Binocular vision

This essay reviews major developments - empirical and theoretical - in the field of binocular vision during the last 25 years. We limit our survey primarily to work on human stereopsis, binocular rivalry and binocular contrast summation, with discussion where relevant of single-unit neurophysiology and human brain imaging. We identify several key controversies that have stimulated important work on these problems. In the case of stereopsis those controversies include position vs. phase encoding of disparity, dependence of disparity limits on spatial scale, role of occlusion in binocular depth and surface perception, and motion in 3D. In the case of binocular rivalry, controversies include eye vs. stimulus rivalry, role of “top-down” influences on rivalry dynamics, and the interaction of binocular rivalry and stereopsis. Concerning binocular contrast summation, the essay focuses on two representative models that highlight the evolving complexity in this field of study.     

Binocular fields with lateral-eyed vision

A simple geometrical model is constructed of the binocular field in animals with laterally directed eyes (such as the pigeon). Height and width are derived as a function of elevation, for eye-centred and for cyclopean co-ordinates. Stereoscopic vision in the frontal field is considered, and it is pointed out that convergence movements can facilitate stereopsis even in an afoveate periphery.     

Binocular vision section.

The participants at the 1991 Meetings of the Section on Binocular Vision and Perception presented a substantial amount of valuable theoretical and clinical information. There was considerable and valuable interaction between the audience and panel, especially after the symposium concerned with new techniques and how to use them. The exchange of specialized knowledge through discussions at symposiums such as these represents one of the best features of Academy meetings. These symposiums reemphasize and remind us of the expertise of our Academy members in management of binocular vision anomalies.     

26例复视患者的双眼视觉

目的了解复视患者双眼视觉的特点。方法采用同视机及立体视觉检查图检测复视患者的双眼视觉,记录结果并进行统计学分析。结果复视患者都可以查到异常的重合点,水平复视和垂直复视的水平融合范围均小于正常的融合范围,差异均有显著性意义(P<0.05);复视患者都可以查到周边立体视:用同视机检查可以查出三级功能而用立体视觉检查图则查不到近立体视。结论复视患者可能存在有三级双眼单视功能。     

Binocular vision after lens implantation

Orthoptic tests for binocular vision were performed on 107 patients with intraocular lenses 3 to 10 months after surgery. The tests carried out were: cover test, Worth-test, Lang's two-pencil-test, the TNO-test and Lang's stereo-test. The implanted lenses were of the four-loop Binkhorst type. They were all implanted after planned extracapsular surgery. Visual acuity 3 to 10 months after operation was 0.5 or more in 95% of the patients (0.8 or more in 53% of the patients). Refraction in spheric equivalents was -0.7 +/- 1.26 diopters. The calculated optical aniseikonia was 2.2% +/- 1.8%. Orthotropia as disclosed by the unilateral cover-test prevailed in 81% of the patients. Most of the patients were exotrop (14 patients for the near, 6 patients for the near and the far). The results of Lang's two-pencil-test were positive in 89%. The Worth-test (polarized, for distance) showed suppression in 23% of the patients. The random-dot-test (TNO-test) showed positive results in 68% (retinal disparities 1980 arc seconds or less), in 57% (480 arc seconds or less), and the new Lang stereotest in 58% (1200 arc seconds or less) of the patients.     

Binocular vision and fusion movements

Summary The previous chapter begins with a discussion of the relation between binocular vision and fusion movement based on one's own interpretation built upon the ideas of many writers and one's own opinions.The concepts of binocular vision and fusion movement are inseparably united because the sensory and motor effects of vision in its broadest sense are indistinguishable.We speak in detail of localisation in space, this being primarily egocentric, that is, in relation to the observer, but which may also be relative, that is, when it concerns the relation of the stimuli to each other in space. We observe space about us as three-dimensional; the coordination-system of this Euclidian space originates in the ego. This is the system in which various sensations aroused by stimuli from the objective space are organised in the subjective space, the conception of which exists a priori.Attention is then paid to the precision with which the eye can localise these cardinal surfaces. This can be determined experimentally. The manner in which both retinae work together becomes thus apparent. This is included in the conception of identical points and disparate points, essential ideas in the understanding of stereopsis. This may be normal, disturbed or anomalous, the localisation in space showing corresponding differences in character.The localisation theory of Roelofs is discussed. This determining the relation between the retinal stimulus, the light sensation, the motor impulse and the resulting fusion movement. The value of this theory in comparison with those of Hering, Tschermak e.a. is discussed. To understand the functional unit the double eye one must distinguish the significance of sensory fusion (synchysis of v. Kries) and that of motor fusion and know the margins within which these occur. The influence of the observation time on synchysis indicates that this is probably a cortical function. The retinal origin effusion movements is made very acceptable by the theory of Roelofs.Finally a critical review of various methods for examining stereoscopic vision is given, attention being paid especially to the fact that the instruments used in practice are mostly unsuitable for research work.

---

Zusammenfassung Nach einer Übersicht über die Beziehungen des Binokularsehens und der Fusion geben Autoren ihre persönliche Ansicht zu dieser Frage.Da die sensitiven und die motorischen Effekte nicht zu unterscheiden sind, ist es unmöglich das Binokularsehen von den Fusionsbewegungen zu trennen.Es wird dann die Lokalisation im Raum untersucht. Diese ist zunächst egozentrisch, sie kann auch relativ sein, d.h. das Verhältnis verschiedener Stimuli untereinander betreffen.Experimentell kann bewiesen werden wie die beiden Netzhäute zusammenarbeiten. Dies kann durch die identischen und disparaten Netzhautpunkte erklärt werden. Das stereoskopische Sehen kann normal, geschädigt oder anormal sein, und die Lokalisation im Raum ist in jedem Falle verschieden.Was die Lokalisationstheorie von Roelofs anbelangt, so wird sie mit der klassischen Theorien von Hering, Tschermak u.a. verglichen. Die Fusionsbewegungen scheinen wohl ihren Ursprung in der Netzhaut zu nehmen, wie es aus der Theorie von Roelofs hervorgeht.Zum Schluss wird darauf hingewiesen, dass die gewöhnlich zur Untersuchung des Stereoskopischen Sehens benutzten Apparate in der Mehrzahl für die wissenschaftliche Arbeit ungeeignet sind.

---

Résumé Le premier chapitre s'ouvre par une discussion sur la relation entre la vision binoculaire et les mouvements de fusion; l'interprétation personnelle des auteurs se fonde sur les idées d'autres auteurs et sur leurs propres opinions.Les notions de vision binoculaire et de mouvements de fusion sont inséparables, car il est impossible de distinguer les effets sensitifs et moteurs de la vision.Les auteurs étudient en détail la localisation dans l'espace; celle-ci est primitivement égocentrique par rapport à l'observateur, mais elle peut aussi être relative, c'est à dire concerner le rapport des stimuli entre eux dans l'espace. Nous concevons l'espace environnant comme tri-dimentionnel. Le système de coordination de cet espace euclidien prend son origine dans le moi. C'est le système par lequel les diverses sensations provoquées par les stimuli de l'espace objectif sont organisées en espace subjectif, dont la conception existe a priori.Puis les auteurs attirent l'attention sur la précision avec laquelle l'oeil peut localiser ces surfaces principales, ce qui peut être déterminé expérimentalement. La manière dont les deux rétines coopèrent devient ainsi évidente. Elle s'explique par la conception des points identiques et des points disparates, notions essentielles pour la compréhension de la stéréoscopie. La vision stéréoscopique peut être normale, troublée ou anormale, la localisation dans l'espace variant suivant les cas.Les auteurs discutent la théorie de localisation de Roelofs, qui détermine la relation entre les stimuli rétiniens, la sensation lumineuse, l'impulsion motrice et le mouvement de fusion qui en résulte. Ils comparent la valeur de cette théorie à celle des théories de Hering, Tschermak et d'autres auteurs.Pour comprendre l'unité fonctionnelle double oeil, il faut distinguer les notions de fusion sensorielle (synchysis de v. Kries) et de fusion motrice, et connaître leurs limites. L'influence de la durée d'observation sur le synchysis montre qu'il s'agit probablement d'une fonction corticale. La théorie de Roelofs rend très acceptable l'origine rétinienne des mouvements de fusion.Enfin les auteurs font une revue critique des diverses méthodes d'examen de la vision stéréoscopique, en attirant particulièrement l'attention sur le fait que les appareils utilisés en pratique sont pour la plupart impropres au travail de recherche.

     

Binocular vision without visual stress

The use of changes in fixation disparity, the associated phoria, and the dissociated phoria in assessing the degree of visual stress requires that we know the effect of vision under close working conditions (40 cm) on these parameters. The authors have previously reported that reading under the stress of abnormally low illumination, or at too close a working distance (20 cm), increases fixation disparity and associated phoria and is associated with symptoms and visual discomfort. The current study shows that reading at photopic levels of illumination and at a working distance of 40 cm does not change the magnitudes of fixation disparity and associated phoria. Reading under these conditions is not accompanied by an onset of symptoms or visual discomfort. This result indicates that changes in fixation disparity and associated phoria are a product of visual stress and are not produced by reading itself.     

Binocular vision in strabismic humans with alternating fixation

Grating acuity, interocular suppression and binocular interaction were evaluated at different positions in the visual field of strabismic humans with alternating fixation. In all cases, the suppression of the deviated eye was most intense in a region corresponding to the fovea of the fixating eye, but reduced or absent in the periphery. In addition, suppression was found in part of the peripheral visual field of the fixating eye. For most subjects, the monocular properties of both eyes were normal. However, for one subject with a strong preference for one of the eyes, visual acuity and luminance detection were selectively impaired in the chronically suppressed regions of the non-preferred eye. Regardless of which eye was currently used for fixation, the visual information available to the subject came from both eyes. In parts of the visual field, the two eyes tended to replace each other. In the far periphery, and especially in the upper and lower hemifield, signals from the two eyes were often combined in a binocular perception of depth.     

Binocular vision in concomitant strabismus

It was discovered that in a small angle concomitant squint there occurs a kind of binocular vision maintained by abnormal retinal correspondence. This phenomenon may be discovered by a campimetric examination, by VEP and by other psychophysical tests. There appear accomodational movements which tend to maintain a stable angle of deviation which enables a binocular vision. Analysis of these movements is presented.     

Binocular vision in congenital glaucoma

We have studied binocular vision in a group of 189 patients suffering from congenital glaucoma, before and after treatment, as well as the elements upon which vision depends. Therapeutic modalities, including occlusion are discussed. We insist on the possibility of recovering binocular vision in congenital glaucoma.     

屈光参差性弱视儿童治愈后的双眼视觉研究

【摘要】 目的 了解屈光参差性弱视儿童治愈后双眼视觉状况。设计 回顾性病例系列。研究对象 屈光参差性弱视儿童74例,正常儿童74例。方法 采用同视机和颜少明《立体视觉检查图》对74例 经治疗矫正视力已≥0.9的屈光参差性弱视儿童和74例正常儿童的双眼视觉功能进行检测。主要指 标  同时知觉、远融合范围、定性远立体视、 立体视锐度。结果 （1）屈光参差性弱视儿童基本 治愈后其远立体视低于正常儿童（χ2 =11.331,P=0.001）;同时视（χ2 =1.855,P=0.173）及 远融合范围（χ2 =1.012,P=0.603）无明显差异。（2）屈光参差性弱视儿童基本治愈后其近立体 视锐度明显低于正常儿童（χ2 =27.759,P=0.000）。（3）屈光参差性弱视程度越轻,近立体视 锐度的改善越显著（χ2 =17.116,P=0.009）;而同时视（χ2 =0.879,P=0.644）、远融合范围 （χ2 =7.930,P=0.094）、远立体视（χ2 =2.854,P=0.240）的改善无明显差异。结论 屈光参 差性弱视严重影响立体视觉的发育。即使治疗后视力达到正常,其立体视仍低于正常儿童。屈光参 差程度越重,对近立体视锐度的影响越显著。（眼科,2012, 21: 395-397）