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- A simple modification of the Farnsworth-Munsell 100-Hue test for much faster assessment of color vision. [Journal Article]
- Indian J Ophthalmol 2014 Jun; 62(6):721-3.
Purpose:The Farnsworth-Munsell (FM) 100-hue test is well known but is also time consuming, especially its analytical component. To reduce this needless time-waste during precious working hours, a simple modification was devised.
Design:Prospective, comparative, observational study. Materials and
Methods:A transparent clear plastic carrier box replaced the opaque one, allowing ready digital photodocumentation of top and bottom without even opening the box, or handling/inverting the caps -200 reportedly normals and 50 known color vision defectives could be easily tested on this modified-FM and results stored, allowing rapid turnover. The captured scores with patient ID were analyzed, at leisure, outside hospital time, saving 45-60 minutes/patient. After recording, the box was promptly handed over to the next subject for rearrangement. Times taken for test/patient were recorded.
Results:Running time was reduced from 60-75 min to ~15 min/patient with no waste of invaluable lab hours. Turnover time is limited to capturing two photographs (~60 sec). The box is relatively cheap and easy to maintain.
Conclusions:Our simplified FM 100-hue test allowed rapid assessment of color visions with easy data storage of both top and bottom.
- miRNAs 182 and 183 Are Necessary to Maintain Adult Cone Photoreceptor Outer Segments and Visual Function. [JOURNAL ARTICLE]
- Neuron 2014 Jul 4.
The outer segments of cones serve as light detectors for daylight color vision, and their dysfunction leads to human blindness conditions. We show that the cone-specific disruption of DGCR8 in adult mice led to the loss of miRNAs and the loss of outer segments, resulting in photoreceptors with significantly reduced light responses. However, the number of cones remained unchanged. The loss of the outer segments occurred gradually over 1 month, and during this time the genetic signature of cones decreased. Reexpression of the sensory-cell-specific miR-182 and miR-183 prevented outer segment loss. These miRNAs were also necessary and sufficient for the formation of inner segments, connecting cilia and short outer segments, as well as light responses in stem-cell-derived retinal cultures. Our results show that miR-182- and miR-183-regulated pathways are necessary for cone outer segment maintenance in vivo and functional outer segment formation in vitro.
- Biological Sunscreens Tune Polychromatic Ultraviolet Vision in Mantis Shrimp. [JOURNAL ARTICLE]
- Curr Biol 2014 Jul 3.
Stomatopod crustaceans, or mantis shrimp, are renowned for their complex visual systems. Their array of 16 types of photoreceptors provides complex color reception, as well as linear and circular polarization sensitivity [1-6]. The least-understood components of their retina are the UV receptors, of which there are up to six distinct, narrowly tuned spectral types . Here we show that in the stomatopod species Neogonodactylus oerstedii, this set of receptors is based on only two visual pigments. Surprisingly, five of the six UV receptor types contain the same visual pigment. The various UV receptors are spectrally tuned by a novel set of four short- and long-pass UV-specific optical filters in the overlying crystalline cones. These filters are composed of various mycosporine-like amino acid (MAA) pigments. Commonly referred to as "nature's sunscreens," MAAs are usually employed for UV photoprotection [7, 8], but mantis shrimp uniquely incorporate them into powerful spectral tuning filters, extending and diversifying their preeminently elaborate photoreceptive arsenal. VIDEO ABSTRACT:
- A pilot study of the effect of intravenous erythropoetin on improvement of visual function in patients with recent indirect traumatic optic neuropathy. [JOURNAL ARTICLE]
- Graefes Arch Clin Exp Ophthalmol 2014 Jul 2.
To evaluate the efficacy of intravenous erythropoietin (EPO) on improvement of visual function and color vision in patients with recent indirect traumatic optic neuropathy (TON).In a case series, 18 eyes of 18 patients with diagnosis of indirect TON with duration of less than 2 weeks underwent 20,000 IU intravenous EPO injections daily for 3 days. Best corrected visual acuity (BCVA) and color vision were checked by Ishihara test before, 1, and 3 months after injections. BCVA and color vision were compared before, 1, and 3 months after injections.The mean BCVA improved from a baseline of 2.21 ± 0.97 to 1.48 ± 1.29 and 1.31 ± 1.27 log MAR at months 1 and 3, respectively. The differences were statistically significant (P = 0.001, P < 0.001). Color vision was changed from a baseline 2.24 ± 4.29 to 2.94 ± 4.64 and 3.41 ± 5.09 plates at months 1 and 3, respectively. We observed some qualitative improvement that was, however, statistically insignificant at the time of evaluation. (P = 0.063, P = 0.068).This case series showed noticeable effect of EPO on improvement of visual function in patients with recent indirect TON.
- Illuminant estimation for color constancy: why spatial-domain methods work and the role of the color distribution. [JOURNAL ARTICLE]
- J Opt Soc Am A Opt Image Sci Vis 2014 May 1; 31(5):1049-1058.
Color constancy is a well-studied topic in color vision. Methods are generally categorized as (1) low-level statistical methods, (2) gamut-based methods, and (3) learning-based methods. In this work, we distinguish methods depending on whether they work directly from color values (i.e., color domain) or from values obtained from the image's spatial information (e.g., image gradients/frequencies). We show that spatial information does not provide any additional information that cannot be obtained directly from the color distribution and that the indirect aim of spatial-domain methods is to obtain large color differences for estimating the illumination direction. This finding allows us to develop a simple and efficient illumination estimation method that chooses bright and dark pixels using a projection distance in the color distribution and then applies principal component analysis to estimate the illumination direction. Our method gives state-of-the-art results on existing public color constancy datasets as well as on our newly collected dataset (NUS dataset) containing 1736 images from eight different high-end consumer cameras.
- Solving the inverse grating problem with the naked eye. [JOURNAL ARTICLE]
- Opt Lett 2014 Jun 15; 39(12):3547-3550.
We make use of the color sensitivity of the naked human eye to solve the inverse grating problem. We conduct color-matching experiments between simulated colors and the color of the zero diffraction order, and show that human color vision may reveal structure dimensions at an accuracy in the order of ten nanometers, which is comparable to the precision of destructive methods such as scanning electron microscopy. Our results suggest that for a wide range of structures, the color observation may help to get quick, but still accurate, results, without any sophisticated instrumentation.
- Predicting the brightness of unrelated self-luminous stimuli. [JOURNAL ARTICLE]
- Opt Express 2014 Jun 30; 22(13):16298-16309.
In a magnitude estimation experiment, twenty observers rated the brightness of several unrelated, self-luminous stimuli surrounded by a dark background. The performance of a number of existing vision models, color appearance models and models based on the concept of equivalent luminance in predicting brightness has been investigated. Due to a severe underestimation of the Helmholtz-Kohlrausch effect, none of the models performed acceptable. Increasing the weight of the colorfulness contribution to the brightness attribute in the CAM97u model results in a very good correlation between the model predictions and the visually perceived brightness. Finally the experimental results and the brightness prediction from the modified model CAM97u,m are verified through a matching experiment and a validation magnitude estimation experiment.
- Constraints on Dilution From a Narrow Attentional Zoom Reveal How Spatial and Color Cues Direct Selection. [JOURNAL ARTICLE]
- Vision Res 2014 Jun 25.
Distractor interference is subject to dilution from other nontarget elements, and the level of dilution is affected by attention. This study explores the nature of dilution when the location and color of the target is known in advance. Experiments 1 and 2 show that attention is effectively limited to the precued region, so that it is the non-target letters appearing at the cued locations that are responsible for most of the dilution, and not those appearing at the uncued locations. Furthermore, this dilution occurs relatively early in processing. Experiment 3 demonstrates that top-down attentional control can prevent dilution, because foreknowledge of the target color leads to quick attention shifts. Experiment 4 illustrates bottom-up attentional control in preventing dilution when the distractor is a color singleton that is segregated from the diluting nontargets. The results show that dilution is modulated by both top-down and bottom-up factors, that it can occur even when attention is restricted to a relatively small region, and that it occurs early in processing, but not so early that it avoids the effects of attention. They provide new challenges for earlier accounts suggesting that dilution is widespread and unfettered by attention. Likewise, some parts of the results are difficult to reconcile with the alternative perceptual load theory, but they do support a form of dilution that is limited by attentional boundaries. Because of that link to attention, dilution is a useful tool for measuring how attention is guided by information about target location and color.
- Atypical Bourneville sclerosis without epilepsy and mental retardation: case report and literature review. [Journal Article]
- Rom J Morphol Embryol 2014; 55(2):413-8.
Twenty-four-year-old woman without familiar detected signs of Bourneville's disease or tuberous sclerosis complex (TSC) was diagnosed with this disease by casual discovery on cerebral magnetic resonance imaging (MRI) of an intraventricular tumor, after symptoms consist in headache, equilibrium disturbances, and progressive loss of vision. MRI shows an intracranial mass, 33÷24÷30 mm in size, localized at the level of third ventricle and lateral ventricles, with irregular shape, interesting the foramen of Monroe. There are also nodular areas of calcification and a supratentorial hydrocephalus involving the lateral ventricles and the posterior part of the third ventricle. The patients present facial angiofibromas, but from the classical triad of the disease, the epilepsy and mental retardation were absent, the patient never presented seizures. The total removal of the tumor (peace to peace) was performed surgically, the macroscopic features of resected tumor (20÷10÷10 mm) was of white-gray color, elastic consistency, localized in the both lateral ventricles (left>right) and into the third ventricle, traversing the foramen Monroe. The histopatological examination associated with specific localization of tumor and the facial angiofibromas are very suggestive for subependimar giant cell astrocytoma (SEGA). We have a rare case of atypical or incomplete TSC in which the epileptic seizures and the mental retardation are absent, the intelligence is normal, but occur some psychical symptoms: anxiety, sleeplessness, and autism or behavior disturbances. The evolution of this case was marked by complications because of postoperative hydrocephalus and multiple shunt insertions and revisions were performed after the tumor resection.
- Unsupervised Learning of Cone Spectral Classes from Natural Images. [JOURNAL ARTICLE]
- PLoS Comput Biol 2014 Jun; 10(6):e1003652.
The first step in the evolution of primate trichromatic color vision was the expression of a third cone class not present in ancestral mammals. This observation motivates a fundamental question about the evolution of any sensory system: how is it possible to detect and exploit the presence of a novel sensory class? We explore this question in the context of primate color vision. We present an unsupervised learning algorithm capable of both detecting the number of spectral cone classes in a retinal mosaic and learning the class of each cone using the inter-cone correlations obtained in response to natural image input. The algorithm's ability to classify cones is in broad agreement with experimental evidence about functional color vision for a wide range of mosaic parameters, including those characterizing dichromacy, typical trichromacy, anomalous trichromacy, and possible tetrachromacy.