Age-Related Maculopathy (ARM, macular degeneration)
An age-related degeneration of the macula portion of the retina, the area used for fine visual discrimination (e.g. reading).

Commonly known as "lazy eye," it is reduced vision in an eye with no observable pathology or reason for the decrease in acuity.

The sense or act of hearing.

A type of chemical which acts similar to epinephrine (adrenaline).

Of or relating to both ears.

Having or requiring the use of two eyes.

Binocular disparity
Lack of the two eyes seeing the same object.

Binocular fixation/coordination
The process of having both eyes directed at the same object at the same time. This is essential to having good depth perception.

Biological marker
A protein or other finding in blood specimens that is present in a particular disease.

Involuntary spasm of the eyelid muscles that may cause excessive blinking.

The inability to see.

Botulinum A toxin (Botox)
A toxin from bacteria that, in very small doses, causes temporary muscle relaxation.

Centimeter (cm)
0.45 inch.

Computational modeling
(Of visual perception) a method of predicting the psychophysical or neurophysiological measurements of visual performance.

The transparent front portion of the eyeball (like the glass on a watch).

Crossed-eye disorder
See strabismus.

Depth perception
The ability to judge depth or the relative distance of objects in space.

Diabetes mellitus
Increased level of blood sugar. Over time, can lead to vascular complications in the eyes, kidneys, and extremeties.

Double vision.

An abnormality in the functioning of an organ or other part or system of the body.

Eccentric viewing
Looking with an area of the retina outside the fovea.

Electroretinogram (ERG)
An electrical recording of the health of the retina; similar to an electrocardiogram (EKG) for the health of the heart.

Eye alignment
Position of the eye.

A small pit or depression of the center of the macula, within the retina of the eye, where visual perception is most acute. Disease or injury to the fovea can lead to loss of fine-detailed vision, such as reading, and loss of contrast sensitivity.

Functional magnetic resonance imaging (fMRI)
The MRI is a sophisticated, non-x-ray picture of an area of the body. It has the ability to provide very fine detail, similar to a CAT scan. With functional (f) MRI, the image relates information about blood flow to an area of the body, which is related to its activity or function.

An abnormal condition of elevated pressure in the eye. Can eventually result in loss of vision, even blindness. May cause damage to the fibers of the optic nerve.

Kinesthetic feedback
Feedback from the muscular system.

A central area in the retina of the eye that is distinguished by its characteristic yellow color, and which contains the fovea, where vision is most acute.

Multifocal ERG (mfERG)
An ERG which simultaneously demonstrates electrical signals from many specific areas of the retina.

Multifocal VEP (mfVEP)
A VEP which simultaneously demonstrates electrical signals from many specific areas of the visual part of the brain (occipital cortex).

Multisensory feedback
Feedback from several of the senses, e.g. vision, hearing, touch, etc.

Neural processing
The way in which neurons (nerve cells) send signals to other nerve cells or the brain.

A cell that transmits nerve impulses and is the basic functional unit of the nervous system.

A toxin capable of destroying nerve tissue.

Relating to the influence of nerves upon nutrition and maintenance of the normal condition of tissues.

Normal and pathological ocular motility
Normal and abnormal eye alignment and/or movements.

Rotating the eye; involving the rotation of the eye, e.g. in certain diseases

Oculomotor system
The system of brain areas and muscles that move the eye.

The positioning of something, or the position or direction in which something lies.

An apparent change in the position of an object when the person looking at the object changes position.

The property of a drug.

The ability to change function, adapting to a new environment.

Primary visual cortex
The first portion of the cortex of the brain that receive visual signals from the eye.

An artificial substitute for a missing body part, as denture, hand, leg, eye.

A light-receptive nervous tissue membrane on the inside of the eye, continuous with the optic nerve, that receives images of external objects and transmits visual impulses through the optic nerve to the brain.

Retinopathy of prematurity (ROP)
Retinal vascular changes that occur in the eyes of some premature babies, sometimes due to increased oxygen in their environment. When severe, can lead to retinal detachment and blindness.

Saccadic eye movements
Very rapid eye movements.

Sweep visual evoked potential system
A technique to rapidly measure the electrical signals from the visual part of the brain resulting from a visual stimulus. It is most valuable in estimating the vision in infants and young children.

Smooth pursuit
Slow, following eye movements.

Sound localization
Determining where a sound is coming from.

3-D vision.

An abnormal ocular condition in which the eyes are not straight. One example is crossed eyes.

The area of the brain that relays sensory impulses to the cerebral cortex. The cerebral cortex is the portion of the brain that interprets the signal.

The path of a body in space.

Visual accommodation
A process by which the eye adjusts and is able to focus, producing a sharp image at various, changing distances from the object seen. With increasing age the lens becomes harder and less flexible, resulting in a loss of accommodation, and the ability to focus on nearby objects.

Visual evoked potential (VEP)
An electrical signal measured from the visual part of the brain (occipital cortex) resulting from a light or other visual stimulus.

Visual pathway
The pathway over which a visual sensation is transmitted from the retina to the brain. The visual pathway consists of an optic nerve, the fibers of an optic nerve traveling to the optic chiasm to the lateral geniculate body of the thalamus, and optic radiations terminating in the occipital lobe.

Visual scene
What we see.