1873:) or checkerboard patterns (which produce larger responses than stripes). Behavioral responses are not required and brain waves created by the presentation of the patterns are recorded instead. The patterns become finer and finer until the evoked brain wave just disappears, which is considered to be the endpoint measure of visual acuity. In adults and older, verbal children capable of paying attention and following instructions, the endpoint provided by the VEP corresponds very well to the psychophysical measure in the standard measurement (i.e. the perceptual endpoint determined by asking the subject when they can no longer see the pattern). There is an assumption that this correspondence also applies to much younger children and infants, though this does not necessarily have to be the case. Studies do show the evoked brain waves, as well as derived acuities, are very adult-like by one year of age.
46:
1949:, cerebral visual impairments, inability to track fast-moving objects, or one of many other visual impairments and still have "normal" visual acuity. Thus, "normal" visual acuity does not imply normal vision. The reason visual acuity is very widely used is that it is easily measured, its reduction (after correction) often indicates some disturbance, and that it often corresponds with the normal daily activities a person can handle, and evaluates their impairment to do them (even though there is heavy debate over that relationship).
749:. To see detail, two sets of receptors must be intervened by a middle set. The maximum resolution is that 30 seconds of arc, corresponding to the foveal cone diameter or the angle subtended at the nodal point of the eye. To get reception from each cone, as it would be if vision was on a mosaic basis, the "local sign" must be obtained from a single cone via a chain of one bipolar, ganglion, and lateral geniculate cell each. A key factor of obtaining detailed vision, however, is inhibition. This is mediated by neurons such as the
282:
433:
734:
102:
4301:
source has used data from actual vehicle accidents to arrive at a looming threshold – and that value, 0.0275 rad/sec, is an order of magnitude larger than that derived from laboratory studies. In this study, we examine a much broader range of real-world accident data to obtain an estimate of the reasonable upper end of the looming threshold. The results show a range of 0.0397 to 0.0117 rad/sec...
1930:
letter's total size, which in this case would be 1 minute of arc (visual angle). The significance of the 6/6 standard can best be thought of as the lower limit of normal, or as a screening cutoff. When used as a screening test, subjects that reach this level need no further investigation, even though the average visual acuity with a healthy visual system is typically better.
1641:(The results of the Hand Motion test are often recorded without the testing distance. This is due to the fact that this test is performed after the patient cannot "pass" the Counting Fingers test. At this point, the examiner is usually directly in front of the patient, and it is assumed that the Hand Motion test is performed at a testing distance of 1 foot or less.)
341:(x) the distance at which a person with 6/6 acuity would discern the same optotype. Thus, 6/12 means that a person with 6/6 vision would discern the same optotype from 12 metres away (i.e. at twice the distance). This is equivalent to saying that with 6/12 vision, the person possesses half the spatial resolution and needs twice the size to discern the optotype.
730:(the only kind of photoreceptors existing in the fovea's very center of 300 μm diameter), thus having the highest resolution and best color vision. Acuity and color vision, despite being mediated by the same cells, are different physiologic functions that do not interrelate except by position. Acuity and color vision can be affected independently.
2029:(SAVT), and horizontal and vertical motion acuity are limited by lateral motion thresholds. The lateral motion limit is generally below the looming motion limit, and for an object of a given size, lateral motion becomes the more insightful of the two, once the observer moves sufficiently far away from the path of travel. Below these thresholds
1877:
complex behavioral and attentional responses, involving brain areas not directly involved in processing vision, to mature. Thus the visual brain may detect the presence of a finer pattern (reflected in the evoked brain wave), but the "behavioral brain" of a small child may not find it salient enough to pay special attention to.
2728:
and movement orientation, velocity is in terms of the distance units, and zero distance is straight ahead. Far object distances, close set-backs, and low velocities generally lower the salience of lateral motion. Detection with close or null set-back can be accomplished through the pure scale changes
1985:
The smallest detectable visual angle produced by a single fine dark line against a uniformly illuminated background is also much less than foveal cone size or regular visual acuity. In this case, under optimal conditions, the limit is about 0.5 arc seconds or only about 2% of the diameter of a foveal
1542:
number. Using the metre as a unit of measurement, (fractional) visual acuity is expressed relative to 6/6. Otherwise, using the foot, visual acuity is expressed relative to 20/20. For all practical purposes, 20/20 vision is equivalent to 6/6. In the decimal system, acuity is defined as the reciprocal
766:
layer that gives the photoreceptors a "second chance" to absorb the light, thus improving the ability to see in the dark. This is what causes an animal's eyes to seemingly glow in the dark when a light is shone on them. The RPE also has a vital function of recycling the chemicals used by the rods and
753:
and horizontal cells, which functionally render the spread or convergence of signals inactive. This tendency to one-to-one shuttle of signals is powered by brightening of the center and its surroundings, which triggers the inhibition leading to a one-to-one wiring. This scenario, however, is rare, as
178:
to focus light. When the combined refractive power of the cornea and lens is too high for the length of the eye, the retinal image will be in focus in front of the retina and out of focus on the retina, yielding myopia. A similar poorly focused retinal image happens when the combined refractive power
2001:
with the two eyes. For more complex targets, stereoacuity is similar to normal monocular visual acuity, or around 0.6–1.0 arc minutes, but for much simpler targets, such as vertical rods, may be as low as only 2 arc seconds. Although stereoacuity normally corresponds very well with monocular acuity,
1929:
6/6 is the visual acuity needed to discriminate two contours separated by 1 arc minute – 1.75 mm at 6 metres. This is because a 6/6 letter, E for example, has three limbs and two spaces in between them, giving 5 different detailed areas. The ability to resolve this therefore requires 1/5 of the
1925:
eye with correction) is approximately 6/5 to 6/4, so it is inaccurate to refer to 6/6 visual acuity as "perfect" vision. On the contrary, Tscherning writes, "We have found also that the best eyes have a visual acuity which approaches 2, and we can be almost certain that if, with a good illumination,
1838:
The measurement of visual acuity in infants, pre-verbal children and special populations (for instance, disabled individuals) is not always possible with a letter chart. For these populations, specialised testing is necessary. As a basic examination step, one must check whether visual stimuli can be
1809:
Patients who are illiterate in the language whose letters and/or numbers appear on the chart will be registered as having very low visual acuity if this is not known. Some patients will not tell the examiner that they do not know the optotypes, unless asked directly about it. Brain damage can result
1694:
he term "blindness" means central visual acuity of 20/200 or less in the better eye with the use of a correcting lens. An eye that is accompanied by a limitation in the fields of vision such that the widest diameter of the visual field subtends an angle no greater than 20 degrees shall be considered
1570:
presents defects sufficiently pronounced to be easily established." Most observers may have a binocular acuity superior to 6/6; the limit of acuity in the unaided human eye is around 6/3–6/2.4 (20/10–20/8), although 6/3 was the highest score recorded in a study of some US professional athletes. Some
1565:
A visual acuity of 6/6 is frequently described as meaning that a person can see detail from 6 metres (20 ft) away the same as a person with "normal" eyesight would see from 6 metres. If a person has a visual acuity of 6/12, they are said to see detail from 6 metres (20 ft) away the same as
949:
of the light. Thus, black lines on a grating will be mixed with the intervening white lines to make a gray appearance. Defective optical issues (such as uncorrected myopia) can render it worse, but suitable lenses can help. Images (such as gratings) can be sharpened by lateral inhibition, i.e., more
892:
Any pathological process in the visual system, even in older humans beyond the critical period, will often cause decreases in visual acuity. Thus measuring visual acuity is a simple test in accessing the health of the eyes, the visual brain, or pathway to the brain. Any relatively sudden decrease in
1801:
Visual acuity measurement involves more than being able to see the optotypes. The patient should be cooperative, understand the optotypes, be able to communicate with the physician, and many more factors. If any of these factors is missing, then the measurement will not represent the patient's real
757:
Light travels from the fixation object to the fovea through an imaginary path called the visual axis. The eye's tissues and structures that are in the visual axis (and also the tissues adjacent to it) affect the quality of the image. These structures are: tear film, cornea, anterior chamber, pupil,
707:
of the human eye is 28 arc seconds or 0.47 arc minutes; this gives an angular resolution of 0.008 degrees, and at a distance of 1 km corresponds to 136 mm. This is equal to 0.94 arc minutes per line pair (one white and one black line), or 0.016 degrees. For a pixel pair (one white and one
329:
equivalent of which is 20/20 vision: At 6 metres or 20 feet, a human eye with that performance is able to separate contours that are approximately 1.75 mm apart. Vision of 6/12 corresponds to lower performance, while vision of 6/3 to better performance. Normal individuals have an acuity of 6/4
1561:
of the acuity number. The LogMAR scale converts the geometric sequence of a traditional chart to a linear scale. It measures visual acuity loss: positive values indicate vision loss, while negative values denote normal or better visual acuity. This scale is commonly used clinically and in research
785:
If the optics of the eye were otherwise perfect, theoretically, acuity would be limited by pupil diffraction, which would be a diffraction-limited acuity of 0.4 minutes of arc (minarc) or 6/2.6 acuity. The smallest cone cells in the fovea have sizes corresponding to 0.4 minarc of the visual field,
631:
Antonio Medina and
Bradford Howland of the Massachusetts Institute of Technology develop a novel eye testing chart using letters that become invisible with decreasing acuity, rather than blurred as in standard charts. They demonstrate the arbitrary nature of the Snellen fraction and warn about the
415:
seeks to find the prescription that will provide the best corrected visual performance achievable. The resulting acuity may be greater or less than 6/6 = 1.0. Indeed, a subject diagnosed as having 6/6 vision will often actually have higher visual acuity because, once this standard is attained, the
4208:
When an observer moves forward in the environment, the image on his or her retina expands. The rate of this expansion conveys information about the observer's speed and the time to collision... this rate might also be estimated from changes in the size (or scale) of image features... we show, ...
1789:
So, distant visual acuity of 6/10 and 6/8 with pinhole in the right eye will be: DscOD 6/10 PH 6/8. Distant visual acuity of count fingers and 6/17 with pinhole in the left eye will be: DscOS CF PH 6/17. Near visual acuity of 6/8 with pinhole remaining at 6/8 in both eyes with spectacles will be:
1629:
Ability to distinguish whether or not there is movement of the examiner's hand directly in front of the patient's eyes. This test method is only used after a patient shows little or no success with the
Counting Fingers test. The letters HM, and the testing distance, would represent the patient's
1569:
The definition of 6/6 is somewhat arbitrary, since human eyes typically have higher acuity, as
Tscherning writes, "We have found also that the best eyes have a visual acuity which approaches 2, and we can be almost certain that if, with a good illumination, the acuity is only equal to 1, the eye
4300:
A number of laboratory researchers have reported values of the looming threshold to be in the range of 0.003 radian/sec. Forensic practitioners routinely use elevated values of the looming threshold, e.g., 0.005–0.008, to account for the complexity of real-world driving tasks. However, only one
1657:
at the patient's pupil and asks the patient to either point to the light source, or describe the direction that the light is coming from (up, out, straight ahead, down and out, etc.). If the patient is able to perceive light, the letters LP are recorded to represent the patient's acuity. If the
611:(ETDRS). These charts are used in all subsequent clinical studies, and did much to familiarize the profession with the new layout and progression. Data from the ETDRS were used to select letter combinations that give each line the same average difficulty, without using all letters on each line.
513:
oculist, makes improvements to eye chart test types that were developed by
Heinrich Kuechler. He publishes, in German, French, English and other languages, a set of reading samples to document functional vision. He uses fonts that were available in the State Printing House in Vienna in 1854 and
1876:
For reasons not totally understood, until a child is several years old, visual acuities from behavioral preferential looking techniques typically lag behind those determined using the VEP, a direct physiological measure of early visual processing in the brain. Possibly it takes longer for more
1581:
When visual acuity is below the largest optotype on the chart, the reading distance is reduced until the patient can read it. Once the patient is able to read the chart, the letter size and test distance are noted. If the patient is unable to read the chart at any distance, they are tested as
1981:
rather than the retina. Supporting this idea, vernier acuity seems to correspond very closely (and may have the same underlying mechanism) enabling one to discern very slight differences in the orientations of two lines, where orientation is known to be processed in the visual cortex.
774:, visual acuity is affected by the size of the pupil. Optical aberrations of the eye that decrease visual acuity are at a maximum when the pupil is largest (about 8 mm), which occurs in low-light conditions. When the pupil is small (1–2 mm), image sharpness may be limited by
1605:
Ability to count fingers at a given distance. This test method is only used after it has been determined that the patient is not able to make out any of the letters, rings, or images on the acuity chart. The letters CF, and the testing distance, would represent the patient's acuity.
1805:
Visual acuity is a subjective test meaning that if the patient is unwilling or unable to cooperate, the test cannot be done. A patient who is sleepy, intoxicated, or has any disease that can alter their consciousness or mental status, may not achieve their maximum possible acuity.
920:
Though the resolving power depends on the size and packing density of the photoreceptors, the neural system must interpret the receptors' information. As determined from single-cell experiments on the cat and primate, different ganglion cells in the retina are tuned to different
459:
Care must be taken that viewing conditions correspond to the standard, such as correct illumination of the room and the eye chart, correct viewing distance, enough time for responding, error allowance, and so forth. In
European countries, these conditions are standardized by the
1990:
of surrounding cones. The mechanism of detection is the ability to detect such small differences in contrast or illumination, and does not depend on the angular width of the bar, which cannot be discerned. Thus as the line gets finer, it appears to get fainter but not thinner.
830:(unequal refractive error between the two eyes), or covering or patching the eye during medical treatment, will usually result in a severe and permanent decrease in visual acuity and pattern recognition in the affected eye if not treated early in life, a condition known as
416:
subject is considered to have normal (in the sense of undisturbed) vision and smaller optotypes are not tested. Subjects with 6/6 vision or "better" (20/15, 20/10, etc.) may still benefit from an eyeglass correction for other problems related to the visual system, such as
1685:
A person meets the criteria for permanent blindness under section 95 of the Social
Security Act if the corrected visual acuity is less than 6/60 on the Snellen Scale in both eyes or there is a combination of visual defects resulting in the same degree of permanent visual
1904:
Visual acuity depends upon how accurately light is focused on the retina, the integrity of the eye's neural elements, and the interpretative faculty of the brain. "Normal" visual acuity (in central, i.e. foveal vision) is frequently considered to be what was defined by
1888:) as the brain attempts to track the moving stripes. There is a good correspondence between the optokinetic and usual eye-chart acuities in adults. A potentially serious problem with this technique is that the process is reflexive and mediated in the low-level
272:
Visual acuity is a measure of how well small details are resolved in the very center of the visual field; it therefore does not indicate how larger patterns are recognized. Visual acuity alone thus cannot determine the overall quality of visual function.
293:
is a measure of the spatial resolution of the visual processing system. VA, as it is sometimes referred to by optical professionals, is tested by requiring the person whose vision is being tested to identify so-called optotypes – stylized letters,
762:(RPE) is responsible for, among many other things, absorbing light that crosses the retina so it cannot bounce to other parts of the retina. In many vertebrates, such as cats, where high visual acuity is not a priority, there is a reflecting
2190:
711:
6/6 vision is defined as the ability to resolve two points of light separated by a visual angle of one minute of arc, corresponding to 60 PPD, or about 290–350 pixels per inch for a display on a device held 250 to 300 mm from the eye.
834:. The decreased acuity is reflected in various abnormalities in cell properties in the visual cortex. These changes include a marked decrease in the number of cells connected to the affected eye as well as cells connected to both eyes in
817:
Proper development of normal visual acuity depends on a human or an animal having normal visual input when it is very young. Any visual deprivation, that is, anything interfering with such input over a prolonged period of time, such as a
2683:
3898:"SSR 90-5c: Sections 216(i)(1)(B) and 223(c)(1) and (d)(1)(B) of the Social Security Act (42 U.S.C. 416(i)(1)(B) and 423(c)(1) and (d)(1)(B)) Disability insurance benefits – Interpreting the statutory blindness provision"
2353:
1816:
Variables such as pupil size, background adaptation luminance, duration of presentation, type of optotype used, interaction effects from adjacent visual contours (or "crowding") can all affect visual acuity measurement.
2549:
1854:
on one side compared with a blank page on the other side – the bars become progressively finer or closer together, and the endpoint is noted when the child in its adult carer's lap equally prefers the two sides.
865:, where about half of the fibers from each eye cross over to the opposite side and join fibers from the other eye representing the corresponding visual field, the combined nerve fibers from both eyes forming the
3154:
vary quite a bit. The approximate value of 2 degrees is taken from
Strasburger et al. (2011), Table 4. It results from Anstis's (1974) Figure 1, with the foveal value assumed to be the standard 20/20 acuity.
2842:
790:
that bypasses any defects in the eye's optics and projects a pattern of dark and light bands directly on the retina. Laser interferometers are now used routinely in patients with optical problems, such as
1670:
erception) are recorded. A patient with no light perception in one eye is considered blind in the respective eye. If NLP is recorded in both eyes, the patient is described as having total blindness.
1617:(The results of this test, on the same patient, may vary from examiner to examiner. This is due more to the size differences of the various examiners' hands and fingers, than to fluctuating vision.)
950:
highly excited cells inhibiting the less excited cells. A similar reaction is in the case of chromatic aberrations, in which the color fringes around black-and-white objects are inhibited similarly.
1562:
because the lines are of equal length and so it forms a continuous scale with equally spaced intervals between points, unlike
Snellen charts, which have different numbers of letters on each line.
232:
can be of equal importance in everyday life. Acuity declines towards the periphery first steeply and then more gradually, in an inverse-linear fashion (i.e. the decline follows approximately a
2002:
it may be very poor, or absent, even in subjects with normal monocular acuities. Such individuals typically have abnormal visual development when they are very young, such as an alternating
365:
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. That size is specified as a
1957:
Normally, visual acuity refers to the ability to resolve two separated points or lines, but there are other measures of the ability of the visual system to discern spatial differences.
4384:
3624:
2787:
2722:
2446:
2262:
2087:
1977:. Because the limit of vernier acuity is well below that imposed on regular visual acuity by the "retinal grain" or size of the foveal cones, it is thought to be a process of the
715:
Thus, visual acuity, or resolving power (in daylight, central vision), is the property of cones. To resolve detail, the eye's optical system has to project a focused image on the
310:, or other patterns – on a printed chart (or some other means) from a set viewing distance. Optotypes are represented as black symbols against a white background (i.e. at maximum
1681:
Various countries have defined statutory limits for poor visual acuity that qualifies as a disability. For example, in
Australia, the Social Security Act defines blindness as:
179:
of the cornea and lens is too low for the length of the eye except that the focused image is behind the retina, yielding hyperopia. Normal refractive power is referred to as
1850:
cards (presented by a technician from behind a window in the wall) to check whether the child is more visually attentive to a random presentation of vertical or horizontal
3232:
2113:
1653:
Ability to perceive any light. This test method is used only after a patient shows little or no success with the Hand Motion test. In this test, an examiner shines a
933:) is equally important in determining visual acuity. In particular, that size is largest in the fovea's center, and decreases with increasing distance from there.
3164:
Kandel, Himal; Nguyen, Vuong; Piermarocchi, Stefano; Ceklic, Lala; Teo, Kelvin; Arnalich-Montiel, Francisco; Miotto, Stefania; Daien, Vincent; Gillies, Mark C.;
205:
Neural factors that limit acuity are located in the retina, in the pathways to the brain, or in the brain. Examples of conditions affecting the retina include
1637:
would mean that the patient was able to distinguish movement of the examiner's hand from a maximum distance of 2 feet directly in front of the examiner.
2611:
2017:
to calculate a vision performance score (core score). This specific test of visual function has been shown to correlate to professional sports performance.
925:, so some ganglion cells at each location have better acuity than others. Ultimately, however, it appears that the size of a patch of cortical tissue in
782:). Between these extremes is the pupil diameter that is generally best for visual acuity in normal, healthy eyes; this tends to be around 3 or 4 mm.
377:
chart is a visual angle of 5 arc minutes (1 arc min = 1/60 of a degree), which is a 43 point font at 20 feet. By the design of a typical optotype (like a
4371:
3319:
2448:) of horizontal and vertical motion as well. They can be measured and defined by the threshold detection of movement of an object traveling at distance
1973:
acuity is about 8 arc seconds or 0.13 arc minutes, compared to about 0.6 arc minutes (6/4) for normal visual acuity or the 0.4 arc minute diameter of a
134:. Neural factors include the health and functioning of the retina, of the neural pathways to the brain, and of the interpretative faculty of the brain.
1835:'s visual acuity is approximately 6/133, developing to 6/6 well after the age of six months in most children, according to a study published in 2009.
3591:
1884:
drum, where the subject is placed inside the drum and surrounded by rotating black and white stripes. This creates involuntary abrupt eye movements (
941:
Besides the neural connections of the receptors, the optical system is an equally key player in retinal resolution. In the ideal eye, the image of a
2270:
1699:
A person's visual acuity is registered documenting the following: whether the test was for distant or near vision, the eye(s) evaluated and whether
3274:
2980:
Acuity is highest in a tiny area, sometimes called the "foveal bouquet", with a diameter of only 8–16 minutes of arc (see
Strasburger, 2020, p. 10)
2010:
754:
cones may connect to both midget and flat (diffuse) bipolars, and amacrine and horizontal cells can merge messages just as easily as inhibit them.
145:(e.g., "20/20 vision"), which describes someone's ability to recognize small details at a far distance. This ability is compromised in people with
2472:
2009:
Another test, including Visual acuity (EVTS/OptimEyes), uses targets which change in size, contrast, and viewing time. This test was developed by
608:
344:
A simple and efficient way to state acuity is by converting the fraction to a decimal: 6/6 then corresponds to an acuity (or a Visus) of 1.0 (see
3463:
Grimm; Rassow; Wesemann; Saur; Hilz (1994). "Correlation of optotypes with the Landolt Ring – a fresh look at the comparability of optotypes".
814:) is represented by at least 60% of the visual cortex. Many of these neurons are believed to be involved directly in visual acuity processing.
3424:
2053:
angular velocity detection threshold (SAVT) limit of visual acuity. It has a practical value of 0.0275 rad/s. For a person with SAVT limit of
4262:
Only when the subtended angular velocity of the lead vehicle exceeded about 0.003 rad/s were the subjects able to scale the relative velocity
596:
539:
and advocated for standardized vision tests. Snellen's optotypes are not identical to the test letters used today. They were printed in an "
850:(colloquially: "3D vision"). The period of time over which an animal is highly sensitive to such visual deprivation is referred to as the
4381:
3632:
2605:). In application this means that an orthogonally traveling object will not be discernible as moving until it has reached the distance
621:
The International Council of Ophthalmology approves a new "Visual Acuity Measurement Standard", also incorporating the above features.
1917:, that is Snellen's chart 6/6-metre, 20/20 feet, 1.00 decimal or 0.0 logMAR. In young humans, the average visual acuity of a healthy,
2795:
1613:
would mean the patient was able to count the examiner's fingers from a maximum distance of 5 feet directly in front of the examiner.
381:
or a Landolt C), the critical gap that needs to be resolved is 1/5 this value, i.e., 1 arc min. The latter is the value used in the
1813:
A motor inability can make a person respond incorrectly to the optotype shown and negatively affect the visual acuity measurement.
411:
Acuity is a measure of visual performance and does not relate to the eyeglass prescription required to correct vision. Instead, an
2369:
The SAVT has the same kind of importance to driving safety and sports as the static limit. The formula is derived from taking the
166:(ametropia): errors in how the light is refracted in the eye. Causes of refractive errors include aberrations in the shape of the
126:'s ability to recognize small details with precision. Visual acuity depends on optical and neural factors. Optical factors of the
202:). For example, in the case of myopia, the correction is to reduce the power of the eye's refraction by a so-called minus lens.
461:
355:
3250:"Determining the appropriate font size, and use of colour and contrast for underwater displays - for Defence R & D Canada"
155:, which describes someone's ability to recognize small details at a near distance. This ability is compromised in people with
4346:
3969:
3738:
3663:
2965:
4393:
582:
Hugh Taylor uses these design principles for a "Tumbling E Chart" for illiterates, later used to study the visual acuity of
1862:(VEPs or VECPs), which can be used to estimate visual acuity in doubtful cases and expected severe vision loss cases like
1963:
measures the ability to align two line segments. Humans can do this with remarkable accuracy. This success is regarded as
1776:
The abbreviation PH is followed by the visual acuity as measured with a pinhole occluder, which temporarily corrects for
3165:
945:
can subtend 0.5 micrometre on the retina. This is certainly not the case, however, and furthermore the pupil can cause
369:, which is the angle, at the eye, under which the optotype appears. For 6/6 = 1.0 acuity, the size of a letter on the
4362:
2006:, or eye turn, where both eyes rarely, or never, point in the same direction and therefore do not function together.
3851:
1578:, are believed to have an acuity of around 20/2; in this respect, their vision is much better than human eyesight.
498:, Germany. He argues for need to standardize vision tests and produces three reading charts to avoid memorization.
269:
is a constant of approximately 2 degrees. At 2 degrees eccentricity, for example, acuity is half the foveal value.
3881:
1863:
786:
which also places a lower limit on acuity. The optimal acuity of 0.4 minarc or 6/2.6 can be demonstrated using a
1869:
VEP testing of acuity is somewhat similar to preferential looking in using a series of black and white stripes (
632:
accuracy of visual acuity determined by using charts of different letter types, calibrated by Snellen's system.
607:
layout, implemented with Sloan letters, to establish a standardized method of visual acuity measurement for the
217:(caused by the visual brain not having developed properly in early childhood) and by brain damage, such as from
2049:
There is a specific acuity limit in detecting an approaching object's looming motion. This is regarded as the
4368:
4319:. Lippincott Williams & Wilkins. 2004. V.1 C.5, V.1 C.33, V.2 C.2, V.2 C.4, V.5 C.49, V.5 C.51, V.8 C.17.
4087:
Displacement thresholds for peripheral motion were affected by acuity limits for speeds below 0.5 degrees/s.
3326:
326:
221:
or stroke. When optical factors are corrected for, acuity can be considered a measure of neural functioning.
3789:
350:
below), while 6/3 corresponds to 2.0, which is often attained by well-corrected healthy young subjects with
4057:"Spatial and temporal limits of motion perception across variations in speed, eccentricity, and low vision"
1926:
the acuity is only equal to 1, the eye presents defects sufficiently pronounced to be easily established."
1793:"Dynamic visual acuity" defines the ability of the eye to visually discern fine detail in a moving object.
28:
2756:
2691:
2415:
2231:
2056:
559:
introduces the broken ring, now known as the Landolt ring, which later becomes an international standard.
506:
3832:
767:
cones in photon detection. If the RPE is damaged and does not clean up this "shed" blindness can result.
4164:
Schrater PR, Knill DC, Simoncelli EP (12 April 2001). "Perceiving visual expansion without optic flow".
3820:
Physiologic Optics: Dioptrics of the Eye, Functions of the Retina, Ocular Movements and Binocular Vision
2377:
with respect to distance, and then multiplying by velocity to obtain the time rate of visual expansion (
93:
4429:
3731:
The eye of the reader: foveal and peripheral perception – from letter recognition to the joy of reading
878:
759:
3289:
187:, in which contours of a particular orientation are blurred, and more complex corneal irregularities.
4274:
Maddox ME, Kiefer A (September 2012). "Looming Threshold Limits and Their Use in Forensic Practice".
2885:
2363:
2200:
1969:. Under optimal conditions of good illumination, high contrast, and long line segments, the limit to
307:
514:
labels them with the numbers from that printing house catalogue, currently known as Jaeger numbers.
3431:
60:
2906:
2185:{\displaystyle D\lessapprox {\sqrt {{\frac {S\cdot v}{\dot {\theta _{t}}}}-{\frac {S^{2}}{4}}}},}
1859:
3377:
4424:
4414:
3897:
2555:
1558:
930:
600:
354:. Stating acuity as a decimal number is the standard in European countries, as required by the
338:
334:
218:
2724:
for lateral motion is generally ≥ 0.0087 rad/s with probable dependence on deviation from the
3585:
2038:
2034:
1881:
893:
visual acuity is always a cause for concern. Common causes of decreases in visual acuity are
861:
coming out of the back of the eye. The two optic nerves come together behind the eyes at the
745:
The grain of a photographic mosaic has just as limited resolving power as the "grain" of the
583:
314:). The distance between the person's eyes and the testing chart is set so as to approximate "
24:
741:
is at about 15.5° in the outside direction (e.g. in the left visual field for the left eye).
4175:
4117:
3998:
3987:"The Effect of Visual Function on the Batting Performance of Professional Baseball Players"
3985:
Laby, Daniel M.; Kirschen, David G.; Govindarajulu, Usha; DeLand, Paul (14 November 2019).
3354:
Probebuchstaben zur Bestimmung der Sehschärfe [Test letters for measuring visual acuity
2225:
2030:
2014:
1892:, not in the visual cortex. Thus someone can have a normal optokinetic response and yet be
1843:
902:
750:
325:
A reference value above which visual acuity is considered normal is called 6/6 vision, the
210:
3913:"Visual acuity norms in pre-school children: the Multi-Ethnic Pediatric Eye Disease Study"
3116:
Anstis, S. M. (1974). "A chart demonstrating variations in acuity with retinal position".
8:
2931:
2562:
is the ratio of the orthogonal distance to the set-back distance, the angular time rate (
1994:
1810:
in a patient not being able to recognize printed letters, or being unable to spell them.
942:
806:
in the posterior part of the brain responsible for processing visual stimuli, called the
738:
737:
The diagram shows the relative acuity of the human eye on the horizontal meridian. The
233:
4215:
the visual system contains mechanisms that are explicitly sensitive to changes in scale.
4179:
4121:
4002:
3727:
Im Auge des Lesers: foveale und periphere Wahrnehmung – vom Buchstabieren zur Lesefreude
3506:
Wertheim T (1894). "Über die indirekte Sehschärfe" [On indirect visual acuity].
3352:
3078:
491:
444:
procedure and as such relates the physical characteristics of a stimulus to a subject's
4419:
4291:
4228:
Hoffmann ER, Mortimer RG (July 1996). "Scaling of relative velocity between vehicles".
4199:
4143:
4027:
3986:
3937:
3912:
3706:
3702:
3689:Østerberg, G. (1935). "Topography of the layer of rods and cones in the human retina".
3534:
3488:
3379:
Optotypi ad visum determinandum secundum formulam = d/D. Ed. 8, metrico systemate [
3202:
3169:
3016:
2991:
2936:
2901:
1893:
1547:, the orientation of which can be reliably identified. A value of 1.0 is equal to 6/6.
914:
727:
704:
688:
for resolution is large, and acuity small. There are no rods in the very center of the
531:
Probebuchstaben zur Bestimmung der Sehschärfe [Test letters for measuring visual acuity
199:
151:
3754:
Rohrschneider, K. (2004). "Determination of the location of the fovea on the fundus".
3448:
Landolt E (1888). "Méthode optométrique simple" [A simple optometric method].
2678:{\displaystyle D\lessapprox {\sqrt {{\frac {B\cdot v}{{\dot {\theta }}_{t}}}-B^{2}}},}
4342:
4295:
4253:
4245:
4241:
4209:
observers can estimate expansion rates from scale-change information alone, and that
4191:
4135:
4078:
4032:
4014:
3965:
3942:
3771:
3734:
3710:
3659:
3573:
3569:
3538:
3480:
3476:
3268:
3249:
3207:
3189:
3133:
3129:
3083:
3021:
2961:
2921:
1942:
1870:
1851:
1700:
922:
779:
771:
758:
lens, vitreous, and finally the retina. The posterior part of the retina, called the
697:
569:
453:
311:
229:
224:
Visual acuity is typically measured while fixating, i.e. as a measure of central (or
119:
3492:
4283:
4237:
4203:
4183:
4166:
4147:
4125:
4108:
4068:
4022:
4006:
3932:
3924:
3763:
3698:
3565:
3530:
3472:
3197:
3181:
3125:
3073:
3063:
3011:
3003:
2916:
2865:
2738:
1998:
1922:
1918:
1777:
1771:
1695:
for purposes in this paragraph as having a central visual acuity of 20/200 or less.
1554:
870:
847:
843:
351:
228:) vision, for the reason that it is highest in the very center. However, acuity in
163:
80:
4388:
4375:
3928:
3402:
3051:
2880:
2875:
2852:
2725:
2575:
2559:
2025:
The eye has acuity limits for detecting motion. Forward motion is limited by the
1974:
1938:
1535:
886:
851:
803:
763:
716:
685:
661:
657:
653:
645:
225:
206:
66:
3606:
322:
attempts to focus (far acuity), or at a defined reading distance (near acuity).
281:
149:, also known as short-sightedness or near-sightedness. Another visual acuity is
4010:
2264:
can be measured from the distance at which a looming object is first detected:
1960:
1906:
1566:
a person with "normal" eyesight would see it from 12 metres (39 ft) away.
807:
787:
746:
677:
556:
522:
319:
315:
195:
175:
2348:{\displaystyle {\dot {\theta }}_{t}\approx {\frac {4S\cdot v}{S^{2}+4D^{2}}},}
885:, and then to the visual cortex along a collection of nerve fibers called the
4408:
4287:
4249:
4018:
3193:
3007:
2911:
1978:
1970:
1914:
1826:
1520:
1519:
Visual acuity is often measured according to the size of letters viewed on a
926:
835:
827:
799:
681:
672:. Spatial resolution is then much lower. This is due to spatial summation of
441:
378:
370:
51:
2544:{\displaystyle {\dot {\theta }}_{t}\approx {\frac {B\cdot v}{B^{2}+D^{2}}}.}
4195:
4082:
4036:
3946:
3775:
3211:
3087:
3025:
2374:
1934:
1708:
1571:
1550:
862:
689:
604:
366:
259:
105:
4257:
4139:
3577:
3556:
Medina A, Howland B (1988). "A novel high-frequency visual acuity chart".
3542:
3484:
3137:
1880:
A simple but less-used technique is checking oculomotor responses with an
901:, which affect the optical path, diseases that affect the retina, such as
4399:
3767:
3678:
acuity as reciprocal of degrees visual angle, divided by the foveal value
2891:
1965:
946:
866:
858:
775:
184:
74:
2044:
929:
that processes a given location in the visual field (a concept known as
795:, to assess the health of the retina before subjecting them to surgery.
708:
black pixel) this gives a pixel density of 128 pixels per degree (PPD).
535:
In later editions of his book, Snellen called the letters of his charts
337:(6) is the distance in metres between the subject and the chart and the
290:
3715:. Østerberg's figure is reproduced in Strasburger et al. (2011), Fig. 4
3170:"Quality of life impact of eye diseases: a Save Sight Registries study"
2926:
2847:
Radial motion is encountered in clinical and research environments, in
2571:
2370:
2003:
1889:
1543:
value of the size of the gap (measured in arc minutes) of the smallest
917:, and diseases affecting the visual cortex such as tumors and strokes.
839:
823:
568:
Theodor Wertheim in Berlin presents detailed measurements of acuity in
540:
445:
432:
421:
191:
180:
4276:
Proceedings of the Human Factors and Ergonomics Society Annual Meeting
3185:
1690:
In the US, the relevant federal statute defines blindness as follows:
4187:
4130:
4103:
2896:
2050:
1946:
1885:
1654:
1544:
1524:
831:
724:
665:
649:
536:
495:
490:
Vision test types are invented in 1843 by the German ophthalmologist
449:
417:
382:
374:
295:
214:
156:
3833:"Sports Vision Testing: An Innovative Approach To Increase Revenues"
3068:
1783:
PHNI means no improvement of visual acuity using a pinhole occluder.
448:
and their resulting responses. Measurement can be taken by using an
190:
Refractive errors can mostly be corrected by optical means (such as
19:"6/6", "20/20", and "20/20 vision" redirect here. For the date, see
4073:
4056:
2848:
1987:
1910:
1557:) logarithm of the minimum angle of resolution (MAR), which is the
906:
894:
882:
874:
819:
792:
673:
669:
456:, by optical instruments, or by computerized tests like the FrACT.
412:
299:
2870:
2741:
in accordance to its definition, hence the ratio of the velocity
2563:
2362:
term is omitted for small objects relative to great distances by
2199:
term is omitted for small objects relative to great distances by
1832:
1704:
1539:
1528:
733:
693:
526:
303:
101:
45:
4104:"Conjecture on the Visual Estimation of Relative Radial Motion"
3984:
3304:
2837:{\displaystyle {\dot {\theta }}_{t}\lessapprox {\frac {v}{R}}.}
2567:
1858:
Another popular technique is electro-physiologic testing using
898:
811:
810:. The central 10° of field (approximately the extension of the
720:
510:
171:
146:
131:
123:
20:
3163:
2460:
orthogonal to the direction of view, from a set-back distance
2089:, the looming motion of a directly approaching object of size
1721:
N (near) for the evaluation done at 15.7 inches (400 mm).
668:
do not have sufficient sensitivity and vision is subserved by
3450:
Bulletins et Mémoires de la Société Française d'Ophtalmologie
910:
544:
88:
3508:
Zeitschrift für Psychologie und Physiologie der Sinnesorgane
3103:
On differences between peripheral and foveal pattern masking
3049:
909:, diseases affecting the optic pathway to the brain such as
1933:
Some people may have other visual problems, such as severe
1575:
3317:
1718:
D (distant) for the evaluation done at 20 feet (6 m).
1658:
patient is unable to perceive any light, the letters NLP (
3418:
3416:
3233:
Encyclopædia Britannica 2006 Ultimate Reference Suite DVD
465:
359:
167:
127:
4396:
Chapter from the Webvision reference, University of Utah
4055:
Lappin JS, Tadin D, Nyquist JB, Corn AL (January 2009).
3895:
42 U.S.C. § 416(i)(1)(B) (Supp. IV 1986). Cited in
3325:. International Council of Ophthalmology. Archived from
4221:
4163:
3910:
3462:
696:), and highest performance in low light is achieved in
652:
receptor cells which have high spatial density (in the
4054:
3959:
3733:] (in German). Zürich: Transmedia Stäubli Verlag.
3413:
3248:
Morrison, James Barbour , Joanna Zander (April 2008).
2955:
4159:
4157:
3052:"Peripheral vision and pattern recognition: a review"
2798:
2759:
2694:
2614:
2475:
2418:
2273:
2234:
2116:
2059:
2045:
Subtended angular velocity detection threshold (SAVT)
213:. Examples of conditions affecting the brain include
159:, also known as long-sightedness or far-sightedness.
54:
that is frequently used for visual far acuity testing
4211:
pure scale changes can produce motion after-effects.
1986:
cone. This produces a contrast of about 1% with the
183:. Other optical causes of low visual acuity include
1899:
979:
869:. This ultimately forms the physiological basis of
4154:
2836:
2781:
2716:
2677:
2543:
2440:
2347:
2256:
2184:
2081:
1553:is another commonly used scale, expressed as the (
4050:
4048:
4046:
3647:
3045:
3043:
3041:
3039:
3037:
3035:
857:The eye is connected to the visual cortex by the
533:, containing charts for measuring visual acuity.
4406:
4227:
3911:Pan Y, Tarczy-Hornoch K, Cotter SA (June 2009).
3756:Investigative Ophthalmology & Visual Science
3521:Taylor H (1981). "Racial Variations in Vision".
3290:"Software for visual psychophysics: an overview"
330:or better (depending on age and other factors).
3050:Strasburger H, Rentschler I, Jüttner M (2011).
2992:"seven myths on crowding and peripheral vision"
2960:(4th ed.). Boston: Butterworth-Heinemann.
873:. The tracts project to a relay station in the
162:A common optical cause of low visual acuity is
137:The most commonly referred-to visual acuity is
4378:, International Council of Ophthalmology, 1984
4339:Clinical Procedures for the Ocular Examination
4323:
4267:
4043:
3100:
3032:
2027:subtended angular velocity detection threshold
4097:
4095:
3960:Carlson N, Kurtz D, Heath D, Hines C (1990).
3815:
3813:
3753:
3747:
3590:: CS1 maint: DOI inactive as of April 2024 (
3555:
3105:(Thesis). University of California, Berkeley.
1796:
656:) and allow high acuity of 6/6 or better. In
609:Early Treatment of Diabetic Retinopathy Study
4336:
4273:
3830:
3422:
3273:: CS1 maint: multiple names: authors list (
1534:In some countries, acuity is expressed as a
3369:
3344:
3287:
2989:
130:influence the sharpness of an image on its
4101:
4092:
3962:Clinical Procedures for Ocular Examination
3858:. University of Michigan Museum of Zoology
3810:
3382:(8 ed.). London: Williams and Norgate
3318:Visual Functions Committee (25 May 1984).
2956:Cline D, Hofstetter HW, Griffin J (1997).
44:
4129:
4072:
4026:
3936:
3688:
3201:
3174:Clinical & Experimental Ophthalmology
3077:
3067:
3015:
3724:
3653:
3505:
3281:
3247:
3225:
3223:
3221:
1997:is the ability to detect differences in
732:
525:, a Dutch ophthalmologist, publishes in
431:
280:
100:
4400:The Freiburg Visual Acuity Test (FrACT)
4326:Таблица для исследования остроты зрения
3447:
3400:
3375:
3350:
2101:, is not detectable until its distance
306:, standardized Cyrillic letters in the
4407:
3849:
3658:. New York: Plenum Press. p. 28.
3520:
3115:
2206:To exceed the SAVT, an object of size
2033:is experienced in accordance with the
1820:
1523:or the size of other symbols, such as
3964:. Norwalk, CT: Appleton & Lange.
3296:
3218:
3109:
676:, i.e. a number of rods merge into a
4330:Table for the study of visual acuity
3320:"Visual acuity measurement standard"
3302:
3240:
2983:
2949:
2782:{\displaystyle {\dot {\theta }}_{t}}
2717:{\displaystyle {\dot {\theta }}_{t}}
2441:{\displaystyle {\dot {\theta }}_{t}}
2257:{\displaystyle {\dot {\theta }}_{t}}
2082:{\displaystyle {\dot {\theta }}_{t}}
1896:with no conscious visual sensation.
1752:Usage of spectacles during the test
1676:
436:Manual hand eye test in Ghana (2018)
118:) commonly refers to the clarity of
3831:Kirschen DG, Laby DM (1 May 2006).
3604:
1860:visual evoked (cortical) potentials
13:
4369:Visual Acuity Measurement Standard
4332:] (in Russian) (3rd ed.).
4309:
4230:Accident Analysis & Prevention
3703:10.1111/j.1755-3768.1935.tb04723.x
3535:10.1093/oxfordjournals.aje.a113067
3425:"Measuring Vision and Vision Loss"
2570:) of lateral motion is simply the
936:
333:In the expression 6/x vision, the
14:
4441:
4356:
4102:Weinberger H (19 February 1971).
3305:"The Freiburg Visual Acuity Test"
2407:
1952:
285:Eye examination for visual acuity
4213:These two findings suggest that
3625:"Visual Acuity of the Human Eye"
3477:10.1097/00006324-199401000-00002
2737:The motion acuity limit affects
2732:
2020:
1839:fixated, centered and followed.
4324:Golovin SS, Sivtsev DA (1927).
3978:
3953:
3904:
3889:
3870:
3843:
3824:
3782:
3718:
3681:
3672:
3617:
3598:
3549:
3514:
3499:
3456:
3441:
3394:
3311:
1909:as the ability to recognize an
440:Visual acuity is measured by a
345:
236:). The decline is according to
4382:Visual Acuity of the Human Eye
4317:Duane's Clinical Ophthalmology
3357:. Utrecht: P. W. Van De Weijer
3157:
3144:
3094:
2974:
1780:such as myopia or astigmatism.
723:having the highest density of
427:
1:
4363:How Visual Acuity is Measured
4341:(3rd ed.). McGraw Hill.
2943:
953:
639:
276:
174:, and reduced ability of the
4242:10.1016/0001-4575(96)00005-X
3929:10.1097/OPX.0b013e3181a76e55
3607:"The Limits of Human Vision"
3570:10.1016/0275-5408(88)90083-x
3465:Optometry and Vision Science
3401:Enerson, Ole Daniel (2017).
3130:10.1016/0042-6989(74)90049-2
2958:Dictionary of Visual Science
2578:multiplied by the velocity (
1864:Leber's congenital amaurosis
29:2020 Vision (disambiguation)
7:
2888:, for testing visual acuity
2858:
1633:For example, the recording
1609:For example, the recording
778:of light by the pupil (see
122:, but technically rates an
10:
4446:
4011:10.1038/s41598-019-52546-2
1842:More formal testing using
1824:
1797:Measurement considerations
879:lateral geniculate nucleus
760:retinal pigment epithelium
680:, in turn connecting to a
543:Paragon" font (i.e. using
471:
304:symbols for the illiterate
18:
3572:(inactive 8 April 2024).
3510:(in German) (7): 172–187.
3452:(in French) (6): 213–214.
3101:Barghout-Stein L (1999).
2412:There are acuity limits (
2364:small-angle approximation
2228:is experienced. The SAVT
2201:small-angle approximation
2013:with colleagues and uses
838:, resulting in a loss of
507:Eduard Jäger von Jaxtthal
464:(EN ISO 8596, previously
358:(EN ISO 8596, previously
87:
73:
59:
43:
38:
4387:6 September 2012 at the
4288:10.1177/1071181312561146
3886:as at 20 September 2011.
3654:Ali MA, Klyne M (1985).
3376:Snellen, Herman (1885).
3351:Snellen, Herman (1862).
3008:10.1177/2041669520913052
2990:Strasburger, H. (2020).
2224:; beyond that distance,
1715:Distance from the chart
383:international definition
4337:Carlson; Kurtz (2004).
3882:"Table 13, Schedule 1B"
3423:Colenbrander A (2001).
2907:Pediatric ophthalmology
3790:"Contrast sensitivity"
3558:Ophthalmic Physiol Opt
3288:Strasburger H (2014).
2838:
2783:
2718:
2679:
2545:
2442:
2349:
2258:
2186:
2083:
1900:"Normal" visual acuity
1697:
1688:
931:cortical magnification
742:
719:, a region inside the
698:near peripheral vision
644:Daylight vision (i.e.
601:National Eye Institute
584:Australian Aboriginals
437:
420:, ocular injuries, or
286:
219:traumatic brain injury
108:
23:. For other uses, see
3852:"Family Accipitridae"
3837:Optometric Management
3656:Vision in Vertebrates
2886:Golovin–Sivtsev table
2839:
2784:
2719:
2680:
2546:
2443:
2350:
2259:
2187:
2095:, moving at velocity
2084:
1882:optokinetic nystagmus
1766:) without correctors.
1692:
1683:
959:Visual acuity scales
822:, severe eye turn or
736:
435:
308:Golovin–Sivtsev table
284:
104:
25:2020 (disambiguation)
4365:at Prevent Blindness
3856:Animal Diversity Web
3768:10.1167/iovs.03-1157
3725:Hunziker HW (2006).
3697:(Suppl. 6): 11–103.
3691:Acta Ophthalmologica
3292:. VisionScience.com.
3166:Watson, Stephanie L.
2796:
2757:
2692:
2612:
2473:
2416:
2271:
2232:
2226:subjective constancy
2218:must be closer than
2114:
2057:
2031:subjective constancy
2015:item response theory
1913:when it subtended 5
1844:preferential looking
1733:) for the right eye.
903:macular degeneration
788:laser interferometer
684:, and the resulting
260:degrees visual angle
211:macular degeneration
106:LogMAR – ETDRS Chart
4180:2001Natur.410..816S
4122:1971Natur.229..562W
4003:2019NatSR...916847L
3877:Social Security Act
3687:Original figure in
3635:on 6 September 2012
3629:NDT Resource Center
3437:on 4 December 2014.
2729:of looming motion.
2212:moving as velocity
1995:Stereoscopic acuity
1821:Testing in children
1740:) for the left eye.
1538:, and in some as a
960:
943:diffraction grating
923:spatial frequencies
802:is the part of the
728:photoreceptor cells
258:is eccentricity in
4374:7 May 2021 at the
3991:Scientific Reports
3900:. 9 November 1990.
3246:Table 3, page 20,
2937:Near visual acuity
2902:Optical resolution
2834:
2779:
2714:
2675:
2541:
2438:
2345:
2254:
2182:
2079:
2035:Stevens' power law
1871:sine wave gratings
1790:NccOU 6/8 PH 6/8.
1759:) with correctors.
958:
915:multiple sclerosis
743:
705:angular resolution
648:) is subserved by
438:
385:of visual acuity:
287:
200:refractive surgery
109:
4430:Visual perception
4348:978-0-07-137078-3
4174:(6830): 816–819.
4061:Journal of Vision
3971:978-0-07-184920-3
3740:978-3-7266-0068-6
3665:978-0-306-42065-8
3186:10.1111/ceo.14050
3056:Journal of Vision
2967:978-0-7506-9895-5
2922:Retinal summation
2829:
2809:
2770:
2705:
2670:
2655:
2646:
2536:
2486:
2466:with the formula
2429:
2340:
2284:
2245:
2177:
2175:
2155:
2153:
2070:
2039:Weber–Fechner law
1778:refractive errors
1701:corrective lenses
1677:Legal definitions
1674:
1673:
1647:Light Perception
1599:Counting Fingers
1517:
1516:
780:diffraction limit
772:photographic lens
637:
636:
570:peripheral vision
492:Heinrich Kuechler
454:Ferdinand Monoyer
318:" in the way the
300:pediatric symbols
230:peripheral vision
99:
98:
16:Clarity of vision
4437:
4352:
4333:
4320:
4304:
4303:
4271:
4265:
4264:
4225:
4219:
4218:
4188:10.1038/35071075
4161:
4152:
4151:
4133:
4131:10.1038/229562a0
4099:
4090:
4089:
4076:
4052:
4041:
4040:
4030:
3982:
3976:
3975:
3957:
3951:
3950:
3940:
3908:
3902:
3901:
3893:
3887:
3885:
3874:
3868:
3867:
3865:
3863:
3847:
3841:
3840:
3828:
3822:
3817:
3808:
3807:
3805:
3803:
3794:
3786:
3780:
3779:
3762:(9): 3257–3258.
3751:
3745:
3744:
3722:
3716:
3714:
3685:
3679:
3676:
3670:
3669:
3651:
3645:
3644:
3642:
3640:
3631:. Archived from
3621:
3615:
3613:
3611:
3602:
3596:
3595:
3589:
3581:
3553:
3547:
3546:
3523:Am. J. Epidemiol
3518:
3512:
3511:
3503:
3497:
3496:
3460:
3454:
3453:
3445:
3439:
3438:
3436:
3430:. Archived from
3429:
3420:
3411:
3410:
3403:"Herman Snellen"
3398:
3392:
3391:
3389:
3387:
3373:
3367:
3366:
3364:
3362:
3348:
3342:
3341:
3339:
3337:
3331:
3324:
3315:
3309:
3308:
3300:
3294:
3293:
3285:
3279:
3278:
3272:
3264:
3262:
3260:
3244:
3238:
3237:
3227:
3216:
3215:
3205:
3161:
3155:
3148:
3142:
3141:
3113:
3107:
3106:
3098:
3092:
3091:
3081:
3071:
3047:
3030:
3029:
3019:
2987:
2981:
2978:
2972:
2971:
2953:
2932:Troxler's fading
2917:Refractive error
2866:Angular diameter
2843:
2841:
2840:
2835:
2830:
2822:
2817:
2816:
2811:
2810:
2802:
2788:
2786:
2785:
2780:
2778:
2777:
2772:
2771:
2763:
2752:
2746:
2723:
2721:
2720:
2715:
2713:
2712:
2707:
2706:
2698:
2684:
2682:
2681:
2676:
2671:
2669:
2668:
2656:
2654:
2653:
2648:
2647:
2639:
2635:
2624:
2622:
2604:
2550:
2548:
2547:
2542:
2537:
2535:
2534:
2533:
2521:
2520:
2510:
2499:
2494:
2493:
2488:
2487:
2479:
2465:
2459:
2453:
2447:
2445:
2444:
2439:
2437:
2436:
2431:
2430:
2422:
2403:
2361:
2354:
2352:
2351:
2346:
2341:
2339:
2338:
2337:
2322:
2321:
2311:
2297:
2292:
2291:
2286:
2285:
2277:
2263:
2261:
2260:
2255:
2253:
2252:
2247:
2246:
2238:
2223:
2217:
2211:
2198:
2191:
2189:
2188:
2183:
2178:
2176:
2171:
2170:
2161:
2156:
2154:
2149:
2148:
2139:
2137:
2126:
2124:
2106:
2100:
2094:
2088:
2086:
2085:
2080:
2078:
2077:
2072:
2071:
2063:
1894:cortically blind
1772:Pinhole occluder
1747:) for both eyes.
1585:
1584:
981:
961:
957:
871:binocular vision
848:binocular vision
844:depth perception
836:cortical area V1
494:(1811–1873), in
476:
475:
407:
405:
403:
402:
399:
396:
352:binocular vision
316:optical infinity
164:refractive error
83:
69:
48:
36:
35:
4445:
4444:
4440:
4439:
4438:
4436:
4435:
4434:
4405:
4404:
4389:Wayback Machine
4376:Wayback Machine
4359:
4349:
4315:
4312:
4310:Further reading
4307:
4272:
4268:
4226:
4222:
4162:
4155:
4100:
4093:
4067:(30): 30.1–14.
4053:
4044:
3983:
3979:
3972:
3958:
3954:
3909:
3905:
3896:
3894:
3890:
3880:
3875:
3871:
3861:
3859:
3848:
3844:
3829:
3825:
3818:
3811:
3801:
3799:
3792:
3788:
3787:
3783:
3752:
3748:
3741:
3723:
3719:
3686:
3682:
3677:
3673:
3666:
3652:
3648:
3638:
3636:
3623:
3622:
3618:
3609:
3603:
3599:
3583:
3582:
3554:
3550:
3519:
3515:
3504:
3500:
3461:
3457:
3446:
3442:
3434:
3427:
3421:
3414:
3399:
3395:
3385:
3383:
3374:
3370:
3360:
3358:
3349:
3345:
3335:
3333:
3329:
3322:
3316:
3312:
3303:Bach M (2016).
3301:
3297:
3286:
3282:
3266:
3265:
3258:
3256:
3245:
3241:
3229:
3228:
3219:
3162:
3158:
3153:
3149:
3145:
3118:Vision Research
3114:
3110:
3099:
3095:
3069:10.1167/11.5.13
3062:(5): 13, 1–82.
3048:
3033:
2988:
2984:
2979:
2975:
2968:
2954:
2950:
2946:
2941:
2881:Fovea centralis
2876:Eye examination
2861:
2853:virtual-reality
2821:
2812:
2801:
2800:
2799:
2797:
2794:
2793:
2773:
2762:
2761:
2760:
2758:
2755:
2754:
2751:
2748:
2745:
2742:
2735:
2708:
2697:
2696:
2695:
2693:
2690:
2689:
2664:
2660:
2649:
2638:
2637:
2636:
2625:
2623:
2621:
2613:
2610:
2609:
2603:
2599:
2595:
2591:
2587:
2583:
2579:
2576:inverse tangent
2560:subtended angle
2529:
2525:
2516:
2512:
2511:
2500:
2498:
2489:
2478:
2477:
2476:
2474:
2471:
2470:
2464:
2461:
2458:
2455:
2452:
2449:
2432:
2421:
2420:
2419:
2417:
2414:
2413:
2410:
2402:
2398:
2394:
2390:
2386:
2382:
2378:
2359:
2333:
2329:
2317:
2313:
2312:
2298:
2296:
2287:
2276:
2275:
2274:
2272:
2269:
2268:
2248:
2237:
2236:
2235:
2233:
2230:
2229:
2222:
2219:
2216:
2213:
2210:
2207:
2196:
2166:
2162:
2160:
2144:
2140:
2138:
2127:
2125:
2123:
2115:
2112:
2111:
2105:
2102:
2099:
2096:
2093:
2090:
2073:
2062:
2061:
2060:
2058:
2055:
2054:
2047:
2023:
1955:
1939:color blindness
1902:
1846:techniques use
1829:
1823:
1802:visual acuity.
1799:
1764:sine correctore
1738:oculus sinister
1679:
1536:vulgar fraction
956:
939:
937:Optical aspects
887:optic radiation
852:critical period
804:cerebral cortex
662:scotopic vision
646:photopic vision
642:
474:
430:
400:
397:
394:
393:
391:
389:
279:
268:
249:
242:
207:detached retina
139:distance acuity
79:
65:
55:
32:
17:
12:
11:
5:
4443:
4433:
4432:
4427:
4422:
4417:
4403:
4402:
4397:
4391:
4379:
4366:
4358:
4357:External links
4355:
4354:
4353:
4347:
4334:
4321:
4311:
4308:
4306:
4305:
4282:(1): 700–704.
4266:
4236:(4): 415–421.
4220:
4153:
4091:
4074:10.1167/9.1.30
4042:
3977:
3970:
3952:
3903:
3888:
3869:
3850:Kirschbaum K.
3842:
3823:
3809:
3781:
3746:
3739:
3717:
3680:
3671:
3664:
3646:
3616:
3597:
3548:
3513:
3498:
3455:
3440:
3412:
3393:
3368:
3343:
3310:
3295:
3280:
3239:
3230:"eye, human".
3217:
3180:(4): 386–397.
3156:
3151:
3150:Estimates of E
3143:
3124:(7): 589–592.
3108:
3093:
3031:
2982:
2973:
2966:
2947:
2945:
2942:
2940:
2939:
2934:
2929:
2924:
2919:
2914:
2909:
2904:
2899:
2894:
2889:
2883:
2878:
2873:
2868:
2862:
2860:
2857:
2845:
2844:
2833:
2828:
2825:
2820:
2815:
2808:
2805:
2776:
2769:
2766:
2749:
2747:to the radius
2743:
2734:
2731:
2711:
2704:
2701:
2686:
2685:
2674:
2667:
2663:
2659:
2652:
2645:
2642:
2634:
2631:
2628:
2620:
2617:
2601:
2597:
2593:
2589:
2585:
2581:
2552:
2551:
2540:
2532:
2528:
2524:
2519:
2515:
2509:
2506:
2503:
2497:
2492:
2485:
2482:
2462:
2456:
2450:
2435:
2428:
2425:
2409:
2408:Lateral motion
2406:
2400:
2396:
2392:
2388:
2384:
2380:
2356:
2355:
2344:
2336:
2332:
2328:
2325:
2320:
2316:
2310:
2307:
2304:
2301:
2295:
2290:
2283:
2280:
2251:
2244:
2241:
2220:
2214:
2208:
2193:
2192:
2181:
2174:
2169:
2165:
2159:
2152:
2147:
2143:
2136:
2133:
2130:
2122:
2119:
2103:
2097:
2091:
2076:
2069:
2066:
2046:
2043:
2022:
2019:
2011:Daniel M. Laby
1961:Vernier acuity
1954:
1953:Other measures
1951:
1915:minutes of arc
1907:Herman Snellen
1901:
1898:
1825:Main article:
1822:
1819:
1798:
1795:
1787:
1786:
1785:
1784:
1781:
1769:
1768:
1767:
1760:
1757:cum correctore
1750:
1749:
1748:
1741:
1734:
1726:Eye evaluated
1724:
1723:
1722:
1719:
1709:contact lenses
1678:
1675:
1672:
1671:
1651:
1648:
1644:
1643:
1627:
1624:
1620:
1619:
1603:
1600:
1596:
1595:
1592:
1589:
1515:
1514:
1511:
1508:
1505:
1502:
1499:
1496:
1492:
1491:
1488:
1485:
1482:
1479:
1476:
1473:
1469:
1468:
1465:
1462:
1459:
1456:
1453:
1450:
1446:
1445:
1442:
1439:
1436:
1433:
1430:
1427:
1423:
1422:
1419:
1416:
1413:
1410:
1407:
1404:
1400:
1399:
1396:
1393:
1390:
1387:
1384:
1381:
1377:
1376:
1373:
1370:
1367:
1364:
1361:
1358:
1354:
1353:
1350:
1347:
1344:
1341:
1338:
1335:
1331:
1330:
1327:
1324:
1321:
1318:
1315:
1312:
1308:
1307:
1304:
1301:
1298:
1295:
1292:
1289:
1285:
1284:
1281:
1278:
1275:
1272:
1269:
1266:
1262:
1261:
1258:
1255:
1252:
1249:
1246:
1243:
1239:
1238:
1235:
1232:
1229:
1226:
1223:
1220:
1216:
1215:
1212:
1209:
1206:
1203:
1200:
1197:
1193:
1192:
1189:
1186:
1183:
1180:
1177:
1174:
1170:
1169:
1166:
1163:
1160:
1157:
1154:
1151:
1147:
1146:
1143:
1140:
1137:
1134:
1131:
1128:
1124:
1123:
1120:
1117:
1114:
1111:
1108:
1105:
1101:
1100:
1097:
1094:
1091:
1088:
1085:
1082:
1078:
1077:
1074:
1071:
1068:
1065:
1062:
1059:
1055:
1054:
1051:
1048:
1045:
1042:
1039:
1036:
1032:
1031:
1028:
1025:
1022:
1019:
1016:
1013:
1009:
1008:
1005:
1002:
999:
996:
993:
990:
986:
985:
982:
977:
974:
971:
968:
965:
955:
952:
938:
935:
927:visual area V1
881:, part of the
808:occipital lobe
747:retinal mosaic
641:
638:
635:
634:
628:
624:
623:
618:
614:
613:
599:et al. of the
593:
589:
588:
579:
575:
574:
565:
561:
560:
557:Edmund Landolt
554:
550:
549:
523:Herman Snellen
520:
516:
515:
504:
500:
499:
488:
484:
483:
480:
473:
470:
442:psychophysical
429:
426:
409:
408:
278:
275:
266:
247:
240:
196:contact lenses
97:
96:
91:
85:
84:
77:
71:
70:
63:
57:
56:
49:
41:
40:
15:
9:
6:
4:
3:
2:
4442:
4431:
4428:
4426:
4425:Medical signs
4423:
4421:
4418:
4416:
4415:Ophthalmology
4413:
4412:
4410:
4401:
4398:
4395:
4394:Visual Acuity
4392:
4390:
4386:
4383:
4380:
4377:
4373:
4370:
4367:
4364:
4361:
4360:
4350:
4344:
4340:
4335:
4331:
4327:
4322:
4318:
4314:
4313:
4302:
4297:
4293:
4289:
4285:
4281:
4277:
4270:
4263:
4259:
4255:
4251:
4247:
4243:
4239:
4235:
4231:
4224:
4217:
4216:
4212:
4205:
4201:
4197:
4193:
4189:
4185:
4181:
4177:
4173:
4169:
4168:
4160:
4158:
4149:
4145:
4141:
4137:
4132:
4127:
4123:
4119:
4116:(5286): 562.
4115:
4111:
4110:
4105:
4098:
4096:
4088:
4084:
4080:
4075:
4070:
4066:
4062:
4058:
4051:
4049:
4047:
4038:
4034:
4029:
4024:
4020:
4016:
4012:
4008:
4004:
4000:
3996:
3992:
3988:
3981:
3973:
3967:
3963:
3956:
3948:
3944:
3939:
3934:
3930:
3926:
3923:(6): 607–12.
3922:
3918:
3917:Optom Vis Sci
3914:
3907:
3899:
3892:
3883:
3878:
3873:
3857:
3853:
3846:
3838:
3834:
3827:
3821:
3816:
3814:
3798:
3791:
3785:
3777:
3773:
3769:
3765:
3761:
3757:
3750:
3742:
3736:
3732:
3728:
3721:
3712:
3708:
3704:
3700:
3696:
3692:
3684:
3675:
3667:
3661:
3657:
3650:
3634:
3630:
3626:
3620:
3608:
3601:
3593:
3587:
3579:
3575:
3571:
3567:
3563:
3559:
3552:
3544:
3540:
3536:
3532:
3528:
3524:
3517:
3509:
3502:
3494:
3490:
3486:
3482:
3478:
3474:
3470:
3466:
3459:
3451:
3444:
3433:
3426:
3419:
3417:
3408:
3404:
3397:
3381:
3380:
3372:
3356:
3355:
3347:
3332:on 7 May 2021
3328:
3321:
3314:
3306:
3299:
3291:
3284:
3276:
3270:
3255:
3251:
3243:
3235:
3234:
3226:
3224:
3222:
3213:
3209:
3204:
3199:
3195:
3191:
3187:
3183:
3179:
3175:
3171:
3167:
3160:
3147:
3139:
3135:
3131:
3127:
3123:
3119:
3112:
3104:
3097:
3089:
3085:
3080:
3075:
3070:
3065:
3061:
3057:
3053:
3046:
3044:
3042:
3040:
3038:
3036:
3027:
3023:
3018:
3013:
3009:
3005:
3001:
2997:
2993:
2986:
2977:
2969:
2963:
2959:
2952:
2948:
2938:
2935:
2933:
2930:
2928:
2925:
2923:
2920:
2918:
2915:
2913:
2912:Psychophysics
2910:
2908:
2905:
2903:
2900:
2898:
2895:
2893:
2890:
2887:
2884:
2882:
2879:
2877:
2874:
2872:
2869:
2867:
2864:
2863:
2856:
2854:
2850:
2849:dome theaters
2831:
2826:
2823:
2818:
2813:
2806:
2803:
2792:
2791:
2790:
2774:
2767:
2764:
2740:
2739:radial motion
2733:Radial motion
2730:
2727:
2709:
2702:
2699:
2672:
2665:
2661:
2657:
2650:
2643:
2640:
2632:
2629:
2626:
2618:
2615:
2608:
2607:
2606:
2577:
2573:
2569:
2565:
2561:
2557:
2538:
2530:
2526:
2522:
2517:
2513:
2507:
2504:
2501:
2495:
2490:
2483:
2480:
2469:
2468:
2467:
2454:and velocity
2433:
2426:
2423:
2405:
2376:
2372:
2367:
2365:
2342:
2334:
2330:
2326:
2323:
2318:
2314:
2308:
2305:
2302:
2299:
2293:
2288:
2281:
2278:
2267:
2266:
2265:
2249:
2242:
2239:
2227:
2204:
2202:
2179:
2172:
2167:
2163:
2157:
2150:
2145:
2141:
2134:
2131:
2128:
2120:
2117:
2110:
2109:
2108:
2074:
2067:
2064:
2052:
2042:
2040:
2036:
2032:
2028:
2021:Motion acuity
2018:
2016:
2012:
2007:
2005:
2000:
1996:
1992:
1989:
1983:
1980:
1979:visual cortex
1976:
1972:
1968:
1967:
1962:
1958:
1950:
1948:
1944:
1940:
1936:
1931:
1927:
1924:
1920:
1916:
1912:
1908:
1897:
1895:
1891:
1887:
1883:
1878:
1874:
1872:
1867:
1865:
1861:
1856:
1853:
1849:
1848:Teller acuity
1845:
1840:
1836:
1834:
1828:
1827:Infant vision
1818:
1814:
1811:
1807:
1803:
1794:
1791:
1782:
1779:
1775:
1774:
1773:
1770:
1765:
1761:
1758:
1754:
1753:
1751:
1746:
1745:oculi uterque
1742:
1739:
1735:
1732:
1731:oculus dexter
1728:
1727:
1725:
1720:
1717:
1716:
1714:
1713:
1712:
1711:) were used:
1710:
1706:
1702:
1696:
1691:
1687:
1682:
1669:
1665:
1661:
1656:
1652:
1649:
1646:
1645:
1642:
1639:
1638:
1636:
1628:
1625:
1622:
1621:
1618:
1615:
1614:
1612:
1604:
1601:
1598:
1597:
1593:
1591:Abbreviation
1590:
1587:
1586:
1583:
1579:
1577:
1573:
1572:birds of prey
1567:
1563:
1560:
1556:
1552:
1548:
1546:
1541:
1537:
1532:
1530:
1526:
1522:
1521:Snellen chart
1512:
1509:
1506:
1503:
1500:
1497:
1494:
1493:
1489:
1486:
1483:
1480:
1477:
1474:
1471:
1470:
1466:
1463:
1460:
1457:
1454:
1451:
1448:
1447:
1443:
1440:
1437:
1434:
1431:
1428:
1425:
1424:
1420:
1417:
1414:
1411:
1408:
1405:
1402:
1401:
1397:
1394:
1391:
1388:
1385:
1382:
1379:
1378:
1374:
1371:
1368:
1365:
1362:
1359:
1356:
1355:
1351:
1348:
1345:
1342:
1339:
1336:
1333:
1332:
1328:
1325:
1322:
1319:
1316:
1313:
1310:
1309:
1305:
1302:
1299:
1296:
1293:
1290:
1287:
1286:
1282:
1279:
1276:
1273:
1270:
1267:
1264:
1263:
1259:
1256:
1253:
1250:
1247:
1244:
1241:
1240:
1236:
1233:
1230:
1227:
1224:
1221:
1218:
1217:
1213:
1210:
1207:
1204:
1201:
1198:
1195:
1194:
1190:
1187:
1184:
1181:
1178:
1175:
1172:
1171:
1167:
1164:
1161:
1158:
1155:
1152:
1149:
1148:
1144:
1141:
1138:
1135:
1132:
1129:
1126:
1125:
1121:
1118:
1115:
1112:
1109:
1106:
1103:
1102:
1098:
1095:
1092:
1089:
1086:
1083:
1080:
1079:
1075:
1072:
1069:
1066:
1063:
1060:
1057:
1056:
1052:
1049:
1046:
1043:
1040:
1037:
1034:
1033:
1029:
1026:
1023:
1020:
1017:
1014:
1011:
1010:
1006:
1003:
1000:
997:
994:
991:
988:
987:
983:
978:
975:
972:
969:
966:
963:
962:
951:
948:
944:
934:
932:
928:
924:
918:
916:
912:
908:
904:
900:
896:
890:
888:
884:
880:
876:
872:
868:
864:
860:
855:
853:
849:
845:
841:
837:
833:
829:
828:anisometropia
825:
821:
815:
813:
809:
805:
801:
800:visual cortex
796:
794:
789:
783:
781:
777:
773:
768:
765:
761:
755:
752:
748:
740:
735:
731:
729:
726:
722:
718:
713:
709:
706:
701:
699:
695:
691:
687:
683:
682:ganglion cell
679:
675:
671:
667:
663:
659:
655:
654:central fovea
651:
647:
633:
629:
626:
625:
622:
619:
616:
615:
612:
610:
606:
602:
598:
594:
591:
590:
587:
585:
580:
577:
576:
573:
571:
566:
563:
562:
558:
555:
552:
551:
548:
546:
542:
538:
532:
528:
524:
521:
518:
517:
512:
508:
505:
502:
501:
497:
493:
489:
486:
485:
481:
478:
477:
469:
467:
463:
462:European norm
457:
455:
451:
447:
443:
434:
425:
423:
419:
414:
388:
387:
386:
384:
380:
376:
372:
371:Snellen chart
368:
363:
361:
357:
356:European norm
353:
349:
348:
342:
340:
336:
331:
328:
323:
321:
317:
313:
309:
305:
301:
297:
296:Landolt rings
292:
283:
274:
270:
265:
261:
257:
253:
246:
239:
235:
231:
227:
222:
220:
216:
212:
208:
203:
201:
197:
193:
188:
186:
182:
177:
173:
169:
165:
160:
158:
154:
153:
148:
144:
140:
135:
133:
129:
125:
121:
117:
113:
112:Visual acuity
107:
103:
95:
92:
90:
86:
82:
78:
76:
72:
68:
64:
62:
58:
53:
52:Snellen chart
47:
42:
39:Visual acuity
37:
34:
30:
26:
22:
4338:
4329:
4325:
4316:
4299:
4279:
4275:
4269:
4261:
4233:
4229:
4223:
4214:
4210:
4207:
4171:
4165:
4113:
4107:
4086:
4064:
4060:
3997:(1): 16847.
3994:
3990:
3980:
3961:
3955:
3920:
3916:
3906:
3891:
3876:
3872:
3860:. Retrieved
3855:
3845:
3836:
3826:
3819:
3800:. Retrieved
3797:LEA-Test Ltd
3796:
3784:
3759:
3755:
3749:
3730:
3726:
3720:
3694:
3690:
3683:
3674:
3655:
3649:
3637:. Retrieved
3633:the original
3628:
3619:
3605:Deering MF.
3600:
3586:cite journal
3561:
3557:
3551:
3529:(1): 62–80.
3526:
3522:
3516:
3507:
3501:
3468:
3464:
3458:
3449:
3443:
3432:the original
3406:
3396:
3386:12 September
3384:. Retrieved
3378:
3371:
3361:12 September
3359:. Retrieved
3353:
3346:
3334:. Retrieved
3327:the original
3313:
3298:
3283:
3257:. Retrieved
3254:researchgate
3253:
3242:
3231:
3177:
3173:
3159:
3146:
3121:
3117:
3111:
3102:
3096:
3059:
3055:
2999:
2996:i-Perception
2995:
2985:
2976:
2957:
2951:
2846:
2753:must exceed
2736:
2687:
2554:Because the
2553:
2411:
2375:visual angle
2368:
2357:
2205:
2194:
2048:
2026:
2024:
2008:
1993:
1988:illumination
1984:
1964:
1959:
1956:
1935:visual field
1932:
1928:
1903:
1879:
1875:
1868:
1857:
1847:
1841:
1837:
1830:
1815:
1812:
1808:
1804:
1800:
1792:
1788:
1763:
1756:
1744:
1737:
1730:
1698:
1693:
1689:
1684:
1680:
1667:
1663:
1659:
1640:
1634:
1632:
1631:
1623:Hand Motion
1616:
1610:
1608:
1607:
1580:
1568:
1564:
1549:
1533:
1518:
940:
919:
897:and scarred
891:
863:optic chiasm
856:
816:
797:
784:
769:
756:
744:
714:
710:
703:The maximum
702:
690:visual field
678:bipolar cell
643:
630:
620:
605:LogMAR chart
603:chooses the
595:
581:
567:
534:
530:
458:
452:invented by
439:
410:
367:visual angle
364:
346:
343:
332:
324:
288:
271:
263:
255:
251:
244:
237:
223:
204:
189:
161:
150:
142:
138:
136:
115:
111:
110:
33:
3879:1991 (Cth)
3564:(1): 14–8.
3471:(1): 6–13.
3407:Whonamedit?
3259:20 December
3002:(2): 1–45.
2892:Hyperacuity
1975:foveal cone
1966:hyperacuity
1762:sc: (Latin
1594:Definition
967:10 ft
964:20 ft
947:diffraction
877:called the
867:optic tract
859:optic nerve
776:diffraction
597:Rick Ferris
428:Measurement
339:denominator
185:astigmatism
152:near acuity
75:MedlinePlus
4409:Categories
3862:30 January
2944:References
2927:Strabismus
2855:headsets.
2572:derivative
2371:derivative
2358:where the
2195:where the
2004:strabismus
1941:, reduced
1919:emmetropic
1890:brain stem
1755:cc (Latin
1743:OU (Latin
1736:OS (Latin
1729:OD (Latin
1574:, such as
1559:reciprocal
1525:Landolt Cs
954:Expression
840:stereopsis
824:strabismus
739:blind spot
640:Physiology
529:his book,
422:presbyopia
347:Expression
277:Definition
192:eyeglasses
181:emmetropia
143:far acuity
50:A typical
4420:Optometry
4296:109898296
4250:0001-4575
4019:2045-2322
3711:220560741
3194:1442-6404
2897:Landolt C
2851:, and in
2819:⪅
2807:˙
2804:θ
2768:˙
2765:θ
2703:˙
2700:θ
2658:−
2644:˙
2641:θ
2630:⋅
2619:⪅
2505:⋅
2496:≈
2484:˙
2481:θ
2427:˙
2424:θ
2306:⋅
2294:≈
2282:˙
2279:θ
2243:˙
2240:θ
2158:−
2151:˙
2142:θ
2132:⋅
2121:⪅
2068:˙
2065:θ
2051:subtended
1947:amblyopia
1937:defects,
1923:ametropic
1886:nystagmus
1655:pen light
1582:follows:
1545:Landolt C
973:3 m
970:6 m
895:cataracts
832:amblyopia
793:cataracts
658:low light
537:optotypes
496:Darmstadt
450:eye chart
418:hyperopia
401:gap size
390:acuity =
379:Snellen E
375:Landolt C
335:numerator
254:), where
234:hyperbola
215:amblyopia
157:hyperopia
4385:Archived
4372:Archived
4196:11298449
4083:19271900
4037:31728011
3947:19430325
3776:15326148
3493:24533843
3269:cite web
3212:35080803
3168:(2022).
3088:22207654
3079:11073400
3026:32489576
2859:See also
1943:contrast
1921:eye (or
1911:optotype
1852:gratings
1630:acuity.
1426:20/12.5
989:20/1000
976:Decimal
907:diabetes
883:thalamus
875:midbrain
820:cataract
770:As in a
751:amacrine
541:Egyptian
468:58220).
413:eye exam
362:58220).
312:contrast
4258:8870768
4204:4406675
4176:Bibcode
4148:4290244
4140:4925353
4118:Bibcode
4028:6856529
3999:Bibcode
3938:2742505
3802:21 July
3578:3419824
3543:7457480
3485:8146001
3236:. 2008.
3203:9303885
3138:4419807
3017:7238452
2871:Dioptre
2574:of the
2558:of the
2556:tangent
2373:of the
1971:vernier
1945:, mild
1833:newborn
1705:glasses
1555:decadic
1540:decimal
1529:E Chart
1527:or the
1498:10/3.3
1495:20/6.6
1219:20/100
1196:20/125
1173:20/160
1153:10/100
1150:20/200
1130:10/125
1127:20/250
1107:10/150
1104:20/300
1084:10/200
1081:20/400
1061:10/250
1058:20/500
1038:10/300
1035:20/600
1015:10/400
1012:20/800
992:10/500
984:LogMAR
899:corneas
842:, i.e.
764:tapetum
694:foveola
660:(i.e.,
527:Utrecht
472:History
446:percept
404:
392:
289:Visual
170:or the
94:28631-0
67:D014792
4345:
4294:
4256:
4248:
4202:
4194:
4167:Nature
4146:
4138:
4109:Nature
4081:
4035:
4025:
4017:
3968:
3945:
3935:
3774:
3737:
3709:
3662:
3576:
3541:
3491:
3483:
3336:29 May
3210:
3200:
3192:
3136:
3086:
3076:
3024:
3014:
2964:
2688:where
1703:(i.e.
1551:LogMAR
1513:−0.48
1510:0.333
1490:−0.40
1481:3/1.2
1478:6/2.4
1467:−0.30
1458:3/1.5
1449:20/10
1444:−0.20
1441:0.625
1432:6/3.8
1421:−0.10
1412:3/2.4
1409:6/4.8
1403:20/16
1383:10/10
1380:20/20
1363:6/7.5
1360:10/12
1357:20/25
1343:3/4.5
1337:10/15
1334:20/30
1314:10/20
1311:20/40
1297:3/7.5
1291:10/25
1288:20/50
1268:10/30
1265:20/60
1245:10/40
1242:20/80
1222:10/50
1199:10/62
1185:0.125
1176:10/80
1116:0.067
1087:6/120
1064:6/150
1047:0.033
1041:6/180
1024:0.025
1021:3/120
1018:6/240
998:3/150
995:6/300
911:tumors
812:macula
721:macula
545:serifs
511:Vienna
482:Event
291:acuity
262:, and
226:foveal
198:, and
172:cornea
147:myopia
132:retina
124:animal
120:vision
81:003396
21:June 6
4328:[
4292:S2CID
4200:S2CID
4144:S2CID
3793:(PDF)
3729:[
3707:S2CID
3639:7 May
3610:(PDF)
3489:S2CID
3435:(PDF)
3428:(PDF)
3330:(PDF)
3323:(PDF)
2726:fovia
1999:depth
1686:loss.
1666:ight
1635:HM 2'
1611:CF 5'
1588:Name
1576:hawks
1507:3.00
1484:2.50
1475:10/4
1472:20/8
1461:2.00
1452:10/5
1438:1.60
1429:10/6
1415:1.25
1406:10/8
1398:0.00
1392:1.00
1375:0.10
1372:1.25
1369:0.80
1352:0.18
1346:0.67
1329:0.30
1323:0.50
1317:6/12
1306:0.40
1300:0.40
1294:6/15
1283:0.48
1277:0.33
1271:6/18
1260:0.60
1254:0.25
1251:3/12
1248:6/24
1237:0.70
1231:0.20
1228:3/15
1225:6/30
1214:0.80
1211:6.25
1208:0.16
1205:3/19
1202:6/38
1191:0.90
1182:3/24
1179:6/48
1168:1.00
1162:0.10
1159:3/30
1156:6/60
1145:1.10
1142:12.5
1139:0.08
1136:3/37
1133:6/75
1122:1.18
1113:3/45
1110:6/90
1099:1.30
1093:0.05
1090:3/60
1076:1.40
1070:0.04
1067:3/75
1053:1.48
1044:3/90
1030:1.60
1007:1.70
1001:0.02
717:fovea
692:(the
666:cones
627:1988
617:1984
592:1982
578:1978
564:1894
553:1888
519:1862
503:1854
487:1843
479:Year
89:LOINC
4343:ISBN
4254:PMID
4246:ISSN
4192:PMID
4136:PMID
4079:PMID
4033:PMID
4015:ISSN
3966:ISBN
3943:PMID
3864:2010
3804:2018
3772:PMID
3735:ISBN
3660:ISBN
3641:2006
3592:link
3574:PMID
3539:PMID
3481:PMID
3388:2023
3363:2023
3338:2015
3275:link
3261:2023
3208:PMID
3190:ISSN
3134:PMID
3084:PMID
3022:PMID
2962:ISBN
2037:and
1831:The
1504:3/1
1501:6/2
1487:0.4
1464:0.5
1455:6/3
1435:3/2
1418:0.8
1389:3/3
1386:6/6
1366:3/4
1349:1.5
1340:6/9
1320:3/6
1303:2.5
1274:3/9
913:and
905:and
798:The
725:cone
686:unit
674:rods
670:rods
650:cone
509:, a
320:lens
209:and
176:lens
61:MeSH
27:and
4284:doi
4238:doi
4184:doi
4172:410
4126:doi
4114:229
4069:doi
4023:PMC
4007:doi
3933:PMC
3925:doi
3764:doi
3699:doi
3566:doi
3531:doi
3527:113
3473:doi
3198:PMC
3182:doi
3126:doi
3074:PMC
3064:doi
3012:PMC
3004:doi
2596:· d
2588:= d
2564:rad
2404:).
2395:· d
2387:= d
2197:S/4
2107:is
1707:or
1650:LP
1626:HM
1602:CF
1165:10
1119:15
1096:20
1073:25
1050:30
1027:40
1004:50
980:MAR
846:by
664:),
547:).
466:DIN
373:or
360:DIN
327:USC
168:eye
141:or
128:eye
4411::
4298:.
4290:.
4280:50
4278:.
4260:.
4252:.
4244:.
4234:28
4232:.
4206:.
4198:.
4190:.
4182:.
4170:.
4156:^
4142:.
4134:.
4124:.
4112:.
4106:.
4094:^
4085:.
4077:.
4063:.
4059:.
4045:^
4031:.
4021:.
4013:.
4005:.
3993:.
3989:.
3941:.
3931:.
3921:86
3919:.
3915:.
3854:.
3835:.
3812:^
3795:.
3770:.
3760:45
3758:.
3705:.
3695:13
3693:.
3627:.
3588:}}
3584:{{
3560:.
3537:.
3525:.
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