Binocular vision refers to seeing with both eyes at the same time. Each eye sees the surroundings from a slightly different angle. The brain combines these two separate images into a single picture. This is how our spatial (three-dimensional) vision is created, allowing us to judge distances well—for example when climbing stairs, driving a car, or catching a ball.
If binocular vision is impaired, ophthalmologists speak of a binocular vision disorder. Possible causes include, for example, strabismus (squinting/crossed eyes), severe refractive errors, or large differences between the two eyes.
Reduced binocular vision is not disruptive for most people in most everyday situations. Typical situations in which reduced 3D function becomes noticeable include, for example, pouring a drink into a glass and having more difficulty hitting the glass. It is also typical that affected individuals find 3D films less impressive than people with perfect binocular function.
Binocular or 3D vision can be assessed and quantitatively measured with specific tests, just like visual acuity. Patients may have only slightly reduced or severely reduced 3D function.
Although reduced 3D function rarely causes problems in everyday life, it can be an important indication of other conditions (e.g., microstrabismus). Because reduced binocular function is a risk factor for developing strabismus—and can also influence the prognosis after eye muscle surgery (strabismus surgery)—a thorough assessment is an important part of our examination, regardless of whether disturbances in binocular vision are noticed in daily life.
If there are noticeable issues, for example with fine motor skills—especially in children—the coordination between the eyes should be examined by an eye doctor early on. Often, glasses, visual exercises, or other therapies can help ensure that both eyes work together as well as possible again.