Living with Monocular Vision
Monocular vision is a condition in which one eye is blind, or one eye is unable to register images in coordination with the other eye. There are a number of common obstacles that are associated with this type of impaired vision. The most common is the inability to determine the depth of objects that are close to a person, typically within three feet. This loss in proximate (close-up) depth perception is due to the loss of an important binocular depth cue, stereopsis. Stereopsis is the most acute kind of depth perception, characterized by three-dimensional vision.
People living with monocular vision must rely on the summation of nine weaker depth perception cues: accommodation, linear perspective, interposition, texture gradient, relative size, light and shadow, relative brightness, aerial perspective, and motion parallax. The definition of each depth perception cue is listed below for reference.
Accommodation (focusing) – is the change in dioptric power of the intraocular lens to see an object near to them more clearly. The more power needed, the closer the object must be.
Linear perspective – is a visual phenomenon in which parallel lines converge in the distance. The further separated the lines become, the closer the object must be.
Interposition (overlapping) – is a visual phenomenon in which the view of an object is partially blocked by another object. The object being blocked must be behind the object that is blocking it.
Texture gradient – is the amount of detail in an object. The more details in the object, the closer the object will be perceived.
Relative size – is a visual phenomenon in which an object that produces a larger retinal image than a similar object will be perceived as being closer. If the direction of light is known, then light and shadows can be used as visual cues in determining the elevation or recession of an object.
Relative brightness – is the visual phenomenon in which closer objects reflect more light into the eye. If two similar objects are equally close, the brighter object will be perceived as being even closer.
Aerial perspective – is the visual phenomenon that distant objects appear hazier than closer objects. This depth perception cue is caused by the reflective nature of water molecules in the atmosphere.
Motion parallax – is the apparent displacement of objects in space while moving. This depth perception cue causes closer objects to move faster than distant objects.
Learning to utilize these monocular vision cues, patients can adjust quickly to their new perspective on life. As a general rule, Ocular Prosthetics, Inc.’s board certified ocularists recommend that patients accommodate by constantly scanning to compensate for their loss in peripheral vision. Frequent head movements are a must for capturing the entire visual field. For more information on adjusting to life with monocular vision please contact any of our Southern California office locations. An ocularist will be available to discuss any specific questions or concerns you may have. We look forward to speaking with you!