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  • cornea
  • The optics of the eye create an image of the visual world on the retina (through the cornea and lens), which serves much the same function as the film in a camera. (wikipedia.org)
  • After the glass was removed by this method and the cornea healed, Fyodorov found that the boy's visual acuity had improved significantly. (wikipedia.org)
  • logMAR
  • Results Experiment 1: The mean age of participants in the adult study was 28.47±7.93 yrs and their mean uncorrected logMAR acuity was 0.9±0.2. (uwaterloo.ca)
  • clinical
  • Currently, the Teller Acuity Cards (TACs) are considered the gold standard for clinical testing and are effective in obtaining a quick estimate of an infant's VA, but they have certain drawbacks. (uwaterloo.ca)
  • stimuli
  • The current study investigates a new method to objectively assess visual acuity in infants, which is uses a video gaze tracker (GT) and computer-generated stimuli, developed in the lab of M. Eizenman at the University of Toronto. (uwaterloo.ca)
  • Objective GT VA was compared with VA measured with subjective responses using the same stimuli and with Teller Acuity Cards (TACs). (uwaterloo.ca)
  • functional
  • The theory (for which empirical support has yet to be developed) states that in each functional module of the visual cortex, Fourier analysis is performed on the receptive field and the neurons in each module are thought to respond selectively to various orientations and frequencies of sine wave gratings. (wikipedia.org)
  • vision
  • Introduction The importance of colour vision cannot be overemphasized and it is hypothesized that colour vision in the visual system evolved as a means of overcoming the extremely unfavourable lighting conditions in the natural environment of early vertebrates (Maximov 2000). (scribd.com)
  • Chart with different orientation of the capital letter 'E' as used to test acuity of distance vision. (sciencephoto.com)
  • Visual acuity is typically measured while fixating, i.e. as a measure of central (or foveal) vision, for the reason that it is highest there. (wikipedia.org)
  • However, acuity in peripheral vision can be of equal (or sometimes higher) importance in everyday life. (wikipedia.org)
  • A reference value above which visual acuity is considered normal is called 6/6 vision, the USC equivalent of which is 20/20 vision: At 6 meters or 20 feet, a human eye with that performance is able to separate contours that are approximately 1.75 mm apart. (wikipedia.org)
  • In the expression 6/x vision, the numerator (6) is the distance in meters between the subject and the chart and the denominator (x) the distance at which a person with 6/6 acuity would discern the same optotype. (wikipedia.org)
  • The latter is the value used in the international definition of visual acuity: Acuity = 1/gap size [arc min] Acuity is a measure of visual performance and does not relate to the eyeglass prescription required to correct vision. (wikipedia.org)
  • Indeed, a subject diagnosed as having 6/6 vision will often actually have higher visual acuity because, once this standard is attained, the subject is considered to have normal (in the sense of undisturbed) vision and smaller optotypes are not tested. (wikipedia.org)
  • Any further reduction in vision acuity is not observed until the individual is between the ages thirty to forty. (wikipedia.org)
  • They provide organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. (wikipedia.org)
  • chart
  • The distance between the person's eyes and the testing chart is set so as to approximate "optical infinity" in the way the lens attempts to focus (far acuity), or at a defined reading distance (near acuity). (wikipedia.org)
  • Visual acuity is measured by the smallest letters that can be distinguished on a chart and is governed by the anatomical spacing of the mosaic of sensory elements on the retina. (wikipedia.org)
  • perception
  • By combining the information received in each eye, binocular summation can improve visual acuity, contrast sensitivity, flicker perception, and brightness perception. (wikipedia.org)
  • Some of the ways in which binocular summation improves binocular visual performance are Brightness perception. (wikipedia.org)
  • In the study of visual perception, sinusoidal gratings are frequently used to probe the capabilities of the visual system. (wikipedia.org)
  • When all of the visual cortex neurons that are influenced by a specific scene respond together, the perception of the scene is created by the summation of the various sine-wave gratings. (wikipedia.org)
  • In relation to this syndrome, the author described, among other disorders, the inverted perception disorder (visual, tactile and auditive) and the multisensory and motor facilitation. (wikipedia.org)
  • This syndrome, caused by a unilateral parietooccipital cortical lesion equidistant from the visual, tactile, and auditory projection areas, is a bilateral, symmetric and multisensory disorder, which presents dynamic phenomena like the disintegration of sensory qualities which are united in normal perception, but which are progressively lost when the intensity of the stimulus decreases, and partially recovered when the stimulus increases or by means of multisensory or motor facilitation. (wikipedia.org)
  • Causes
  • Central serous retinopathy (CSR), also known as central serous chorioretinopathy (CSC or CSCR), is an eye disease which causes visual impairment, often temporary, usually in one eye. (wikipedia.org)
  • observer
  • The experimenter controlled the staircase method and an observer used the objective information of visual fixations using the software to judge if the grating was seen or not. (uwaterloo.ca)
  • cortex
  • In support of this theory is the experimental observation that the visual cortex neurons respond even more robustly to sine-wave gratings that are placed at specific angles in their receptive fields than they do to edges or bars. (wikipedia.org)
  • precise
  • The precise distance at which acuity is measured is not important as long as it is sufficiently far away and the size of the optotype on the retina is the same. (wikipedia.org)
  • An Amsler grid can be useful in documenting the precise area of the visual field involved. (wikipedia.org)
  • optic nerve
  • These are sent to various visual centres of the brain through the fibres of the optic nerve. (wikipedia.org)
  • The optic nerve is a central tract of many axons of ganglion cells connecting primarily to the lateral geniculate body, a visual relay station in the diencephalon (the rear of the forebrain). (wikipedia.org)
  • The visual signals are then transmitted to the brain via the optic nerve. (wikipedia.org)
  • ability
  • The distinction between resolving power or acuity, literally sharpness, which depends on the spacing of the individual receptors through which the outside world is sampled, and the ability to identify individual locations in the sensory space is universal among modalities. (wikipedia.org)
  • limit
  • This defines the resolution limit and the basis of visual acuity. (wikipedia.org)
  • A sophisticated circuitry in the brain identifies the location of a visual feature by assessing the "center of gravity" of the light over several receptors, a task that can be accomplished with much higher precision than the resolution limit set by the receptor spacing. (wikipedia.org)
  • treatment
  • This side effect report can indicate a possible existence of increased vulnerability to Genteal Mild Lubricant Eye Drops (nvo) treatment in female patients suffering from NA, resulting in Visual Acuity Reduced . (patientsville.com)
  • Performance
  • We hypothesize that the performance of specific adaptation and substitution exercises will result in an improvement in visual acuity during head movements while those patients performing placebo exercises will show no improvement. (clinicaltrials.gov)
  • Instead, an eye exam seeks to find the prescription that will provide the best corrected visual performance achievable. (wikipedia.org)
  • Purpose
  • The purpose of this study was to examine the effect of an exercise intervention on visual acuity during head movement in patients with unilateral and bilateral vestibular hypofunction. (clinicaltrials.gov)
  • size
  • The advantage of this arrangement is that the same visual axis is sampled from a larger area of the eye, thereby increasing sensitivity by a factor of seven, without increasing the size of the eye or reducing its acuity. (wikipedia.org)
  • among
  • There was no obvious difference among the mean acuities obtained by 6 objective GT protocols, the subjective GT protocol and the TACs. (uwaterloo.ca)
  • field
  • The examinee's task is to perceive these artificial distortions and mark their locations on the visual field. (wikipedia.org)
  • A blurred or gray spot in the central visual field is common when the retina is detached. (wikipedia.org)
  • loss
  • MacuLogix Inc) can aid in the diagnosis of early-stage, or subclinical, age-related macular degeneration before visual loss occurs and even before structural changes are observed, and adds to the information obtained from retina cameras and OCT imaging. (modernmedicine.com)
  • Diabetes mellitus is a common health problem in developed countries, with diabetic macular oedema (DMO) being a major cause of visual loss. (modernmedicine.com)
  • BCVA
  • Best-corrected visual acuity (BCVA) and central subfield thickness were collected at baseline and at 1-, 2-, 3-, and 6-month follow-up. (unifesp.br)
  • Acuidade visual melhor corrigida (BCVA) e a espessura subcampo central (CST ) foram coletadas no início e em 1, 2, 3 e 6 meses de seguimento. (unifesp.br)
  • Correlations between best-corrected visual acuity (BCVA) or number of IVRs after 12 months and OCT parameters such as external limiting membrane (ELM), ellipsoid zone (EZ), interdigitation zone (IZ), photoreceptor outer segment (PROS) length at first resolution of macular edema (ME) were assessed. (arvojournals.org)
  • patients
  • Twenty-three percent of patients achieved improvements in visual function beyond the MCID threshold and 35% saw improvement beyond the MDC. (beds.ac.uk)
  • Even though antibiotics can have negative impacts on the retina in high concentrations, the facts that visual acuity worsens in 65% of endophthalmitis patients and prognosis gets poorer the longer an infection goes untreated make immediate intervention necessary. (wikipedia.org)
  • symptoms
  • Common symptoms include facial pain , swelling in the buccal region as in our case or in tonsillar fossa (1) or with more specific symptoms according to the extension of the tumor such as proptosis, diplopia and reduced visual acuity in case of orbital extension or nasal congestion and anosmia if extension into nasal cavity or sinuses (2, 4) Treatment is surgical (1, 2, 3, 5). (eurorad.org)
  • Some newcomers will die of the initial infection and many will adapt only partly, with a mix of permanent symptoms such as vastly increased visual acuity along with complete deafness. (wikipedia.org)
  • Results
  • The major disadvantage is the requirement for best corrected visual acuity to be at least 0.8(decimal) to avoid false positive results. (springer.com)
  • Apperceptive visual agnosia results in profound difficulties on a patient's ability to recognize visually presented information. (wikipedia.org)
  • Psychologists and educational specialists working on visual acuity used a tachistoscope to conclude, that with training, an average person could identify minute images flashed on the screen for only one five-hundredth of a second (2 ms). Though the images used were of airplanes, the results had implications for reading. (wikipedia.org)
  • sometimes
  • Because the disalignments are often smaller than the diameter and spacing of retinal receptors, vernier acuity sometimes requires cortical processing aperiphernd "pooling" to detect it. (wikipedia.org)
  • mean
  • The mean pre-operative VF-14 score for the 'all first eyes' group was 86.7 (on a 0-100 scale where 100 is full visual function). (beds.ac.uk)
  • important
  • Given the thresholds for a minimal detectable change (MDC) and a minimal clinically important difference (MCID), do gains in visual function reach the MDC and MCID thresholds? (beds.ac.uk)
  • Health
  • Physical strength, mental acuity, and overall health can begin to deteriorate as a person ages and they may not even be aware it is happening. (wikipedia.org)
  • line
  • For near fixation, the patient should hold an accommodative target (fixation stick) at 33 cm, ensuring it is in line with their visual axis. (wikipedia.org)
  • For example, an audience of customers at a speed reading seminar will be instructed to use a finger or pen to make these shapes on a page and told that this will speed up their visual cortex, increase their visual span to take in the whole line, and even imprint the information into their subconscious for later retrieval. (wikipedia.org)
  • high
  • A plausible explanation for this is the very high levels of pre-operative visual functioning. (beds.ac.uk)
  • With such high levels of visual function, the scope for improvements in functioning is very limited. (beds.ac.uk)
  • found
  • Both in the myopia and control group, no statistically significant inter-ocular differences were found in spherical equivalent and distance corrected visual acuity. (arvojournals.org)
  • months
  • Although used successfully for over a century, PK requires many months of refractive adjustments before the eye achieves visual stability. (meajo.org)
  • At approximately three to twelve months old, it surpasses grating acuity in foveal vision in humans. (wikipedia.org)
  • Page
  • It involves drawing invisible shapes on a page of text in order to broaden the visual span for speed reading. (wikipedia.org)