peripheral vision

The inner boundaries of peripheral vision can be defined in any of several ways depending on the context. In everyday language the term "peripheral vision" is often used to refer to what in technical usage would be called "far peripheral vision." This is vision outside of the range of stereoscopic vision. It can be conceived as bounded at the center by a circle 60° in radius or 120° in diameter, centered around the fixation point, i.e., the point at which one's gaze is directed.{{cite book|last1=Sardegna|first1=Jill|last2=Shelly|first2=Susan|last3=Rutzen|first3=Allan Richard|author4=Scott M Steidl|title=The Encyclopedia of Blindness and Vision Impairment|url=https://books.google.com/books?id=l7UN5asLD0cC&pg=PA253|access-date=30 November 2014|year=2002|publisher=Infobase Publishing|isbn=978-0-8160-6623-0|page=253}} However, in common usage, peripheral vision may also refer to the area outside a circle 30° in radius or 60° in diameter.{{cite book|last1=Grosvenor|first1=Theodore|last2=Grosvenor|first2=Theodore P.|title=Primary Care Optometry|url=https://books.google.com/books?id=uEmQKPAOwccC&pg=PA129|access-date=29 November 2014|year=2007|publisher=Elsevier Health Sciences|isbn=978-0-7506-7575-8|page=129}}{{cite book|last=Bhise|first=Vivek D.|title=Ergonomics in the Automotive Design Process|url=https://books.google.com/books?id=XgVHut1fVJQC&pg=PA68|access-date=30 November 2014|date=15 September 2011|publisher=CRC Press|isbn=978-1-4398-4210-2|page=68}} In vision-related fields such as physiology, ophthalmology, optometry, or vision science in general, the inner boundaries of peripheral vision are defined more narrowly in terms of one of several anatomical regions of the central retina, in particular the fovea and the macula.{{cite journal|last1=Strasburger|first1=Hans|last2=Rentschler|first2=Ingo|last3=Jüttner|first3=Martin|title=Peripheral vision and pattern recognition: A review|journal=Journal of Vision|volume=11|issue=5|year=2011|pages=13|url=http://jov.arvojournals.org/article.aspx?articleid=2191825|issn=1534-7362|doi=10.1167/11.5.13|pmid=22207654|doi-access=free|pmc=11073400}}

The fovea is a cone-shaped depression in the central retina measuring 1.5 mm in diameter, corresponding1 mm = 3.436° to 5° of the visual field.{{cite book|last=Millodot|first=Michel|title=Dictionary of Optometry and Visual Science|url=https://books.google.com/books?id=3gygBAAAQBAJ&pg=PT250|access-date=30 November 2014|date=30 July 2014|publisher=Elsevier Health Sciences UK|isbn=978-0-7020-5188-3|page=250}} The outer boundaries of the fovea are visible under a microscope, or with microscopic imaging technology such as OCT or microscopic MRI. When viewed through the pupil, as in an eye exam (using an ophthalmoscope or retinal photography), only the central portion of the fovea may be visible. Anatomists refer to this as the clinical fovea, and say that it corresponds to the anatomical foveola, a structure with a diameter of 0.35 mm corresponding to 1 degree of the visual field. In clinical usage the central part of the fovea is typically referred to simply as the fovea.{{cite book|last=Small|first=Robert G. |title=The Clinical Handbook of Ophthalmology|url=https://books.google.com/books?id=J0mO1sk6zj8C&pg=PA134|access-date=29 November 2014|date=15 August 1994|publisher=CRC Press|isbn=978-1-85070-584-0|page=134}}{{cite book|last1=Peyman|first1=Gholam A.|author-link1=Gholam A. Peyman|last2=Meffert|first2=Stephen A.|last3=Chou|first3=Famin|author4=Mandi D. Conway|title=Vitreoretinal Surgical Techniques|url=https://books.google.com/books?id=gEaQ0wiM7JwC&pg=PA6|access-date=29 November 2014|date=27 November 2000|publisher=CRC Press|isbn=978-1-85317-585-5|pages=6–7}}{{cite book|last=Alfaro|first=D. Virgil|title=Age-related Macular Degeneration: A Comprehensive Textbook|url=https://books.google.com/books?id=npJ1tCXX-LAC&pg=PA3|access-date=29 November 2014|year=2006|publisher=Lippincott Williams & Wilkins|isbn=978-0-7817-3899-6|page=3}}

In terms of visual acuity, "foveal vision" may be defined as vision using the part of the retina in which a visual acuity of at least 20/20 (6/6 metric or 0.0 LogMAR; internationally 1.0) is attained. This corresponds to using the foveal avascular zone (FAZ) with a diameter of 0.5 mm representing 1.5° of the visual field (although often idealized as perfect circles, the central structures of the retina tend to be irregular ovals). Thus, foveal vision may also be defined as the central 1.5–2° of the visual field. Vision within the fovea is generally called central vision, while vision outside of the fovea, or even outside the foveola, is called peripheral, or indirect vision.

A ring-shaped region surrounding the fovea, known as the parafovea, is sometimes taken to represent an intermediate form of vision called paracentral vision.{{cite book|last=Colman|first=Andrew M.|title=A Dictionary of Psychology|url=https://books.google.com/books?id=XxGbsjKjPZsC&pg=PA546|access-date=30 November 2014|year=2009|publisher=Oxford University Press|isbn=978-0-19-953406-7|page=546}} The parafovea has an outer diameter of 2.5 mm representing 8° of the visual field.{{cite journal|last1=Swanson|first1=William H.|last2=Fish|first2=Gary E.|title=Color matches in diseased eyes with good acuity: detection of deficits in cone optical density and in chromatic discrimination|journal=Journal of the Optical Society of America A |volume=12|issue=10|year=1995 |pages=2230–2236|issn=1084-7529|doi=10.1364/JOSAA.12.002230|pmid=7500203|bibcode=1995JOSAA..12.2230S }}{{cite book | last1 = Polyak | first1 = S. L. | title = The Retina | year = 1941 | publisher = The University of Chicago Press | location = Chicago}}

The macula, the next larger region of the retina, is defined as having at least two layers of ganglia (bundles of nerves and neurons) and is sometimes taken as defining the boundaries of central vs. peripheral vision{{cite book|last=Morris|first=Christopher G.|title=Academic Press Dictionary of Science and Technology|url=https://books.google.com/books?id=nauWlPTBcjIC&pg=PA1610|access-date=29 November 2014|year=1992|publisher=Gulf Professional Publishing|isbn=978-0-12-200400-1|page=1610}}{{cite book|last=Landolt|first=Edmund|author-link=Edmund Landolt|editor=Swan M.Burnett|title=A Manual of Examination of the Eyes|publisher=D.G. Brinton|url=https://archive.org/details/b21512619|access-date=29 November 2014|year=1879|page=[https://archive.org/details/b21512619/page/201 201]}}{{cite book|last=Johnston|first=J. Milton|title=Eye Studies; a Series of Lessons on Vision and Visual Tests|url=https://archive.org/details/eyestudiesaseri00johngoog|access-date=29 November 2014|year=1892|publisher=Johnston|page=[https://archive.org/details/eyestudiesaseri00johngoog/page/n72 56]}} (but this is controversial{{cite journal | last = Strasburger | first = Hans | title = Seven myths on crowding and peripheral vision | journal = i-Perception | volume = 11 | issue = 3 | date = May 19, 2020 | url = https://journals.sagepub.com/doi/10.1177/2041669520913052 | doi = 10.1177/2041669520913052 | doi-access = free | pmc = 7238452 }}). Estimates of the macula’s size differ,since there are no precise borders its diameter estimated at 6° – 10°{{cite book |last= Oyster |first= Clyde W.|date= 1999|title= The Human Eye, Structure and Function | location= Sunderland, Mass.|publisher= Sinauer Associates |isbn= 0-87893-645-9}}; sizes based on data of Polyak, Oesterberg, and Curcio. (corresponding to 1.7 – 2.9 mm), up to 17° of the visual field (5.5 mm).{{cite book |last1=Gupta |first1=AK.|last2=Mazumdar |first2=Shahana |last3=Choudhry|first3=Saurabh|title=Practical Approach to Ophthalmoscopic Retinal Diagnosis|url=https://books.google.com/books?id=OuK0cbytQWwC&pg=PA4|access-date=30 November 2014|year=2010|publisher=Jaypee Brothers Publishers |isbn=978-81-8448-877-7|page=4}} The term is familiar in the general public through the widespread macular degeneration (AMD) at older age, where central vision is lost.

When viewed from the pupil, as in an eye exam, only the central portion of the macula may be visible. Known to anatomists as the clinical macula (and in clinical setting as simply the macula) this inner region is thought to correspond to the anatomical fovea.{{cite book|last1=Alfaro|first1=D. Virgil|last2=Kerrison|first2=John B.|title=Age-Related Macular Degeneration|url=https://books.google.com/books?id=HZhtBAAAQBAJ&pg=PT36|access-date=30 November 2014|date=4 September 2014|publisher=Wolters Kluwer Health|isbn=978-1-4698-8964-1|pages=36–7}}

A dividing line between near and mid peripheral vision at 30° radius can be based on several features of visual performance.

Visual acuity declines systematically up to 30° eccentricity: At 2°, acuity is half the foveal value, at 4° one-third, at 6° one-fourth etc. At 30°, it is one-sixteenth the foveal value.The decline is according to E₂/(E₂+E), where E is eccentricity in degrees visual angle, and E₂ is a constant of approximately 2°. An E₂ value of 2° results from Anstis’s (1974) Figure 1, with the foveal value assumed to be standard 20/20 acuity. From thereon the decline is steeper.{{cite journal | last1 = Anstis | first1 = S. M. | title = A chart demonstrating variations in acuity with retinal position | journal = Vision Research | volume = 14 | pages = 589–592| year = 1974 | issue = 7 | doi=10.1016/0042-6989(74)90049-2| pmid = 4419807 }}{{cite book|last1=Besharse|first1=Joseph C. |last2=Bok |first2=Dean|title=The Retina and Its Disorders |url=https://books.google.com/books?id=xi9FyjeKQncC&pg=PA4 |year=2011|publisher=Academic Press|isbn=978-0-12-382198-0|page=4}} (Note that it would be wrong to say, the value were halved every 2°, as said in some textbooks or in previous versions of this article.)

Color perception is strong at 20° but weak at 40°.{{cite journal|last1=Abramov|first1=Israel|last2=Gordon|first2=James|last3=Chan|first3=Hoover|title=Color appearance in the peripheral retina: effects of stimulus size|journal=Journal of the Optical Society of America A|volume=8 |issue=2 |year=1991 |pages=404–414 |issn=1084-7529 |doi=10.1364/JOSAA.8.000404|pmid=2007915|bibcode=1991JOSAA...8..404A }} In dark-adapted vision, light sensitivity corresponds to rod density,{{cn|date=July 2021}} which peaks just at 18°. From 18° towards the center, rod density declines rapidly. From 18° away from the center, rod density declines more gradually, in a curve with distinct inflection points resulting in two humps. The outer edge of the second hump is at about 30°, and corresponds to the outer edge of good night vision.{{cite book|last=Sebag|first=J.|title=Vitreous|date=October 2014|url=https://books.google.com/books?id=CxusBAAAQBAJ&pg=PA484|access-date=2 December 2014|publisher=Springer|isbn=978-1-4939-1086-1|page=484}}{{cite book|author=Li Zhaoping|title=Understanding Vision: Theory, Models, and Data|url=https://books.google.com/books?id=AuHoAwAAQBAJ&pg=PA37|access-date=2 December 2014|date=8 May 2014|publisher=OUP Oxford|isbn=978-0-19-100830-6|page=37}}{{cite book|last=McIlwain|first=James T.|title=An Introduction to the Biology of Vision|url=https://archive.org/details/introductiontobi0000mcil|url-access=registration|access-date=2 December 2014|date=28 November 1996|publisher=Cambridge University Press|isbn=978-0-521-49890-6|page=[https://archive.org/details/introductiontobi0000mcil/page/92 92]}}

File:Traquair 1938 Fig 1 modified.pngThe outer boundaries of peripheral vision correspond to the boundaries of the visual field as a whole. For a single eye, the extent of the visual field can be (roughly) defined in terms of four angles, each measured from the fixation point, i.e., the point at which one's gaze is directed. These angles, representing four cardinal directions, are 60° upwards, 60° nasally (towards the nose), 70–75° downwards, and 100–110° temporally (away from the nose and towards the temple).{{cite journal | last = Rönne | first = Henning | title = Zur Theorie und Technik der Bjerrrumschen Gesichtsfelduntersuchung | journal = Archiv für Augenheilkunde | volume = 78 | issue = 4 | pages = 284–301| year = 1915 }}{{cite book |last= Traquair |first = Harry Moss |date= 1938 |title= An Introduction to Clinical Perimetry, Chpt. 1 |location= London|publisher= Henry Kimpton |pages = 4–5}}{{cite book|last1=Savino|first1=Peter J.|last2=Danesh-Meyer|first2=Helen V.|title=Color Atlas and Synopsis of Clinical Ophthalmology -- Wills Eye Institute -- Neuro-Ophthalmology|url=https://books.google.com/books?id=6RgSZGWQZGIC&pg=PA12|access-date=9 November 2014|date=1 May 2012|publisher=Lippincott Williams & Wilkins|isbn=978-1-60913-266-8|page=12}}{{cite book|last1=Ryan|first1=Stephen J.|last2=Schachat|first2=Andrew P.|last3=Wilkinson|first3=Charles P. |author4=David R. Hinton |author5=SriniVas R. Sadda |author6=Peter Wiedemann |author6-link=Peter Wiedemann |title=Retina|url=https://books.google.com/books?id=PdAsuzFRv5oC&pg=PT342|access-date=9 November 2014|date=1 November 2012|publisher=Elsevier Health Sciences|isbn=978-1-4557-3780-2|page=342}}{{cite book|last1=Trattler|first1=William B.|last2=Kaiser|first2=Peter K.|last3=Friedman|first3=Neil J.|title=Review of Ophthalmology: Expert Consult - Online and Print|url=https://books.google.com/books?id=AazA_9TQnHYC&pg=PA255|access-date=9 November 2014|date=5 January 2012|publisher=Elsevier Health Sciences|isbn=978-1-4557-3773-4|page=255}}{{cite journal |last1=Strasburger |first1=H. |last2=Jüttner |first2=M. |date=April 2024 |issue=15 |journal=Journal of Vision |title=Erratum. Corrections to: Strasburger, Rentschler & Jüttner (2011), Peripheral Vision and Pattern Recognition |url=https://jov.arvojournals.org/article.aspx?articleid=2793585 |volume=24 |doi=10.1167/jov.24.4.15 |doi-access=free |pmc=11033599 }} For both eyes the combined visual field is 130–135° vertically{{cite book|last=Dagnelie|first=Gislin|title=Visual Prosthetics: Physiology, Bioengineering, Rehabilitation|url=https://archive.org/details/Gislin_Dagnelie_Visual_Prosthetics|access-date=9 November 2014|date=21 February 2011|publisher=Springer Science & Business Media|isbn=978-1-4419-0754-7|page=[https://archive.org/details/Gislin_Dagnelie_Visual_Prosthetics/page/n401 398]}}{{cite book|last=Dohse|first=K.C.|title=Effects of Field of View and Stereo Graphics on Memory in Immersive Command and Control|url=https://books.google.com/books?id=p2pSW2D4s7gC&pg=PA6|access-date=9 November 2014|year=2007|isbn=978-0-549-33503-0|page=6}} and 200–220° horizontally.{{Citation

| last1 = Szinte

| first1 = Martin

| last2 = Cavanagh

| first2 = Patrick

| title = Apparent Motion from Outside the Visual Field, Retinotopic Cortices May Register Extra-Retinal Positions

| date = 15 October 2012

| journal = PLOS ONE

| doi = 10.1371/journal.pone.0047386

| quote = With our head and eyes steady, our normal binocular vision covers a visual field of about 200 to 220 degrees of visual angle.

| volume=7

| issue = 10

| pages=e47386

| pmid=23077606

| pmc=3471811

| bibcode = 2012PLoSO...747386S

| doi-access = free

}}

The loss of peripheral vision while retaining central vision is known as tunnel vision, and the loss of central vision while retaining peripheral vision is known as central scotoma{{cn|date=July 2022}}.

Peripheral vision is weak in humans, especially at distinguishing detail, color, and shape. This is because the density of receptor and ganglion cells in the retina is greater at the center and lowest at the edges, and, moreover, the representation in the visual cortex is much smaller than that of the fovea (see visual system for an explanation of these concepts). The distribution of receptor cells across the retina is different between the two main types, rod cells and cone cells. Rod cells are unable to distinguish color and peak in density in the near periphery (at 18° eccentricity), while cone cell density is highest in the very center, the fovea. Note that this does not mean that there is a lack of cones representing in the periphery; colors can be distinguished in peripheral vision.{{cite journal|last1=Tyler|first1=Christopher|title=Peripheral Color Demo|journal=i-Perception|volume=6|issue=6|year=2015|pages=5|doi=10.1177/2041669515613671|pmid=27551354|pmc=4975120|doi-access=free}}

Flicker fusion thresholds decline towards the periphery, but do that at a lower rate than other visual functions; so the periphery has a relative advantage at noticing flicker. Peripheral vision is also relatively good at detecting motion (a feature of Magno cells).

Central vision is relatively weak in the dark (scotopic vision) since cone cells lack sensitivity at low light levels. Rod cells, which are concentrated further away from the fovea, operate better than cone cells in low light. This makes peripheral vision useful for detecting faint light sources at night (like faint stars). Because of this, pilots are taught to use peripheral vision to scan for aircraft at night. {{Citation needed|date=February 2010}}

Image:Eye movements of a chess champion nc.jpg

The distinctions between foveal (sometimes also called central) and peripheral vision are reflected in subtle physiological and anatomical differences in the visual cortex. Different visual areas contribute to the processing of visual information coming from different parts of the visual field, and a complex of visual areas located along the banks of the interhemispheric fissure (a deep groove that separates the two brain hemispheres) has been linked to peripheral vision. It has been suggested that these areas are important for fast reactions to visual stimuli in the periphery, and monitoring body position relative to gravity.{{cite journal | author=Palmer SM, Rosa MG | year=2006 | title=A distinct anatomical network of cortical areas for analysis of motion in far peripheral vision | journal=Eur J Neurosci | volume=24 |pages=2389–405 | doi=10.1111/j.1460-9568.2006.05113.x | pmid=17042793 | issue=8| s2cid=21562682 }}

The main functions of peripheral vision are:

• recognition of well-known structures and forms with no need to focus by the foveal line of sight
• identification of similar forms and movements (Gestalt psychology laws)
• delivery of sensations which form the background of detailed visual perception

File:Mairead cropped.png

When viewed at large angles, the iris and pupil appear to be rotated toward the viewer due to the optical refraction in the cornea. As a result, the pupil may still be visible at angles greater than 90°.{{cite journal|last1=Spring|first1=K. H.|last2=Stiles|first2=W. S.|title=Apparent Shape and Size of the Pupil Viewed Obliquely|journal=British Journal of Ophthalmology|volume=32|issue=6|year=1948|pages=347–354|issn=0007-1161|doi=10.1136/bjo.32.6.347|pmc=510837|pmid=18170457}}{{cite journal|last1=Fedtke|first1=Cathleen|last2=Manns|first2=Fabrice|last3=Ho|first3=Arthur|title=The entrance pupil of the human eye: a three-dimensional model as a function of viewing angle|journal=Optics Express|volume=18|issue=21|year=2010|pages=22364–76|issn=1094-4087|doi=10.1364/OE.18.022364|pmc=3408927|pmid=20941137|bibcode=2010OExpr..1822364F }}{{cite journal|last1=Mathur|first1=A.|last2=Gehrmann|first2=J.|last3=Atchison|first3=D. A.|title=Pupil shape as viewed along the horizontal visual field|journal=Journal of Vision|volume=13|issue=6|year=2013|pages=3|issn=1534-7362|doi=10.1167/13.6.3|pmid=23648308|url=http://www.journalofvision.org/content/13/6/3.full|doi-access=free}}

The rim of the retina contains a large concentration of cone cells. The retina extends farthest in the superior-nasal 45° quadrant (in the direction from the pupil to the bridge of the nose) with the greatest extent of the visual field in the opposite direction, the inferior temporal 45° quadrant (from the pupil of either eye towards the bottom of the nearest ear). Vision at this extreme part of the visual field is thought to be possibly concerned with threat detection, measuring optical flow, color constancy, or circadian rhythm.{{cite journal|last1=Mollon|first1=J D|last2=Regan|first2=B C|last3=Bowmaker|first3=J K|title=What is the function of the cone-rich rim of the retina?|journal=Eye|volume=12|issue=3b|year=1998|pages=548–552|issn=0950-222X|doi=10.1038/eye.1998.144|pmid=9775216|url=http://vision.psychol.cam.ac.uk/jdmollon/papers/MollonReganBowmaker.pdf|doi-access=free}}{{cite journal|last1=Williams|first1=Robert W.|title=The human retina has a cone-enriched rim|journal=Visual Neuroscience|volume=6|issue=4|year=1991|pages=403–6|issn=0952-5238|doi=10.1017/S0952523800006647|pmid=1829378|s2cid=10369867 }}{{cite journal|last1=To|first1=M.P.S.|last2=Regan|first2=B.C.|last3=Wood|first3=Dora|last4=Mollon|first4=J.D.|title=Vision out of the corner of the eye|journal=Vision Research|volume=51|issue=1|year=2011|pages=203–214|issn=0042-6989|doi=10.1016/j.visres.2010.11.008|pmid=21093472|doi-access=free}}

{{Div col|colwidth=22em}}

• Averted vision
• Bitemporal hemianopsia
• Depth perception
• Eye movement
• Eye movement in music reading
• Fovea
• Perimetry
• Visual field
• Visual perception
• Tunnel vision
• Binocular vision
• Macular degeneration
• Glaucoma

{{div col end}}

{{Reflist|30em}}

{{Stereoscopy}}

{{Mental processes}}

{{DEFAULTSORT:Peripheral Vision}}

Category:Vision

Category:Stereoscopy

Category:Visual perception