Ocular dominance

Ocular dominance, sometimes called eye dominance or eyedness,^[1] is the tendency to prefer visual input from one eye to the other.^[2] 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.^[3] 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. There is thus no direct analogy between "handedness" and "eyedness" as lateral phenomena.

Approximately two thirds of the population is right-eye dominant and one third left-eye dominant;^[1][4][5][6] however in a small portion of the population neither eye is dominant. Dominance does appear to change depending upon direction of gaze^[2][7] due to image size changes on the retinas.^[8] There also appears to be a higher prevalence of left-eye dominance in those with Williams–Beuren syndrome,^[9] and possibly in migraine sufferers as well.^[10] Eye dominance has been categorized as "weak" or "strong";^[11] highly profound cases are sometimes caused by amblyopia or strabismus.

In those with anisometropic myopia (i.e. different amounts of nearsightedness between the two eyes), the dominant eye has been found to be the one with more myopia.^[12][13]

Importance of ocular dominance

Since 'worse eye dominance' goes against nature and common sense (i.e., in 'handedness', the stronger/faster/better hand is dominant, enabling quicker and more accurate actions, reactions, and decision-making) studies should be done to determine whether the myopes in question (virtually all of them) undergo a reversal of their normal better eye dominance as a result of continuously wearing their prescribed lenses, and if so then investigations are needed into whether opticians are incorrectly prescribing lenses which bring both eyes to equal eyesight (rather than leaving the worse eye slightly undercorrected) and thus inducing the abnormal reversal and contributing to continued worsening eyesight.

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);^[14] however, recent studies have shown this not to be the case. In a study of professional baseball players, hand-ocular dominance patterns did not show an effect on batting average or ERA.^[15] Similarly, a recent South African study found that "cricketers were not more likely to have crossed dominance" than the normal population.^[16]

Ocular dominance is an important consideration in predicting patient satisfaction with monovision correction in cataract surgery,^[17] refractive surgery, and contact lens wear.

Determination of ocular dominance

A person's dominant eye "is determined by subjective alignment of two objects presented at a stereodisparity far beyond Panum's area".^[18] There are a number of ways to do this:

1. 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)^[19][1].
2. 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) ^[19][2] [3].
3. 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).^[12]
4. 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.^[12]
5. Certain stereograms [4].
6. The Pinhole test.^[20]
7. The Ring test.^[21]
8. 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.^{[citation needed]}
9. The Camera Test. The subject brings a camera up to his/her face. Whichever eye is used to look through the viewfinder is the dominant eye.^{[citation needed]} This particular test is more indicative than it is certain; it is similar to unexpectedly throwing a ball at someone to see which hand they catch it with, which usually turns out to be the dominant hand.

Forced choice tests of dominance, such as the Dolman method, allow only a right or left eye result.^[12]

Treatment

It is possible to change eye dominance by actively suppressing the visual field of the dominant eye. This is achieved with an eye patch bandage that covers the dominant eye, with adhesive tape around the patch perimeter.

The eye patch does not need to be black to blot out all light, and the dominant eye does not need to stay closed. The eye patch simply presents the dominant eye with a static unchanging visual field containing nothing of visual importance, and the brain is forced to rely on the suppressed eye for visual information.

The experience does cause irritation and frustration for the eye patch wearer since their visual capabilities for comprehension will be reduced until the brain starts to adapt to not being able to use the dominant eye.

See also

• Ocular dominance column

References

1. ^ ^{a b} Chaurasia BD, Mathur BB (1976). "Eyedness". Acta Anat (Basel) 96 (2): 301–5. doi:10.1159/000144681. PMID 970109. 
2. ^ ^{a b} Khan AZ, Crawford JD (2001). "Ocular dominance reverses as a function of horizontal gaze angle". Vision Res. 41 (14): 1743–8. doi:10.1016/S0042-6989(01)00079-7. PMID 11369037. 
3. ^ Porac C, Coren S (1975). "Is eye dominance a part of generalized laterality?". Percept Mot Skills 40 (3): 763–9. PMID 1178363. 
4. ^ Reiss MR; Reiss, Gilfe (1997). "Ocular dominance: some family data". Laterality 2 (1): 7–16. doi:10.1080/135765097397602. PMID 15513049. 
5. ^ Ehrenstein WH, Arnold-Schulz-Gahmen BE, Jaschinski W (2005). "Eye preference within the context of binocular functions". Graefes Arch. Clin. Exp. Ophthalmol. 243 (9): 926–32. doi:10.1007/s00417-005-1128-7. PMID 15838666. 
6. ^ Eser I, Durrie DS, Schwendeman F, Stahl JE, Association between ocular dominance and refraction, Journal of Refractive Surgery, September 2008, pp. 685-9
7. ^ Quartley J, Firth AY (2004). "Binocular sighting ocular dominance changes with different angles of horizontal gaze". Binocul Vis Strabismus Q 19 (1): 25–30. PMID 14998366. 
8. ^ Banks MS, Ghose T, Hillis JM (2004). "Relative image size, not eye position, determines eye dominance switches". Vision Res. 44 (3): 229–34. doi:10.1016/j.visres.2003.09.029. PMID 14642894. 
9. ^ Van Strien JW, Lagers-Van Haselen GC, Van Hagen JM, De Coo IF, Frens MA, Van Der Geest JN (2005). "Increased prevalences of left-handedness and left-eye sighting dominance in individuals with Williams-Beuren syndrome". J Clin Exp Neuropsychol 27 (8): 967–76. doi:10.1080/13803390490919119. PMID 16207621. 
10. ^ Aygül R, Dane S, Ulvi H (2005). "Handedness, eyedness, and crossed hand-eye dominance in male and female patients with migraine with and without aura: a pilot study". Percept Mot Skills 100 (3 Pt 2): 1137–42. PMID 16158700. 
11. ^ Handa T, Shimizu K, Mukuno K, Kawamorita T, Uozato H (2005). "Effects of ocular dominance on binocular summation after monocular reading adds". J Cataract Refract Surg 31 (8): 1588–92. doi:10.1016/j.jcrs.2005.01.015. PMID 16129296. 
12. ^ ^{a b c d} Cheng CY, Yen MY, Lin HY, Hsia WW, Hsu WM (2004). "Association of ocular dominance and anisometropic myopia". Invest. Ophthalmol. Vis. Sci. 45 (8): 2856–60. doi:10.1167/iovs.03-0878. PMID 15277513. 
13. ^ Goldschmidt E, Lyhne N, Lam CS (2004). "Ocular anisometropia and laterality". Acta Ophthalmol Scand 82 (2): 175–8. doi:10.1111/j.1600-0420.2004.00230.x. PMID 15043536. 
14. ^ Brian Ariel. "Sports Vision Training: An expert guide to improving performance by training the eyes."
15. ^ Laby DM, Kirschen DG, Rosenbaum AL, Mellman MF (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. 
16. ^ Thomas NG, Harden LM, Rogers GG (2005). "Visual evoked potentials, reaction times and eye dominance in cricketers". J Sports Med Phys Fitness 45 (3): 428–33. PMID 16230997. 
17. ^ Handa T, Mukuno K, Uozato H, et al. (2004). "Ocular dominance and patient satisfaction after monovision induced by intraocular lens implantation". J Cataract Refract Surg 30 (4): 769–74. doi:10.1016/j.jcrs.2003.07.013. PMID 15093637. 
18. ^ Kromeier M, Heinrich SP, Bach M, Kommerell G (2006). "Ocular prevalence and stereoacuity". Ophthalmic Physiol Opt 26 (1): 50–6. doi:10.1111/j.1475-1313.2005.00344.x. PMID 16390482. 
19. ^ ^{a b} Roth HL, Lora AN, Heilman KM (2002). "Effects of monocular viewing and eye dominance on spatial attention". Brain 125 (Pt 9): 2023–35. doi:10.1093/brain/awf210. PMID 12183348. 
20. ^ Berens C, Zerbe J (1953). "A new pinhole test and eye-dominance tester". Am. J. Ophthalmol. 36 (7:1): 980–1. PMID 13065383. 
21. ^ Safra D (1989). "[The "Ring Test" for evaluating eye dominance]" (in German). Klin Monatsbl Augenheilkd 195 (1): 35–6. doi:10.1055/s-2008-1046410. PMID 2796230.