 Eyes and Brain Injury
http://www.neuroskills.com/tbi/boccipit.shtml 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). |
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A Classification of Eye Movement Abnormalities and Strabismus [PDF] ABOUT VISION PROBLEMS ASSOCIATED WITH BRAIN INJURIES All About Amblyopia (lazy eye) Amblyopia causes more visual loss
in the under 40 group than all the
injuries and diseases combined
in this age group. Visual acuity test Visual acuity tests may be performed in many different ways. It is a quick way to detect vision problems and is frequently used in schools or for mass screening. Driver license bureaus often use a small device that can test the eyes both together and individually. Amblyopia is the loss of an eye's ability to see details. The condition appears in one eye. The cause is by lack of use of that eye in early childhood. http://www.nlm.nih.gov/medlineplus/ency/article/001014.htm Normal pupil The pupils of an individual are usually very symmetrical in appearance. In certain instances the pupils may vary in size. Occasionally, differing pupil size is inherited and there is no underlying disorder. Varying pupil size may also be due to infection, tumors, disease or trauma. Anisocoria: Enlargement of one pupil; Pupils of different size; Eyes/pupils different size http://www.nlm.nih.gov/medlineplus/ency/article/003314.htm Blepharitis Blepharitis is an inflammation of the lash follicles at the eyelid margins due to excess growth in lash follicles of bacteria normally present on the skin. Blepharitis http://www.nlm.nih.gov/medlineplus/ency/article/001619.htm Blindness Cataract A cataract is a cloudy or opaque area in the lens of the eye. Cataracts usually develop as a person gets older and may run in families. Other environmental factors such as smoking or exposure to toxic substances can also accelerate the development of a cataract. Cataracts can cause visual problems such as difficulty seeing at night, seeing halos around lights, and sensitivity to glare.  CMV retinitis Cytomegalovirus is a large herpes-type virus commonly found in humans that can cause serious infections in people with impaired immunity. Chorioretinitis, which may cause blindness, is treated with antiviral medications, which may stop the replication of the virus but will not destroy it. CMV retinitis http://www.nlm.nih.gov/medlineplus/ency/article/000665.htm Color blindness tests Color blindness is the inability to distinguish the differences between certain colors. The most common type is red-green color blindness, where red and green are seen as the same color. Usually Isihara (pseudoisochromatic) plates are used to test color vision. They are made of dot patterns composed of primary colors. These dot patterns represent a symbol that is superimposed on a background of randomly mixed colors. The test can determine certain abnormalities in a person's color vision. Color vision test http://www.nlm.nih.gov/medlineplus/ency/article/003387.htm Click here: Color Blind 2 Crossed eyes People are very sensitive to other individuals' eye positions. By looking at another person's eye position, one can very effectively gauge where they are looking. People are also sensitive to eyes that are not looking in the same direction, which is referred to as crossed eyes (strabismus). Other more specific medical terms refer to eyes turned either outward or inward, or that are abnormally rotated. Any appearance of crossed eyes in young children should be immediately evaluated, as should recent onset of crossed eyes in an adult.  Lacrimal gland The lacrimal gland lies within the orbit on the outer portion of the upper eye. The gland continually secretes tears which moisten, lubricate, and protect the surface of the eye. Excess tears drain into small ducts which empty into the nasal cavity. Dry eyes http://www.nlm.nih.gov/medlineplus/ency/article/003087.htm External and internal eye anatomy The cornea allows light to enter the eye. As light passes through the eye the iris changes shape by expanding and letting more light through or constricting and letting less light through to change pupil size. The lens then changes shape to allow the accurate focusing of light on the retina. Light excites photoreceptors that eventually, through a chemical process, transmit nerve signals through the optic nerve to the brain. The brain processes these nerve impulses into sight. Head and eye Echoencephalogram An echoencephalogram is a diagnostic procedure which uses ultrasound to test for abnormalities in the eye. The ultrasound helps evaluate the farthest part of the eyeball when there are cataracts. The test may help diagnose retinal detachment or other disorders and evaluate orbital lesions and intraocular lesions. Eye and orbit ultrasound http://www.nlm.nih.gov/medlineplus/ency/article/003797.htm First aid kit The essentials of a good first aid kit include a variety of bandages, medications, and equipment to stabilize injuries until proper medical attention can be administered. Eye emergencies Eye lens anatomy The lens of the eye is normally clear. If the lens becomes cloudy or is opacified it is called a cataract. Before and after strabismus repair Strabismus surgery corrects and aligns the muscles of the eye. Eye muscle repair - series: Normal anatomy The conjunctiva links the eyeball to the eye socket. The external muscles of the eye are found behind the conjunctiva. Eye muscle repair http://www.nlm.nih.gov/medlineplus/ency/article/002961.htm Eye pain Bloodshot eyes The white portion of the eye (sclera) can appear red when the vessels on the surface become enlarged. This may result from mechanical irritation, environmental irritants (such as extremely dry air, excess sun exposure), allergic reactions, infection, and other medical conditions. A bright red, uniformly dense bloody area on the sclera results from a small amount of bleeding (hemorrhage) into the conjunctiva. It is a fairly common occurrence and is usually caused by straining or coughing. It generally clears up on its own after a few days. Eye redness Stye A stye is a relatively common infection. Styes are often caused by staphylococcus and occur in the glands that open onto the lid margin. They are red, swollen, and painful. Eyelid bump http://www.nlm.nih.gov/medlineplus/ency/article/001009.htm Ptosis, drooping of the eyelid Drooping of the eyelid is called ptosis. Ptosis may result from damage to the nerve that controls the muscles of the eyelid, problems with the muscle strength (as in myasthenia gravis), or from swelling of the lid. Eyelid drooping http://www.nlm.nih.gov/medlineplus/ency/article/003035.htm Blepharoplasty - series: Indications Eyelid surgery (blepharoplasty) is used to correct "puffy bags" below the eyes and drooping upper lids that make the patient look older and tired or that interferes with vision. Eyelid surgery will not remove wrinkles around the eyes, lift sagging eyebrows, or eliminate dark circles under the eyes. Eyelid lift http://www.nlm.nih.gov/medlineplus/ency/article/002977.htm Eye muscles The orbicularis occuli muscles circle the eyes and are located just under the skin. Parts of this muscle act to open and close the eyelids and are important muscles in facial expression. Eyelid twitch http://www.nlm.nih.gov/medlineplus/ency/article/000756.htm Periorbital cellulitis Periorbital cellulitis is an acute infection of the tissues surrounding the eye, which may progress to orbital cellulitis with protrusion of the eyeball. Complications include meningitis. Eyes - bulging http://www.nlm.nih.gov/medlineplus/ency/article/003033.htm Retinal dye injection Retinal dye injection is used to determine if there is proper circulation in the retinal vessels in the eye. When dye is injected in a vein in the arm, a rapid series of photographs are taken. Among other things this test can detect problems such as blockages or tumors. Fluorescein angiography http://www.nlm.nih.gov/medlineplus/ency/article/003846.htm Foreign objects in eye Foreign objects in the eye usually are flushed out through the natural blinking and tearing action of the eye. If the foreign body can be seen on the inner surface of either the lower or upper lid, try to gently flush it out with water or use a cotton-tipped swab to invert the eyelid and inspect the underside. Seek medical attention if the foreign body cannot be removed, or if there is still discomfort or blurred vision after removal. Eye - foreign object in http://www.nlm.nih.gov/medlineplus/ency/article/002084.htm Glaucoma Glaucoma is a condition of increased fluid pressure inside the eye. The increased pressure causes compression of the retina and the optic nerve which can eventually lead to nerve damage. Glaucoma can cause partial vision loss, with blindness as a possible eventual outcome. Glaucoma http://www.nlm.nih.gov/medlineplus/ency/article/001620.htm 
HEMIANOPSIA --and neuroanatomy http://www.indiana.edu/~pietsch/hemianopsia.html Heterochromia Heterochromia is the presence of different colored eyes in the same person. Heterochromia in humans appears either as a hereditary trait unassociated with other disease, as a symptom of various syndromes or as the result of a trauma. Heterochromia http://www.nlm.nih.gov/medlineplus/ency/article/003319.htm Hypertensive retinopathy Damage to the retina from high blood pressure is called hypertensive retinopathy. It occurs as the existing high blood pressure causes changes to the microvasculature of the retina. Some of the first findings in the disease are flame hemorrhages and cotton wool spots. As hypertensive retinopathy progressives, hard exudates can appear around the macula along with swelling of the macula and the optic nerve, causing impairment of vision. In severe cases permanent damage to the optic nerve or macula can occur. Hypertensive retinopathy http://www.nlm.nih.gov/medlineplus/ency/article/000999.htm Iris The iris is the colored portion of the eye, amembrane located between the cornea and lens that regulates the entrance of light into the eye by contracting and dilating. Lateral eye anatomy The cornea is the clear watch glass covering in the front of the eye. The cornea works with the lens of the eye to focus images on the retina. The retina is the internal layer of the eye that receives and transmits focused images. The retina is normally red due to its rich blood supply.  Retina The retina is the internal layer of the eye that receives and transmits focused images. The retina is normally red due to its rich blood supply. Melanoma of the eye http://www.nlm.nih.gov/medlineplus/ency/article/001022.htm Normal, near, and farsightedness Normal vision occurs when light is focused directly on the retina rather than in front or behind it. A person with normal vision can see objects clearly near and faraway. Nearsightedness results in blurred vision when the visual image is focused in front of the retina, rather than directly on it. It occurs when the physical length of the eye is greater than the optical length. For this reason, nearsightedness often develops in the rapidly growing school-aged child or teenager, and progresses during the growth years, requiring frequent changes in glasses or contact lenses. A nearsighted person sees near objects clearly, while objects in the distance are blurred. Farsightedness is the result of the visual image being focused behind the retina rather than directly on it. It may be caused by the eyeball being too small or the focusing power being too weak. Farsightedness is often present from birth, but children can often tolerate moderate amounts without difficulty and most outgrow the condition. A farsighted person sees faraway objects clearly, while objects that are near are blurred. Pathophysiology of Ganglion Cell Death and Optic Nerve Degeneration Workshop Photophobia Farsighted A person who is farsighted has the abillity to see objects clearly far away but not see as clearly closeup. Farsightedness usually occurs naturally with the aging process. Presbyopia http://www.nlm.nih.gov/medlineplus/ency/article/001026.htm Progress in Eye and Vision Research 1999-2006 [PDF] |