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下面是摘抄国际眼科学杂志的一篇论文。
优势眼测量法的研究
作者：Nimet nay Gündoan, Ay瘙塂e Canan Yazc, Ayten 瘙塁im瘙塂ek 作者单位：土耳其安卡拉市，巴斯肯特大学医学院生理学系
【摘要】 目的：为了检查一项新的性能测试，对同以受试者用两种不同的方法进行检测和再测试，并比较和讨论这些检测方法的可靠性。
方法：共179个大学生（平均年龄±标准差为19.37±1.62）a自愿参加这项由110名女性（61.5%）和69名男性(38.5%)组成的调查。优势眼由两种不同的方法检测，一个为McManus方法，一个为Gündoan方法。利用SPSS的重测信度的可靠性分析保证该项调查的可靠性。结果：McManus方法检测128名（71.5%）参加者右眼为优势眼，无性别差异。同样利用Gündoan 方法再检测发现110名（61.5%）参加者右眼为优势眼。 两种方法的检测结果由Fisher确切概率法分析发现呈显著性相关(P<0.01)，一致性数值为为κ=0.256，P<0.001。利用McManus法发现女性参加者中74名（67.3%）右眼为优势眼，36名（32.7%）左眼为优势眼。利用Gündoan法再检测发现62名女(56.4%)右眼为优势眼，48名女(43.6%)左眼为优势眼。通过Fisher确切概率法分析发现McManus和Gündoan两种方法在女性优势眼检测方面呈显著性相关(P<0.05),一致性数值为κ=0.239, P<0.01。在男性参与者中，通过McManus法检测右眼优势眼为54眼(78.3%)，左眼优势眼为15眼(21.7%)，利用Gündoan法再检测右眼优势眼为48眼(69.6%),左眼优势眼为21眼(30.4%)。利用χ2检验和Fisher确切概率法分析数据。利用Kappa一致性检验分析不同方法的一致性。比例的比较由z检验完成，P值小于0.05为差异显著。
结论：通过检测观察到女性和男性均以右眼优势眼为主，没有性别差异。右眼优势这种功能性偏侧化现象可能是由于大脑左半球的主导作用造成的。这对于将来在一侧面偏重方面的研究很重要，也许会成为一个重要的模式系统。
【关键词】 优势眼 优势眼测量法 功能性不对称 一侧面偏重
INTRODUCTION
In humans, the right cerebral hemisphere is dominant in visuospatial and nonverbal function such as art, architecture, geometry and mathematics, whereas the left cerebral hemisphere is dominant in recent verbal functions such as rhetoric, literature, and poetry [14]. Many theorists, particularly in the area of education, have focused on cerebral functional asymmetry called cerebral laterality, was diagnosed by hand preference. But various times the educational system has strong encouraged all children to write with their right hand. Although manifested handedness may be altered by training, but no attempts are made to change the eye dominance for detecting laterality and many authors have seen that dominant eye as a more fundamental measure of underlying cerebral laterality [58].
Despite having been written about for at least 400 years [9], and probably recognized much earlier, little is known about the functional origins of eye dominance [10]. Although many researchers would agree with the position of Peters [11] that just bilateral brain is likely to have problems in cocoordinating the rapid movements of the larynx and vocal cords in producing speech, so bilateral control will also be ineffective in eye movements, where "medial rectus of one eye has to be coordinated with lateral rectus muscle of the other eye" so that process may be better controlled by single, unilateral control mechanism which will give a reliable clue on the subject of the functional laterality of cerebral hemisphere.[10] Dominant eye is associated with hand preference which is most conventionally assessed in terms of the hand used for writing. However precise numerical nature of the relationship is extremely difficult to explain, and in a recent metaanalysis of the literature it was found that about 35% of righthanders and about 57% of lefthanders were left eye dominant[10]. The principal problem of the association of handedness and eye dominance is suggested to be asymmetrical distribution of the proportions (35% and 57%) are themselves asymmetrically distributed to either side of a value of 50% which can be regarded as the biological baseline for laterality [12]. Because of this fluctuating asymmetry between right and left eyes aroused a question in our mind: Could it be related with methodological errors? Could it be contaminated by hand preference? Which method could be more reliable for dominant eye measurement without hand contaminations? In order to clarify the role of methodological diversity in fluctuating asymmetry between the right and left eye dominances we establish a new measurable eye dominance performance method which will depend on objective criterions for assessing dominant eye.
MATERIALS AND METHODS
Participants This study was performed in accordance with the ethical standards of the Declaration of Helsinki 1994 which was approved by the local Ethics Committee of Ba瘙塂kent University (KA06/04). 179 healthy students with normal visual acuity (69 males, 38.5%, 110 females 61.5%) were investigated by assessing dominanteye. The age of all participants varied between 16 to 24 years (M=19.37 years SD±1.62). The ethnic origin was Caucasian. Informed consent was obtained from each participant.
Recruiment of the Students We explain to the students that if they have personal interest on the subject of cerebral laterality they should contact with us for participating voluntarily for the survey.
Procedure
McManus Tests Eye dominance assessed by monocular procedure, in which sighting was primarily with a single eye chosen by participants. All subjects were tested individually in the day lightened laboratory room during 12.0013.00 with adequate instruments. Eye dominance was assessed by performance measurement according to McManus test in which there were three items for eye sighting such as: looking through a narrow opening into a dark bottle, looking through keyhole, looking down monocular microscope [1315]. This test was performed twice. The eye that was unequivocally preferred in this situation was scored on a point scale 1=always left, 2=either, 3=always right. Dominant eye was accepted to be the left eye if the average score < 2 and to be the right eye if total score was ≥2[15]. Participants who had either eye dominant and who were aware of having a difference in acuity of more than two dioptres in their eyes were excluded.
Gündoan Test’s The same subjects were retested in the same laboratory conditions by means of the nearfar alignment test. The subject has to align two reference points in the horizontal eyelevel plane. The line running through the two targets intersects the interocular axis at mid point between the eyes. The intersection can be imagined as the fictive vantage point from which the two targets appear in the same direction. Two equal size black round shape reference points were used. The first point as a near point (NP) was on the middle of the fixed transparent thin glass board 0.4m away from the eyes which had two centimeter schedule were placed on both sides. The second reference point was a mobile far point (FP) 3.0 m away from the eyes on the wall (Figure 1A and Figure 2A). The subjects were asked to place their jaws and foreheads on the jaw support and headrest, and an elastic band was gently secured in order to avoid head movements. Then the subjects were asked to focus both eyes on the FP as the examiner move the FP till it comes at the same line with the reference NP. When the two points were overlapping in the same line, the subject was then directed to close one eye without moving his or her head and eyes. The examiner questioned whether points were shifting or not. If the reference NP shifted from the FP in the horizontal plane when one eye was closed, examiner asked to read the shifting distance between two points from the transparent board where centimeter schedule was placed on the two sides of the reference NP (Figure 1B,2B). The same procedure was repeated for other eye. The eye representing minimum shifting distance between two points was accepted to be dominant. Some subjects have very slight mismatches of shifting distant for both eyes were considered as two of them were dominant and these few subjects were excluded.Dominant eye measurement illustrated by Figure 2.
Statistical Analysis Data were shown as n(%). χ2 test and Fisher exact test were used for the analysis of categorical data. The agreement between different methods was analyzed with Kappa statistics. Comparison of proportions was made by two proportions z test. P<0.05 was considered as significant. Statistical analysis was performed using the SPSS 11.5 and MINITAB 13.0 for Windows.
RESULTS
Gündoan method depends on the measurement of shifting distance between NP and FPs on the horizontal plane for each eye when one of eye was closed. Without gender difference the mean values of shifting distance for all participants were (2.16±2.44)cm for the right eye, (3.35±2.47)cm for the left eye, the difference was significant (P<0.01). Among females the mean values of shifting distance were (2.38±2.38)cm for the right eye, (3.05±2.41)cm for the left eyes, the difference was also significant (P<0.01). In males the mean values of shifting distance were (1.81±2.51)cm for right eye, (3.83±2.50)cm for left eyes, the difference was not significant. It was remarkable that minimum and maximum values were exactly similar in all groups for both of two eyes (Table 1).
Without gender difference the incidence of right eye dominance were found for 128 subjects (71.50 %) by McManus test and for the same population the right eye dominance were found for 110 (61.5 %) subjects by Gündoan test. The left eye dominance were also found for 51 (28.5%) subjects by McManus test [15] and 69 (38.5%) subjects were found by Gündoan methods (P<0.05) for the same population (Table 2). 128 subjects which were found with right eye dominant by Mc Manus test, only 89 subjects of those were assessed with right eye dominant by Gündoan method and rest of 39 were assessed as they had left eye dominant.
According to McManus method, 51 subjects were assessed as they had left eye dominant, but among those only 30 subjects assessed with left eye dominant according to Gündoan test method. The rest of 21 subjects assessed as they had right eye dominant (Table 2). These two methods for detection of dominant eye was found to be related significantly according to Kappa test (P<0.001;κ=0.256). In females 74 subjects were found with right eye dominant and 36 subjects were found with left eye dominant by McManus test. But only 48 subjects of those were assessed with right eye dominant by Gündoan method and rest of 26 were assessed with left eye dominant. According to McManus method, 36 subjects were assessed as they had left eye dominant, but among those only 22 subjects assessed with left eye dominant according to Gündoan test method. The rest of 14 subjects assessed as they had right eye dominant. According to Gündoan test 62 subject were found with right eye dominance, 48 subjects were found with left eye dominant (Table 3).
In males, 54 subjects were found with right eye dominant and 15 subjects were found with left eye dominant by McManus test. But only 41 subjects of 54 subjects were assessed with right eye dominant by Gündoan method and rest of 13 were assessed with left eye dominant. According to McManus[15] method, 15 subjects were assessed as they had left eye dominant, but among those only 8 subjects assessed with left eye dominant according to Gündoan test method. The rest of 7 subjects assessed as they had right eye dominant. According to Gündoan test, 48 subjects were found with right eye dominance, 21 subjects were found with left eye dominant ( Table 4).
DISCUSSION
Ocular dominance was determined by means of the nearfar alignment test [16]. In this test the subject is asked to hold a pencil in one hand directly in front of himor herself. Then the subject is asked to align the tip with a point on distant wall with both eyes open. The subject is then asked alternatively to close one eye. Only when dominant eye is open and the other eye closed will the tip of pencil remain in good alignment with the point on the wall. The rest is repeated with the pencil in other hand [16, 17]. When in doubt a variant of the test another test method was administered, in which the subject is asked to focus on a point on distant wall through a hole formed by the opposed thumb and index finger of one hand then the hand is moved toward the face while focusing on the same point, until one of the eyes is reached, which indicates the dominant eye [18, 19]. Holding a pencil in hand or forming a hole by two fingers eye dominance can be contaminated by handedness.
On the other hand during monocular activities for assessing dominant eye holding some objects by hands, for instance observing the eye used to sight down a rifle may produce a spurious association with handedness due to the rifle typically being held with a finger of dominant hand on the trigger. Similarly looking through a small object such as kaleidoscope or bottle which is held in one hand, then the holding of object in dominant hand may well distort measures of association between handedness and eye dominance [10,15]. These methodological insufficiencies for detecting dominant eye were caused errors by hand use contamination. For this reason these methods were modified by Gündoan with restricting hand movements all through the tests (Figure 2). More over we add centimeter schedules on the two sides of NP which were gave us opportunity to have objective and measurable results for diagnosis of dominant eye (Figure 1B, Figure 2B).
Table 1The descriptive analyses(minmax)cm for measurements of shifting distance between two reference points for both eyes（略）
Table 2 Without gender difference dominant eye results for two methods were compared（略）
Table 3 Dominant eye results of two methods were compared for female subjects（略）
Table 4 Dominant eye results of two methods were compared for male subjects（略）
Previous studies to date have concluded that righteye dominance was greater than the lefteye dominance [1921]. In our study the ratios of right eye dominance was also found higher than the left eye dominance as without gender difference the right eye dominance were 71.5 % and 61.5% (Table 2) and among females the ratios were as 67.3%, 56.4%, and in males the ratios were 78.3% and 69.6% according to McManus and Gündoan tests respectively (Table 3, 4). So in our study we also found right eye dominance were greater than lefteye dominance both in male and female subjects as it was found for handedness in our previous study[22]. Interestingly, slight differences in using different brain areas for language processing were recognized between males and females [2325].
Authors mentioned that males use to prefer of their left eye rather than the right eye for monocular tasks such as sighting through a tube, about one third of the population was suggested to be left eye dominant [13]. In the first part of our study we assessed dominant eye with monocular activities by McManus test [15]. The subjects were asked to look trough a tip of dark bottle and the subjects were used to hold the bottle with their hand (Figure 6). As the subjects in the pictures A1 and A2 the bottle were holding by right hands in the picture A3 and A4 the other subjects prefer to hold with their left hands. This hand preference can be affected aye dominance determination as we mention before. This could be the cause of little differences between McManus [15] and Gündoan testretest results.
Figure 1 Ocular dominance was determined by means of the nearfar alignment test for right eye (RE) and for left eye (LE) A:The distance between near point (NP) and the far point (FP) from the eyes are seen;B:The centimeter schedule was placed on the two sides of the NP on the fixed transparent glass board for measuring shifting distance（略）
Figure 2 Eye dominance was measured by Gündoan performance method in the laboratory A icture shows reference FP which has mobile ability, according the direction of subject;Bicture shows the subject’s NP on the transparent glass in front of the eye level and also it can be seen hands and head fixation positions（略）
Figure 3 Without gender difference dominant eye results for two methods were compared（略）
Figure 4 Dominant eye distributions among female students（略）
Figure 5 The dominant eye distributions among male students（略）
In order to exclude hand contamination, during dominant eye assessment all through the performance tests period hand movements restricted (Figure 2B). Because of the frontal eye fields, which are important for the control of voluntary saccades, are located only about 20 mm anterior to the sensorimotor cortex for the hands [26]. So our test period this hand moving restriction, was not contaminated by handedness. We thought that hand movement restrictions should be very important point for correct assessment of eye dominance. Restricting head movements was also important for correct assessment of dominant eye which was stated to be altered according to visual field is being left or right side of the target point [27]. In our study restricting head movements we prevented shifting visual field during dominant eye assessment. Moreover when we asked form the subjects to close one of their eye the shifting distances between NP to FPs means were (2.16±2.44)cm for right eyes and (3.35±2.47)cm for left eyes. The difference between two values without gender difference were significant (P<0.01). In females the right eye mean value was (2.38±2.38)cm, left eye (3.05±2.41)cm. The difference between these two values was significant (P<0.01). In males the right eye(1.81±2.51)cm left eye (3.83±2.50)cm the difference betweenFigure 6 Monocular activities of McManus test. Looking through a bottlethese two values was not significant (ns) (Table 1). The comparisons of right and left eye shifting distance for all groups were analyzed by Wilcoxon sign test.
In all subjects minimum and maximum deviation distances values for both right and left eyes were showed constant distance as (0.006.50)cm (Table 1). This is an very important point for our study when we compared with previous study of Baykal et al[21] whose shifting distance values were much more higher than ours. Further more focusing point distances of our study were more homogenous [21]. This homogenous measurement seems to confirm the reliability of the Gündoan. During monocular activities such as McManus test researcher has not chance for objective criteria as measuring shifting distance and focusing points for a reliable diagnosis. In this point we thought Gündoan method may be found more reliable method for detecting dominant eye. On the other hand we put attention on a subject reliated with questions that which property was accepted by authors for detecting dominant eye? Sighting dominance, acuity dominance or sensory dominance? In the best review of the phenomenon on the basis of the assessment eye dominance authors mentioned that a carefully distinguish should be performed by investigators for sighting dominance from the others [28]. It was seen that a wide range of performance measures of dominance, sighting dominance has been proposed for dominant eye assessment [29, 30].
If the concept of eye dominance is to be useful for detecting cerebral functional laterality it should be reliable. It is therefore worth noting that a number of studies have found high consistency of repeated measures of sighting dominance [19, 31, 32]. This was the reason of our testing and retesting research procedure of our study and we compared Gündoan method results with the other most largely used monocular selection method of McManus for the same subjects.
Dominant eye has sometime been assessed using questionnaires concern with monocular activities [33, 34]. During monocular activities subject is asked to look through a small object which is held in one hand, then holding of object in dominant hand may well distort measure of the association between hand preference and eye dominance. In monocular activities show two specific problems; first the items may refer to activities such as holding a rifle, a bottle, or a kaleidoscope which are contaminated by hand preference [35]; and second there may be a process of set, whereby once a subject has consistently answered "right" or "left" to many handedness items, then they will merely carry on answering in same direction to other questions concerning eye dominance [10]. Because of those specific problems in our study we applied performance test for both McManus and Gündoan tests.
CONCLUSION
Gündoan performance test depend on measurement sigfting distance between reference points which can able to give a objective criterias for dominant eye assesment. It seems one of practically applicatable and reliable method for detecting dominant eye. The eye dominance was considering to show functional laterality due to the dominance one of hemisphere. It is an important topic future research in laterality, and it may well become an important model system for future research.
ACKNOWLEDGMENTS
Authors would like to appreciate Fatih zkul for his technical support during design of the eye dominance measurement device, and we would also like to thank to our university students for their voluntary participation to our reseach programme and to our medical research group students as Alp Tuna Beksac, Mehmet Emre G naydin, Sema Kurban and Isik Ocak for their excellent assistance during data collection.
英语水平好的，可以参考一下。 |
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楼主: 弦音
发表于 2010-6-10 13:15
显身卡
发表于 2010-6-11 18:26