The Brain

Occipital Lobe

Functions:

Vision

Observed Problems:

Defects in vision (Visual Field Cuts).
Difficulty with locating objects in environment.
Difficulty with identifying colors (Color Agnosia).
Production of hallucinations Visual illusions - inaccurately seeing objects.
Word blindness - inability to recognize words.
Difficulty in recognizing drawn objects.
Inability to recognize the movement of an object (Movement Agnosia).
Difficulties with reading and writing.

Blindsight

If the visual cortex is damaged by stroke or other injury, patients lose the ability to see things in part of the visual field. The abnormal blind area in the visual field is called a hemianopia (hem-i-an-NO-pia). Some patients with hemianopias involving as much as half the visual field can nevertheless reach out and touch objects in the "blind" area. This is called blindsight.

Blindsight is relatively rare. It is not found in every patient with hemianopias. However, blindsight intrigues investigators because it seems to suggest that visual information can find its way into the brain through some unconscious route.

The occipital lobes are the center of our visual perception system. They are not particularly vulnerable to injury because of their location at the back of the brain, although any significant trauma to the brain could produce subtle changes to our visual-perceptual system, such as visual field defects and scotomas. The Peristriate region of the occipital lobe is involved in visuospatial processing, discrimination of movement and color discrimination (Westmoreland et al., 1994). Damage to one side of the occipital lobe causes homonomous loss of vision with exactly the same "field cut" in both eyes. Disorders of the occipital lobe can cause visual hallucinations and illusions. Visual hallucinations (visual images with no external stimuli) can be caused by lesions to the occipital region or temporal lobe seizures. Visual illusions (distorted perceptions) can take the form of objects appearing larger or smaller than they actually are, objects lacking color or objects having abnormal coloring. Lesions in the parietal-temporal-occipital association area can cause word blindness with writing impairments (alexia and agraphia) (Kandel, Schwartz & Jessell, 1991).
Centre for Neuroskills

The main job of your occipital lobes is to decode visual information, so they are active right now, as you read these lines. Form, color, and movement are all analyzed by your occipital lobes. By associating these visual perceptions with remembered images, this part of your brain, also known as the visual cortex, lets you recognize and identify objects.
Henri Laborit (1914-1995)

References
"CNS - TBI Resource Guide," World Wide Web.
"Occipital Lobes," researched, and written by:Bruno Dubuc, Graphic design:Denis Paquet, World Wide Web.