Ocular dominance

Ocular dominance, sometimes called eye preference 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 (See Optic Tract for more details). There is thus no direct analogy between "handedness" and "eyedness" as lateral phenomena.^[4]

Approximately 70% of the population are right-eye dominant and 29% left-eye dominant.

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.^[13] 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.^[14]

Dominance can change and may switch between the eyes depending on the task and physical condition of the subject (i.e. fatigue).^{[citation needed]}

Effects

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.

In a 1998 study of professional baseball players, hand–ocular dominance patterns did not show an effect on

A person's dominant eye "is determined by subjective alignment of two objects presented at a stereodisparity far beyond Panum's area".^[21] 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).^[22][23][24]
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).^[23][25][26]
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).^[27]
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.^[27]
5. Certain stereograms.^[28]
6. The pinhole test.^[29]
7. The ring test.^[30]
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.
9. A dichoptic motion coherence threshold test yields a quantified indication of ocular dominance.^[31]

Forced choice tests of dominance, such as the Dolman method, allow only a right or left eye result.^[27]

See also

• Ocular dominance column
• Right- and left-hand traffic

References