scholarly journals Current Medical Therapy and Future Trends in the Management of Glaucoma Treatment

2020 ◽  
Vol 2020 ◽  
pp. 1-14 ◽  
Author(s):  
Barbara Cvenkel ◽  
Miriam Kolko
Keyword(s):  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Future Trends ◽  
Neuroprotective Agents ◽  
Sustained Drug Delivery ◽  
Progressive Loss ◽  
Neuroprotective Therapy ◽  
Rate Of Progression ◽  
New Treatment

Glaucoma is a neurodegenerative disease characterized by progressive loss of retinal ganglion cells and their axons. Lowering of intraocular pressure (IOP) is currently the only proven treatment strategy for glaucoma. However, some patients show progressive loss of visual field and quality of life despite controlled IOP which indicates that other factors are implicated in glaucoma. Therefore, approaches that could prevent or decrease the rate of progression and do not rely on IOP lowering have gained much attention. Effective neuroprotection has been reported in animal models of glaucoma, but till now, no neuroprotective agents have been clinically approved. The present update provides an overview of currently available IOP-lowering medications. Moreover, potential new treatment targets for IOP-lowering and neuroprotective therapy are discussed. Finally, future trends in glaucoma therapy are addressed, including sustained drug delivery systems and progress toward personalized medicine.

Image Sharpness and Contrast Tuning in the Early Visual Pathway

2017 ◽  
Vol 27 (08) ◽  
pp. 1750045 ◽  
Author(s):  
Eduardo Sánchez ◽  
Rubén Ferreiroa ◽  
Adrián Arias ◽  
Luis M. Martínez
Keyword(s):  
Functional Organization ◽  
Ganglion Cells ◽  
Receptive Fields ◽  
Local Contrast ◽  
Retinal Ganglion ◽  
Image Sharpness ◽  
Image Processing Techniques ◽  
Thalamic Relay ◽  
Processing Techniques

The center–surround organization of the receptive fields (RFs) of retinal ganglion cells highlights the presence of local contrast in visual stimuli. As RF of thalamic relay cells follow the same basic functional organization, it is often assumed that they contribute very little to alter the retinal output. However, in many species, thalamic relay cells largely outnumber their retinal inputs, which diverge to contact simultaneously several units at thalamic level. This gain in cell population as well as retinothalamic convergence opens the door to question how information about contrast is transformed at the thalamic stage. Here, we address this question using a realistic dynamic model of the retinothalamic circuit. Our results show that different components of the thalamic RF might implement filters that are analogous to two types of well-known image processing techniques to preserve the quality of a higher resolution version of the image on its way to the primary visual cortex.

Autonomic drugs in the treatment of canine and feline glaucoma – Part I: Medications that lower intraocular pressure by increasing the outflow of aqueous humour

2014 ◽  
Vol 17 (4) ◽  
pp. 741-752 ◽  
Author(s):  
T. Maślanka
Keyword(s):  
Intraocular Pressure ◽  
Aqueous Humour ◽  
Ganglion Cells ◽  
Pharmacological Therapy ◽  
Small Animals ◽  
Retinal Ganglion ◽  
Current State ◽  
Progressive Loss ◽  
Uveoscleral Outflow ◽  
Trabecular Outflow

Abstract One characteristic of the most common types of glaucoma is increased intraocular pressure (IOP), which has a damaging effect on optic nerve axons, leading to progressive loss of retinal ganglion cells. Therefore, ocular hypotensive drugs are the mainstay of pharmacological therapy for glaucoma. This review article, which is the first part of a two-part series, is dedicated to autonomic drugs which lower IOP by increasing the outflow of aqueous humour. These agents are subdivided into two groups: (a) drugs that lower IOP by increasing the trabecular outflow and the uveoscleral outflow (i.e. nonselective adrenergic agonists), and (b) medications that lower IOP by opening of the drainage angle and by increasing the conventional outflow via the trabecular outflow (i.e. parasympathomimetics). This paper summarizes the current state of knowledge on the mechanism of action of these drugs and their effect on IOP in dogs and cats. Moreover, it discusses possible undesirable side effects of these medications and presents the current ideas about their role and position in the medical management of glaucoma in small animals

scholarly journals Epiretinal stimulation with local returns enhances selectivity at cellular resolution

2018 ◽  
Author(s):  
Victoria H. Fan ◽  
Lauren E. Grosberg ◽  
Sasidhar S. Madugula ◽  
Pawel Hottowy ◽  
Wladyslaw Dabrowski ◽  
...  
Keyword(s):  
Ganglion Cells ◽  
Electrode Array ◽  
Artificial Vision ◽  
Retinal Ganglion ◽  
Retinal Neurons ◽  
Cellular Resolution ◽  
Electrode Recording ◽  
Current Spread ◽  
Evoked Activity

AbstractObjectiveEpiretinal prostheses are designed to restore vision in people blinded by photoreceptor degenerative diseases, by directly activating retinal ganglion cells (RGCs) using an electrode array implanted on the retina. In present-day clinical devices, current spread from the stimulating electrode to a distant return electrode often results in the activation of many cells, potentially limiting the quality of artificial vision. In the laboratory, epiretinal activation of RGCs with cellular resolution has been demonstrated with small electrodes, but distant returns may still cause undesirable current spread. Here, the ability of local return stimulation to improve the selective activation of RGCs at cellular resolution was evaluated.ApproachA custom multi-electrode array (512 electrodes, 10 μm diameter, 60 μm pitch) was used to simultaneously stimulate and record from RGCs in isolated primate retina. Stimulation near the RGC soma with a single electrode and a distant return was compared to stimulation in which the return was provided by six neighboring electrodes.Main resultsLocal return stimulation enhanced the capability to activate cells near the central electrode (<30 μm) while avoiding cells farther away (>30 μm). This resulted in an improved ability to selectively activate ON and OFF cells, including cells encoding immediately adjacent regions in the visual field.SignificanceThese results suggest that a device that restricts the electric field through local returns could optimize activation of neurons at cellular resolution, improving the quality of artificial vision.Novelty & SignificanceThe effectiveness of local return stimulation for enhancing the electrical activation of retinal neurons was tested using high-density multi-electrode recording and stimulation in isolated macaque retina. The results suggest that local returns may reduce unwanted evoked activity and thus optimize the selectivity of stimulation at cellular resolution. Similar patterns could be implemented in a future high-resolution prosthesis to permit a more faithful replication of normal retinal activity for the treatment of incurable blindness.

scholarly journals Relationship between Daytime Sleepiness and Intrinsically Photosensitive Retinal Ganglion Cells in Glaucomatous Disease

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Carolina P. B. Gracitelli ◽  
Gloria Liliana Duque-Chica ◽  
Ana Laura de Araújo Moura ◽  
Marina Roizenblatt ◽  
Balazs V. Nagy ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Retinal Ganglion Cells ◽  
Daytime Sleepiness ◽  
Epworth Sleepiness Scale ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Pupillary Reflex

Patients with glaucoma showed to have higher daytime sleepiness measured by Epworth sleepiness scale. In addition, this symptom was associated with pupillary reflex and polysomnography parameters. These ipRGC functions might be impaired in patients with glaucoma, leading to worse quality of life.

scholarly journals Medical Management of Glaucoma in the 21st Century from a Canadian Perspective

2016 ◽  
Vol 2016 ◽  
pp. 1-22 ◽  
Author(s):  
Paul Harasymowycz ◽  
Catherine Birt ◽  
Patrick Gooi ◽  
Lisa Heckler ◽  
Cindy Hutnik ◽  
...  
Keyword(s):  
Medical Management ◽  
Vision Loss ◽  
Ganglion Cells ◽  
Field Testing ◽  
Retinal Nerve Fibre Layer ◽  
Retinal Ganglion ◽  
Canadian Perspective ◽  
Recent Developments ◽  
Nerve Fibre Layer

Glaucoma is a medical term describing a group of progressive optic neuropathies characterized by degeneration of retinal ganglion cells and retinal nerve fibre layer and resulting in changes in the optic nerve head. Glaucoma is a leading cause of irreversible vision loss worldwide. With the aging population it is expected that the prevalence of glaucoma will continue to increase. Despite recent advances in imaging and visual field testing techniques that allow establishment of earlier diagnosis and treatment initiation, significant numbers of glaucoma patients are undiagnosed and present late in the course of their disease. This can lead to irreversible vision loss, reduced quality of life, and a higher socioeconomic burden. Selection of therapeutic approaches for glaucoma should be based on careful ocular examination, patient medical history, presence of comorbidities, and awareness of concomitant systemic therapies. Therapy should also be individualized to patients’ needs and preferences. Recent developments in this therapeutic field require revisiting treatment algorithms and integration of traditional and novel approaches in order to ensure optimal visual outcomes. This article provides an overview of recent developments and practice trends in the medical management of glaucoma in Canada. A discussion of the surgical management is beyond the scope of this paper.

Progressive Loss of Retinal Ganglion Cells in Activating Protein-2β Neural Crest Cell Knockout Mice

2021 ◽  
pp. 1-7
Author(s):  
Aftab Taiyab ◽  
Anthony Saraco ◽  
Monica Akula ◽  
Paula Deschamps ◽  
Alexander K. Ball ◽  
...  
Keyword(s):  
Neural Crest ◽  
Retinal Ganglion Cells ◽  
Knockout Mice ◽  
Ganglion Cells ◽  
Neural Crest Cell ◽  
Retinal Ganglion ◽  
Progressive Loss ◽  
Crest Cell

scholarly journals Management of glaucoma with neuroprotective drug

1970 ◽  
Vol 9 (4) ◽  
pp. 199-203
Author(s):  
Md Nurul Islam
Keyword(s):  
Cell Death ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Medical Science ◽  
Retinal Ganglion ◽  
Progressive Loss ◽  
Independent Mechanism ◽  
Pressure Independent ◽  
Neuro Protection ◽  
Dependent Mechanism

Glaucoma is an optic neuropathy characterized by progressive loss of retinal ganglion cells (RGCs). Death of ganglion cells is not always only pressure dependent mechanism but also have several pressure independent mechanism that establish a cascade of changes that ultimately leads to cell death. Neuro- protection is a process that attempt to preserve the cells that were spared during initial insult, but are still vulnerable to damage. Although not yet available, a neuroprotective agent would be great use that rescue neurons already compromised or that promote regrowth of axonal or dendritic connection to restore function. This review based on literature, giving the idea of varies mechanism of RGC death delineated by research and discussed some pharmacological agent believed to have a neuroprotective role in glaucoma. DOI: 10.3329/bjms.v9i4.6685Bangladesh Journal of Medical Science Vol.09 No.4 July 2010 pp.199-203

scholarly journals Model-Based Recommendations for Optimal Surgical Placement of Epiretinal Implants

2019 ◽  
Author(s):  
Michael Beyeler ◽  
Geoffrey M. Boynton ◽  
Ione Fine ◽  
Ariel Rokem
Keyword(s):  
Visual Experience ◽  
Ganglion Cells ◽  
Electrode Array ◽  
Patient Specific ◽  
Retinal Ganglion ◽  
Retinal Implant ◽  
Implant Placement ◽  
Retinal Implants ◽  
Visual Percept

AbstractA major limitation of current electronic retinal implants is that in addition to stimulating the intended retinal ganglion cells, they also stimulate passing axon fibers, producing perceptual ‘streaks’ that limit the quality of the generated visual experience. Recent evidence suggests a dependence between the shape of the elicited visual percept and the retinal location of the stimulating electrode. However, this knowledge has yet to be incorporated into the surgical placement of retinal implants. Here we systematically explored the space of possible implant configurations to make recommendations for optimal intraocular positioning of the electrode array. Using a psychophysically validated computational model, we demonstrate that better implant placement has the potential to reduce the spatial extent of axonal activation in existing implant users by up to ∼55 %. Importantly, the best implant location, as inferred from a population of simulated virtual patients, is both surgically feasible and is relatively stable across individuals. This study is a first step towards the use of computer simulations in patient-specific planning of retinal implant surgery.

scholarly journals Current Perspective of Hydrogen Sulfide as a Novel Gaseous Modulator of Oxidative Stress in Glaucoma

Antioxidants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 671
Author(s):  
Yuan Feng ◽  
Verena Prokosch ◽  
Hanhan Liu
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Sulfide ◽  
Retinal Ganglion Cells ◽  
Vascular System ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Progressive Loss ◽  
Current Perspective ◽  
Main Clinical Manifestation

Glaucoma is a group of diseases characterized by the progressive loss of retinal ganglion cells and their axons. Elevated intraocular pressure (IOP) is the main clinical manifestation of glaucoma. Despite being in the focus of the studies for decades, the characteristic and the exact pathology of neurodegeneration in glaucoma remains unclear. Oxidative stress is believed to be one of the main risk factors in neurodegeneration, especially its damage to the retinal ganglion cells. Hydrogen sulfide (H2S), the recently recognized gas signaling molecule, plays a pivotal role in the nervous system, vascular system, and immune system. It has also shown properties in regulating oxidative stress through different pathways in vivo. In this review, we summarize the distribution and the properties of H2S within the eye with an emphasis on its role in modulating oxidative stress in glaucoma.

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