Abstract: Optical coherence tomography angiography (OCTA) is a fast, non-invasive imaging modality that provides detailed information on retinal and choroidal vascular flow and macular structure. OCTA offers an accurate three-dimensional view of the individual retinal vascular plexuses and the choriocapillaris which facilitates the detection of the microvascular abnormalities in a variety of macular diseases. The perfusion indices (vessel density and flow index) are valuable parameters evaluated by OCTA that allow a quantitative interpretation of changes in the retinal vasculature that can reflect the severity of disease. Crystalline retinopathy encompasses a group of conditions whose distinctive feature is the presence of retinal crystals often located in the posterior pole. Select crystalline retinopathies also demonstrate retinal vascular abnormalities as well. Considering that the OCTA is a novel imaging modality and crystalline retinopathies are relatively rare conditions, there are currently few reports of OCTA findings associated with crystalline retinopathy. The advent of OCTA allows visualization of vascular and structural changes in crystalline retinopathies that are unique and cannot be appreciated on other imaging modalities, including fluorescein angiography (FA). This article reviews novel OCTA findings which provide new insights in the pathogenesis of crystalline retinopathies, including Bietti crystalline retinopathy, talc retinopathy, macular telangiectasia type 2, tamoxifen retinopathy, and Sj?gren-Larsson Syndrome maculopathy.
Abstract: Uveitis can cause significant visual morbidity and often affects younger adults of working age. Anterior uveitis, or inflammation limited to the anterior chamber (AC), iris, and/or ciliary body comprises the majority of uveitis cases. Current clinical biomarkers and conventional grading scales for intraocular inflammation are mostly subjective and have only a moderate degree of interobserver reliability, and as such they have significant limitations when used in either clinical practice or research related to uveitis. In recent years, novel imaging techniques and applications have emerged that can supplement exam findings to detect subclinical disease, monitor quantitative biomarkers of disease progression or treatment effect, and provide overall a more nuanced understanding of disease entities. The first part of this review discusses automated algorithms for optical coherence tomography (OCT) image processing and analysis as a means to assess and describe intraocular inflammation with higher resolution than that afforded by conventional AC and vitreous cell ordinal grading scales. The second half of the review focuses on anterior segment OCT and OCT angiography (OCTA) in scleritis and iritis, especially with regards to their ability to directly image and characterize the pathologic structures and vasculature underlying these diseases. Finally, we briefly review experimental animal research with promising but more distant human clinical applications, including in vivo molecular microscopy of inflammatory markers and investigation of gold nanoparticles as a potential contrast agent in OCT imaging. Imaging modalities are discussed in the broader context of trends within the field of uveitis towards greater objectivity and quantifiable outcome measures and biomarkers.
Abstract: Vogt-Koyanagi-Harada syndrome (VKH) is a bilateral granulomatous panuveitis associated with serous retinal detachments and vitritis, and can be associated with extraocular manifestations of meningismus, poliosis, vitiligo, hearing loss, and headaches. It is mediated by CD4+ T cells that target melanocytes in the eye, ear, meninges, and skin. It classically presents in 4 different phases: prodromal, uveitic, convalescent, and recurrent. There have been considerable advances in our understanding of the disease in recent years, and options for treatment have also expanded beyond systemic corticosteroids though these remain the mainstay of therapy in patients with VKH. This brief review will focus on updates in the diagnosis and treatment of VKH, specifically advances in imaging techniques including the use of optical coherence tomography angiography (OCTA) and enhanced depth imaging (EDI) optical coherence tomography (OCT). OCT parameters that are diagnostically predictive of acute VKH compared to other exudative maculopathies include the presence of subretinal membranous structures, a high retinal detachment, subretinal hyperreflective dots, and RPE folds. Evaluations of choroidal thickness using EDI-OCT demonstrate predominant involvement of the outer choroid in the acute inflammatory phase of VKH, consistent with histopathological analysis. OCTA may emerge as an alternative to fluorescein angiography (FA) and indocyanine angiography (ICGA) but is limited at this time due to its small field of view. While the mainstay of treatment of acute VKH continues to be systemic corticosteroids, biological response modifiers (BRMs) such as adalimumab and infliximab have been shown to be effective in the management of adult and pediatric VKH with one benefit being a faster onset of action compared to conventional immunosuppression. Literature Search: A literature search was done in PubMed using the words “Vogt Koyanagi Harada” “imaging” “diagnosis” “treatment” “therapy “posterior uveitis”.
Abstract: Optical coherence tomography (OCT) is a technology that is widely used to assess structural abnormalities in the retina for a variety of pediatric conditions. The introduction of this instrument has allowed for widespread access to minimally invasive standardized, reproducible quantified structural assessments of the optic nerve and retina. This has had important implications in pediatric optic neuropathies, populations in whom monitoring of disease activity is essential to making treatment decisions. OCT has had particular relevance for inflammatory optic neuropathies, as onset of an inflammatory optic neuropathy may herald the onset of a chronic inflammatory disorder of the central nervous system (CNS) such as multiple sclerosis, neuromyelitis optica spectrum disorder (aquaporin 4 antibody positive), and myelin oligodendrocyte glycoprotein (MOG) associated disorders. This paper will focus on the application of OCT technology to this group of disorders in pediatrics. After reviewing pediatric-specific anatomic and practical issues pertinent to OCT, we will review knowledge related to the use of OCT in inflammatory pediatric optic neuropathies, with a focus on structural outcomes and their correlation with functional outcome metrics.
Abstract: Hereditary, metabolic and toxic optic neuropathies cause bilateral, central vision loss and therefore can result in severe impairment in visual function. Accurate, early diagnosis is critical, as nutritional and toxic optic neuropathies may be reversible if identified early, and diagnosis of hereditary optic neuropathies can prevent unnecessary invasive workup, provide prognostic information, and allow for effective genetic counseling. Optical coherence tomography (OCT) is a valuable tool that aids in the diagnosis and prognostication of optic neuropathies as it allows for quantification of changes in the retinal ganglion cells (RGCs) and retinal nerve fiber layer (RNFL) over time. We review the characteristic clinical presentations of hereditary, metabolic and toxic optic neuropathies, with an emphasis on OCT findings.
Abstract: Optical coherence tomography (OCT) provides a non-invasive analysis of the retina in vivo. Lesions which compress the anterior visual pathway can cause anterograde and retrograde neuro-degeneration. Retrograde structural changes to the retina can be detected by OCT. Analyzing patterns of change on OCT can guide diagnostic and treatment decisions for lesions compressing the optic nerve and chiasm to minimize loss of visual function. From our review of current literature, it is clear that thinning of both the retinal nerve fiber and ganglion cell layers (GCLs) can indicate compression. These parameters correlate with visual function loss as detected by perimetry. Furthermore, these measurements have shown to be the most reliable biomarkers to date in predicting visual recovery after treatment of these compressive lesions.
Abstract: Optical coherence tomography (OCT) is a widely used non-invasive medical imaging technology that has revolutionized clinical care in ophthalmology. New developments, such as OCT angiography (OCTA) are expected to contribute even further to the widespread use of OCT-based imaging devices in the diagnosis and monitoring of patients with ophthalmic diseases. In recent years, many of the disadvantages such as limited field of view and imaging artefacts have been substantially reduced. Similar to the progress achieved in the assessment of retinal disorders, OCT is expected to change the approach to patients seen in the neuro-ophthalmology clinic. In this article, we review the technical features of OCT and OCT-based imaging techniques, highlighting the specific factors that should be taken into account when interpreting OCT in the field of neuro-ophthalmology.
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.
