The cornea and its adnexa pose a unique situation of a tightly defined set of requirements for its function. This includes: transparency, perfect built to obtain appropriate refractive power, protective barrier from microbial invaders. Moreso, the cornea also endures extreme external physical conditions (temperature, high and low humidity, winds and alike). All these functions are maintained while preserving a constant state of homogenous wetting. Toward that end the cornea is equipped with an elaborated network of sensory neural network. While enabling the blinking reflex and maintaining the physiological steady state of wetting, this neural network also makes the cornea prone to the discomfort that with or without associated changes seen on medical examination. ISOPT Clinical 2018 discussion touched upon this hypercomplex situation, addressing the role of inflammation and its resulting discomfort in dry eye conditions. The discussion also engulfed the emerging neuropathic pain syndrome that is recently gaining more attention. Another related topic was the utilization of autologous serum tears and its ability to provide amelioration to desperate patients. Finally, the panel discussed the issue of treating corneal infection, including when and how to utilize steroids in the course of therapy. We assume the reader will find interest in this discussion that directly addresses issues seen day in and day out in our busy clinics.
Children born preterm with periventricular leukomalacia (PVL) demonstrate increased difficulties with tasks requiring visuomotor integration. The visuomotor integration network encompasses brain regions within frontal, parietal, and occipital cortices. Because of their proximity to the lateral ventricle the underlying white matter pathways are at a high risk of damage following PVL-related hypoxic-ischemic white matter injury. This study provides an exploratory analysis of the structural and functional connections within the visuomotor integration network, along with an a priori evaluation of the superior longitudinal fasciculus, inferior fronto-occipital fasciculus, and frontal aslant tract. For each pathway, tracts within both hemispheres revealed decreased volume and number of reconstructed fibers and an increase in quantitative anisotropy and generalized fractional anisotropy. The connectivity results also indicate that there may be changes to both the structural integrity and functional integration of neural networks involved with visuomotor integration functions in children with PVL.
The complete assessment of vision-related abilities should consider visual function (the performance of components of the visual system) and functional vision (visual task-related ability). Assessment methods are highly dependent upon individual characteristics (eg, the presence and type of visual impairment). Typical visual function tests assess factors such as visual acuity, contrast sensitivity, color, depth, and motion perception. These properties each represent an aspect of visual function and may impact an individual's level of functional vision. The goal of any functional vision assessment should be to measure the visual task-related ability under real-world scenarios. Recent technological advancements such as virtual reality can provide new opportunities to improve traditional vision assessments by providing novel objective and ecologically valid measurements of performance, and allowing for the investigation of their neural basis. In this review, visual function and functional vision evaluation approaches are discussed in the context of traditional and novel acquisition methods.
The light-sensitive photoreceptors in the retina are extremely metabolically demanding and have the highest density of mitochondria of any cell in the body. Both physiological and pathological retinal vascular growth and regression are controlled by photoreceptor energy demands. It is critical to understand the energy demands of photoreceptors and fuel sources supplying them to understand neurovascular diseases. Retinas are very rich in lipids, which are continuously recycled as lipid-rich photoreceptor outer segments are shed and reformed and dietary intake of lipids modulates retinal lipid composition. Lipids (as well as glucose) are fuel substrates for photoreceptor mitochondria. Dyslipidemia contributes to the development and progression of retinal dysfunction in many eye diseases. Here, we review photoreceptor energy demands with a focus on lipid metabolism in retinal neurovascular disorders.
Phosphoinositide 3-kinases (PI3Ks) are a family of lipid kinases that play a critical role in transmitting signals from cell-surface molecules to intracellular protein effectors. Key PI3Ks include PI3Kα, PI3Kβ, and PI3Kδ, which are regulated by receptors. The signaling pathway comprising the PI3Ks, along with a Ser/Thr kinase (AKT), a proto-oncogene product (mouse double minute (MDM)2), and a tumor suppressor protein (p53), plays an essential role in experimental proliferative vitreoretinopathy (PVR), which is a fibrotic blinding eye disorder. However, which PI3K isoforms are involved in PVR is unknown. A major characteristic of PVR is the formation of epi (or sub)-retinal membranes that consist of extracellular matrix and cells, including retinal pigment epithelium (RPE) cells, glial cells, and macrophages. RPE cells are considered key players in PVR pathogenesis. Using immunoblotting and immunofluorescence analyses, we herein provide the evidence that PI3Kδ is highly expressed in human RPEs when it is primarily expressed in leukocytes. We also found that PI3Kδ inactivation through two approaches, CRISPR/Cas9-mediated depletion and a PI3Kδ-specific inhibitor (idelalisib), not only blocks vitreous-induced activation of AKT and MDM2 but also abrogates a vitreous-stimulated decrease in p53. Furthermore, we demonstrate that PI3Kδ inactivation prevents vitreous-induced proliferation, migration, and contraction of human RPEs. These results suggest that PI3Kδ may represent a potential therapeutic target for RPE-related eye diseases, including PVR.
Importance: The DRCR Retina Network Protocol S randomized clinical trial suggested that the mean visual acuity of eyes with proliferative diabetic retinopathy (PDR) treated with ranibizumab is not worse at 5 years than that of eyes treated with panretinal photocoagulation (PRP). Moreover, the ranibizumab group had fewer new cases of diabetic macular edema (DME) with vision loss or vitrectomy but had 4 times the number of injections and 3 times the number of visits. Although 2-year cost-effectiveness results of Protocol S were previously identified, incorporating 5-year data from Protocol S could alter the longer-term cost-effectiveness of the treatment strategies from the perspective of the health care system. Objective: To evaluate 5- and 10-year cost-effectiveness of therapy with ranibizumab, 0.5 mg, compared with PRP for treating PDR. Design, Setting, and Participants: A preplanned secondary analysis of the Protocol S randomized clinical trial using efficacy, safety, and resource utilization data through 5 years of follow-up for 213 adults diagnosed with PDR and simulating results through 10 years. Interventions: Intravitreous ranibizumab, 0.5 mg, at baseline and as frequently as every 4 weeks based on a structured retreatment protocol vs PRP at baseline for PDR; eyes in both groups could receive ranibizumab for concomitant DME with vision loss. Main Outcomes and Measures: Incremental cost-effectiveness ratios (ICERs) of ranibizumab therapy compared with PRP were evaluated for those with and without center-involved DME (CI-DME) and vision loss (Snellen equivalent, 20/32 or worse) at baseline. Results: The study included 213 adults with a mean (SD) age of 53 (12) years, of whom 92 (43%) were women and 155 (73%) were white. The ICER of the ranibizumab group compared with PRP for patients without CI-DME at baseline was $582 268 per quality-adjusted life-year (QALY) at 5 years and $742 202/QALY at 10 years. For patients with baseline CI-DME, ICERs were $65 576/QALY at 5 years and $63 930/QALY at 10 years. Conclusions and Relevance: This study suggests that during 5 to 10 years of treatment, ranibizumab, 0.5 mg, as given in the studied trial compared with PRP may be within the frequently cited range considered cost-effective in the United States for eyes presenting with PDR and vision-impairing CI-DME, but not for those with PDR but without vision-impairing CI-DME. Substantial reductions in anti-vascular endothelial growth factor cost may make the ranibizumab therapy cost-effective within this range even for patients without baseline CI-DME. Trial Registration: ClinicalTrials.gov identifier: NCT01489189.
PURPOSE: To compare the thickness of the limbal epithelium (LE) and the bulbar conjunctival epithelium (BCE) between patients with dry eye disease (DED) with and without ocular graft-versus-host disease (GVHD). METHODS: This cross-sectional study enrolled 40 patients with moderate to severe DED including 20 with and 20 without chronic ocular GVHD. All patients had a comprehensive clinical ophthalmic assessment. Moreover, the thickness of the LE and BCE in both nasal and temporal regions of both eyes was measured using spectral domain optical coherence tomography. RESULTS: The average LE thickness in all patients with dry eye (GVHD and non-GVHD) was 65.8 ± 11.9 μm temporally and 69.7 ± 11.1 μm nasally (P = 0.02). The average BCE thickness was 55.8 ± 11.4 μm temporally and 60.1 ± 11.0 μm nasally (P = 0.03). There were no statistically significant differences between GVHD and non-GVHD groups in LE thickness (69.6 ± 11.7 vs. 66.1 ± 6.2 μm, respectively, P = 0.31) or BCE thickness (58.9 ± 9.6 vs. 57.3 ± 9.8 μm, respectively, P = 0.82). There was a significant correlation between LE thickness and BCE thickness (P = 0.01, Rs = 0.41). A statistically significant negative correlation was also observed between LE thickness and age (P = 0.002, Rs = -0.35). There were no significant correlations between the thickness of the LE or BCE and other clinical parameters. CONCLUSIONS: No difference exists in the thickness of the ocular surface epithelia between dry eyes with and without ocular GVHD, which would suggest that these epithelial changes may be independent of the underlying etiology and possibly only reflect the disease severity. Furthermore, there are regional variations in the thickness of the ocular surface epithelia in patients with DED.
Cerebral/cortical visual impairment (CVI) is characterized by higher order visual dysfunction caused by injury to the retrogeniculate visual pathways and brain structures which subserve visual processing. CVI has become the leading cause of significant vision loss in children in developed countries, but continues to be an under-recognized cause of visual disability with respect to services aimed at maximizing visual development. Current criteria which are used to define visual disability rely on measures of visual acuity and visual field. Many children who require specialized vision services do not qualify, because these standard definitions of vision impairment do not account for CVI. In order to appropriately identify patients with CVI and offer the resources which may positively impact functional use of vision, the definition of visual impairment and blindness needs to be modified. This commentary calls for a change in the definition of visual impairment and blindness to acknowledge those persons with brain-based vision impairment.
Kruszka P, Hu T, Hong S, Signer R, Cogné B, Isidor B, Mazzola SE, Giltay JC, van Gassen KLI, England EM, Pais L, Ockeloen CW, Sanchez-Lara PA, Kinning E, Adams DJ, Treat K, Torres-Martinez W, Bedeschi MF, Iascone M, Blaney S, Bell O, Tan TY, Delrue M-A, Jurgens J, Barry BJ, Engle EC, Savage SK, Fleischer N, Martinez-Agosto JA, Boycott K, Zackai EH, Muenke M. Phenotype delineation of ZNF462 related syndrome. Am J Med Genet A 2019;179(10):2075-2082.Abstract
Zinc finger protein 462 (ZNF462) is a relatively newly discovered vertebrate specific protein with known critical roles in embryonic development in animal models. Two case reports and a case series study have described the phenotype of 10 individuals with ZNF462 loss of function variants. Herein, we present 14 new individuals with loss of function variants to the previous studies to delineate the syndrome of loss of function in ZNF462. Collectively, these 24 individuals present with recurring phenotypes that define a multiple congenital anomaly syndrome. Most have some form of developmental delay (79%) and a minority has autism spectrum disorder (33%). Characteristic facial features include ptosis (83%), down slanting palpebral fissures (58%), exaggerated Cupid's bow/wide philtrum (54%), and arched eyebrows (50%). Metopic ridging or craniosynostosis was found in a third of study participants and feeding problems in half. Other phenotype characteristics include dysgenesis of the corpus callosum in 25% of individuals, hypotonia in half, and structural heart defects in 21%. Using facial analysis technology, a computer algorithm applying deep learning was able to accurately differentiate individuals with ZNF462 loss of function variants from individuals with Noonan syndrome and healthy controls. In summary, we describe a multiple congenital anomaly syndrome associated with haploinsufficiency of ZNF462 that has distinct clinical characteristics and facial features.
PURPOSE: To compare the visual outcomes and adverse events associated with optical correction using an intraocular lens (IOL), contact lenses, or spectacles after cataract surgery in children 2 years of age or younger. METHODS: Literature searches were conducted in PubMed, the Cochrane Library, and the databases of clinical trials in February 2019, without date or language restrictions. The search resulted in 194 potentially relevant citations, and 34 were selected for full-text review. Fourteen studies were determined to be relevant to the assessment criteria and were selected for inclusion in this assessment. The panel methodologist then assigned a level of evidence rating to these studies. RESULTS: Intraocular lenses were associated with visual outcomes similar to outcomes for contact lenses or spectacles for children who had both bilateral and unilateral cataracts. Intraocular lenses were also associated with an increased risk of visual axis opacities. All treatments were associated with a similar incidence of glaucoma. Although ocular growth was similar for all treatments, infants younger than 6 months who underwent IOL implantation had large myopic shifts that often resulted in high myopia or severe anisometropia later in childhood. Corneal endothelial cell counts were lower in eyes that underwent IOL implantation. The incidence of strabismus was similar with all treatments. CONCLUSIONS: Intraocular lens implantation is not recommended for children 6 months of age or younger because there is a higher incidence of visual axis opacities with this treatment compared with aphakia. The best available evidence suggests that IOL implantation can be done safely with acceptable side effects in children older than 6 months of age. However, the unpredictability of ocular growth means that these children will often have large refractive errors later in childhood that may necessitate an IOL exchange or wearing spectacles or contact lenses with a large refractive correction. In addition, the training and experience of the surgeon as well as ocular and systemic comorbidities should be taken into consideration when deciding whether IOL implantation would be appropriate.
Cortical/cerebral visual impairment (CVI) is now the main cause of visual impairment in developed countries, yet it remains poorly understood. Four hundred and ninteen teachers of the visually impaired (TVIs) from across the United States responded to a questionnaire targeted at evaluating the preparedness of TVIs to serve their students with CVI. The TVIs were asked about their background knowledge, their abilities to assess a student with CVI, and their abilities to apply what they know to best help their students. The primary finding was that there is a perceived unmet need for TVIs to receive formal training in CVI during their certification. The results of this survey provide a foundation for future research on CVI knowledge and education among TVIs.
Collagen crosslinking provides the mechanical strength required for physiological maintenance of the extracellular matrix in most tissues in the human body, including the cornea. Aging and diabetes mellitus (DM) are processes that are both associated with increased collagen crosslinking that leads to increased corneal rigidity. By contrast, keratoconus (KC) is a corneal thinning disease associated with decreased mechanical stiffness leading to ectasia of the central cornea. Studies have suggested that crosslinking mediated by reactive advanced glycation end products during DM may protect the cornea from KC development. Parallel to this hypothesis, riboflavin-mediated photoreactive corneal crosslinking has been proposed as a therapeutic option to halt the progression of corneal thinning by inducing intra- and intermolecular crosslink formation within the collagen fibrils of the stroma, leading to stabilization of the disease. Here, we review the pathobiology of DM and KC in the context of corneal structure, the epidemiology behind the inverse correlation of DM and KC development, and the chemical mechanisms of lysyl oxidase-mediated crosslinking, advanced glycation end product-mediated crosslinking, and photoreactive riboflavin-mediated corneal crosslinking. The goal of this review is to define the biological and chemical pathways important in physiological and pathological processes related to collagen crosslinking in DM and KC.
Genome-wide association studies (GWAS) have identified genetic variants associated with age-related macular degeneration (AMD), one of the leading causes of blindness in the elderly. However, it has been challenging to identify the cell types associated with AMD given the genetic complexity of the disease. Here we perform massively parallel single-cell RNA sequencing (scRNA-seq) of human retinas using two independent platforms, and report the first single-cell transcriptomic atlas of the human retina. Using a multi-resolution network-based analysis, we identify all major retinal cell types, and their corresponding gene expression signatures. Heterogeneity is observed within macroglia, suggesting that human retinal glia are more diverse than previously thought. Finally, GWAS-based enrichment analysis identifies glia, vascular cells, and cone photoreceptors to be associated with the risk of AMD. These data provide a detailed analysis of the human retina, and show how scRNA-seq can provide insight into cell types involved in complex, inflammatory genetic diseases.
PURPOSE: To review the roles of analytic and innovative thought in advancing knowledge, using past examples in ophthalmology, and to explore potential strategies to improve our understanding of age-related macular degeneration (AMD) and develop new therapies. DESIGN: Presented as the 2018 Charles L. Schepens, MD, Lecture at the American Academy of Ophthalmology Retina Subspecialty Day, Chicago, Illinois, on October 26, 2018. PARTICIPANTS: None. METHODS: Review of published literature and sources on creativity and innovation. MAIN OUTCOME MEASURES: Recommendations for future AMD research. RESULTS: Innovative solutions to problems often seem intuitively obvious in hindsight. Yet, some problems seem impossible to solve. In the 1990s, AMD was a significant unmet need, with only destructive therapies for neovascular disease. This changed with the development of 2 therapies: (1) verteporfin photodynamic therapy (PDT) and (2) anti-vascular endothelial growth factor (VEGF) therapies, which are now administered to millions of people annually around the world. Now, we are frustrated by the lack of therapies for early and intermediate AMD and geographic atrophy. Photodynamic therapy and anti-VEGF drug development occurred through a combination of analytic thought and creative disruption through innovation. To get past our current impasse in understanding and treating AMD, we need to harness both analysis and innovation. We have many important building blocks in place-information on genetics, clinical findings, imaging, and histology-and have identified key pathways and potential therapeutic targets. Perhaps we need additional investigation, analysis, and integration to improve our understanding through work on structure/function and genotype/phenotype correlations and development of imaging and systemic biomarkers. We likely also need an innovative disruption. This innovation might be the concept that there are subtypes of early and intermediate AMD characterized by specific clinical phenotypes, genotype, functional characteristics, and biomarkers that are dependent on particular pathways and treatable with a specific agent. We need to encourage innovation in each of us within our research and clinical community. CONCLUSIONS: Although we have accumulated extensive knowledge about AMD, we are currently at an impasse in the development of new treatments. We need to continue the analytic process, but at the same time encourage innovative disruption to develop successful AMD therapies.
Mesenchymal stromal cells (MSCs) are multipotent stem cells that participate in tissue repair and possess considerable immunomodulatory potential. MSCs have been shown to promote allograft survival, yet the mechanisms behind this phenomenon have not been fully defined. Here, we investigate the capacity of MSCs to suppress the allogeneic immune response by secreting the pleiotropic molecule hepatocyte growth factor (HGF). Using an in vivo mouse model of corneal transplantation, we report that MSCs promote graft survival in an HGF-dependent manner. Moreover, our data indicate that topically administered recombinant HGF (a) suppresses antigen-presenting cell maturation in draining lymphoid tissue, (b) limits T-helper type-1 cell generation, (c) decreases inflammatory cell infiltration into grafted tissue, and (d) is itself sufficient to promote transplant survival. These findings have potential translational implications for the development of HGF-based therapeutics. Stem Cells Translational Medicine 2019;8:1030-1040.
For this "hot topic" session in uveitis we selected first and foremost an issue that puts our clinical work and research in "holding pattern." The issue is our method of evaluating the severity of uveitis. We posed the following questions to our esteemed panelists: 1.The relative significance of cells vs. flare in following uveitis patients 2.Cells/flare measurements 3.A glance into the future and the relevance of endpoints in clinical studies and their methodologies While there are different opinions in managing and monitoring uveitis patients, there seems to be an agreement on the high need of improving objective mode/s of reliably measuring both cells and flare and better understand their significance.
: To determine the imaging approach for evaluating intraocular foreign bodies (IOFBs) by comparing the ability of different modalities [plain film x-ray, computed tomography (CT), magnetic resonsance imaging (MRI), convetional ultrasound, and ultrasound biomicroscopy] to detect and characterize IOFBs. : Systematic review of the literature. : CT is the most practical first step for evaluating patients with suspected IOFBs because it can detect a wide range of IOFB types at small limitis of detection. MRI and ultrasound are best reserved as adjunctive tests in most cases although these tests may provide important insights especially with wood, plastic, and glass IOFBs. Imaging characteristics of metal, wood, glass, plastic, stone, concrete, and graphite IOFBs are reviewed. : Understanding the limits of detection for each IOFB type and imaging modality as well as the characteristic features of different IOFBs is of paramount importance to optimizing the management of ocular trauma patients.