Essay on Visual Acuity as a Function of Retinal Eccentricity

In the first article, Knight, Mazzi and Savazzi (2015) made 3 hypotheses. The first hypothesis was that the Transcranial Magnetic Stimulation (TMS) threshold would change when the background changed from uniform to pattern (Knight et al., 2015). The second hypothesis was that the likelihood of the participant sensing light versus dark percepts would change when global luminance of the background changed (Knight et al., 2015). The third hypothesis was that the likelihood of light versus dark percepts would stay the same at different TMS intensities (Knight et al., 2015). The study had 16 participants who all wore corrective lens (Knight et al., 2015). To test the threshold of phosophenes, a Method of Constant Stimuli (MOCS) was used (Knight et al., 2015). The participants received 120 randomly administered trials with pulses from TMS under two different background conditions (Knight et al., 2015). A paired t-test was used to analyze the difference in stimulator intensity threshold for inducing percepts between background conditions (Knight et al., 2015). A repeated-measures analysis of variance

In the Snellen fraction 20/20, the first number represents the test distance, 20 feet. The second number represents the distance that the average eye can see the letters on a certain line of the eye chart. So, 20/20 means that the eye being tested can read a certain size letter when it is 20 feet away. If a person sees 20/40, at 20 feet from the chart that person can read letters that a person with 20/20 vision could read from 40 feet away. The 20/40 letters are twice the size of 20/20 letters; however, it does not mean 50% vision since 20/20 sounds like it is one half of 20/40. If 20/20 is considered 100% visual effiency, 20/40 visual acuity is 85% efficient.

5.) Complete a literature search on patient acuity classification systems. What is the best approach to resolve this issue?

ABSTRACT: The aim of this paper is to defend a broad concept of visual perception, according to which it is a sufficient condition for visual perception that subjects receive visual information in a way which enables them to give reliably correct answers about the objects presented to them. According to this view, blindsight, non-epistemic seeing, and conscious visual experience count as proper types of visual perception. This leads to two consequences concerning the role of the phenomenal qualities of visual experiences. First, phenomenal qualities are not necessary in order to see something, because in the case of blindsight, subjects can see objects without experiences phenomenal

Visual attention is the collective title given to the cognitive mechanisms that allow us to attend some visual stimuli over others, improving processing efficiency (McMains & Kastner, 2009). Here only covert visual attention, i.e. attention without head or eye-movement, will be considered. This is appropriate, since it seems that the primary purpose of eye-movements is to enhance visual acuity (Posner, 1980, p.9), which is not necessary for simple target detection required by the present study. There is a debate concerning the type of information that covert visual attention operates on, specifically if attention is deployed to specific areas in space or to perceptual objects.

The most central part of the macula, the fovea, is formed by 0.35 mmwide depression and represents the retinal region of greatest visual acuity . The fovea has the highest density of cone photoreceptors .The long axons of the foveal cones form Henle’s layer. The central 500 mm of the fovea contains no retinal capillaries (the foveal avascular zone [FAZ]), making the fovea dependent on blood supply from the choriocapillaries.( Curcio CA,1990)

Accommodation is a monocular cue involving the ciliary muscles attached to the lens in each eye which contract to alter the lenses’ shape to enable the eye to focus on nearby objects. This process is achieved when the lens changes its shape. It is the adjustment of the eye in which it enables to keep an object in focus

“Rebalancing binocular vision in amblyopia” by Jian Ding and Dennis M Levi is an important article on how to help correct asymmetric vision in people. Ding and Levi do an extraordinary job of describing the technical science behind amblyopia and introduce a new and innovative technique of an old concept to improve the effectiveness. When humans look at something, they are seeing the image with each eye separately and then those images are sent through signals to the brain where the brain forms them into one cohesive picture that is then interpreted. Each eye sees a slightly different image than the other but then in turn each eye suppresses the other a certain amount in order to see the picture as one whole picture. This type of vision of seeing

Below each histogram are separate charts that depict the amount of time the eye was deprived in each kitten, shown in months but measured in days. The numbers running across the bottoms of both of the (larger) histograms, refer to the ocular dominance groups, which tells us which groups of cells are driven by the contralateral, or the non-deprived eye (in this case, the left), and which are driven by the ipsilateral, or deprived eye (in this case, the right). There are seven ocular dominance groups, and in a typical distribution of subjects without having suffered monocular deprivation, those groups closer to group one are driven by the right eye and those closer to group seven are driven by the left eye, with group four being equally driven by both. The numbers that run up the sides of the histograms refer to the number of cells that are in each ocular dominance group. In Figure 2A, the results were recorded at 31 days of age. They showed to be abnormal, as it was clear that vision was dominant in the left (non-sutured, contralateral) eye was completely normal, while there were signs of fatigue in the right eye (sutured, ipsilateral). This set of results gives the histogram in Figure 2A a skewed appearance, as the cells in

Our eyes are vital organs because they help us visualize our surroundings. But are our eyes perfect in seeing what’s right in front of us? Sadly I learned in our evolution, nature messed up at one point and gave us blind spots in our eyes. This project shows why we have these blind spots, how to discover them, and how big they are. I researched on how our eyes see things; why when one eye is closed, the other eye sometimes can’t see what’s in front of it. I also found during my research a formula that is used to estimate the size of a human eye’s blind spot. I performed an experiment using Blind Spot Test card I made to verify the existence of blind spots in my eyes. I also collected data

This is Jacob Thurston. I don't know if you remember me but I wanted to follow up with you. I understand you are not available to train anyone at this time. However, I would really appreciate if we could be professional acquaintances. To this end, I wanted to share a couple of interesting items I have uncovered during my journey of self education in the Ocularist field which I believe you may appreciate.

Some of the issues that plague individuals with cortical visual impairment are losses within central and/or peripheral vision, inability to perceive depth, sensitivity to light, color or contrast and frustration. Research by Roman, Baker-Nobles, Dutton, Luiselli, Flener, Jan, Lantzy, Matsuba, Mayer, Newcomb, & Nielson states that ‘CVI should be defined, albeit arbitrarily, by a reduction in visual acuity, in the visual fields, or in a child’s ability to see compared to other children of the same age.” (Roman, Baker-Nobles, Dutton, Luiselli, Flener, Jan, Lantzy, Matsuba, Mayer, Newcomb, & Nielson, 2010)

The visual cortex is also referred to as the striate cortex due to the line of Gennari, which is stripes of axons from the lateral geniculate body. These axons are referred to as ocular dominance columns. These columns respond to light input preferentially from one eye over the other eye. These columns are important for binocular vision, or the use of both eyes for vision. This finding and the discovery of ocular dominance columns teaches us that the brain exhibits cortical plasticity, or the ability of the brain to change over the course of an individual's lifetime. It was discovered that monocular deprivation (deprivation of one eye for an extended period of time) resulted in degradation of ocular dominance columns and the non-deprived eye

\Subsubsection{Evaluation Metrics} For the intra-subject experiment, we used the synthetic deformation as the ground truth and measured a rooted mean squared deformation error (RMDE):\mbox{RMDE}=\sqrt{\frac{1}{N_{M_{g}}}\sum_{\boldsymbol{x}\in M_{g}}\left\Vert \boldsymbol{T}_{\mbox{reg}}\left(\boldsymbol{x}\right)-\boldsymbol{T}_{\mbox{known}}\left(\boldsymbol{x}\right)\right\Vert ^{2}}where \boldsymbol{T}_{\mbox{reg}} and \boldsymbol{T}_{\mbox{known}} are the registered and known deformation field, respectively; M_{g} is a mask image derived from the target image g, and N_{M_{g}} is the number of voxels of the foreground region. This metric has the unit of

In 1973, Pinochet led a coup to overthrow Allende’s democratic government and implemented a dictatorship. The consequences of implementing this type of government leads to the creation of a repressive state that turns to violence in order to keep control. In Chile, the state squashed all opposition, which mainly consisted of the left, by killing and disappearing them but most of the time they were exiled. Those who were exiled were automatically labeled as radical exiles who did not let their political situation prevent them from continuing their fight against the repressive state. This characterization of exile is challenged in Roberto Bolaño’s short story, Mauricio (“The Eye”) Silva. The story is about an exile of Chile, Mauricio “The Eye”