Ocular dominance, sometimes called eye dominance 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 due to the fact that 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. There is thus no direct analogy between "handedness" and "eyedness" as lateral phenomena.
Approximately two-thirds of the population is right-eye dominant; however, neither eye is dominant in a small portion of the populationTemplate:Fix/category. 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.
Importance of ocular dominance
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 especially 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, recent studies have shown this not to be the case. In a study of professional baseball players, hand-ocular dominace patterns did not show an effect on batting average or ERA. Similarly, a recent South African study found that "cricketers were not more likely to have crossed dominance" than the normal population.
Determination of ocular dominance
- 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 observer extends one arm, forms a small, circular opening with the thumb and index finger, then with both eyes open views a distant object through the opening. 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 "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.Template:Fix/category
- The Camera Test. The subject brings a camera up to his/her face. Whichever eye they use to look through the eyehole is their dominant eye.
"Forced choice" tests of dominance, such as the Dolman method, allow only a right or left eye result.
- Chaurasia BD, Mathur BB. "Eyedness." Acta Anat (Basel). 1976;96(2):301-5.PMID 970109.
- Khan AZ, Crawford JD. "Ocular dominance reverses as a function of horizontal gaze angle." Vision Res. 2001 Jun;41(14):1743-8. PMID 11369037
- Porac C, Coren S. Is eye dominance a part of generalized laterality? Percept Mot Skills. 1975 Jun;40(3):763-9. PMID 1178363.
- Reiss MR. "Ocular dominance: some family data." Laterality. 1997;2(1):7-16. PMID 15513049.
- Ehrenstein WH, Arnold-Schulz-Gahmen BE, Jaschinski W. "Eye preference within the context of binocular functions." Graefes Arch Clin Exp Ophthalmol. 2005 Sep;243(9):926-32. Epub 2005 Apr 19. PMID 15838666.
- Quartley J, Firth AY. "Binocular sighting ocular dominance changes with different angles of horizontal gaze." Binocul Vis Strabismus Q. 2004;19(1):25-30. PMID 14998366.
- Banks MS, Ghose T, Hillis JM. "Relative image size, not eye position, determines eye dominance switches." Vision Res. 2004 Feb;44(3):229-34. PMID 14642894.
- Van Strien JW, Lagers-Van Haselen GC, Van Hagen JM, De Coo IF, Frens MA, Van Der Geest JN. "Increased prevalences of left-handedness and left-eye sighting dominance in individuals with Williams-Beuren syndrome." J Clin Exp Neuropsychol. 2005 Nov;27(8):967-76. PMID 16207621.
- Aygul R, Dane S, Ulvi H. Handedness, eyedness, and crossed hand-eye dominance in male and female patients with migraine with and without aura: a pilot study. Percept Mot Skills. 2005 Jun;100(3 Pt 2):1137-42. PMID 16158700
- Handa T, Shimizu K, Mukuno K, Kawamorita T, Uozato H. "Effects of ocular dominance on binocular summation after monocular reading adds." J Cataract Refract Surg. 2005 Aug;31(8):1588-92. PMID 16129296
- Cheng CY, Yen MY, Lin HY, Hsia WW, Hsu WM. "Association of ocular dominance and anisometropic myopia." Invest Ophthalmol Vis Sci. 2004 Aug;45(8):2856-60. PMID 15277513.
- Goldschmidt E, Lyhne N, Lam CS. "Ocular anisometropia and laterality." Acta Ophthalmol Scand. 2004 Apr;82(2):175-8. PMID 15043536.
- Brian Ariel. "Sports Vision Training: An expert guide to improving performance by training the eyes."
- Laby DM, Kirschen DG, Rosenbaum AL, Mellman MF. "The effect of ocular dominance on the performance of professional baseball players." Ophthalmology. May 1998;105(5):864-866. PMID 9593388
- Thomas NG, Harden LM, Rogers GG. "Visual evoked potentials, reaction times and eye dominance in cricketers." J Sports Med Phys Fitness. 2005 Sep;45(3):428-33. PMID 16230997
- Handa T, Mukuno K, Uozato H, Niida T, Shoji N, Minei R, Nitta M, Shimizu K. "Ocular dominance and patient satisfaction after monovision induced by intraocular lens implantation." J Cataract Refract Surg. 2004 Apr;30(4):769-74. PMID 15093637.
- Kromeier M, Heinrich SP, Bach M, Kommerell G. "Ocular prevalence and stereoacuity." Ophthalmic Physiol Opt. 2006 Jan;26(1):50-6. PMID 16390482
- Roth HL, Lora AN, Heilman KM. "Effects of monocular viewing and eye dominance on spatial attention." Brain. 2002 Sep;125(Pt 9):2023-35. PMID 12183348.
- Berens C, Zerbe J. "A new pinhole test and eye-dominance tester." Am J Ophthalmol. 1953 Jul;36(7:1):980-1. PMID 13065383
- Safra D. [The "Ring Test" for evaluating eye dominance]. Klin Monatsbl Augenheilkd. 1989 Jul;195(1):35-6. PMID 2796230