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"Color Vision"
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Three-year results of phase I retinal gene therapy trial for CNGA3-mutated achromatopsia: results of a non randomised controlled trial
AimsTo determine long-term safety and efficacy outcomes of a subretinal gene therapy for CNGA3-associated achromatopsia. We present data from an open-label, nonrandomised controlled trial (NCT02610582).MethodsDetails of the study design have been previously described. Briefly, nine patients were treated in three escalating dose groups with subretinal AAV8.CNGA3 gene therapy between November 2015 and October 2016. After the first year, patients were seen on a yearly basis. Safety assessment constituted the primary endpoint. On a secondary level, multiple functional tests were carried out to determine efficacy of the therapy.ResultsNo adverse or serious adverse events deemed related to the study drug occurred after year 1. Safety of the therapy, as the primary endpoint of this trial, can, therefore, be confirmed. The functional benefits that were noted in the treated eye at year 1 were persistent throughout the following visits at years 2 and 3. While functional improvement in the treated eye reached statistical significance for some secondary endpoints, for most endpoints, this was not the case when the treated eye was compared with the untreated fellow eye.ConclusionThe results demonstrate a very good safety profile of the therapy even at the highest dose administered. The small sample size limits the statistical power of efficacy analyses. However, trial results inform on the most promising design and endpoints for future clinical trials. Such trials have to determine whether treatment of younger patients results in greater functional gains by avoiding amblyopia as a potential limiting factor.
Journal Article
Crayola! : the secrets of the cool colors and hot hues
\"An introduction to the science behind the worldwide phenomenon known as Crayola Crayons as well as the concepts of color theory and how color plays an important role our everyday lives\"-- Provided by publisher.
BOOK
Gene therapy for red–green colour blindness in adult primates
Gene therapy in colour
It is often assumed that critical periods exist for the development of vision and other neural capabilities and that they end prior to adolescence. For example, it might be expected that gene therapy in adults with congenital vision disorders would be impossible. But experiments in adult spider monkeys who are normally red–green colour blind show that it is possible to add a third photopigment (human opsin) into some of their retinal cells by gene therapy. The monkeys acquire a new dimension of colour vision as a result. Not only does this suggest a possible therapy for a common congenital visual defect in humans (clinical trials are now under way), but also it demonstrates the extreme neuroplasticity of visual processing and points to possible routes by which trichromatic vision evolved.
Red–green colour blindness is the most common single locus genetic disorder. Gene therapy is now used in adult monkeys, colour blind since birth, to provide the receptoral basis for trichromatic colour vision. Despite the expectation from classic visual deprivation experiments that neural connections established during development are incapable of processing an input not present from birth, treated monkeys displayed trichromatic colour vision behaviour.
Red–green colour blindness, which results from the absence of either the long- (L) or the middle- (M) wavelength-sensitive visual photopigments, is the most common single locus genetic disorder. Here we explore the possibility of curing colour blindness using gene therapy in experiments on adult monkeys that had been colour blind since birth. A third type of cone pigment was added to dichromatic retinas, providing the receptoral basis for trichromatic colour vision. This opened a new avenue to explore the requirements for establishing the neural circuits for a new dimension of colour sensation. Classic visual deprivation experiments
1
have led to the expectation that neural connections established during development would not appropriately process an input that was not present from birth. Therefore, it was believed that the treatment of congenital vision disorders would be ineffective unless administered to the very young. However, here we show that the addition of a third opsin in adult red–green colour-deficient primates was sufficient to produce trichromatic colour vision behaviour. Thus, trichromacy can arise from a single addition of a third cone class and it does not require an early developmental process. This provides a positive outlook for the potential of gene therapy to cure adult vision disorders.
Journal Article
The biology of color
Animals live in a colorful world, but we rarely stop to think about how this color is produced and perceived, or how it evolved. Cuthill et al. review how color is used for social signals between individual animals and how it affects interactions with parasites, predators, and the physical environment. New approaches are elucidating aspects of animal coloration, from the requirements for complex cognition and perception mechanisms to the evolutionary dynamics surrounding its development and diversification. Science , this issue p. eaan0221 Coloration mediates the relationship between an organism and its environment in important ways, including social signaling, antipredator defenses, parasitic exploitation, thermoregulation, and protection from ultraviolet light, microbes, and abrasion. Methodological breakthroughs are accelerating knowledge of the processes underlying both the production of animal coloration and its perception, experiments are advancing understanding of mechanism and function, and measurements of color collected noninvasively and at a global scale are opening windows to evolutionary dynamics more generally. Here we provide a roadmap of these advances and identify hitherto unrecognized challenges for this multi- and interdisciplinary field.
Journal Article
Implications of inherited color vision deficiency on occupations: A neglected entity
Purpose:
To highlight the plight of individuals with congenital color vision deficiency (CVD).
Methods:
This is a retrospective study in which 191 electronic medical records of individuals with the diagnosis of inherited CVD, who visited the eye institute, between January 2010 and January 2021 were included. The inclusion criteria included diagnosis based on the failure in pseudoisochromatic plates (Ishihara / Hardy, Rand and Rittler (HRR) and age range between 18 and 35 years. The patient's medical history, age, gender, type of defect, and preference for colored contact lenses was noted. Medical records were excluded if the participant had any other ocular pathology apart from congenital CVD.
Results:
At least 30% (57/191) of the individuals explicitly requested for color vision examination for a job-related purpose. Amongst them, the most common jobs aspired were army (~25%; [14/57]) followed by police (21%; [12/57]). There was only 2.6% (5/191) of individuals in which the type of CVD (protan/deutan) was classified. Only 5.2% of them (10/191) sought an X-Chrome contact lens trial.
Conclusion:
This study reported the occupational setbacks experienced by individuals with CVD. This study highlights the need to identify CVD at a younger age, thereby avoiding occupational-related setbacks later in life.
Journal Article
Color appearance models
\"The essential resource for readers needing to understand visual perception and for those trying to produce, reproduce and measure color appearance in various applications such as imaging, entertainment, materials, design, architecture and lighting.This book builds upon the success of previous editions, and will continue to serve the needs of those professionals working in the field to solve practical problems or looking for background for on-going research projects. It would also act as a good course text for senior undergraduates and postgraduates studying color science.The 3rd Edition of Color Appearance Models contains numerous new and expanded sections providing an updated review of color appearance and includes many of the most widely used models to date, ensuring its continued success as the comprehensive resource on color appearance models.Key features: Presents the fundamental concepts and phenomena of color appearance (what objects look like in typical viewing situations) and practical techniques to measure, model and predict those appearances. Includes the clear explanation of fundamental concepts that makes the implementation of mathematical models very easy to understand. Explains many different types of models, and offers a clear context for the models, their use, and future directions in the field\"-- Provided by publisher.
Book
Achromatopsia: Genetics and Gene Therapy
Achromatopsia (ACHM), also known as rod monochromatism or total color blindness, is an autosomal recessively inherited retinal disorder that affects the cones of the retina, the type of photoreceptors responsible for high-acuity daylight vision. ACHM is caused by pathogenic variants in one of six cone photoreceptor-expressed genes. These mutations result in a functional loss and a slow progressive degeneration of cone photoreceptors. The loss of cone photoreceptor function manifests at birth or early in childhood and results in decreased visual acuity, lack of color discrimination, abnormal intolerance to light (photophobia), and rapid involuntary eye movement (nystagmus). Up to 90% of patients with ACHM carry mutations in
CNGA3
or
CNGB3
, which are the genes encoding the alpha and beta subunits of the cone cyclic nucleotide-gated (CNG) channel, respectively. No authorized therapy for ACHM exists, but research activities have intensified over the past decade and have led to several preclinical gene therapy studies that have shown functional and morphological improvements in animal models of ACHM. These encouraging preclinical data helped advance multiple gene therapy programs for
CNGA3
- and
CNGB3
-linked ACHM into the clinical phase. Here, we provide an overview of the genetic and molecular basis of ACHM, summarize the gene therapy-related research activities, and provide an outlook for their clinical application.
Journal Article