001). CONCLUSIONS: Given sufficient time and treatment, nearly all uveitic ME resolves, but episodes of relapse were common. Visual acuity results were better among eyes with resolved ME, suggesting that control of inflammation and resolution of ME might be visually relevant treatment targets.
Purpose: To discuss the potential contribution of rod and cone synapses to the loss of visual function in retinal injury and disease. Methods: The published literature and the authors' own work were reviewed. Results: Retinal detachment is used as a case study of rod spherule and cone pedicle plasticity after injury. Both rod and cone photoreceptors terminals are damaged after detachment although the structural changes observed are only partially overlapping. For second-order neurons, only those associated with rod spherules respond consistently to injury by remodeling. Examination of signaling pathways involved in plasticity of conventional synapses and in neural development has been and may continue to be productive in discovering novel therapeutic targets. Rho kinase (ROCK) inhibition is an example of therapy that may reduce synaptic damage by preserving normal synaptic structure of rod and cone cells. Conclusions: We hypothesize that synaptic damage contributes to poor visual restoration after otherwise successful anatomical repair of retinal detachment. A similar situation may exist for patients with degenerative retinal disease. Thus, synaptic structure and function should be routinely studied, as this information may disclose therapeutic strategies to mitigate visual loss.
Five vascular endothelial growth factor receptor (VEGFR) ligands (VEGF-A, -B, -C, -D, and placental growth factor [PlGF]) constitute the VEGF family. VEGF-A binds VEGF receptors 1 and 2 (VEGFR1/2), whereas VEGF-B and PlGF only bind VEGFR1. Although much research has been conducted on VEGFR2 to elucidate its key role in retinal diseases, recent efforts have shown the importance and involvement of VEGFR1 and its family of ligands in angiogenesis, vascular permeability, and microinflammatory cascades within the retina. Expression of VEGFR1 depends on the microenvironment, is differentially regulated under hypoxic and inflammatory conditions, and it has been detected in retinal and choroidal endothelial cells, pericytes, retinal and choroidal mononuclear phagocytes (including microglia), Müller cells, photoreceptor cells, and the retinal pigment epithelium. Whilst the VEGF-A decoy function of VEGFR1 is well established, consequences of its direct signaling are less clear. VEGFR1 activation can affect vascular permeability and induce macrophage and microglia production of proinflammatory and proangiogenic mediators. However the ability of the VEGFR1 ligands (VEGF-A, PlGF, and VEGF-B) to compete against each other for receptor binding and to heterodimerize complicates our understanding of the relative contribution of VEGFR1 signaling alone toward the pathologic processes seen in diabetic retinopathy, retinal vascular occlusions, retinopathy of prematurity, and age-related macular degeneration. Clinically, anti-VEGF drugs have proven transformational in these pathologies and their impact on modulation of VEGFR1 signaling is still an opportunity-rich field for further research.
Bacterial infections of the cornea, or bacterial keratitis (BK), are notorious for causing rapidly fulminant disease and permanent vision loss, even among treated patients. In the last sixty years, dramatic upward trajectories in the frequency of BK have been observed internationally, driven in large part by the commercialization of hydrogel contact lenses in the late 1960s. Despite this worsening burden of disease, current evidence-based therapies for BK - including broad-spectrum topical antibiotics and, if indicated, topical corticosteroids - fail to salvage vision in a substantial proportion of affected patients. Amid growing concerns of rapidly diminishing antibiotic utility, there has been renewed interest in urgently needed novel treatments that may improve clinical outcomes on an individual and public health level. Bridging the translational gap in the care of BK requires the identification of new therapeutic targets and rational treatment design, but neither of these aims can be achieved without understanding the complex biological processes that determine how bacterial corneal infections arise, progress, and resolve. In this chapter, we synthesize the current wealth of human and animal experimental data that now inform our understanding of basic BK pathophysiology, in context with modern concepts in ocular immunology and microbiology. By identifying the key molecular determinants of clinical disease, we explore how novel treatments can be developed and translated into routine patient care.
PURPOSE: To critically evaluate the potential impact of the coronavirus disease (COVID-19) pandemic on global ophthalmology and VISION 2020. DESIGN: Perspective supplemented with epidemiologic insights from available online databases. METHODS: We extracted data from the Global Vision Database (2017) and Global Burden of Disease Study (2017) to highlight temporal trends in global blindness since 1990, and provide a narrative overview of how COVID-19 may derail progress toward the goals of VISION 2020. RESULTS: Over 2 decades of VISION 2020 advocacy and program implementation have culminated in a universal reduction of combined age-standardized prevalence of moderate-to-severe vision impairment (MSVI) across all world regions since 1990. Between 1990 and 2017, low-income countries observed large reductions in the age-standardized prevalence per 100,000 persons of vitamin A deficiency (25,155 to 19,187), undercorrected refractive disorders (2,286 to 2,040), cataract (1,846 to 1,690), onchocerciasis (5,577 to 2,871), trachoma (506 to 159), and leprosy (36 to 26). Despite these reductions, crude projections suggest that more than 700 million persons will experience MSVI or blindness by 2050, principally owing to our growing and ageing global population. CONCLUSIONS: Despite the many resounding successes of VISION 2020, the burden of global blindness and vision impairment is set to reach historic levels in the coming years. The impact of COVID-19, while yet to be fully determined, now threatens the hard-fought gains of global ophthalmology. The postpandemic years will require renewed effort and focus on vision advocacy and expanding eye care services worldwide.
Bacterial corneal infections, or bacterial keratitis (BK), are ophthalmic emergencies that frequently lead to irreversible visual impairment. Though increasingly recognized as a major cause of global blindness, modern paradigms of evidence-based care in BK have remained at a diagnostic and therapeutic impasse for over half a century. Current standards of management - based on the collection of corneal cultures and the application of broad-spectrum topical antibiotics - are beset by important yet widely underrecognized limitations, including approximately 30% of all patients who will develop moderate to severe vision loss in the affected eye. Though recent advances have involved a more clearly defined role for adjunctive topical corticosteroids, and novel therapies such as corneal crosslinking, overall progress to improve patient and population-based outcomes remains incommensurate to the chronic morbidity caused by this disease. Recognizing that the care of BK is guided by the clinical axiom, "time equals vision", this chapter offers an evidence-based synthesis for the clinical management of these infections, underscoring critical unmet needs in disease prevention, diagnosis, and treatment.
PURPOSE OF REVIEW: This review will discuss the utility of high-resolution anterior segment optical coherence tomography (HR-OCT), in-vivo confocal microscopy (IVCM) and ultrasound biomicroscopy (UBM) in characterizing and diagnosing various ocular surface tumors, namely ocular surface squamous neoplasia (OSSN), conjunctival lymphoma and conjunctival melanoma. The strengths and limitations of each imaging modality will be discussed along with the characteristics findings of each lesion on each imaging platform. RECENT FINDINGS: HR-OCT can consistently be utilized in the clinic setting to distinguish between epithelial ocular surface tumors such as OSSN as compared with subepithelial tumors such as conjunctival lymphoma and conjunctival melanoma given their distinctive findings. IVCM can be used as an adjunct to HR-OCT to obtain cellular and surface characteristics, whereas UBM can be used to assess tumor depth and thickness for larger and highly pigmented lesions as well as to detect intraocular invasion. SUMMARY: HR-OCT, IVCM and UBM are all helpful imaging modalities to diagnose and characterize various ocular surface tumors and can serve as valuable adjuncts to monitor treatment response and assess for recurrence ocular surface tumors.
Purpose: To investigate the nature of anatomical and functional recovery kinetics after epiretinal membrane (ERM) removal. Methods: The records of 42 patients (45 eyes) with idiopathic ERM treated with pars plana vitrectomy and surgical peeling of the ERM performed by a single surgeon at Massachusetts Eye and Ear between 2012 and 2017 were retrospectively reviewed. Outcome measures included spectral domain optical coherence tomography-measured central macular thickness (CMT) pre-operatively and at post-operative day 1, week 1, months 1, 3, 6, 12 and 24 as well as best-corrected visual acuity (BCVA). Correlations between baseline or early values and final anatomical and functional outcomes were investigated. Results: Improvement in CMT was statistically significant after 1 week, 1, 3, 6, 12 and 24 months ( < 0.01). BCVA improvement was statistically significant after 1, 6, 12 and 24 months follow-up (<0.01). The improvement of BCVA and CMT with time was found to be logarithmic (R =0.96, R =0.84) suggesting that early (<30 days) post-operative functional and anatomical changes may be predictive of long-term outcomes. Preoperative BCVA and CMT revealed a weak positive correlation with the respective BCVA and CMT at 24 months (R=0.13 and R=0.16). When plotted as a percentage of the fellow normal eye CMT, first week proportional improvement in CMT from pre-operative baseline was found to be correlated with final CMT proportional decrease (R=0.72) suggesting that first week postoperative CMT could be predictive of final CMT. Conclusion: There is a logarithmic improvement in CMT and BCVA after ERM peel with BCVA improvement following the CMT improvement. Early (less than 30 days) post-operative anatomical changes can be predictive of long-term anatomical outcomes.
In the last two decades rodents have been on the rise as a dominant model for visual neuroscience. This is particularly true for earlier levels of information processing, but a number of studies have suggested that also higher levels of processing such as invariant object recognition occur in rodents. Here we provide a quantitative and comprehensive assessment of this claim by comparing a wide range of rodent behavioral and neural data with convolutional deep neural networks. These networks have been shown to capture hallmark properties of information processing in primates through a succession of convolutional and fully connected layers. We find that performance on rodent object vision tasks can be captured using low to mid-level convolutional layers only, without any convincing evidence for the need of higher layers known to simulate complex object recognition in primates. Our approach also reveals surprising insights on assumptions made before, for example, that the best performing animals would be the ones using the most abstract representations-which we show to likely be incorrect. Our findings suggest a road ahead for further studies aiming at quantifying and establishing the richness of representations underlying information processing in animal models at large.
Wagner A, Wang C, Fessler J, DeTomaso D, Avila-Pacheco J, Kaminski J, Zaghouani S, Christian E, Thakore P, Schellhaass B, Akama-Garren E, Pierce K, Singh V, Ron-Harel N, Douglas VP, Bod L, Schnell A, Puleston D, Sobel RA, Haigis M, Pearce EL, Soleimani M, Clish C, Regev A, Kuchroo VK, Yosef N. Metabolic modeling of single Th17 cells reveals regulators of autoimmunity. Cell 2021;184(16):4168-4185.e21.Abstract
Metabolism is a major regulator of immune cell function, but it remains difficult to study the metabolic status of individual cells. Here, we present Compass, an algorithm to characterize cellular metabolic states based on single-cell RNA sequencing and flux balance analysis. We applied Compass to associate metabolic states with T helper 17 (Th17) functional variability (pathogenic potential) and recovered a metabolic switch between glycolysis and fatty acid oxidation, akin to known Th17/regulatory T cell (Treg) differences, which we validated by metabolic assays. Compass also predicted that Th17 pathogenicity was associated with arginine and downstream polyamine metabolism. Indeed, polyamine-related enzyme expression was enhanced in pathogenic Th17 and suppressed in Treg cells. Chemical and genetic perturbation of polyamine metabolism inhibited Th17 cytokines, promoted Foxp3 expression, and remodeled the transcriptome and epigenome of Th17 cells toward a Treg-like state. In vivo perturbations of the polyamine pathway altered the phenotype of encephalitogenic T cells and attenuated tissue inflammation in CNS autoimmunity.
INTRODUCTION: Contrast sensitivity function (CSF) may better estimate a patient's visual function compared with visual acuity (VA). Our study evaluates the quick CSF (qCSF) method to measure visual function in eyes with macular disease and good letter acuity. METHODS: Patients with maculopathies (retinal vein occlusion, macula-off retinal detachment, dry age-related macular degeneration and wet age-related macular degeneration) and good letter acuity (VA ≥20/30) were included. The qCSF method uses an intelligent algorithm to measure CSF across multiple spatial frequencies. All maculopathy eyes combined and individual macular disease groups were compared with healthy control eyes. Main outcomes included area under the log CSF (AULCSF) and six CS thresholds ranging from 1 cycle per degree (cpd) to 18 cpd. RESULTS: 151 eyes with maculopathy and 93 control eyes with VA ≥20/30 were included. The presence of a maculopathy was associated with significant reduction in AULCSF (β: -0.174; p<0.001) and CS thresholds at all spatial frequencies except for 18 cpd (β: -0.094 to -0.200 log CS, all p<0.01) compared with controls. Reductions in CS thresholds were most notable at low and intermediate spatial frequencies (1.5 cpd, 3 cpd and 6 cpd). CONCLUSION: CSF measured with the qCSF active learning method was found to be significantly reduced in eyes affected by macular disease despite good VA compared with healthy control eyes. The qCSF method is a promising clinical tool to quantify subtle visual deficits that may otherwise go unrecognised by current testing methods.
PURPOSE: To review the clinical features, microbiology, management, and incidence of bacterial dacryoadenitis at our institution. METHODS: This was a case series examining patients with bacterial dacryoadenitis from 2004 to 2020. Charts were reviewed for demographics, comorbidities, presenting symptoms and signs, radiology, microbiology, and management. Main outcomes included need for surgical intervention or inpatient admission. RESULTS: Forty-five patients with bacterial dacryoadenitis had a mean age of 46.1 years. Presenting symptoms included eyelid edema (100%), extraocular motility restriction (53.3%), and purulent discharge (75.5%). Based on computed tomography or magnetic resonance imaging, 9 (20.5%) patients presented with definite abscess and 15 (34%) presented with a phlegmon or early abscess. Eleven patients (24.4%) required surgical drainage. Twenty patients (44.4%) required admission, for an average stay of 4 days (range 2-8 days). Common organisms included Haemophilus influenzae, Streptococcus pneumoniae, and Staphylococcus aureus. Presence of an early abscess or phlegmon correlated with need for drainage (p < 0.01). Extraocular motility restriction correlated with need for drainage (p = 0.02) and admission (p = 0.05). The incidence of bacterial dacryoadenitis at our institution increased as a percentage of confirmed dacryoadenitis cases; from 2004 to 2010 the incidence was 0 to 9.1% per year, while from 2010 to 2019 the incidence ranged from 7.7 to 36.2%. In 2019, our institution had 17 cases (incidence 36.2%) of bacterial dacryoadenitis. CONCLUSIONS: Bacterial dacryoadenitis is a major cause of dacryoadenitis, and its incidence may be increasing. It can resolve with minimal complications if managed appropriately, although some patients may require surgical drainage or admission for intravenous antibiotics.
Glaucoma leads to millions of cases of visual impairment and blindness around the world. Its susceptibility is shaped by both environmental and genetic risk factors. Although over 120 risk loci have been identified for glaucoma, a large portion of its heritability is still unexplained. Here we describe the foundation of the Genetics of GLaucoma Evaluation in the AMish (GGLEAM) study to investigate the genetic architecture of glaucoma in the Ohio Amish, which exhibits lower genetic and environmental heterogeneity compared to the general population. To date, we have enrolled 81 Amish individuals in our study from Holmes County, Ohio. As a part of our enrollment process, 62 GGLEAM study participants (42 glaucoma-affected and 20 unaffected individuals) received comprehensive eye examinations and glaucoma evaluations. Using the data from the Anabaptist Genealogy Database, we found that 80 of the GGLEAM study participants were related to one another through a large, multigenerational pedigree containing 1586 people. We plan to integrate the health and kinship data obtained for the GGLEAM study to interrogate glaucoma genetics and pathophysiology in this unique population.