Binocular vision

Under binocular vision ( both eyes binocular = ) refers to all sensory and motor aspects of the common vision of right and left eye. In contrast, refers to the seeing with only one eye or independently held using a plurality of eyes as Monokularsehen.

Sensors

As the first stage of sensory binocular vision applies the simultaneous vision, the simultaneous perception of the visual impressions of both eyes. The next step is called the fusion, and is the ability to merge the images of both eyes into a single image. This is the basis for the third and highest form of binocular vision, stereoscopic vision ( stereopsis ). These forms are also summarizes as binocular.

Basics

Requirement for binocular vision is the correspondence between certain regions of the retina of both eyes. In general, the image of a floating object is at physiologically identical localized retinal points that perceive it at the same point in space, and overlap so. This is called a normal Sehrichtungsgemeinschaft or normal retinal correspondence ( NRC ). Since this state is coupled to the foveae of both eyes in the normal case, one also speaks of bifovealer Sehrichtungsgemeinschaft. Depending on the prevailing conditions correspond to the quality of binocular vision is present.

The set of points that fall on corresponding retinal points in the fixation of an object, called horopter. This horopter is a line that is similar, slightly curved parabola. Objects that are close in front or behind this horopter are not usually seen twice, although they fall on non-corresponding retinal points. This area is called Panumareal or Panumraum. In this zone through the pictures slightly offset ( lateral disparity ) is produced spatial vision. When the limits of Panumareals exceeded the so-called physiological diplopia occurs.

Molding

There are basically three different types of binocular functions.

Simultaneous vision

Fusion

Stereopsis

Methods of investigation

There are numerous and diverse research methods and procedures for the examination of the various forms of binocular vision, which generally come in Orthoptics used. These subjective statements of the patient (eg, image localization ) to take into account as well as objective factors (eg strabismus ). Generally you can apparatus method (eg Haploskope ) differ from those that come in a test in free space is used. It is not rare the proceedings, while examining the same function, but clearly produce due to different arrangements, degree of dissociation and the principles underlying divergent results. In addition, some studies take place in a very unnatural test environments, which in turn is to be considered in assessing the results. In the table, some methods are listed representative for individual degrees of dissociation.

Pathology

Disorders of binocular vision can have very different reasons, forms and thus have an effect. Main features include diplopia and confusion, as well as the suppression of the visual impression of an eye to counteract impending double vision. These always go hand in hand with the loss of spatial vision.

• Diplopia is caused by irritated at a squinting eye retina, which have a different spatial localization to that of the non- squinting eye. So you perceive identical objects at different locations in the room with both eyes. Diplopia means the loss of fusion ability and visuospatial upon receipt of the simultaneous vision.
• However, confusion arises when different objects fall on the retina with the same spatial localization. Both eyes So you see different things in identical place in the room, thereby triggering a kind of competition for the localization of. Confusion occurs nevertheless because usually the onset of inhibition mechanisms ( scotomas ) in daily life as well as not on, but can be evoked (eg, with dark red glass filter) for measuring objective look angles in examination situations.
• Suppression is the mechanism called that the visual impression of the squinting eye is suppressed completely or partially with eyes open on both sides. This mechanism can only certain retinal areas concern ( central scotoma, Fixierpunktskotom ), or it leads to a complete elimination of the perception of the squinting eye, which in turn can cause amblyopia. In contrast to other causes visual field defects can only prove this inhibition mechanism, when both eyes are open. The suppression of an eye means the loss of all binocular.

Another fault arises (as opposed to a o NRK) from an abnormal or anomalous retinal correspondence Sehrichtungsgemeinschaft ( ARK). This is the phenomenon that occurs during the fixation of an object to stimulant physiologically identical retinal points that can nevertheless lead to an abnormal superposition of the images. It correspond this is usually the fovea of one eye with a non- foveal retina of the other eye. If, in this situation to a superposition of the images, there is a so-called harmonious abnormal retinal correspondence ( HARK ). In contrast, it is called a discordant anomalous retinal correspondence ( Dhark ) if it does not come under these circumstances to a superposition of fixed images. As a result of HARK can develop so-called subnormal, that is qualitatively different inferior, binocular vision. Can express themselves so for example in a small fusion width or only roughly pronounced spatial vision.

Disorders of fusion and stereopsis can also by pronounced differences in size of the retinal images ( Aniseikonien ) caused that no longer allow a congruent image overlay registration and fusion.

A sensory- motor disorder of binocular vision, the fixation disparity; they expressed through a lack of accuracy of the Vergenzsystems and by the inability to bifovealer fixation under fusional stress.

Another, but much rarer disorder of binocular vision known as fusionis horror. In this state, the ability to Suppresion has lost touch closely lying diplopia due to a small squint angle. This can be caused, for example by orthoptic or pleoptische exercise treatments that have not reached a production of normal binocularity in such cases, however, a reduction of the double image inhibition. Result is a can not be eliminated, permanent double vision in small distance.

Etiology

The most common causes of disorders of binocular vision sensor are all forms of strabismus and nystagmus. However, optical, organic and neurological problems (for example, gaze palsy ) can affect binocular vision in varying degrees. The treatment belongs in the hands of ophthalmologists, Strabologen and possibly Neuroophthalmologen or neurologist. The preparation and adjustment of special lenses (eg prisms) is performed by opticians.

Motor activity

The motor aspects of binocular vision treat next to the physiology and pathophysiology of the musculoskeletal system of the eyes to one another their position. They are described inter alia in Articles eye movements and strabismus.