Contrast is the differential luminance between one object and another. Contrast sensitivity (CS) quantifies the ability to detect this difference: estimating contrast threshold provides information about the quality of vision and helps diagnose and monitor eye diseases. High contrast visual acuity assessment is traditionally performed in the eye care practice, whereas the estimate of the discrimination of low contrast targets, an important complementary task for the perception of details, is far less employed. An example is driving when the contrast between vehicles, obstacles, pedestrians, and the background is reduced by fog. Many conditions can selectively degrade CS, while visual acuity remains intact. In addition to spatial CS, “temporal” CS is defined as the ability to discriminate luminance differences in the temporal domain, i.e., to discriminate information that reaches the visual cortex as a function of time. Likewise, temporal sensitivity of the visual system can be investigated in terms of critical fusion frequency (CFF), an indicator of the integrity of the magnocellular system that is responsible for the perception of transient stimulations. As a matter of fact, temporal resolution can be abnormal in neuro-ophthalmological clinical conditions. This paper aims at considering CS and its application to the clinical practice.
Abstract: Diabetic retinopathy (DR) remains a leading cause of irreversible vision loss in adult populations around the globe. Despite growing evidence of the effectiveness of routine assessments and early intervention, DR screening strategies are not widely implemented largely due to an inadequate availability of resources to cope with the growing burden of diabetes. Advances in technology in the field of DR screening are clearly warranted and the recent emergence of deep learning-based artificial intelligence (AI) grading of retinal pathology offers significant potential benefits including an increased efficiency, accessibility and affordability of screening programmes.
Abstract: The disease burden of diabetic retinopathy (DR) is tremendous around the world. While DR is correlated with hemoglobin A1c (HbA1c) and duration of diabetes, genetic differences likely account for variation in susceptibility to DR. DR is a polygenic disorder with demonstrated heritability. However, linkage and admixture analyses, candidate gene association studies, and genome-wide association studies (GWAS) have not identified many loci for DR that can be consistently replicated. Larger, collaborative, multi-ethnic GWAS are needed to identify common variants with small effects. Rigorous defining of controls groups as patients with a long duration of diabetes without DR, and case groups as patients with severe DR will also aid in finding genes associated with DR. Replication in independent cohorts will be key to establishing associated loci for DR. Investigations of mitochondrial DNA and epigenetics in DR are ongoing. Whole exome sequencing presents new opportunities to identify rare variants that might be implicated in DR development. Continued research in the genetic epidemiology of DR is needed, with the potential to elucidate pathogenesis and treatment of an important disease.
Abstract: Retinal angiogenic diseases, such as diabetic retinopathy (DR) and age-related macular degeneration (AMD) represent the leading causes of vision impairment in developed countries. There is strong evidence that dysregulated metabolic pathways contribute to DR as known risk factors do not explain all cases and the phenomenon of metabolic memory persists for decades or longer. Some early studies also showed that changes of plasma metabolic profiles are associated with AMD. Metabolic abnormalities can be explored using the techniques of the new science of metabolomics. In this presentation, several metabolomics workflows as well as the application of data independent acquisition mass spectrometry (DIA-MS) in metabolomics will be discussed. Our recent findings from metabolomics studies on DR and AMD will be presented.
Abstract: Blinding diseases such as photoreceptor degenerations are debilitating conditions that severely impair daily lives of affected patients. This group of diseases are amenable to photoreceptor replacement therapies and recent transplantation studies provided proof-of-principle for functional recovery at the retinal and behavioral level, though the actual mechanism of repair still needs further investigations. The immune system responds in several ways upon photoreceptor engraftment, resulting in T-cell and macrophage infiltrations and, consequently, decrease in graft survival. Most studies on the role of the immune system suggest a detrimental effect in a therapeutic setting. Conversely, the opposite idea wherein the immune system can be activated towards a protective state was also explored in other experimental paradigms. Here, Neves and colleagues explored the potential of cross-species studies and, to a certain extent, the concept of a protective immune system in retinal degeneration and therapy. Mesencephalic astrocyte-derived neurotrophic factor (MANF) was identified in this study as a novel factor that, by modulating the immune system, can slow down photoreceptor degeneration and improve transplantation outcome.
Abstract: We reviewed randomized controlled trials associated with the intravitreal use of aflibercept for this article. These studies proved that aflibercept is an effective anti-vascular endothelial growth factor agent for the treatment of neovascular age-related macular degeneration (nAMD), myopic choroidal neovascularization (mCNV), diabetic macular edema (DME), and macular edema associated with retinal vein occlusion. The incidence of severe ocular or systemic complications after intravitreal administration of aflibercept was low.
