Vision Terms

 A

Amblyopia:  Amblyopia is a developmental neurological condition where visual acuity is impaired.  During the time when the eyes and brain are still developing together (usually considered between birth and seven years of age) a clear image needs to be transmitted to the brain from each eye…

AstigmatismThe very front surface of the eye (the cornea) can most simply be thought of as spherical in shape.  This special shape provides most of the light-focusing power to the eye…

B

Binocular VisionOur visual system is designed to use and process information from both eyes seamlessly and instantaneously.  Our two eyes are designed to work as a team, aiming at the same place at the same time to provide us a rich amount of information about our environment…

C

Contrast SensitivityThis is the ability to discriminate between the bright and dark areas of whatever you are looking at.  A healthy retina can help discriminate very small differences between light and dark areas, and this helps give richness of detail such as facial features, patterns on clothing, and road signs.  When you turn the level of contrast up on your TV or computer monitor, you are darkening the dark areas and lightening the light areas, and in the extremes the fine details (the grays) are washed out…

ConvergenceObjects that are far, far away from our eyes do not require any convergence, or “crossing-in.”  For these distances, both of our eyes are basically pointed straight ahead and in parallel…

D

Depth PerceptionHumans use many clues to determine where we are and where other objects are in space, often to a very precise degree…

F

FixationFixation is a term used to describe what we do when our eyes stop their normal movements to gather more detailed information.  In fact, our eyes make imperceptible, rapid movements even while “fixating” to ensure no loss of information…

FocusingJust like a camera’s autofocus our own eyes can bring things into clear focus, no matter how close or far the object is from our eyes…

H

HyperopiaWith hyperopia, the closer an object is to the eye the more difficult it is for the eye to maintain clear focus.  Because the eye is excessively short, light comes to a focus “after” it hits the retina causing a blurry image…

M

MyopiaWith myopia, objects that are further away appear blurrier than things that are closer to your eyes.  This is most often caused by the lengthening of the eyeball, however an increase in the curvature of the front surface of the eye (the cornea) can have the same effect…

P

Peripheral VisionAlthough vision is commonly thought of in terms of central vision (foveal vision) which gives us the fine detail of objects and color, our peripheral vision is vitally important to all of our day to day activities.  Our sense of balance, performance in sports, ability to read, as well as just walking around without bumping into things would be much more challenging or impossible without good peripheral vision…

S

StrabismusA Strabismus occurs when a person’s eyes do not align properly.  Sometimes this is very apparent cosmetically (as in wall-eyes or crossed eyes) or it may only be picked up during a comprehensive eye exam…

T

TrackingVision can be thought of as a series of snapshots, the brain takes hundreds such pictures every second.  The eyes are constantly moving to feed this visual information to the brain.  The way in which we describe the major types of eye movements are fixations, pursuits, and saccades…

V

Visual AcuityVisual acuity is quite simply the ability to see the finest details of an object, whether it is a tree on a far-away mountain or the intricate pattern of a butterfly’s wing.  The most common way we speak of visual acuity though says nothing about our visual performance up close…

Visual AttentionVisual attention is the ability to literally keep the eyes tracking and focused on a particular task in the face of many other sensory distractions.  This process is of course aided by providing both eyes the best-corrected vision and the clearest focused image possible…

Visual Discrimination

Visual Memory

Visual Motor Integration