Abstract: Effective and safe electrical stimulation of the retinal ganglion cells is at the heart of retinal prosthesis design. However, the effectiveness and safety demand of the electrical stimulation is often at odds against each other. Besides, the nerve fiber layer above retinal ganglion cells limits the spatial resolution of stimulation. Also, current retinal prosthesis still cannot selectively activate the ON or OFF visual pathways, thus cannot relay the correct luminance information to the brain. With decades of development, the stimulation protocol for retinal implants began to tackle these problems. We believe that a novel design of electrical stimulation scheme, combined with gene therapy technique, can improve the selectivity and spatial resolution of retinal implants and further lower the damage caused by electric stimulation.
Abstract: Focal intraretinal alterations have been studied to advance our understanding of the pathology of neurodegenerative diseases. The current literature involving focal alterations in the intraretinal layers was reviewed through PubMed using the search terms “focal alteration”, “region of interest”, “optical coherence tomography”, “glaucoma”, “multiple sclerosis”, “Alzheimer’s disease”, “Parkinson disease”, “neurodegenerative diseases” and other related items. It was found that focal alterations of intraretinal layers were different in various neurodegenerative diseases. The typical focal thinning might help differentiate various ocular and cerebral diseases, track disease progression, and evaluate the outcome of clinical trials. Advanced exploration of focal intraretinal alterations will help to further validate their clinical and research utility.
Abstract: Idiopathic intracranial hypertension (IIH) is a condition in which elevated pressure in the cerebrospinal fluid can lead to optic nerve head (ONH) dysfunction and subsequent visual impairment. Physicians are currently limited in their ability to monitor and manage this condition, as clinical symptoms and exam findings are often delayed in response to changes in intracranial pressure. In order to find other biomarkers of disease, researchers are using imaging modalities such as optical coherence tomography (OCT) to observe microscopic changes in the eye in this condition. OCT can create 2-dimensional and 3-dimensional high definition images of the retina of the ONH and has been used to study various conditions such as glaucoma and multiple sclerosis. Numerous studies have used OCT in IIH as well, and they have shown that certain retinal layers and the ONH change in thickness and shape in both the short and long term with intracranial pressure changes. OCT is a promising modality for clinical and scientific evaluation of IIH as it is a noninvasive and practical tool to obtain in depth images. This review will discuss how OCT can be used to assess a patient with IIH, both before and after treatment, along with its limitations and future applications.
Abstract: Ischemic optic neuropathies are among the most common causes of sudden vision loss, especially in patients over age 50. The cause and prognosis of these disorders, and in particular non-arteritic anterior ischemic optic neuropathy, is poorly understood, and treatments remain poor in terms of restoring or preserving vision. Optical coherence tomography (OCT) and OCT angiography have allowed us to identify early and late structural changes in the optic nerve head and retina that may assist in predicting visual outcomes and may lead to greater understanding of pathogenesis and thus the development of effective medical interventions.
Abstract: Age-related macular degeneration (ARMD), one of the most common causes of blindness, should be considered more due to its exponential increase in the coming 20 years as a result of increasing the age of the population. Whereas more recent studies offered newer scaling systems for ARMD, traditionally it is classified as the early and late stages. The main injury in this disease occurred in retinal pigment epithelium (RPE) and the retina. RPE cells have a crucial role in hemostasis and supporting photoreceptors. In the early stages, damages to RPE are minimal and mainly no treatment is needed because most patients are asymptomatic. However, in the late stages, RPE impairment may lead to the invasion of choroidal vessels into the retina. Although anti-angiogenic agents can inhibit this abnormal growth of blood vessels, they cannot stop it completely, and finally, total loss of retinal cells may occur (geographical atrophy). Since this prevalent disease has not had any cure yet, the concept of substituting the RPE cells should be considered. Repairing the injury to central nervous system cells is almost impossible because the regenerative capacity of these cells is limited. Recently, the use of regenerative substitutes has been suggested to replace damaged tissues. Amniotic membrane (AM) has been raised as a suitable substitute for damaged RPE cells due to all of its unique properties: pluripotency, anti-angiogenic effect, and anti-inflammatory effect. Based on the few studies that have been published so far, it seems that the use of this membrane in the treatment of ARMD can be helpful, but more studies are needed.
Abstract: Age-related macular degeneration (AMD) remains a leading cause of severe visual impairment in developing countries. Although dry-type AMD and geographic atrophy (GA) are progressive conditions with the associated decrease of visual functions, no well-established treatment regimen was proposed for the disease. Wet-type AMD is effectively treated with intravitreal anti-angiogenic agents, but frequent injections are a major issue for the affected patients. Recent advances in AMD genetics have provided new insights into the pathogenesis and novel therapeutic targets of AMD, but the benefits of using genetic testing and genotype-based risk models for AMD development and progression still lacks evidence. Novel AMD treatments aim to increase the interval among intravitreal injections through new therapeutic agents and modern delivery devices. Simultaneously, gene therapy for dry and wet AMD is widely studied. Although gene therapy possesses a major superiority over other novel treatments regarding a persistent cure of disease, many challenges exist in the way of its broad impact on the ocular health of AMD patients.
