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: 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: 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.
Background: To evaluate a fully automated vascular density (VD), skeletal density (SD) and fractal dimension (FD) method for the longitudinal analysis of retinal vein occlusion (RVO) eyes using projection-resolved optical coherence tomography angiography (OCTA) images and to evaluate the association between these quantitative variables and the visual prognosis in RVO eyes.
Methods: Retrospective longitudinal observational case series. Patients presenting with RVO to Creteil University Eye Clinic between October 2014 and December 2018 and healthy controls were retrospectively evaluated. Group 1 consisted of central RVO (CRVO) eyes, group 2 consisted of eyes with branch RVO (BRVO) and group 3 of healthy control eyes. OCTA acquisitions (AngioVue RTVue XR Avanti, Optovue, Inc., Freemont, CA) were performed at baseline and last follow up visit. VD, SD, and FD analysis were computed on OCTA superficial and deep vascular complex (SVC, DVC) images at baseline and final follow up using an automated algorithm. Logistic regression was performed to find if and which variable (VD, SD, FD) was predictive for the visual outcome.
Results: Forty-one eyes, of which 21 consecutive eyes of 20 RVO patients (13 CRVO in group 1, 8 BRVO in group 2), and 20 eyes of 20 healthy controls were included. At the level of SVC, VD and FD were significantly lower in RVO eyes compared to controls (P<0.0001 and P=0.0008 respectively). Best-corrected visual acuity (BCVA) at last follow-up visit was associated with baseline VD (P=0.013), FD (P=0.016), and SD (P=0.01) at the level of the SVC, as well as with baseline FD at the DVC level (P=0.046).
Conclusions: Baseline VD, SD, and FD are associated with the visual outcome in RVO eyes. These parameters seem valuable biomarkers and may help improve the evaluation and management of RVO patients.
Objective: In this review, non-transgenic models of age-related macular degeneration (AMD) are discussed, with focuses on murine retinal degeneration induced by sodium iodate and lipid peroxide (HpODE) as preclinical study platforms.
Background: AMD is the most common cause of vision loss in a world with an increasingly aging population. The major phenotypes of early and intermediate AMD are increased drusen and autofluorescence, Müller glia activation, infiltrated subretinal microglia and inward moving retinal pigment epithelium (RPE) cells. Intermediate AMD may progress to advanced AMD, characterized by geography atrophy and/or choroidal neovascularization (CNV). Various transgenic and non-transgenic animal models related to retinal degeneration have been generated to investigate AMD pathogenesis and pathobiology, and have been widely used as potential therapeutic evaluation platforms.
Methods: Two retinal degeneration murine models induced by sodium iodate and HpODE are described. Distinct pathological features and procedures of these two models are compared. In addition, practical protocol and material preparation and assessment methods are elaborated.
Conclusions: Retina degeneration induced by sodium iodate and HpODE in mouse eye resembles many clinical aspects of human AMD and complimentary to the existent other animal models. However, standardization of procedure and assessment protocols is needed for preclinical studies. Further studies of HpODE on different routes, doses and species will be valuable for the future extensive use. Despite many merits of murine studies, differences between murine and human should be always considered.
