Ocular dominance, sometimes called eye preference or eyedness, is the tendency to prefer visual input from one eye to the other. It is somewhat analogous to the laterality of right- or left-handedness; however, the side of the dominant eye and the dominant hand do not always match. This is because both hemispheres control both eyes, but each one takes charge of a different half of the field of vision, and therefore a different half of both retinas (See Optic Tract for more details). There is thus no direct analogy between "handedness" and "eyedness" as lateral phenomena.
Approximately 69.42% of the population are right-eye dominant and 29% left-eye dominant. Dominance does appear to change depending upon direction of gaze due to image size changes on the retinas. There also appears to be a higher prevalence of left-eye dominance in those with Williams–Beuren syndrome, and possibly in migraine sufferers as well. Eye dominance has been categorized as "weak" or "strong"; highly profound cases are sometimes caused by amblyopia or strabismus.
In those with anisometropic myopia (different amounts of nearsightedness between the two eyes), the dominant eye has typically been found to be the one with more myopia. As far as regards subjects with normal binocular vision, the widespread notion that the individual's better-sighted eye would tend to be the dominant eye has been challenged as lacking empirical basis.
Dominance can change and may switch between the eyes depending on the task and physical condition of the subject (i.e. fatigue).
In normal binocular vision there is an effect of parallax, and therefore the dominant eye is the one that is primarily relied on for precise positional information. This may be extremely important in sports which require aim, such as archery, darts or shooting sports.
It has been asserted that cross-dominance (in which the dominant eye is on one side and the dominant hand is on the other) is advantageous in sports requiring side-on stances (e.g. baseball, cricket, golf); however, studies within the last 20 years have shown this not to be the case. In a 1998 study of professional baseball players, hand–ocular dominance patterns did not show an effect on batting average or ERA. Similarly, in 2005, a South African study found that "cricketers were not more likely to have crossed dominance" than the normal population.
The dominant eye has more neural connections to the brain than the other eye does. According to a sixty-person study in the Proceedings of the Royal Society B, in non-dyslexic people, the blue cone-free spot in the dominant eye tends to be round and the same spot in the non-dominant eye tends to be unevenly shaped; in dyslexic people both eyes tend to have round areas. The study suggests this difference may be a potential, and possibly treatable, cause of dyslexia; however, further tests are required to confirm. At least 700 million people worldwide have dyslexia. In response to the study, John Stein of the University of Oxford cautions that while the study is "really interesting", there is no one single cause of dyslexia.
A person's dominant eye "is determined by subjective alignment of two objects presented at a stereodisparity far beyond Panum's area". There are a number of ways to do this:
- The Miles test. The observer extends both arms, brings both hands together to create a small opening, then with both eyes open views a distant object through the opening. The observer then alternates closing the eyes or slowly draws opening back to the head to determine which eye is viewing the object (i.e. the dominant eye).
- The Porta test. The observer extends one arm, then with both eyes open aligns the thumb or index finger with a distant object. The observer then alternates closing the eyes or slowly draws the thumb/finger back to the head to determine which eye is viewing the object (i.e. the dominant eye).
- The Dolman method, also known as the hole-in-the-card test. The subject is given a card with a small hole in the middle, instructed to hold it with both hands, then instructed to view a distant object through the hole with both eyes open. The observer then alternates closing the eyes or slowly draws the opening back to the head to determine which eye is viewing the object (i.e. the dominant eye).
- The convergence near-point test. The subject fixates an object that is moved toward the nose until divergence of one eye occurs (i.e. the non-dominant eye). It is an objective test of ocular dominance.
- Certain stereograms.
- The pinhole test.
- The ring test.
- Lens fogging technique. The subject fixates a distant object with both eyes open and appropriate correction in place. A +2.00 or +2.50 lens is alternately introduced in front of each eye, which blurs the distant object. The subject is then asked to state in which eye is the blur more noticeable. This is the dominant eye.
- A dichoptic motion coherence threshold test yields a quantified indication of ocular dominance.
- Chaurasia BD, Mathur BB (1976). "Eyedness". Acta Anatomica. 96 (2): 301–5. doi:10.1159/000144681. PMID 970109.
- Khan AZ, Crawford JD (June 2001). "Ocular dominance reverses as a function of horizontal gaze angle". Vision Research. 41 (14): 1743–8. doi:10.1016/S0042-6989(01)00079-7. PMID 11369037. S2CID 12186721.
- Porac C, Coren S (June 1975). "Is eye dominance a part of generalized laterality?". Perceptual and Motor Skills. 40 (3): 763–9. doi:10.2466/pms.19188.8.131.523. PMID 1178363. S2CID 33204029.
- Hagemann, N. (2009). "The advantage of being left handed in interactive sports". Attention, Perception, & Psychophysics. 71 (7): 1641–1648. doi:10.3758/APP.71.7.1641. PMID 19801623.
- Reiss MR (1997). "Ocular dominance: some family data". Laterality. 2 (1): 7–16. doi:10.1080/713754254. PMID 15513049.
- Ehrenstein WH, Arnold-Schulz-Gahmen BE, Jaschinski W (September 2005). "Eye preference within the context of binocular functions". Graefe's Archive for Clinical and Experimental Ophthalmology. 243 (9): 926–32. CiteSeerX 10.1.1.60.4432. doi:10.1007/s00417-005-1128-7. PMID 15838666. S2CID 1558803.
- Eser I, Durrie DS, Schwendeman F, Stahl JE (September 2008). "Association between ocular dominance and refraction". Journal of Refractive Surgery. 24 (7): 685–9. doi:10.3928/1081597X-20080901-07. PMID 18811110.
- Quartley J, Firth AY (2004). "Binocular sighting ocular dominance changes with different angles of horizontal gaze". Binocular Vision & Strabismus Quarterly. 19 (1): 25–30. PMID 14998366.
- Banks MS, Ghose T, Hillis JM (February 2004). "Relative image size, not eye position, determines eye dominance switches". Vision Research. 44 (3): 229–34. doi:10.1016/j.visres.2003.09.029. PMID 14642894. S2CID 45772.
- Van Strien JW, Lagers-Van Haselen GC, Van Hagen JM, De Coo IF, Frens MA, Van Der Geest JN (November 2005). "Increased prevalences of left-handedness and left-eye sighting dominance in individuals with Williams-Beuren syndrome". Journal of Clinical and Experimental Neuropsychology. 27 (8): 967–76. doi:10.1080/13803390490919119. PMID 16207621. S2CID 24853662.
- Aygül R, Dane S, Ulvi H (June 2005). "Handedness, eyedness, and crossed hand-eye dominance in male and female patients with migraine with and without aura: a pilot study". Perceptual and Motor Skills. 100 (3 Pt 2): 1137–42. doi:10.2466/pms.100.3c.1137-1142. PMID 16158700. S2CID 28551538.
- Handa T, Shimizu K, Mukuno K, Kawamorita T, Uozato H (August 2005). "Effects of ocular dominance on binocular summation after monocular reading adds". Journal of Cataract and Refractive Surgery. 31 (8): 1588–92. doi:10.1016/j.jcrs.2005.01.015. PMID 16129296. S2CID 41767553.
- Cheng CY, Yen MY, Lin HY, Hsia WW, Hsu WM (August 2004). "Association of ocular dominance and anisometropic myopia". Investigative Ophthalmology & Visual Science. 45 (8): 2856–60. doi:10.1167/iovs.03-0878. PMID 15277513.
- Vincent SJ, Collins MJ, Read SA, Carney LG, Yap MK (December 2011). "Interocular symmetry in myopic anisometropia" (PDF). Optometry and Vision Science. 88 (12): 1454–62. doi:10.1097/OPX.0b013e318233ee5f. PMID 21964662. S2CID 20113627.
- Pointer JS (January 2007). "The absence of lateral congruency between sighting dominance and the eye with better visual acuity". Ophthalmic & Physiological Optics. 27 (1): 106–10. doi:10.1111/j.1475-1313.2006.00414.x. PMID 17239197. S2CID 28900363.
- Ariel B. "Sports Vision Training: An expert guide to improving performance by training the eyes". Archived from the original on 28 September 2007. Retrieved 21 March 2006.
- Laby DM, Kirschen DG, Rosenbaum AL, Mellman MF (May 1998). "The effect of ocular dominance on the performance of professional baseball players". Ophthalmology. 105 (5): 864–6. doi:10.1016/S0161-6420(98)95027-8. PMID 9593388.
- Thomas NG, Harden LM, Rogers GG (September 2005). "Visual evoked potentials, reaction times and eye dominance in cricketers". The Journal of Sports Medicine and Physical Fitness. 45 (3): 428–33. PMID 16230997.
- Handa T, Mukuno K, Uozato H, Niida T, Shoji N, Minei R, Nitta M, Shimizu K (April 2004). "Ocular dominance and patient satisfaction after monovision induced by intraocular lens implantation". Journal of Cataract and Refractive Surgery. 30 (4): 769–74. doi:10.1016/j.jcrs.2003.07.013. PMID 15093637. S2CID 39690729.
- Le Floch A, Ropars G (October 2017). "Left-right asymmetry of the Maxwell spot centroids in adults without and with dyslexia". Proceedings. Biological Sciences. 284 (1865): 20171380. doi:10.1098/rspb.2017.1380. PMC 5666095. PMID 29046375.
- Agence France-Presse (18 October 2017). "Dyslexia: scientists claim cause of condition may lie in the eyes". The Guardian. Retrieved 21 October 2017.
- "Dyslexia eye link spotted by scientists". BBC News. 18 October 2017. Retrieved 21 October 2017.
- Kromeier M, Heinrich SP, Bach M, Kommerell G (January 2006). "Ocular prevalence and stereoacuity". Ophthalmic & Physiological Optics. 26 (1): 50–6. CiteSeerX 10.1.1.570.3941. doi:10.1111/j.1475-1313.2005.00344.x. PMID 16390482. S2CID 7515192.
- "Shooting Eye Dominance for Bows & Guns". www.huntersfriend.com. Retrieved 22 April 2016.
- Roth HL, Lora AN, Heilman KM (September 2002). "Effects of monocular viewing and eye dominance on spatial attention". Brain. 125 (Pt 9): 2023–35. doi:10.1093/brain/awf210. PMID 12183348.
- "Determining your Dominant Eye". Pat Norris Archery. Archived from the original on 19 February 2015.
- "Right or left eye dominant? . . . . . how to check". Archived from the original on 10 December 2001.
- "Eye Dominance Test". SportVue. Archived from the original on 15 February 2008.
- "Stereogram test for right/left eye dominance". Archived from the original on 22 May 2008.
- Berens C, Zerbe J (July 1953). "A new pinhole test and eye-dominance tester". American Journal of Ophthalmology. 36 (7 1): 980–1. doi:10.1016/0002-9394(53)92183-7. PMID 13065383.
- Safra D (July 1989). "[The "Ring Test" for evaluating eye dominance]". Klinische Monatsblätter für Augenheilkunde (in German). 195 (1): 35–6. doi:10.1055/s-2008-1046410. PMID 2796230.
- Li J, Lam CS, Yu M, Hess RF, Chan LY, Maehara G, Woo GC, Thompson B (December 2010). "Quantifying sensory eye dominance in the normal visual system: a new technique and insights into variation across traditional tests". Investigative Ophthalmology & Visual Science. 51 (12): 6875–81. doi:10.1167/iovs.10-5549. PMID 20610837.