1884:) 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.
57:
1960:, 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).
760:. 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
293:
444:
4312:
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...
745:
113:
1941:
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.
1652:(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.)
352:(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.
741:(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.
2040:(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
1888:
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.
2739:
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
1996:
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
1553:
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
777:
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
764:
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
189:
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
2012:
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,
1940:
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
1936:
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,
1849:
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
1820:
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
1705:
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
1581:
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
1576:
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
960:
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
903:
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
1812:
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
768:
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,
718:
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
340:
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
1572:
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
796:
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,
642:
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
426:
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
4219:
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, ...
1800:
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:
1640:
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
1580:
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
4311:
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
1668:
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
622:(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.
524:
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
1887:
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
1592:
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
1992:
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.
785:, 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
1616:
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.
1816:
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.
931:
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
470:
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
2001:
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.
841:(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
427:
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
1696:
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
1915:
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
1899:) 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
283:
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.
304:
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,
773:(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
2201:
722:
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.
845:. 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
828:
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
2694:
3909:"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"
2364:
1827:
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.
2560:
1865:
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.
876:, 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
3165:
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.
2853:
801:
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
1681:
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.
1628:(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.)
961:
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.
1573:
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.
3243:
243:
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
2013:
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
376:
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
1968:
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.
4395:
3635:
2798:
2733:
2457:
2273:
2098:
1988:. 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
726:
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
321:, 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
1692:
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:
190:
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
1861:
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
3602:
3285:
2124:
1664:
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
944:) 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.
3175:
Kandel, Himal; Nguyen, Vuong; Piermarocchi, Stefano; Ceklic, Lala; Teo, Kelvin; Arnalich-Montiel, Francisco; Miotto, Stefania; Daien, Vincent; Gillies, Mark C.;
216:
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
1648:
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.
2622:
2028:
to calculate a vision performance score (core score). This specific test of visual function has been shown to correlate to professional sports performance.
936:, 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
793:). 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.
388:
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
4382:
3330:
2459:) 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
1984:
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
145:. 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.
1846:'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.
1895:
drum, where the subject is placed inside the drum and surrounded by rotating black and white stripes. This creates involuntary abrupt eye movements (
952:
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
2281:
1710:
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
2991:
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)
765:
cones may connect to both midget and flat (diffuse) bipolars, and amacrine and horizontal cells can merge messages just as easily as inhibit them.
156:(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
2483:
2020:
Another test, including Visual acuity (EVTS/OptimEyes), uses targets which change in size, contrast, and viewing time. This test was developed by
355:
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
3474:
Grimm; Rassow; Wesemann; Saur; Hilz (1994). "Correlation of optotypes with the Landolt Ring – a fresh look at the comparability of optotypes".
825:) is represented by at least 60% of the visual cortex. Many of these neurons are believed to be involved directly in visual acuity processing.
472:
366:
3435:
2064:
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
4357:
4273:
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
3980:
3749:
3674:
2976:
550:
and advocated for standardized vision tests. Snellen's optotypes are not identical to the test letters used today. They were printed in an "
861:(colloquially: "3D vision"). The period of time over which an animal is highly sensitive to such visual deprivation is referred to as the
4392:
3643:
2616:). In application this means that an orthogonally traveling object will not be discernible as moving until it has reached the distance
632:
The International Council of Ophthalmology approves a new "Visual Acuity Measurement Standard", also incorporating the above features.
3176:
1928:, 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,
2806:
1624:
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.
392:
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
1824:
A motor inability can make a person respond incorrectly to the optotype shown and negatively affect the visual acuity measurement.
422:
Acuity is a measure of visual performance and does not relate to the eyeglass prescription required to correct vision. Instead, an
2380:
The SAVT has the same kind of importance to driving safety and sports as the static limit. The formula is derived from taking the
177:(ametropia): errors in how the light is refracted in the eye. Causes of refractive errors include aberrations in the shape of the
137:'s ability to recognize small details with precision. Visual acuity depends on optical and neural factors. Optical factors of the
213:). 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.
1874:
3261:"Determining the appropriate font size, and use of colour and contrast for underwater displays - for Defence R & D Canada"
166:, which describes someone's ability to recognize small details at a near distance. This ability is compromised in people with
4404:
593:
Hugh Taylor uses these design principles for a "Tumbling E Chart" for illiterates, later used to study the visual acuity of
1873:(VEPs or VECPs), which can be used to estimate visual acuity in doubtful cases and expected severe vision loss cases like
337:
1974:
measures the ability to align two line segments. Humans can do this with remarkable accuracy. This success is regarded as
1787:
The abbreviation PH is followed by the visual acuity as measured with a pinhole occluder, which temporarily corrects for
517:
39:
956:
can subtend 0.5 micrometre on the retina. This is certainly not the case, however, and furthermore the pupil can cause
380:, 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
4373:
2017:, or eye turn, where both eyes rarely, or never, point in the same direction and therefore do not function together.
3862:
4440:
1589:, are believed to have an acuity of around 20/2; in this respect, their vision is much better than human eyesight.
889:
770:
509:, Germany. He argues for need to standardize vision tests and produces three reading charts to avoid memorization.
280:
is a constant of approximately 2 degrees. At 2 degrees eccentricity, for example, acuity is half the foveal value.
2896:
318:
3892:
2374:
2211:
797:
which also places a lower limit on acuity. The optimal acuity of 0.4 minarc or 6/2.6 can be demonstrated using a
1880:
VEP testing of acuity is somewhat similar to preferential looking in using a series of black and white stripes (
643:
accuracy of visual acuity determined by using charts of different letter types, calibrated by Snellen's system.
618:
layout, implemented with Sloan letters, to establish a standardized method of visual acuity measurement for the
228:(caused by the visual brain not having developed properly in early childhood) and by brain damage, such as from
71:
2060:
There is a specific acuity limit in detecting an approaching object's looming motion. This is regarded as the
4379:
4330:. 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.
4098:
Displacement thresholds for peripheral motion were affected by acuity limits for speeds below 0.5 degrees/s.
3337:
232:
or stroke. When optical factors are corrected for, acuity can be considered a measure of neural functioning.
3800:
2917:
1870:
361:
below), while 6/3 corresponds to 2.0, which is often attained by well-corrected healthy young subjects with
4068:"Spatial and temporal limits of motion perception across variations in speed, eccentricity, and low vision"
1937:
the acuity is only equal to 1, the eye presents defects sufficiently pronounced to be easily established."
1804:"Dynamic visual acuity" defines the ability of the eye to visually discern fine detail in a moving object.
4435:
4425:
2767:
2702:
2566:
2426:
2242:
2067:
1569:
941:
619:
611:
570:
introduces the broken ring, now known as the Landolt ring, which later becomes an international standard.
349:
345:
229:
3843:
2049:
778:
cones in photon detection. If the RPE is damaged and does not clean up this "shed" blindness can result.
4175:
Schrater PR, Knill DC, Simoncelli EP (12 April 2001). "Perceiving visual expansion without optic flow".
3831:
Physiologic Optics: Dioptrics of the Eye, Functions of the Retina, Ocular Movements and Binocular Vision
3596:
2388:
with respect to distance, and then multiplying by velocity to obtain the time rate of visual expansion (
1892:
594:
104:
35:
3742:
The eye of the reader: foveal and peripheral perception – from letter recognition to the joy of reading
2045:
3300:
198:, in which contours of a particular orientation are blurred, and more complex corneal irregularities.
4285:
Maddox ME, Kiefer A (September 2012). "Looming Threshold Limits and Their Use in Forensic Practice".
4186:
4128:
4009:
2236:
2041:
2025:
1980:. Under optimal conditions of good illumination, high contrast, and long line segments, the limit to
1854:
913:
761:
221:
2021:
525:
labels them with the numbers from that printing house catalogue, currently known as Jaeger numbers.
3442:
2942:
2005:
953:
749:
502:
244:
4430:
4302:
4210:
4154:
3717:
3499:
2947:
2912:
2196:{\displaystyle D\lessapprox {\sqrt {{\frac {S\cdot v}{\dot {\theta _{t}}}}-{\frac {S^{2}}{4}}}},}
1904:
925:
738:
715:
607:
210:
162:
3388:
292:
3908:
365:. Stating acuity as a decimal number is the standard in European countries, as required by the
4353:
4264:
4256:
4202:
4146:
4089:
4043:
4025:
3976:
3953:
3782:
3745:
3670:
3584:
3549:
3491:
3279:
3218:
3200:
3144:
3094:
3032:
2972:
2932:
2735:
for lateral motion is generally ≥ 0.0087 rad/s with probable dependence on deviation from the
1953:
1881:
1862:
1711:
933:
790:
782:
708:
580:
464:
322:
240:
130:
904:
visual acuity is always a cause for concern. Common causes of decreases in visual acuity are
872:
coming out of the back of the eye. The two optic nerves come together behind the eyes at the
756:
The grain of a photographic mosaic has just as limited resolving power as the "grain" of the
325:). The distance between the person's eyes and the testing chart is set so as to approximate "
4294:
4248:
4194:
4177:
4136:
4119:
4079:
4033:
4017:
3943:
3935:
3774:
3709:
3576:
3541:
3483:
3208:
3192:
3136:
3084:
3074:
3022:
3014:
2927:
2876:
2749:
2009:
1933:
1929:
1788:
1782:
1565:
881:
858:
854:
752:
is at about 15.5° in the outside direction (e.g. in the left visual field for the left eye).
362:
174:
3998:"The Effect of Visual Function on the Batting Performance of Professional Baseball Players"
3996:
Laby, Daniel M.; Kirschen, David G.; Govindarajulu, Usha; DeLand, Paul (14 November 2019).
3365:
Probebuchstaben zur Bestimmung der Sehschärfe [Test letters for measuring visual acuity
1903:, not in the visual cortex. Thus someone can have a normal optokinetic response and yet be
336:
A reference value above which visual acuity is considered normal is called 6/6 vision, the
4399:
4386:
3924:"Visual acuity norms in pre-school children: the Multi-Ethnic Pediatric Eye Disease Study"
3127:
Anstis, S. M. (1974). "A chart demonstrating variations in acuity with retinal position".
2891:
2886:
2863:
2736:
2586:
2570:
1985:
1949:
1546:
897:
862:
814:
774:
727:
696:
672:
668:
664:
656:
236:
217:
2573:
is the ratio of the orthogonal distance to the set-back distance, the angular time rate (
1821:
in a patient not being able to recognize printed letters, or being unable to spell them.
817:
in the posterior part of the brain responsible for processing visual stimuli, called the
748:
The diagram shows the relative acuity of the human eye on the horizontal meridian. The
4226:
the visual system contains mechanisms that are explicitly sensitive to changes in scale.
4190:
4132:
4013:
3738:
Im Auge des Lesers: foveale und periphere Wahrnehmung – vom Buchstabieren zur Lesefreude
3517:
Wertheim T (1894). "Über die indirekte Sehschärfe" [On indirect visual acuity].
3363:
3089:
455:
procedure and as such relates the physical characteristics of a stimulus to a subject's
4239:
Hoffmann ER, Mortimer RG (July 1996). "Scaling of relative velocity between vehicles".
4038:
3997:
3948:
3923:
3713:
3700:Østerberg, G. (1935). "Topography of the layer of rods and cones in the human retina".
3545:
3390:
Optotypi ad visum determinandum secundum formulam = d/D. Ed. 8, metrico systemate [
3213:
3180:
3027:
3002:
1971:
1917:
1558:, the orientation of which can be reliably identified. A value of 1.0 is equal to 6/6.
818:
798:
757:
699:
for resolution is large, and acuity small. There are no rods in the very center of the
688:
567:
542:
Probebuchstaben zur Bestimmung der Sehschärfe [Test letters for measuring visual acuity
533:
330:
326:
206:
186:
3765:
Rohrschneider, K. (2004). "Determination of the location of the fovea on the fundus".
3459:
Landolt E (1888). "Méthode optométrique simple" [A simple optometric method].
2689:{\displaystyle D\lessapprox {\sqrt {{\frac {B\cdot v}{{\dot {\theta }}_{t}}}-B^{2}}},}
4419:
4306:
4252:
4220:
observers can estimate expansion rates from scale-change information alone, and that
3721:
3580:
3487:
3260:
3140:
2922:
1989:
1981:
1925:
1837:
1531:
937:
846:
838:
810:
769:
lens, vitreous, and finally the retina. The posterior part of the retina, called the
692:
452:
389:
381:
235:
Visual acuity is typically measured while fixating, i.e. as a measure of central (or
62:
3503:
443:
4214:
4158:
2385:
1945:
1719:
1706:
for purposes in this paragraph as having a central visual acuity of 20/200 or less.
1582:
1561:
873:
700:
615:
377:
270:
239:) vision, for the reason that it is highest in the very center. However, acuity in
116:
91:
3939:
3413:
3062:
2036:
The eye has acuity limits for detecting motion. Forward motion is limited by the
77:
3617:
2902:
1976:
957:
877:
869:
786:
333:
attempts to focus (far acuity), or at a defined reading distance (near acuity).
195:
160:, also known as short-sightedness or near-sightedness. Another visual acuity is
85:
4021:
2275:
can be measured from the distance at which a looming object is first detected:
1577:
a person with "normal" eyesight would see it from 12 metres (39 ft) away.
2937:
2582:
2381:
2359:{\displaystyle {\dot {\theta }}_{t}\approx {\frac {4S\cdot v}{S^{2}+4D^{2}}},}
2014:
1900:
896:, and then to the visual cortex along a collection of nerve fibers called the
850:
834:
551:
456:
432:
202:
191:
4298:
4260:
4029:
3204:
3018:
1530:
Visual acuity is often measured according to the size of letters viewed on a
683:. Spatial resolution is then much lower. This is due to spatial summation of
2907:
2555:{\displaystyle {\dot {\theta }}_{t}\approx {\frac {B\cdot v}{B^{2}+D^{2}}}.}
2061:
1957:
1896:
1665:
1555:
1535:
842:
744:
735:
676:
660:
547:
506:
460:
428:
393:
385:
306:
225:
167:
17:
4206:
4093:
4047:
3957:
3786:
3222:
3098:
3036:
112:
56:
4268:
4150:
3588:
3567:
Medina A, Howland B (1988). "A novel high-frequency visual acuity chart".
3553:
3495:
3148:
1891:
A simple but less-used technique is checking oculomotor responses with an
912:, which affect the optical path, diseases that affect the retina, such as
4410:
3778:
3689:
acuity as reciprocal of degrees visual angle, divided by the foveal value
2859:
1998:
1921:
917:
905:
893:
885:
830:
803:
684:
680:
423:
310:
940:
that processes a given location in the visual field (a concept known as
806:, to assess the health of the retina before subjecting them to surgery.
719:
black pixel) this gives a pixel density of 128 pixels per degree (PPD).
546:
In later editions of his book, Snellen called the letters of his charts
348:(6) is the distance in metres between the subject and the chart and the
301:
3726:. Østerberg's figure is reproduced in Strasburger et al. (2011), Fig. 4
3181:"Quality of life impact of eye diseases: a Save Sight Registries study"
2881:
2858:
Radial motion is encountered in clinical and research environments, in
2574:
1843:
1715:
1554:
value of the size of the gap (measured in arc minutes) of the smallest
1550:
1539:
928:, and diseases affecting the visual cortex such as tumors and strokes.
704:
579:
Theodor Wertheim in Berlin presents detailed measurements of acuity in
537:
314:
4287:
Proceedings of the Human Factors and Ergonomics Society Annual Meeting
3196:
1701:
In the US, the relevant federal statute defines blindness as follows:
4198:
4141:
4114:
2578:
909:
822:
731:
521:
501:
Vision test types are invented in 1843 by the German ophthalmologist
182:
157:
142:
134:
31:
3844:"Sports Vision Testing: An Innovative Approach To Increase Revenues"
3079:
1794:
PHNI means no improvement of visual acuity using a pinhole occluder.
459:
and their resulting responses. Measurement can be taken by using an
201:
Refractive errors can mostly be corrected by optical means (such as
30:"6/6", "20/20", and "20/20 vision" redirect here. For the date, see
4084:
4067:
1568:) logarithm of the minimum angle of resolution (MAR), which is the
467:, by optical instruments, or by computerized tests like the FrACT.
921:
743:
555:
442:
291:
111:
99:
2752:
in accordance to its definition, hence the ratio of the velocity
2373:
term is omitted for small objects relative to great distances by
2210:
term is omitted for small objects relative to great distances by
1586:
4115:"Conjecture on the Visual Estimation of Relative Radial Motion"
3315:
2848:{\displaystyle {\dot {\theta }}_{t}\lessapprox {\frac {v}{R}}.}
1869:
Another popular technique is electro-physiologic testing using
821:. The central 10° of field (approximately the extension of the
2471:
orthogonal to the direction of view, from a set-back distance
2100:, the looming motion of a directly approaching object of size
1732:
N (near) for the evaluation done at 15.7 inches (400 mm).
679:
do not have sufficient sensitivity and vision is subserved by
476:
370:
178:
138:
3461:
Bulletins et Mémoires de la Société Française d'Ophtalmologie
3519:
Zeitschrift für Psychologie und Physiologie der Sinnesorgane
3114:
On differences between peripheral and foveal pattern masking
920:, diseases affecting the optic pathway to the brain such as
1944:
Some people may have other visual problems, such as severe
1729:
D (distant) for the evaluation done at 20 feet (6 m).
1669:
patient is unable to perceive any light, the letters NLP (
3429:
3427:
3244:
Encyclopædia Britannica 2006 Ultimate Reference Suite DVD
4407:
Chapter from the Webvision reference, University of Utah
4066:
Lappin JS, Tadin D, Nyquist JB, Corn AL (January 2009).
3906:
42 U.S.C. § 416(i)(1)(B) (Supp. IV 1986). Cited in
3336:. International Council of Ophthalmology. Archived from
707:), and highest performance in low light is achieved in
663:
receptor cells which have high spatial density (in the
3744:] (in German). Zürich: Transmedia Stäubli Verlag.
3259:
Morrison, James Barbour , Joanna Zander (April 2008).
4170:
4168:
3063:"Peripheral vision and pattern recognition: a review"
2809:
2770:
2705:
2625:
2486:
2429:
2284:
2245:
2127:
2070:
2056:
Subtended angular velocity detection threshold (SAVT)
224:. Examples of conditions affecting the brain include
170:, also known as long-sightedness or far-sightedness.
65:
that is frequently used for visual far acuity testing
4222:
pure scale changes can produce motion after-effects.
1997:
cone. This produces a contrast of about 1% with the
194:. Other optical causes of low visual acuity include
990:
880:. This ultimately forms the physiological basis of
98:
84:
70:
49:
2847:
2792:
2727:
2688:
2554:
2451:
2358:
2267:
2195:
2092:
1564:is another commonly used scale, expressed as the (
4061:
4059:
4057:
3056:
3054:
3052:
3050:
3048:
3046:
868:The eye is connected to the visual cortex by the
544:, containing charts for measuring visual acuity.
3922:Pan Y, Tarczy-Hornoch K, Cotter SA (June 2009).
3767:Investigative Ophthalmology & Visual Science
3532:Taylor H (1981). "Racial Variations in Vision".
3301:"Software for visual psychophysics: an overview"
341:or better (depending on age and other factors).
3061:Strasburger H, Rentschler I, Jüttner M (2011).
3003:"seven myths on crowding and peripheral vision"
2971:(4th ed.). Boston: Butterworth-Heinemann.
1703:
1694:
884:. The tracts project to a relay station in the
173:A common optical cause of low visual acuity is
148:The most commonly referred-to visual acuity is
4389:, International Council of Ophthalmology, 1984
4350:Clinical Procedures for the Ocular Examination
2038:subtended angular velocity detection threshold
4108:
4106:
3971:Carlson N, Kurtz D, Heath D, Hines C (1990).
3826:
3824:
3601:: CS1 maint: DOI inactive as of April 2024 (
3116:(Thesis). University of California, Berkeley.
667:) and allow high acuity of 6/6 or better. In
620:Early Treatment of Diabetic Retinopathy Study
8:
3284:: CS1 maint: multiple names: authors list (
1545:In some countries, acuity is expressed as a
141:influence the sharpness of an image on its
3973:Clinical Procedures for Ocular Examination
3869:. University of Michigan Museum of Zoology
3393:(8 ed.). London: Williams and Norgate
3329:Visual Functions Committee (25 May 1984).
2967:Cline D, Hofstetter HW, Griffin J (1997).
1595:
968:
55:
4140:
4083:
4037:
3947:
3212:
3185:Clinical & Experimental Ophthalmology
3088:
3078:
3026:
2832:
2823:
2812:
2811:
2808:
2784:
2773:
2772:
2769:
2719:
2708:
2707:
2704:
2675:
2660:
2649:
2648:
2634:
2632:
2624:
2540:
2527:
2509:
2500:
2489:
2488:
2485:
2443:
2432:
2431:
2428:
2344:
2328:
2307:
2298:
2287:
2286:
2283:
2259:
2248:
2247:
2244:
2177:
2171:
2155:
2149:
2136:
2134:
2126:
2084:
2073:
2072:
2069:
3236:
3234:
3232:
2008:is the ability to detect differences in
536:, a Dutch ophthalmologist, publishes in
486:
4411:The Freiburg Visual Acuity Test (FrACT)
4337:Таблица для исследования остроты зрения
2959:
2112:, is not detectable until its distance
317:, standardized Cyrillic letters in the
3669:. New York: Plenum Press. p. 28.
3594:
3277:
2217:To exceed the SAVT, an object of size
2044:is experienced in accordance with the
1534:or the size of other symbols, such as
46:
3975:. Norwalk, CT: Appleton & Lange.
687:, i.e. a number of rods merge into a
7:
4341:Table for the study of visual acuity
3331:"Visual acuity measurement standard"
2793:{\displaystyle {\dot {\theta }}_{t}}
2728:{\displaystyle {\dot {\theta }}_{t}}
2452:{\displaystyle {\dot {\theta }}_{t}}
2268:{\displaystyle {\dot {\theta }}_{t}}
2093:{\displaystyle {\dot {\theta }}_{t}}
1907:with no conscious visual sensation.
1763:Usage of spectacles during the test
447:Manual hand eye test in Ghana (2018)
129:) commonly refers to the clarity of
3842:Kirschen DG, Laby DM (1 May 2006).
1871:visual evoked (cortical) potentials
4380:Visual Acuity Measurement Standard
4343:] (in Russian) (3rd ed.).
4241:Accident Analysis & Prevention
3714:10.1111/j.1755-3768.1935.tb04723.x
3546:10.1093/oxfordjournals.aje.a113067
3436:"Measuring Vision and Vision Loss"
2581:) of lateral motion is simply the
344:In the expression 6/x vision, the
25:
4113:Weinberger H (19 February 1971).
3316:"The Freiburg Visual Acuity Test"
296:Eye examination for visual acuity
4224:These two findings suggest that
3636:"Visual Acuity of the Human Eye"
3488:10.1097/00006324-199401000-00002
2748:The motion acuity limit affects
1850:fixated, centered and followed.
4335:Golovin SS, Sivtsev DA (1927).
1920:as the ability to recognize an
451:Visual acuity is measured by a
356:
247:). The decline is according to
4393:Visual Acuity of the Human Eye
4328:Duane's Clinical Ophthalmology
3368:. Utrecht: P. W. Van De Weijer
1791:such as myopia or astigmatism.
734:having the highest density of
1:
4374:How Visual Acuity is Measured
4352:(3rd ed.). McGraw Hill.
185:, and reduced ability of the
4253:10.1016/0001-4575(96)00005-X
3940:10.1097/OPX.0b013e3181a76e55
3618:"The Limits of Human Vision"
3581:10.1016/0275-5408(88)90083-x
3476:Optometry and Vision Science
3412:Enerson, Ole Daniel (2017).
3141:10.1016/0042-6989(74)90049-2
2969:Dictionary of Visual Science
2589:multiplied by the velocity (
1875:Leber's congenital amaurosis
40:2020 Vision (disambiguation)
2899:, for testing visual acuity
1644:For example, the recording
1620:For example, the recording
789:of light by the pupil (see
133:, but technically rates an
4457:
4022:10.1038/s41598-019-52546-2
1853:More formal testing using
1835:
1808:Measurement considerations
890:lateral geniculate nucleus
771:retinal pigment epithelium
691:, in turn connecting to a
554:Paragon" font (i.e. using
315:symbols for the illiterate
29:
3583:(inactive 8 April 2024).
3521:(in German) (7): 172–187.
3463:(in French) (6): 213–214.
3112:Barghout-Stein L (1999).
2423:There are acuity limits (
2375:small-angle approximation
2239:is experienced. The SAVT
2212:small-angle approximation
2024:with colleagues and uses
849:, resulting in a loss of
518:Eduard Jäger von Jaxtthal
475:(EN ISO 8596, previously
369:(EN ISO 8596, previously
54:
4398:6 September 2012 at the
4299:10.1177/1071181312561146
3897:as at 20 September 2011.
3665:Ali MA, Klyne M (1985).
3387:Snellen, Herman (1885).
3362:Snellen, Herman (1862).
3019:10.1177/2041669520913052
3001:Strasburger, H. (2020).
2235:; beyond that distance,
1726:Distance from the chart
394:international definition
4348:Carlson; Kurtz (2004).
3893:"Table 13, Schedule 1B"
3434:Colenbrander A (2001).
2918:Pediatric ophthalmology
3801:"Contrast sensitivity"
3569:Ophthalmic Physiol Opt
3299:Strasburger H (2014).
2849:
2794:
2729:
2690:
2556:
2453:
2360:
2269:
2197:
2094:
1911:"Normal" visual acuity
1708:
1699:
942:cortical magnification
753:
730:, a region inside the
709:near peripheral vision
655:Daylight vision (i.e.
612:National Eye Institute
595:Australian Aboriginals
448:
431:, ocular injuries, or
297:
230:traumatic brain injury
119:
34:. For other uses, see
3863:"Family Accipitridae"
3848:Optometric Management
3667:Vision in Vertebrates
2897:Golovin–Sivtsev table
2850:
2795:
2730:
2691:
2557:
2454:
2361:
2270:
2198:
2106:, moving at velocity
2095:
1893:optokinetic nystagmus
1777:) without correctors.
970:Visual acuity scales
833:, severe eye turn or
747:
446:
319:Golovin–Sivtsev table
295:
115:
36:2020 (disambiguation)
4376:at Prevent Blindness
3867:Animal Diversity Web
3779:10.1167/iovs.03-1157
3736:Hunziker HW (2006).
3708:(Suppl. 6): 11–103.
3702:Acta Ophthalmologica
3303:. VisionScience.com.
3177:Watson, Stephanie L.
2807:
2768:
2703:
2623:
2484:
2427:
2282:
2243:
2237:subjective constancy
2229:must be closer than
2125:
2068:
2042:subjective constancy
2026:item response theory
1924:when it subtended 5
1855:preferential looking
1744:) for the right eye.
914:macular degeneration
799:laser interferometer
695:, and the resulting
271:degrees visual angle
222:macular degeneration
117:LogMAR – ETDRS Chart
4191:2001Natur.410..816S
4133:1971Natur.229..562W
4014:2019NatSR...916847L
3888:Social Security Act
3698:Original figure in
3646:on 6 September 2012
3640:NDT Resource Center
3448:on 4 December 2014.
2740:of looming motion.
2223:moving as velocity
2006:Stereoscopic acuity
1832:Testing in children
1751:) for the left eye.
1549:, and in some as a
971:
954:diffraction grating
934:spatial frequencies
813:is the part of the
739:photoreceptor cells
269:is eccentricity in
4385:7 May 2021 at the
4002:Scientific Reports
3911:. 9 November 1990.
3257:Table 3, page 20,
2948:Near visual acuity
2913:Optical resolution
2845:
2790:
2725:
2686:
2552:
2449:
2356:
2265:
2193:
2090:
2046:Stevens' power law
1882:sine wave gratings
1801:NccOU 6/8 PH 6/8.
1770:) with correctors.
969:
926:multiple sclerosis
754:
716:angular resolution
659:) is subserved by
449:
396:of visual acuity:
298:
211:refractive surgery
120:
4441:Visual perception
4359:978-0-07-137078-3
4185:(6830): 816–819.
4072:Journal of Vision
3982:978-0-07-184920-3
3751:978-3-7266-0068-6
3676:978-0-306-42065-8
3197:10.1111/ceo.14050
3067:Journal of Vision
2978:978-0-7506-9895-5
2933:Retinal summation
2840:
2820:
2781:
2716:
2681:
2666:
2657:
2547:
2497:
2477:with the formula
2440:
2351:
2295:
2256:
2188:
2186:
2166:
2164:
2081:
2050:Weber–Fechner law
1789:refractive errors
1712:corrective lenses
1688:Legal definitions
1685:
1684:
1658:Light Perception
1610:Counting Fingers
1528:
1527:
791:diffraction limit
783:photographic lens
648:
647:
581:peripheral vision
503:Heinrich Kuechler
465:Ferdinand Monoyer
329:" in the way the
311:pediatric symbols
241:peripheral vision
110:
109:
27:Clarity of vision
16:(Redirected from
4448:
4363:
4344:
4331:
4315:
4314:
4282:
4276:
4275:
4236:
4230:
4229:
4199:10.1038/35071075
4172:
4163:
4162:
4144:
4142:10.1038/229562a0
4110:
4101:
4100:
4087:
4063:
4052:
4051:
4041:
3993:
3987:
3986:
3968:
3962:
3961:
3951:
3919:
3913:
3912:
3904:
3898:
3896:
3885:
3879:
3878:
3876:
3874:
3858:
3852:
3851:
3839:
3833:
3828:
3819:
3818:
3816:
3814:
3805:
3797:
3791:
3790:
3773:(9): 3257–3258.
3762:
3756:
3755:
3733:
3727:
3725:
3696:
3690:
3687:
3681:
3680:
3662:
3656:
3655:
3653:
3651:
3642:. Archived from
3632:
3626:
3624:
3622:
3613:
3607:
3606:
3600:
3592:
3564:
3558:
3557:
3534:Am. J. Epidemiol
3529:
3523:
3522:
3514:
3508:
3507:
3471:
3465:
3464:
3456:
3450:
3449:
3447:
3441:. Archived from
3440:
3431:
3422:
3421:
3414:"Herman Snellen"
3409:
3403:
3402:
3400:
3398:
3384:
3378:
3377:
3375:
3373:
3359:
3353:
3352:
3350:
3348:
3342:
3335:
3326:
3320:
3319:
3311:
3305:
3304:
3296:
3290:
3289:
3283:
3275:
3273:
3271:
3255:
3249:
3248:
3238:
3227:
3226:
3216:
3172:
3166:
3159:
3153:
3152:
3124:
3118:
3117:
3109:
3103:
3102:
3092:
3082:
3058:
3041:
3040:
3030:
2998:
2992:
2989:
2983:
2982:
2964:
2943:Troxler's fading
2928:Refractive error
2877:Angular diameter
2854:
2852:
2851:
2846:
2841:
2833:
2828:
2827:
2822:
2821:
2813:
2799:
2797:
2796:
2791:
2789:
2788:
2783:
2782:
2774:
2763:
2757:
2734:
2732:
2731:
2726:
2724:
2723:
2718:
2717:
2709:
2695:
2693:
2692:
2687:
2682:
2680:
2679:
2667:
2665:
2664:
2659:
2658:
2650:
2646:
2635:
2633:
2615:
2561:
2559:
2558:
2553:
2548:
2546:
2545:
2544:
2532:
2531:
2521:
2510:
2505:
2504:
2499:
2498:
2490:
2476:
2470:
2464:
2458:
2456:
2455:
2450:
2448:
2447:
2442:
2441:
2433:
2414:
2372:
2365:
2363:
2362:
2357:
2352:
2350:
2349:
2348:
2333:
2332:
2322:
2308:
2303:
2302:
2297:
2296:
2288:
2274:
2272:
2271:
2266:
2264:
2263:
2258:
2257:
2249:
2234:
2228:
2222:
2209:
2202:
2200:
2199:
2194:
2189:
2187:
2182:
2181:
2172:
2167:
2165:
2160:
2159:
2150:
2148:
2137:
2135:
2117:
2111:
2105:
2099:
2097:
2096:
2091:
2089:
2088:
2083:
2082:
2074:
1905:cortically blind
1783:Pinhole occluder
1758:) for both eyes.
1596:
992:
972:
882:binocular vision
859:binocular vision
855:depth perception
847:cortical area V1
505:(1811–1873), in
487:
418:
416:
414:
413:
410:
407:
363:binocular vision
327:optical infinity
175:refractive error
94:
80:
59:
47:
21:
4456:
4455:
4451:
4450:
4449:
4447:
4446:
4445:
4416:
4415:
4400:Wayback Machine
4387:Wayback Machine
4370:
4360:
4347:
4334:
4326:
4323:
4321:Further reading
4318:
4284:
4283:
4279:
4238:
4237:
4233:
4174:
4173:
4166:
4112:
4111:
4104:
4078:(30): 30.1–14.
4065:
4064:
4055:
3995:
3994:
3990:
3983:
3970:
3969:
3965:
3921:
3920:
3916:
3907:
3905:
3901:
3891:
3886:
3882:
3872:
3870:
3860:
3859:
3855:
3841:
3840:
3836:
3829:
3822:
3812:
3810:
3803:
3799:
3798:
3794:
3764:
3763:
3759:
3752:
3735:
3734:
3730:
3699:
3697:
3693:
3688:
3684:
3677:
3664:
3663:
3659:
3649:
3647:
3634:
3633:
3629:
3620:
3615:
3614:
3610:
3593:
3566:
3565:
3561:
3531:
3530:
3526:
3516:
3515:
3511:
3473:
3472:
3468:
3458:
3457:
3453:
3445:
3438:
3433:
3432:
3425:
3411:
3410:
3406:
3396:
3394:
3386:
3385:
3381:
3371:
3369:
3361:
3360:
3356:
3346:
3344:
3340:
3333:
3328:
3327:
3323:
3314:Bach M (2016).
3313:
3312:
3308:
3298:
3297:
3293:
3276:
3269:
3267:
3258:
3256:
3252:
3240:
3239:
3230:
3174:
3173:
3169:
3164:
3160:
3156:
3129:Vision Research
3126:
3125:
3121:
3111:
3110:
3106:
3080:10.1167/11.5.13
3073:(5): 13, 1–82.
3060:
3059:
3044:
3000:
2999:
2995:
2990:
2986:
2979:
2966:
2965:
2961:
2957:
2952:
2892:Fovea centralis
2887:Eye examination
2872:
2864:virtual-reality
2810:
2805:
2804:
2771:
2766:
2765:
2762:
2759:
2756:
2753:
2746:
2706:
2701:
2700:
2671:
2647:
2636:
2621:
2620:
2614:
2610:
2606:
2602:
2598:
2594:
2590:
2587:inverse tangent
2571:subtended angle
2536:
2523:
2522:
2511:
2487:
2482:
2481:
2475:
2472:
2469:
2466:
2463:
2460:
2430:
2425:
2424:
2421:
2413:
2409:
2405:
2401:
2397:
2393:
2389:
2370:
2340:
2324:
2323:
2309:
2285:
2280:
2279:
2246:
2241:
2240:
2233:
2230:
2227:
2224:
2221:
2218:
2207:
2173:
2151:
2138:
2123:
2122:
2116:
2113:
2110:
2107:
2104:
2101:
2071:
2066:
2065:
2058:
2034:
1966:
1950:color blindness
1913:
1857:techniques use
1840:
1834:
1813:visual acuity.
1810:
1775:sine correctore
1749:oculus sinister
1690:
1547:vulgar fraction
967:
950:
948:Optical aspects
898:optic radiation
863:critical period
815:cerebral cortex
673:scotopic vision
657:photopic vision
653:
485:
441:
411:
408:
405:
404:
402:
400:
290:
279:
260:
253:
218:detached retina
150:distance acuity
90:
76:
66:
43:
28:
23:
22:
15:
12:
11:
5:
4454:
4452:
4444:
4443:
4438:
4433:
4428:
4418:
4417:
4414:
4413:
4408:
4402:
4390:
4377:
4369:
4368:External links
4366:
4365:
4364:
4358:
4345:
4332:
4322:
4319:
4317:
4316:
4293:(1): 700–704.
4277:
4247:(4): 415–421.
4231:
4164:
4102:
4085:10.1167/9.1.30
4053:
3988:
3981:
3963:
3914:
3899:
3880:
3861:Kirschbaum K.
3853:
3834:
3820:
3792:
3757:
3750:
3728:
3691:
3682:
3675:
3657:
3627:
3608:
3559:
3524:
3509:
3466:
3451:
3423:
3404:
3379:
3354:
3321:
3306:
3291:
3250:
3241:"eye, human".
3228:
3191:(4): 386–397.
3167:
3162:
3161:Estimates of E
3154:
3135:(7): 589–592.
3119:
3104:
3042:
2993:
2984:
2977:
2958:
2956:
2953:
2951:
2950:
2945:
2940:
2935:
2930:
2925:
2920:
2915:
2910:
2905:
2900:
2894:
2889:
2884:
2879:
2873:
2871:
2868:
2856:
2855:
2844:
2839:
2836:
2831:
2826:
2819:
2816:
2787:
2780:
2777:
2760:
2758:to the radius
2754:
2745:
2742:
2722:
2715:
2712:
2697:
2696:
2685:
2678:
2674:
2670:
2663:
2656:
2653:
2645:
2642:
2639:
2631:
2628:
2612:
2608:
2604:
2600:
2596:
2592:
2563:
2562:
2551:
2543:
2539:
2535:
2530:
2526:
2520:
2517:
2514:
2508:
2503:
2496:
2493:
2473:
2467:
2461:
2446:
2439:
2436:
2420:
2419:Lateral motion
2417:
2411:
2407:
2403:
2399:
2395:
2391:
2367:
2366:
2355:
2347:
2343:
2339:
2336:
2331:
2327:
2321:
2318:
2315:
2312:
2306:
2301:
2294:
2291:
2262:
2255:
2252:
2231:
2225:
2219:
2204:
2203:
2192:
2185:
2180:
2176:
2170:
2163:
2158:
2154:
2147:
2144:
2141:
2133:
2130:
2114:
2108:
2102:
2087:
2080:
2077:
2057:
2054:
2033:
2030:
2022:Daniel M. Laby
1972:Vernier acuity
1965:
1964:Other measures
1962:
1926:minutes of arc
1918:Herman Snellen
1912:
1909:
1836:Main article:
1833:
1830:
1809:
1806:
1798:
1797:
1796:
1795:
1792:
1780:
1779:
1778:
1771:
1768:cum correctore
1761:
1760:
1759:
1752:
1745:
1737:Eye evaluated
1735:
1734:
1733:
1730:
1720:contact lenses
1689:
1686:
1683:
1682:
1662:
1659:
1655:
1654:
1638:
1635:
1631:
1630:
1614:
1611:
1607:
1606:
1603:
1600:
1526:
1525:
1522:
1519:
1516:
1513:
1510:
1507:
1503:
1502:
1499:
1496:
1493:
1490:
1487:
1484:
1480:
1479:
1476:
1473:
1470:
1467:
1464:
1461:
1457:
1456:
1453:
1450:
1447:
1444:
1441:
1438:
1434:
1433:
1430:
1427:
1424:
1421:
1418:
1415:
1411:
1410:
1407:
1404:
1401:
1398:
1395:
1392:
1388:
1387:
1384:
1381:
1378:
1375:
1372:
1369:
1365:
1364:
1361:
1358:
1355:
1352:
1349:
1346:
1342:
1341:
1338:
1335:
1332:
1329:
1326:
1323:
1319:
1318:
1315:
1312:
1309:
1306:
1303:
1300:
1296:
1295:
1292:
1289:
1286:
1283:
1280:
1277:
1273:
1272:
1269:
1266:
1263:
1260:
1257:
1254:
1250:
1249:
1246:
1243:
1240:
1237:
1234:
1231:
1227:
1226:
1223:
1220:
1217:
1214:
1211:
1208:
1204:
1203:
1200:
1197:
1194:
1191:
1188:
1185:
1181:
1180:
1177:
1174:
1171:
1168:
1165:
1162:
1158:
1157:
1154:
1151:
1148:
1145:
1142:
1139:
1135:
1134:
1131:
1128:
1125:
1122:
1119:
1116:
1112:
1111:
1108:
1105:
1102:
1099:
1096:
1093:
1089:
1088:
1085:
1082:
1079:
1076:
1073:
1070:
1066:
1065:
1062:
1059:
1056:
1053:
1050:
1047:
1043:
1042:
1039:
1036:
1033:
1030:
1027:
1024:
1020:
1019:
1016:
1013:
1010:
1007:
1004:
1001:
997:
996:
993:
988:
985:
982:
979:
976:
966:
963:
949:
946:
938:visual area V1
892:, part of the
819:occipital lobe
758:retinal mosaic
652:
649:
646:
645:
639:
635:
634:
629:
625:
624:
610:et al. of the
604:
600:
599:
590:
586:
585:
576:
572:
571:
568:Edmund Landolt
565:
561:
560:
534:Herman Snellen
531:
527:
526:
515:
511:
510:
499:
495:
494:
491:
484:
481:
453:psychophysical
440:
437:
420:
419:
289:
286:
277:
258:
251:
207:contact lenses
108:
107:
102:
96:
95:
88:
82:
81:
74:
68:
67:
60:
52:
51:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
4453:
4442:
4439:
4437:
4436:Medical signs
4434:
4432:
4429:
4427:
4426:Ophthalmology
4424:
4423:
4421:
4412:
4409:
4406:
4405:Visual Acuity
4403:
4401:
4397:
4394:
4391:
4388:
4384:
4381:
4378:
4375:
4372:
4371:
4367:
4361:
4355:
4351:
4346:
4342:
4338:
4333:
4329:
4325:
4324:
4320:
4313:
4308:
4304:
4300:
4296:
4292:
4288:
4281:
4278:
4274:
4270:
4266:
4262:
4258:
4254:
4250:
4246:
4242:
4235:
4232:
4228:
4227:
4223:
4216:
4212:
4208:
4204:
4200:
4196:
4192:
4188:
4184:
4180:
4179:
4171:
4169:
4165:
4160:
4156:
4152:
4148:
4143:
4138:
4134:
4130:
4127:(5286): 562.
4126:
4122:
4121:
4116:
4109:
4107:
4103:
4099:
4095:
4091:
4086:
4081:
4077:
4073:
4069:
4062:
4060:
4058:
4054:
4049:
4045:
4040:
4035:
4031:
4027:
4023:
4019:
4015:
4011:
4007:
4003:
3999:
3992:
3989:
3984:
3978:
3974:
3967:
3964:
3959:
3955:
3950:
3945:
3941:
3937:
3934:(6): 607–12.
3933:
3929:
3928:Optom Vis Sci
3925:
3918:
3915:
3910:
3903:
3900:
3894:
3889:
3884:
3881:
3868:
3864:
3857:
3854:
3849:
3845:
3838:
3835:
3832:
3827:
3825:
3821:
3809:
3802:
3796:
3793:
3788:
3784:
3780:
3776:
3772:
3768:
3761:
3758:
3753:
3747:
3743:
3739:
3732:
3729:
3723:
3719:
3715:
3711:
3707:
3703:
3695:
3692:
3686:
3683:
3678:
3672:
3668:
3661:
3658:
3645:
3641:
3637:
3631:
3628:
3619:
3612:
3609:
3604:
3598:
3590:
3586:
3582:
3578:
3574:
3570:
3563:
3560:
3555:
3551:
3547:
3543:
3539:
3535:
3528:
3525:
3520:
3513:
3510:
3505:
3501:
3497:
3493:
3489:
3485:
3481:
3477:
3470:
3467:
3462:
3455:
3452:
3444:
3437:
3430:
3428:
3424:
3419:
3415:
3408:
3405:
3392:
3391:
3383:
3380:
3367:
3366:
3358:
3355:
3343:on 7 May 2021
3339:
3332:
3325:
3322:
3317:
3310:
3307:
3302:
3295:
3292:
3287:
3281:
3266:
3262:
3254:
3251:
3246:
3245:
3237:
3235:
3233:
3229:
3224:
3220:
3215:
3210:
3206:
3202:
3198:
3194:
3190:
3186:
3182:
3178:
3171:
3168:
3158:
3155:
3150:
3146:
3142:
3138:
3134:
3130:
3123:
3120:
3115:
3108:
3105:
3100:
3096:
3091:
3086:
3081:
3076:
3072:
3068:
3064:
3057:
3055:
3053:
3051:
3049:
3047:
3043:
3038:
3034:
3029:
3024:
3020:
3016:
3012:
3008:
3004:
2997:
2994:
2988:
2985:
2980:
2974:
2970:
2963:
2960:
2954:
2949:
2946:
2944:
2941:
2939:
2936:
2934:
2931:
2929:
2926:
2924:
2923:Psychophysics
2921:
2919:
2916:
2914:
2911:
2909:
2906:
2904:
2901:
2898:
2895:
2893:
2890:
2888:
2885:
2883:
2880:
2878:
2875:
2874:
2869:
2867:
2865:
2861:
2860:dome theaters
2842:
2837:
2834:
2829:
2824:
2817:
2814:
2803:
2802:
2801:
2785:
2778:
2775:
2751:
2750:radial motion
2744:Radial motion
2743:
2741:
2738:
2720:
2713:
2710:
2683:
2676:
2672:
2668:
2661:
2654:
2651:
2643:
2640:
2637:
2629:
2626:
2619:
2618:
2617:
2588:
2584:
2580:
2576:
2572:
2568:
2549:
2541:
2537:
2533:
2528:
2524:
2518:
2515:
2512:
2506:
2501:
2494:
2491:
2480:
2479:
2478:
2465:and velocity
2444:
2437:
2434:
2418:
2416:
2387:
2383:
2378:
2376:
2353:
2345:
2341:
2337:
2334:
2329:
2325:
2319:
2316:
2313:
2310:
2304:
2299:
2292:
2289:
2278:
2277:
2276:
2260:
2253:
2250:
2238:
2215:
2213:
2190:
2183:
2178:
2174:
2168:
2161:
2156:
2152:
2145:
2142:
2139:
2131:
2128:
2121:
2120:
2119:
2085:
2078:
2075:
2063:
2055:
2053:
2051:
2047:
2043:
2039:
2032:Motion acuity
2031:
2029:
2027:
2023:
2018:
2016:
2011:
2007:
2003:
2000:
1994:
1991:
1990:visual cortex
1987:
1983:
1979:
1978:
1973:
1969:
1963:
1961:
1959:
1955:
1951:
1947:
1942:
1938:
1935:
1931:
1927:
1923:
1919:
1910:
1908:
1906:
1902:
1898:
1894:
1889:
1885:
1883:
1878:
1876:
1872:
1867:
1864:
1860:
1859:Teller acuity
1856:
1851:
1847:
1845:
1839:
1838:Infant vision
1831:
1829:
1825:
1822:
1818:
1814:
1807:
1805:
1802:
1793:
1790:
1786:
1785:
1784:
1781:
1776:
1772:
1769:
1765:
1764:
1762:
1757:
1756:oculi uterque
1753:
1750:
1746:
1743:
1742:oculus dexter
1739:
1738:
1736:
1731:
1728:
1727:
1725:
1724:
1723:
1722:) were used:
1721:
1717:
1713:
1707:
1702:
1698:
1693:
1687:
1680:
1676:
1672:
1667:
1663:
1660:
1657:
1656:
1653:
1650:
1649:
1647:
1639:
1636:
1633:
1632:
1629:
1626:
1625:
1623:
1615:
1612:
1609:
1608:
1604:
1602:Abbreviation
1601:
1598:
1597:
1594:
1590:
1588:
1584:
1583:birds of prey
1578:
1574:
1571:
1567:
1563:
1559:
1557:
1552:
1548:
1543:
1541:
1537:
1533:
1532:Snellen chart
1523:
1520:
1517:
1514:
1511:
1508:
1505:
1504:
1500:
1497:
1494:
1491:
1488:
1485:
1482:
1481:
1477:
1474:
1471:
1468:
1465:
1462:
1459:
1458:
1454:
1451:
1448:
1445:
1442:
1439:
1436:
1435:
1431:
1428:
1425:
1422:
1419:
1416:
1413:
1412:
1408:
1405:
1402:
1399:
1396:
1393:
1390:
1389:
1385:
1382:
1379:
1376:
1373:
1370:
1367:
1366:
1362:
1359:
1356:
1353:
1350:
1347:
1344:
1343:
1339:
1336:
1333:
1330:
1327:
1324:
1321:
1320:
1316:
1313:
1310:
1307:
1304:
1301:
1298:
1297:
1293:
1290:
1287:
1284:
1281:
1278:
1275:
1274:
1270:
1267:
1264:
1261:
1258:
1255:
1252:
1251:
1247:
1244:
1241:
1238:
1235:
1232:
1229:
1228:
1224:
1221:
1218:
1215:
1212:
1209:
1206:
1205:
1201:
1198:
1195:
1192:
1189:
1186:
1183:
1182:
1178:
1175:
1172:
1169:
1166:
1163:
1160:
1159:
1155:
1152:
1149:
1146:
1143:
1140:
1137:
1136:
1132:
1129:
1126:
1123:
1120:
1117:
1114:
1113:
1109:
1106:
1103:
1100:
1097:
1094:
1091:
1090:
1086:
1083:
1080:
1077:
1074:
1071:
1068:
1067:
1063:
1060:
1057:
1054:
1051:
1048:
1045:
1044:
1040:
1037:
1034:
1031:
1028:
1025:
1022:
1021:
1017:
1014:
1011:
1008:
1005:
1002:
999:
998:
994:
989:
986:
983:
980:
977:
974:
973:
964:
962:
959:
955:
947:
945:
943:
939:
935:
929:
927:
923:
919:
915:
911:
907:
901:
899:
895:
891:
887:
883:
879:
875:
871:
866:
864:
860:
856:
852:
848:
844:
840:
839:anisometropia
836:
832:
826:
824:
820:
816:
812:
811:visual cortex
807:
805:
800:
794:
792:
788:
784:
779:
776:
772:
766:
763:
759:
751:
746:
742:
740:
737:
733:
729:
724:
720:
717:
712:
710:
706:
702:
698:
694:
693:ganglion cell
690:
686:
682:
678:
674:
670:
666:
665:central fovea
662:
658:
650:
644:
640:
637:
636:
633:
630:
627:
626:
623:
621:
617:
613:
609:
605:
602:
601:
598:
596:
591:
588:
587:
584:
582:
577:
574:
573:
569:
566:
563:
562:
559:
557:
553:
549:
543:
539:
535:
532:
529:
528:
523:
519:
516:
513:
512:
508:
504:
500:
497:
496:
492:
489:
488:
482:
480:
478:
474:
473:European norm
468:
466:
462:
458:
454:
445:
438:
436:
434:
430:
425:
399:
398:
397:
395:
391:
387:
383:
382:Snellen chart
379:
374:
372:
368:
367:European norm
364:
360:
359:
353:
351:
347:
342:
339:
334:
332:
328:
324:
320:
316:
312:
308:
307:Landolt rings
303:
294:
287:
285:
281:
276:
272:
268:
264:
257:
250:
246:
242:
238:
233:
231:
227:
223:
219:
214:
212:
208:
204:
199:
197:
193:
188:
184:
180:
176:
171:
169:
165:
164:
159:
155:
151:
146:
144:
140:
136:
132:
128:
124:
123:Visual acuity
118:
114:
106:
103:
101:
97:
93:
89:
87:
83:
79:
75:
73:
69:
64:
63:Snellen chart
58:
53:
50:Visual acuity
48:
45:
41:
37:
33:
19:
4349:
4340:
4336:
4327:
4310:
4290:
4286:
4280:
4272:
4244:
4240:
4234:
4225:
4221:
4218:
4182:
4176:
4124:
4118:
4097:
4075:
4071:
4008:(1): 16847.
4005:
4001:
3991:
3972:
3966:
3931:
3927:
3917:
3902:
3887:
3883:
3871:. Retrieved
3866:
3856:
3847:
3837:
3830:
3811:. Retrieved
3808:LEA-Test Ltd
3807:
3795:
3770:
3766:
3760:
3741:
3737:
3731:
3705:
3701:
3694:
3685:
3666:
3660:
3648:. Retrieved
3644:the original
3639:
3630:
3616:Deering MF.
3611:
3597:cite journal
3572:
3568:
3562:
3540:(1): 62–80.
3537:
3533:
3527:
3518:
3512:
3479:
3475:
3469:
3460:
3454:
3443:the original
3417:
3407:
3397:12 September
3395:. Retrieved
3389:
3382:
3372:12 September
3370:. Retrieved
3364:
3357:
3345:. Retrieved
3338:the original
3324:
3309:
3294:
3268:. Retrieved
3265:researchgate
3264:
3253:
3242:
3188:
3184:
3170:
3157:
3132:
3128:
3122:
3113:
3107:
3070:
3066:
3010:
3007:i-Perception
3006:
2996:
2987:
2968:
2962:
2857:
2764:must exceed
2747:
2698:
2565:Because the
2564:
2422:
2386:visual angle
2379:
2368:
2216:
2205:
2059:
2037:
2035:
2019:
2004:
1999:illumination
1995:
1975:
1970:
1967:
1946:visual field
1943:
1939:
1914:
1890:
1886:
1879:
1868:
1858:
1852:
1848:
1841:
1826:
1823:
1819:
1815:
1811:
1803:
1799:
1774:
1767:
1755:
1748:
1741:
1709:
1704:
1700:
1695:
1691:
1678:
1674:
1670:
1651:
1645:
1643:
1642:
1634:Hand Motion
1627:
1621:
1619:
1618:
1591:
1579:
1575:
1560:
1544:
1529:
951:
930:
908:and scarred
902:
874:optic chiasm
867:
827:
808:
795:
780:
767:
755:
725:
721:
714:The maximum
713:
701:visual field
689:bipolar cell
654:
641:
631:
616:LogMAR chart
614:chooses the
606:
592:
578:
545:
541:
469:
463:invented by
450:
421:
378:visual angle
375:
357:
354:
343:
335:
299:
282:
274:
266:
262:
255:
248:
234:
215:
200:
172:
161:
153:
149:
147:
126:
122:
121:
44:
18:20:20 Vision
3890:1991 (Cth)
3575:(1): 14–8.
3482:(1): 6–13.
3418:Whonamedit?
3270:20 December
3013:(2): 1–45.
2903:Hyperacuity
1986:foveal cone
1977:hyperacuity
1773:sc: (Latin
1605:Definition
978:10 ft
975:20 ft
958:diffraction
888:called the
878:optic tract
870:optic nerve
787:diffraction
608:Rick Ferris
439:Measurement
350:denominator
196:astigmatism
163:near acuity
86:MedlinePlus
4420:Categories
3873:30 January
2955:References
2938:Strabismus
2866:headsets.
2583:derivative
2382:derivative
2369:where the
2206:where the
2015:strabismus
1952:, reduced
1930:emmetropic
1901:brain stem
1766:cc (Latin
1754:OU (Latin
1747:OS (Latin
1740:OD (Latin
1585:, such as
1570:reciprocal
1536:Landolt Cs
965:Expression
851:stereopsis
835:strabismus
750:blind spot
651:Physiology
540:his book,
433:presbyopia
358:Expression
288:Definition
203:eyeglasses
192:emmetropia
154:far acuity
61:A typical
4431:Optometry
4307:109898296
4261:0001-4575
4030:2045-2322
3722:220560741
3205:1442-6404
2908:Landolt C
2862:, and in
2830:⪅
2818:˙
2815:θ
2779:˙
2776:θ
2714:˙
2711:θ
2669:−
2655:˙
2652:θ
2641:⋅
2630:⪅
2516:⋅
2507:≈
2495:˙
2492:θ
2438:˙
2435:θ
2317:⋅
2305:≈
2293:˙
2290:θ
2254:˙
2251:θ
2169:−
2162:˙
2153:θ
2143:⋅
2132:⪅
2079:˙
2076:θ
2062:subtended
1958:amblyopia
1948:defects,
1934:ametropic
1897:nystagmus
1666:pen light
1593:follows:
1556:Landolt C
984:3 m
981:6 m
906:cataracts
843:amblyopia
804:cataracts
669:low light
548:optotypes
507:Darmstadt
461:eye chart
429:hyperopia
412:gap size
401:acuity =
390:Snellen E
386:Landolt C
346:numerator
265:), where
245:hyperbola
226:amblyopia
168:hyperopia
4396:Archived
4383:Archived
4207:11298449
4094:19271900
4048:31728011
3958:19430325
3787:15326148
3504:24533843
3280:cite web
3223:35080803
3179:(2022).
3099:22207654
3090:11073400
3037:32489576
2870:See also
1954:contrast
1932:eye (or
1922:optotype
1863:gratings
1641:acuity.
1437:20/12.5
1000:20/1000
987:Decimal
918:diabetes
894:thalamus
886:midbrain
831:cataract
781:As in a
762:amacrine
552:Egyptian
479:58220).
424:eye exam
373:58220).
323:contrast
4269:8870768
4215:4406675
4187:Bibcode
4159:4290244
4151:4925353
4129:Bibcode
4039:6856529
4010:Bibcode
3949:2742505
3813:21 July
3589:3419824
3554:7457480
3496:8146001
3247:. 2008.
3214:9303885
3149:4419807
3028:7238452
2882:Dioptre
2585:of the
2569:of the
2567:tangent
2384:of the
1982:vernier
1956:, mild
1844:newborn
1716:glasses
1566:decadic
1551:decimal
1540:E Chart
1538:or the
1509:10/3.3
1506:20/6.6
1230:20/100
1207:20/125
1184:20/160
1164:10/100
1161:20/200
1141:10/125
1138:20/250
1118:10/150
1115:20/300
1095:10/200
1092:20/400
1072:10/250
1069:20/500
1049:10/300
1046:20/600
1026:10/400
1023:20/800
1003:10/500
995:LogMAR
910:corneas
853:, i.e.
775:tapetum
705:foveola
671:(i.e.,
538:Utrecht
483:History
457:percept
415:
403:
300:Visual
181:or the
105:28631-0
78:D014792
4356:
4305:
4267:
4259:
4213:
4205:
4178:Nature
4157:
4149:
4120:Nature
4092:
4046:
4036:
4028:
3979:
3956:
3946:
3785:
3748:
3720:
3673:
3587:
3552:
3502:
3494:
3347:29 May
3221:
3211:
3203:
3147:
3097:
3087:
3035:
3025:
2975:
2699:where
1714:(i.e.
1562:LogMAR
1524:−0.48
1521:0.333
1501:−0.40
1492:3/1.2
1489:6/2.4
1478:−0.30
1469:3/1.5
1460:20/10
1455:−0.20
1452:0.625
1443:6/3.8
1432:−0.10
1423:3/2.4
1420:6/4.8
1414:20/16
1394:10/10
1391:20/20
1374:6/7.5
1371:10/12
1368:20/25
1354:3/4.5
1348:10/15
1345:20/30
1325:10/20
1322:20/40
1308:3/7.5
1302:10/25
1299:20/50
1279:10/30
1276:20/60
1256:10/40
1253:20/80
1233:10/50
1210:10/62
1196:0.125
1187:10/80
1127:0.067
1098:6/120
1075:6/150
1058:0.033
1052:6/180
1035:0.025
1032:3/120
1029:6/240
1009:3/150
1006:6/300
922:tumors
823:macula
732:macula
556:serifs
522:Vienna
493:Event
302:acuity
273:, and
237:foveal
209:, and
183:cornea
158:myopia
143:retina
135:animal
131:vision
92:003396
32:June 6
4339:[
4303:S2CID
4211:S2CID
4155:S2CID
3804:(PDF)
3740:[
3718:S2CID
3650:7 May
3621:(PDF)
3500:S2CID
3446:(PDF)
3439:(PDF)
3341:(PDF)
3334:(PDF)
2737:fovia
2010:depth
1697:loss.
1677:ight
1646:HM 2'
1622:CF 5'
1599:Name
1587:hawks
1518:3.00
1495:2.50
1486:10/4
1483:20/8
1472:2.00
1463:10/5
1449:1.60
1440:10/6
1426:1.25
1417:10/8
1409:0.00
1403:1.00
1386:0.10
1383:1.25
1380:0.80
1363:0.18
1357:0.67
1340:0.30
1334:0.50
1328:6/12
1317:0.40
1311:0.40
1305:6/15
1294:0.48
1288:0.33
1282:6/18
1271:0.60
1265:0.25
1262:3/12
1259:6/24
1248:0.70
1242:0.20
1239:3/15
1236:6/30
1225:0.80
1222:6.25
1219:0.16
1216:3/19
1213:6/38
1202:0.90
1193:3/24
1190:6/48
1179:1.00
1173:0.10
1170:3/30
1167:6/60
1156:1.10
1153:12.5
1150:0.08
1147:3/37
1144:6/75
1133:1.18
1124:3/45
1121:6/90
1110:1.30
1104:0.05
1101:3/60
1087:1.40
1081:0.04
1078:3/75
1064:1.48
1055:3/90
1041:1.60
1018:1.70
1012:0.02
728:fovea
703:(the
677:cones
638:1988
628:1984
603:1982
589:1978
575:1894
564:1888
530:1862
514:1854
498:1843
490:Year
100:LOINC
4354:ISBN
4265:PMID
4257:ISSN
4203:PMID
4147:PMID
4090:PMID
4044:PMID
4026:ISSN
3977:ISBN
3954:PMID
3875:2010
3815:2018
3783:PMID
3746:ISBN
3671:ISBN
3652:2006
3603:link
3585:PMID
3550:PMID
3492:PMID
3399:2023
3374:2023
3349:2015
3286:link
3272:2023
3219:PMID
3201:ISSN
3145:PMID
3095:PMID
3033:PMID
2973:ISBN
2048:and
1842:The
1515:3/1
1512:6/2
1498:0.4
1475:0.5
1466:6/3
1446:3/2
1429:0.8
1400:3/3
1397:6/6
1377:3/4
1360:1.5
1351:6/9
1331:3/6
1314:2.5
1285:3/9
924:and
916:and
809:The
736:cone
697:unit
685:rods
681:rods
661:cone
520:, a
331:lens
220:and
187:lens
72:MeSH
38:and
4295:doi
4249:doi
4195:doi
4183:410
4137:doi
4125:229
4080:doi
4034:PMC
4018:doi
3944:PMC
3936:doi
3775:doi
3710:doi
3577:doi
3542:doi
3538:113
3484:doi
3209:PMC
3193:doi
3137:doi
3085:PMC
3075:doi
3023:PMC
3015:doi
2607:· d
2599:= d
2575:rad
2415:).
2406:· d
2398:= d
2208:S/4
2118:is
1718:or
1661:LP
1637:HM
1613:CF
1176:10
1130:15
1107:20
1084:25
1061:30
1038:40
1015:50
991:MAR
857:by
675:),
558:).
477:DIN
384:or
371:DIN
338:USC
179:eye
152:or
139:eye
4422::
4309:.
4301:.
4291:50
4289:.
4271:.
4263:.
4255:.
4245:28
4243:.
4217:.
4209:.
4201:.
4193:.
4181:.
4167:^
4153:.
4145:.
4135:.
4123:.
4117:.
4105:^
4096:.
4088:.
4074:.
4070:.
4056:^
4042:.
4032:.
4024:.
4016:.
4004:.
4000:.
3952:.
3942:.
3932:86
3930:.
3926:.
3865:.
3846:.
3823:^
3806:.
3781:.
3771:45
3769:.
3716:.
3706:13
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