Purpose

To analyze the response of normal emmetropic subjects to different ocular dominance tests and to analyze the influence of this response in surgically induced monovision.

Design

A prospective study of diagnostic accuracy was carried out to analyze the different tests to determine ocular dominance, without a gold standard test.

Methods

Nine different tests were carried out in a group of 51 emmetropic subjects to determine both motor and sensory ocular dominance. For analysis, patients were divided into two groups according to age. Normal ophthalmologic examination results were the inclusion requirement, with normal binocular vision and good stereoacuity.

Results

A significant percentage of uncertain or ambiguous results in all tests performed was found, except in the hole-in-card and kaleidoscope tests. When the tests were compared, two by two, the correlation or equivalence found was low and was much lower if tests were compared three by three.

Conclusions

No clear ocular dominance was found in most studied subjects; instead, there must be a constant alternating balance between both eyes in most emmetropic persons, but not in those with pathologic features. This fact would explain the great variability both between and within different kinds of tests. Also, it would establish that the monovision technique is well tolerated in most patients, with unsuccessful results only in those patients with strong or clear dominance. Consequently, it seems appropriate to evaluate patient’s dominance before monovision surgery to exclude those individuals with clear dominance.

Article Outline

Methods

Patients

Tests Performed

Hole-in-Card Test

Pointing-a-Finger Test

Kaleidoscope Test

Convergence Near Point Test

Plus 1 D Test (Near and Distance)

Worth Test Near and Distance

Polarized Test Near and Distance

Distance Stereotest

Haidinger Test

Statistical Analysis

Results

Discussion

Acknowledgements

References

Vitae

Surgically induced monovision has been attempted increasingly in recent years, with the aim of giving patients clear vision—both near and far—without the need for spectacles. The monovision technique corrects one eye for distance vision, and the other eye for near. In clinical practice, 95% of monovision patients have the dominant eye corrected for distance viewing, leaving the nondominant one for near vision, with induced anisometropia of not more than 2.50 diopters (D).^{[1] and [2]} This practice is based on the assumption that it will be easier to suppress blur in the nondominant eye than in the dominant one. It is commonly believed that knowing ocular dominance is important before surgery.

In 1903, Rosenbach was the first author to discuss ocular dominance. He claimed that most people had a dominant eye, even though each of their two eyes in isolation may provide equal vision and in unequal vision, the dominant eye is not always the eye with better visual acuity.³ In 1927, Hillemans carried out a study in which he found right ocular dominance in 40% of patients, left ocular dominance in 20% of patients, and uncertain results in 40% of patients.³ Both of these authors applied the pointing-a-finger test, in which patients try to align a pencil with a 6-m target.

The diagnostic tests that try to determine ocular dominance can be divided into two groups. The first group, motor tests, are those tests that force the subject to decide between one eye and the other. The pointing-a-finger and hole-in-card tests are the most widespread in this group. The second group consists of tests that measure a balance of sensory input between the eyes, in some cases permitting a graded quantification of this balance. Most of these tests use binocular rivalry targets^{[4], [5], [6], [7] and [8]} or stereodisparate objects^{[3] and [9]} to evaluate the magnitude of ocular dominance. To discriminate between both groups of tests, the terminology used varies according to different authors. In general, the first group of tests are referred to as sighting eye dominance or ocular dominance tests and the second group of tests as ocular prevalence^{[3] and [9]} or sensory eye dominance^{[4] and [5]} tests. Some studies have tried to evaluate whether the two types of tests are equivalent. Ooi and He, in 2001, concluded that interocular balance determines a sensory eye dominance that cannot be equated with motor eye dominance, suggesting that there is a dichotomy between these two types of eye dominance.⁵ Other reports stated similar conclusions.^{[10] and [11]} However, other study groups, such as Kommerell and associates and Handa and associates, have found a correlation between ocular dominance and prevalence.^{[3] and [4]}

Despite the clear controversy, more and more series of monovision patients are being published. Most of them use only one test to determine the ocular dominance, in general a motor test. The goal of this study was to analyze the response of normal subjects to both kinds of tests to evaluate whether equivalence exists not only between both groups, but also among the different tests within each group. Clarification of the reliability of these tests in predicting ocular dominance in normal subjects may direct further studies usefully in the assessment of ocular dominance in subjects seeking refractive correction in whom monovision may be planned as an outcome.

Methods

Patients

A prospective study of the diagnostic accuracy of ocular dominance tests was carried out in a group of normal subjects. Fifty-one emmetropic subjects with normal ophthalmologic examination results underwent ocular dominance testing (details below). All patients were emmetropic with a spherical equivalent between −1 and +1 in both eyes and equal visual acuity of at least 20/20 in both eyes. Objective and subjective graduation were carried out. Other inclusion requirements were normal binocular vision and fusion, stereoacuity of 60 seconds of arc (sec arc) or better, and normal retinal correspondence; all were checked by synoptophore analysis, TNO Stereoacuity test, and the Bagolini test. Patients who had any motor dysfunction, such as convergence insufficiency, were excluded. All dominance tests were performed with the exact spectacle correction for the test distance, in the same room and under the same luminance conditions. Contrast sensitivity also was tested in each patient to analyze whether an association exists between high contrast sensitivity and ocular dominance. Patients were divided for analysis into two groups by age: a young adult group that included those aged between 18 and 35 years and an adult group that included those aged between 35 and 60 years. This analysis by age group was carried out because binocular functions are known to decline with increasing age.⁶

Tests Performed

To determine sighting ocular dominance or motor dominance, the following tests (which force a choice between one eye or the other) were carried out:

Hole-in-Card Test

The patient holds a card with a hole in the middle using both hands and is asked to view a 6-m target through the hole in the card. The observer then occludes each eye alternately to establish which eye is aligned with the hole and the distance target. The selected eye is considered the dominant eye. The process is repeated; the second time, the subject moves the card slowly toward his face without losing the alignment with the fixation point until the hole is over an eye. This is considered to be the dominant eye (Figure 1).

FIGURE 1. Hole-in-card test. The patient holds a card with a hole in the middle using both hands and is asked to view a 6-m target through the hole in the card. The observer then occludes each eye alternately to establish which eye is aligned with the hole and the distance target. The selected eye is considered the dominant eye.

Pointing-a-Finger Test

The subject is asked to hold a pencil, using both hands and with the arms extended, and align it with a 6-m target. With alternating occlusion, the observer determines which eye remains in line with the distant point. That eye is the dominant one (Figure 2).

FIGURE 2. Pointing-a-finger test. The subject is asked to hold a pencil, using both hands and with the arms extended, and to align it with a 6-m target. With alternating occlusion, the observer determines which eye remains in line with the distant point. That eye is the dominant one.

Kaleidoscope Test

The patient is asked to hold a kaleidoscope using both hands and to look thought it. To do this, the subject will choose one eye, which will be the dominant one. This test also can be carried out using a monocular microscope, camera viewfinder, or similar monocular instrument.

Convergence Near Point Test

During testing for near point of convergence, the eye that breaks first and diverges is the nondominant eye.

To establish the sensory ocular dominance, also called ocular prevalence, the following tests were performed:

Plus 1 D Test (Near and Distance)

With the patient looking at a 6-m distance optotype, a +1 D lens is added first to one eye and then to the other. The patient (knowing that both of them give him worse visual quality than the correct refraction) must decide which of the two situations is more comfortable. If the patient is more comfortable with the +1 D lens over the right eye, then the left eye is the dominant one, and vice versa. The same test is repeated using a near target; however at near, if the patient is more comfortable with the lens over the right eye, the right eye is dominant, and if the patient is more comfortable with the lens over the left eye, the left eye is dominant.

Worth Test Near and Distance

In the Worth four-dot test, the patient views the target wearing red–green spectacles, first with a red filter over the right eye then with the green filter over the right eye. The response to the white dot is what is important. In the case of ocular dominance, this will appear to have a reddish color, with the red filter over the dominant eye, and a greenish color, with the green filter over the dominant eye.

Polarized Test Near and Distance

Two lines of numbers are shown to a subject wearing dissociative polarized spectacles (which cause each line to be seen with a different eye). The subject has to evaluate whether he sees one line of numbers as being sharper than the other, in which case the eye that sees the line more clearly is the dominant one.

Distance Stereotest

The patient, who wears polarized spectacles, is asked to look at a figure situated 6-m distant and that is composed of four lines, two horizontal and two vertical, forming a cross and leaving a gap in the center where there is a point that presents a stereodisparity with the four lines. The patient should observe whether the two vertical lines are aligned with the point or if they are displaced to one side. If there is displacement toward the right, then the right eye is considered the dominant one and vice versa (Figure 3).

FIGURE 3. Distance stereotest. The patient, who wears polarized spectacles, is asked to look at a figure 6-m away that is composed of four lines, two horizontal and two vertical, forming a cross and leaving a gap in the center where there is a point that presents a stereodisparity with the four lines. The patient should observe whether the two vertical lines are aligned with the point or if they are displaced to one side. If there is displacement toward the right, then the right eye is considered the dominant one and vice versa.

Haidinger Test

This test is performed using a synoptophore (Figure 4). The patient sees a light propeller, which revolves clockwise using the right eye, and another propeller that revolves anti-clockwise with the left eye. These are viewed separately at first and then at the same time. Simultaneous viewing gives rise to the perception of a flapping movement, but this may then settle into a predominantly rotational movement. If clockwise movement predominates, the right eye is the dominant one, and if anti-clockwise movement predominates, the left eye is dominant. After dominance has been established, it is quantified by means of decreasing the contrast of the propeller target seen by the dominant eye in 5% percentage steps (from 100% value) until flap movement is observed again or until the opposite rotation is observed. The percentage contrast then is measured, and the original level of dominance is calculated from this. For example, if the perception of a flap movement occurs at 70% contrast, the dominance is calculated as being 30%.

FIGURE 4. Synoptophore. It is necessary to perform a Haidinger test, in which the patient sees a light propeller, which revolves clockwise using the right eye, and another propeller that revolves anti-clockwise with the left eye. These are viewed separately at first and then at the same time. Simultaneous viewing gives rise to the perception of a flapping movement, but this may then settle into a predominantly rotational movement. If clockwise movement predominates, the right eye is the dominant one, and if anti-clockwise movement predominates, the left eye is dominant.

Statistical Analysis

Qualitative variables were expressed in terms of absolute frequencies and percentages, whereas quantitative variables were expressed with means and standard deviations. To measure the association among the qualitative variables and to compare proportions, a two-tailed Pearson chi-square test was used, except when the groups to be analyzed contained insufficient numbers, in which case the Fisher exact test was selected. The κ statistic was used to assess the agreement between the different tests. A P value ≤ .05 was considered to be significant. SPSS software for Windows version 12 (SPSS Inc, Chicago, Illinois, USA) was used for statistical analysis.

Results

There were 26 subjects in the young adults group with a mean ± standard deviation (SD) age of 26 ± two years and an age range of 18 to 34 years. Of the 26 patients, 30.8% were male and 69.2% were female. In the adult group, there were 25 subjects ranging from 36 to 56 years of age and with a mean ± SD age of 43.68 ± 5.91 years. Forty-four percent were male and 56% were female. As per the inclusion criteria, all were emmetropes with 20/20 (1.0) vision in each eye.

The results of sighting ocular dominance tests (i.e., those that force a choice between one eye and the other), are summarized in Table 1. The results of the sensory ocular dominance or ocular prevalence tests (those that evaluate the balance between the eyes) are summarized in Table 2, showing the proportion of cases in which dominance could not be attributed. There was no strong near-distance agreement for the +1 D test (Table 3), the results of which could be a random distribution. In both young and adult groups qualitative levels of dominance using the Haidinger test ranged from 10% to 40%. This test is challenging for patients to perform, and this may explain the high proportion of uncertain dominance using this test, particularly in the older subgroup.

TABLE 1.

Results of Sighting Ocular Dominance Tests in 51 Emmetropic Patients

	Younger Group			Older Group
	Right	Left	Uncertain	Right	Left	Uncertain
Hole-in-card	50	50	—	60	40	—
Finger pointing	46.2	30.8	23	40	48	12
Kaleidoscope	69.2	30.8	—	60	40	—
Convergence near point test	33.3	37.5	29.2	36	24	40

The Table shows the percentage of right, left, and uncertain dominance in different motor tests, testing emmetropic subjects divided by age (a younger group 18 to 35 years of age and an older group 35 to 60 years of age). The hole-in-card and kaleidoscope tests did not have uncertain results. There were no significant differences between the two age groups studied (P > .05).

TABLE 2.

Results of Sensory Ocular Dominance (or Prevalence) Tests in 51 Emmetropic Patients

	Younger Group			Older Group
	Right	Left	Uncertain	Right	Left	Uncertain
+1-diopter test
Distance	38.5	50	11.5	20	52	28
Near	26.9	34.6	38.5	32	36	32
Finger pointing
Distance	11.5	23.1	65.4	8	32	60
Near	7.7	15.4	76.9	8	16	76
Kaleidoscope
Distance	26.9	15.4	57.7	24	28	48
Near	30.8	19.2	50	36	16	48
Distance stereo	7.7	15.4	76.9	4	4	92
Haidinger test	38.5	23.1	38.5	24	16	60

The Table shows the percentage of right, left, uncertain dominance in different sensory tests, testing emmetropic patients divided by age (a younger group 18 to 35 years of age and an older group 35 to 60 years of age). Most of these tests show an important percentage of uncertain results; the test that showed fewer nondominance results was the +1 diopter test for distance. There were no significant differences between the two age groups studied (P > .05).

TABLE 3.

Ocular Dominance Results for Distance and Near Viewing, Testing Emmetropic Patients with +1 Diopter Test

	Younger Group	Older Group
Different eye dominant, near and distance	7	4
Same eye dominant, near and distance	7	10
Dominant eye for one distance and nondominance at another	12	11

The Table shows the number of patients who had the same dominant eye for near and distance viewing, one eye for near and the other for distance, or a result of nondominance for one distance using the +1 diopter test. These results could be a random distribution.

There were no statistically significant differences between test outcomes among the two age groups, although there was a tendency toward differences in some of the test data. The clearest difference was found in the nondominance percentage observed in the two age groups using the Haidinger test, which increased considerably in the older age group. However, larger study numbers would be required to show any statistically significant difference.

Tests were compared, two by two, and the maximum correlation or equivalence in the first group of tests (single with κ > 0.5) was found between the hole-in-card test and the kaleidoscope test: 21 (80.78%) of 26 cases with an index κ of 0.615 in young adults and 21 (84%) of 25 cases with an index κ of 0.667 in mature adults. The equivalence between the hole-in-card and pointing-a-finger tests was 15 (57.69%) of 26 cases in the young group and 17 (68%) of 25 cases in the older group, which seems a very low correlation bearing in mind that the essential mechanism of both tests is practically the same. The correlation between the kaleidoscope test and the convergence near point test also was low: 15 (57.69%) of 26 cases in the young group and 17 (68%) of 25 cases in the older group (Table 4).

TABLE 4.

Correlation between Different Dominance Test Results in Emmetropic Patients

Correlation Between Tests	Younger Group	Older Group
Hole-in-card / pointing-a-finger	58%	68%
Hole-in-card / kaleidoscope	81%	84%
Hole-in-card / convergence near point test	50%	48%
Pointing-a-finger / kaleidoscope	58%	68%
+1 D test / Haidinger test	42%	20%
Hole-in-card / +1 D test	58%	40%
Hole-in-card / Haidinger test	42%	28%
Hole-in-card / +1 D test / Haidinger test	27%	12%

D = diopter.

All the tests performed were compared, two by two and three by three, showing in this Table the percentages of correlation between the results. Note the lower percentage of agreement obtained among most of them. The correlation between the tests that were not collected in this Table was negligible: less than 20% in each case.

Analyzing the correlation between sensory ocular dominance tests, we found that there was only 42% agreement between the Haidinger test results and the +1 D test results (11 of the 26 subjects; κ, 0.167) in the young adult group and 20% (five of 25; κ, 0.144) in the older group. The correlation between the other sensory tests was negligible: less than 20% in each case (Table 4).

Finally, the correlation between the two types of tests was analyzed: sighting ocular dominance and sensory ocular dominance. The agreement between the hole-in-card test and the +1 D distance test was 58% (15 of 26) in young adults and 40% (10 of 25) in older adults. The agreement between the hole-in-card test and Haidinger test was 42.3% (11 of 26) in the younger group and 28% (seven of 25) in the older group. Therefore, there was no statistical correlation in any of the comparisons between the motor and sensory tests (κ < 0.5). When correlation among three tests was analyzed using the hole-in-card test, Haidinger test, and +1 D test, there was a correlation of 27% (seven of 26) in younger group and only 12% (three of 25) in the older group. Comparing other tests three by three resulted in a correlation lower than 27% in each case (Table 4).

Discussion

For an ocular dominance test to be useful clinically, it needs to produce unequivocal results in most patients, and these results must be meaningful in relation to a clinical problem. Analyzing the four sighting ocular dominance tests (Table 1), the pointing-a-finger test and convergence near point test both obtained a significant percentage of nondominance cases (ranging from 12% to 40%), although these are forced choice tests. The justification for these results is that the pointing-a-finger test creates physiological diplopia of the finger while the subject looks at the distant target, and many subjects were unable to choose between two equal images while trying to align the pencil; and in the near point of convergence test, a proportion of the patients broke fixation with both eyes simultaneously and the dominance therefore could not be determined. Only the hole-in-card test and kaleidoscope test do not produce undetermined results, and for this reason, if a single test from this group is chosen for assessment in potential monovision, it should be one of these two; this also probably accounts for the hole-in-card test being one of the most widely used dominance tests. However, other factors must be remembered in the use of this test. First, it has significant intratest variability, and second, it is highly influenced by horizontal gaze angle (ocular dominance can switch at gaze angles of only 15.5 degrees off primary gaze^{[12] and [13]}). In addition, and as this study shows, it has very poor correlation with other motor tests, such as the pointing-a-finger test, which have almost the same mechanism. Because of these issues, the hole-in-card test does not seem to be an ideal test for ocular dominance. All this variability seems to indicate the following fact: either there is not a clear ocular dominance in many of the subjects, or none of the tests seems the appropriate one to detect it.

Of the sensory ocular dominance tests (Table 2), the Worth test, distance stereotest, and polarized test are unable to classify dominance in a high proportion of subjects, despite both the distance stereotest and the polarized test being dominance-specific tests. The Haidinger test, which is the only test in this study that was capable of quantifying the degree of dominance of an eye, also has a high proportion of uncertain results, particularly in mature adults (60%). The +1 D test produced a much lower percentage of nondominance cases, particularly for distance testing: 11.5% in the younger group and 28% in the older group. For near distance, nondominance cases increased slightly: 38.5% in the younger group and 32% in the older group. Furthermore, this test produces the situation most similar to monovision, so it seems to be a useful test. However, very poor correlation exists between the +1 D test, the Haidinger test, the polarized test, and the other sensory tests.

The number of subjects with clear ocular dominance depends on the number and type of tests used. The use of more than one test of ocular dominance will increase specificity but decrease the number of participants with clear ocular dominance. Combining the results of the hole-in-card test and the +1 D test showed 58% concordance in the younger group and 40% in the older group. When three tests were used in combination (hole-in-card, +1 D, and Haidinger test), only 27% concordance in ocular dominance existed in the younger group and 12% existed in the older group.

It is clear from this study that most of the studied subjects did not show clear ocular dominance using the tests carried out, because the results were very variable and little correlation was found between the tests. Most people may have a constant alternating balance between both eyes, rather than clear dominance. This hypothesis explains the great variability both between and within different kinds of test results.

Monovision is a method designed in 1958 by Westmith for presbyopic contact lens wearers, with 50% to 76% success.^{[1] and [14]} Ocular microsurgery development has made possible its use in intraocular lens implantation and refractive surgery (including corneal refractive surgery and phakic lenses). The average success of surgical monovision is approximately 70% to 97.6%.^{[1], [2], [15], [16], [17] and [18]}

Published surgical monovision studies have used a single test to determine the dominant eye before surgery. In addition, in many of these studies, a motor test was chosen, despite the sensory tests approaching more closely the clinical situation of a monovision patient. Sometimes, the dominance test used is not described (how it is carried out, whether it is repeated, and so forth), and sometimes it is not even named.

Despite this, the success rate of the different series is similar. This may be because most of the persons in whom monovision proves successful are those without a clear dominance, whereas the minority of patients who do not tolerate monovision are those who have strong and evident ocular dominance. What would happen if the right eye were always corrected for far viewing? Would the same percentage of successful results be obtained? A study carried out by Jain and associates, which compared the satisfaction level of 24 patients with classical monovision (dominant eye for far distance) and 18 patients with crossed monovision (dominant eye for near distance), found a high degree of satisfaction in both groups (88%) without statistically significant differences between them.¹⁹ Cheng and associates studied patients with myopia and anisometropia higher than 1.75 D and found that the dominant eye was more myopic—with better near vision—in 100% of them.²⁰ Our hypothesis of an absence of true ocular dominance in most of the population would account for these results. But what occurs with the minority of the population in whom monovision fails? Failure of monovision has been reported in individuals with strong preexisting ocular dominance.^{[1], [7] and [21]} If it is accepted that in most individuals dominance is absent, it would be more precise to use the terms “clear” or “real” dominance rather than strong dominance. This would suggest that the tests of ocular dominance, rather than determining right or left dominance, should be directed more toward exclusion of clearly dominant subjects, who would be expected not to tolerate monovision. Another option is to carry out a trial of monovision contact lenses²² before surgery to indicate whether the patient is likely to tolerate permanent monovision.

Another important issue regards the results obtained from tests performed for near and far distances. There seems to be a random association: some subjects have the same dominant eye for both distances; others use one eye for near and the other distance, and so forth. In most cases, we have not shown a clear eye dominance at both distances, but it may be that individuals who have the same dominant eye for far and near (a clear dominant eye) are susceptible to problems, because monovision forces them to change their dominance at one of the two viewing distances.

Finally, we should not forget that the monovision technique induces changes in binocular vision, being restricted in certain professions such as pilots, professional drivers, competition sports, and so forth.¹⁵ Fawcett and associates examined binocular vision in adults with longstanding surgical monovision (six months or more).²³ They found significantly reduced stereoacuity and absence of foveal fusion. Parks observed absence of bifixation after three months with monovision.²⁴ Kushner and Kowal included iatrogenic monovision as one of the five mechanisms that cause diplopia after refractive surgery.²⁵ Consequently, it is important to realize that although most people do not report symptoms, this does not mean that binocular vision is not being modified. The long-term effects of this technique are not completely known as yet. We should not forget that binocular vision is one of our advanced functions as human beings.

To conclude, no clear dominance existed in most of the studied subjects; in fact, the dominant eye changed, in the same person, depending on the test used. Indeed, a constant alternating balance between both eyes should exists in most emmetropic persons and those without pathological features. Among the motor tests, the hole-in-card test is the most effective in that it forces a choice between the eyes, and within the sensory group, the test with fewest uncertain results is the +1 D test, which is also the closest approach to clinical the situation in monovision. According with these results, it seems appropriate to evaluate a patient’s dominance before monovision surgery, not simply to determine right or left dominance, but in fact to exclude those individuals with strong or clear dominance. For that, it would be necessary to carry out more than one test or to use a method that evaluates the magnitude of ocular dominance.

The authors indicate no financial support or financial conflict of interest. Involved in design of study (O.S., P.G.L., R.G.L.); conduct of study (O.S., P.G.L.); Analysis and interpretation (O.S., P.G.L., R.G.L.); writing the article (O.S., C.J.R.); critical revision of the article (P.G.L., R.G.L.); data collection (E.P., E.D.); provision of materials, patients, or resources (P.G.L., R.G.L., E.P., E.D.); and statistical analyses (O.S.). All subjects provided written informed consent before participating in this study, and the tenets of the Declaration of Helsinki were followed. The design and performance of this study were not interventional and were without risk for patients, and were approved by the Ethics Committee of University Hospital “Gregorio Marañon.”

References

1 K.W. Wright, A. Guemes, M.S. Kapadia and S.E. Wilson, Binocular function and patient satisfaction after monovision induced by myopic photorefractive keratectomy, J Cataract Refract Surg 25 (1999), pp. 177–182. Abstract | View Record in Scopus | Cited By in Scopus

2 D.B. Goldberg, Comparison of myopes and hyperopes after laser in situ keratomileusis monovision, J Cataract Refract Surg 29 (2003), pp. 1695–1701. SummaryPlus | Full Text + Links | PDF (205 K) | View Record in Scopus | Cited By in Scopus

3 G. Kommerell, C. Schmitt, M. Kromeier and M. Bach, Ocular prevalence versus ocular dominance, Vis Res 43 (2003), pp. 1397–1403. Abstract | View Record in Scopus | Cited By in Scopus

4 T. Handa, K. Mukuno, H. Uozato, T. Niida, N. Shoji and K. Shimizu, Effects of dominant and nondominant eyes in binocular rivalry, Optom Vis Sci 81 (2004), pp. 377–383. Full Text via CrossRef

5 T.L. Ooi and Z.J. He, Sensory eye dominance, Optometry 72 (2001), pp. 168–177.

6 K. Ukai, H. Ando and J. Kuze, Binocular rivalry alternation rate declines with age, Percept Motor Skills 97 (2003), pp. 393–397. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus

7 T. Handa, K. Mukuno and H. Uozato et al., Ocular dominance and patient satisfaction after monovision induced by intraocular lens implantation, J Cataract Refract Surg 30 (2004), pp. 769–774. SummaryPlus | Full Text + Links | PDF (134 K) | View Record in Scopus | Cited By in Scopus

8 T. Handa, H. Uozato and R. Higa et al., Quantitative measurement of ocular dominance using binocular rivalry induced by retinometers, J Cataract Refract Surg 32 (2006), pp. 831–836. SummaryPlus | Full Text + Links | PDF (206 K) | View Record in Scopus | Cited By in Scopus

9 S.P. Heinrich, M. Kromeier, M. Bach and G. Kommerell, Vernier acuity for stereodisparate objects and ocular prevalence, Vis Res 45 (2005), pp. 1321–1328. Abstract | View Record in Scopus | Cited By in Scopus

10 R. Blake and J. Camisa, On the inhibitory nature of binocular rivalry suppression, J Exp Psychol Hum Percept Perform 5 (1979), pp. 315–323. Abstract | Full Text via CrossRef | View Record in Scopus | Cited By in Scopus

11 C. Porac and S. Coren, Sighting dominance and binocular rivalry, Am J Optom Physiol Opt 55 (1978), pp. 208–213. View Record in Scopus | Cited By in Scopus

12 J. Quartley and A.Y. Firth, Binocular sighting ocular dominance changes with different angles of horizontal gaze, Binocul Vis Strabismus Q 19 (2004), pp. 25–30. View Record in Scopus | Cited By in Scopus

13 A.Z. Khan and J.D. Crawford, Ocular dominance reverses as a function of horizontal gaze angle, Vis Res 41 (2001), pp. 1743–1748. Abstract | View Record in Scopus | Cited By in Scopus

14 S. Greenbaum, Monovision pseudophakia, J Cataract Refract Surg 28 (2002), pp. 1439–1443. SummaryPlus | Full Text + Links | PDF (87 K) | View Record in Scopus | Cited By in Scopus

15 K.R. Johannsdottir and L.B. Stelmach, Monovision: a review of the scientific literature, Optom Vis Sci 78 (2001), pp. 646–651.

16 C.D. Reilly, W.B. Lee, L. Alvarenga, J. Caspar, F. García-Ferrer and M.J. Mannis, Surgical monovision and monovision reversal in LASIK, Cornea 25 (2006), pp. 136–138. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus

17 D. Miranda and R.R. Krueger, Monovision laser in situ keratomileusis for pre-presbyopic and presbyopic patients, J Refract Surg 20 (2004), pp. 325–328. View Record in Scopus | Cited By in Scopus

18 S. Jain, I. Arora and D.T. Azar, Success of monovision in presbyopes: review of the literature and potential applications to refractive surgery, Surv Ophthalmol 40 (1996), pp. 491–499. Abstract | View Record in Scopus | Cited By in Scopus

19 S. Jain, R. Ou and D.T. Azar, Monovision outcomes in presbyopic individuals after refractive surgery, Ophthalmology 108 (2001), pp. 1430–1433. SummaryPlus | Full Text + Links | PDF (318 K) | View Record in Scopus | Cited By in Scopus

20 C.Y. Cheng, M.Y. Y en, H.Y. Lin, W.W. Hsia and W.M. Hsu, Association of ocular dominance and anisometropic myopia, Invest Ophthalmol Vis Sci 45 (2004), pp. 2856–2860. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus

21 T. Handa, K. Shimiku, T. Kawamorita and H. Uozato, Effects of ocular dominance on binocular summation after monocular reading adds, J Cataract Refract Surg 31 (2005), pp. 1588–1592. SummaryPlus | Full Text + Links | PDF (125 K) | View Record in Scopus | Cited By in Scopus

22 M.M. Hom, Monovision and LASIK, J Am Optom Assoc 70 (1999), pp. 117–122.

23 S.L. Fawcett, W.K. Herman, C.D. Alfieri, K.A. Castleberry, M.M. Parks and E.E. Birch, Stereoacuity and foveal fusion in adults with long-standing surgical monovision, JAAPOS 5 (2001), pp. 342–347. Abstract | View Record in Scopus | Cited By in Scopus

24 M.M. Parks, Monofixation syndrome: presbyopia monovision follow-up, Binocul Vis Strabismus Q 15 (2000), p. 312. View Record in Scopus | Cited By in Scopus

25 B.J. Kushner and L. Kowal, Diplopia after refractive surgery: occurrence and prevention, Arch Ophthalmol 121 (2003), pp. 315–321. View Record in Scopus | Cited By in Scopus

Inquiries to Olga Seijas, c/o Infanta Maria Teresa, 18 5° A., 28016 Madrid, Spain

Vitae

Olga Seijas, MD, received her medical degree from Complutense University, Madrid, Spain and is undertaking her forth year of residency training in Ophthalmology in Gregorio Marañon Universitary Hospital, Madrid, Spain. Dr Seijas completed her doctoral research in Complutense University (2005 to 2006) in the subject “High resolution orbital imaging in extra-ocular muscles pathology”. Dr Seijas has several publications, and she has participated in four chapters of different books in the areas of strabismus and binocular vision.