20/20 -the expression for normal eyesight (or 6/6 in countries where metric measurements are used). This notation is expressed as a fraction. The numerator
(1st number) refers to the distance you were from the test chart, which is usually 20 feet (6 meters). The denominator (2nd number) denotes the distance at which a person with normal eyesight could read the line with the smallest letters that you could correctly read. For example, if your visual acuity is 20/100 that means that the line you correctly read at 20 feet could be read by a person with normal vision at 100 feet. The Snellen chart, which consists of letters, numbers, or symbols, is used to test visual acuity (sharpness of eyesight). A refraction test is used to determine the amount of correction needed for a prescription when treating refractive error such as astigmatism, myopia, or hyperopia.
Accommodation- (eye focusing) the eye's ability to adjust its focus by the action of the ciliary muscle, which increases the lens focusing power. When this accommodation skill is working properly, the eye can focus and refocus quickly and effortlessly, which is similar to an automatic focus feature on a camera. The ciliary muscles must contract to adjust for near vision, which causes the eyes crystalline lens, which is flexible, to be squashed. For distant vision, the ciliary muscle must relax and the eyes crystalline lens is stretched out. The ability of the eye to accommodate does decrease with age due to the crystalline lens becoming less flexible causing a condition called presbyopia.
Accommodative Esotropia- (clinical condition) when an individual is focusing on a near object and his or her eyes are turning inward too much. It is caused by either uncorrected hyperopic refractive error and/or a high accommodative convergence/accommodation (AC/A) ratio. The average age of onset is 2 1/2 years. It is most noticeable when the child is tired or sick. This is treated with plus lenses (glasses or contacts) to help straighten the eyes. In some cases, vision therapy and corrective lenses are prescribed. (Please note that Accommodative Esophoria is a condition similar to accommodative esotropia but lesser in extent.)
Accommodative Excess (AE)- This clinical condition is also called accommodative spasm. It is an over focusing, over stimulation of the focusing action of the crystalline lens causing an inability to relax the focusing system which may result in blurry vision when focusing at distance objects. Other symptoms include holding near work closer than normal, headaches with near work (such as reading or using a computer), eyestrain associated with near work, and possible double vision. Clinical signs include: patient accepts more minus on accommodative rock but blurs with plus lenses, lower NRA than PRA, dynamic retinoscopy findings indication of over accommodation and/or slow relaxation of accommodation, and reduced or erratic distance visual acuity. Treatment includes a low plus lens and/or vision therapy.
Accommodative Insufficiency (AI)- This clinical condition is also called non-presbyopic accommodative insufficiency. It is an under focusing, a lack of focusing ability at a near distance. Symptoms include eyestrain, blurred vision, occasional or constant when doing near work (such as reading or using a computer), occasional unusual sensitivity to light, excess tearing, headaches, and general fatigue. Clinical signs include: patient will have difficulty with a minus lens, low amplitude of accommodation, low PRA and higher NRA. Vision therapy is an effective treatment option.
Acuity- clearness of eyesight. Depends on the sharpness of images and the sensitivity of nerve elements in the retina. (See "Near Acuity" and "Distance Acuity")
Add- prescription strength of a plus lens which is used for near vision. A plus lens can be added to another lens such as a minus lens for distance vision. (See "Bifocal Glasses" and "Presbyopia")
After-image- the eye's ability to still see an image during eye blinks and even after the viewed object is no longer present. The most common example is seeing light after the flash of a camera.
Albinism - pigmentation is deficient or absent. May occur in skin, hair, and eyes. Ocular albinism is a pigmentation deficiency occurring mainly in the eyes. Individuals with albinism including ocular albinism commonly have decreased visual acuity (20/70 -20/200), strabismus, photophobia, and nystagmus. There is no known treatment. Individuals may benefit from low-vision aids. Treatment options for strabismus and nystagmus does apply to these individuals.
Alignment- proper fusing (uniting) of images to each eye.
Amblyopia- (clinical condition) reduced visual acuity (poorer than 20/20) which is not correctable by glasses or contacts and is not caused by structural or pathological anomalies. This condition is often called lazy eye because it is typically the result of disuse. It is usually marked by blurred vision in one eye and favoring one eye over the other. About two percent of the population is affected.
Anisometropia- the condition in which the two eyes have different refractive powers.
Asthenopia- eyestrain, symptoms include excessive tearing, itching, burning, visual fatigue, and headache. It can be caused from an uncorrected refractive error, accommodation (eye focusing) disorder, binocularity (eye teaming) disorder, or by extended, intense use of the eyes.
Astigmatism- light rays entering the eye do not all meet at the same point (similar to a frayed string), which results in blurred or distorted vision. An abnormally shaped cornea typically causes this condition. Occasionally astigmatism exists in the lens of the eye. This condition is corrected by a cylindrical (toric) eyeglass or contact lens.
Automated refractor - also called auto refractor. This method determines the eye's refractive error and the best corrective lenses to be prescribed by using a computerized device that varies its optical power mechanically and prints out the results.
Axis- the alignment of the lens cylindrical part; used for correcting astigmatism. This measurement is given in degrees. The values are typically from 90 degrees to 180 degrees.
Bifocal Glasses- used to correct vision at two distances, composed of two ophthalmic lenses such as a plus lens for near vision and a minus lens for distance vision.
Binocular Vision- the simultaneous use of the two eyes.
Binocularity- the ability to use both eyes as a team and to be able to fuse (unite) two visual images into one, three-dimensional image (See Convergence and Divergence).
Blurred Vision- lack of visual clarity or acuity.
Botulinum Toxin Type A (Oculinum, Botox.)- an injection of this poison has been used as an alternative to conventional surgery in selected strabismic patients. It causes a temporary paralysis of an extraocular muscle that leads to a change in eye position. This change has been reported to result in long-lasting and permanent alteration in eye alignment. Although one injection is often sufficient to produce positive results, one-third to one-half of patients may require additional injections. This technique has been most successful when used in adults with small-angle misalignments. It is not commonly used in children. This treatment is also used in patients who have blepharospam (an uncontrollable eye lid spasm).
Cataract- a condition of the crystalline lens, in which the normally clear lens becomes clouded or yellowed, causing blurred or foggy vision. Cataracts may be caused by aging, eye injuries, disease, heredity, or birth defects. Surgery is a treatment option. The affected lens is removed and is replaced with a substitute (implant) lens or with a special type of contact lens. Generally the success rate of cataract surgery is over 90%, if the eye is otherwise healthy.
Ciliary Body - a structure directly behind the iris of the eye and contains the ciliary muscle. (See diagram of the eye)
Ciliary Muscle- a band of muscle and fibers that are attached to the lens that controls the shape of the lens and allows the lens to accommodate (change focus).
Color Perception Test- a test that measures the ability to identify and distinguish colors.
Color Vision Deficiency- also known as Colorblindness. It is the absence of or defect in the perception of colors. Color vision is based on perception of red, green, and blue. If there is a defect in the perception of one of these colors, a color will be perceived as if it were composed only of the other two colors. Based on the color or colors for which there is defective perception, a person may suffer from red, green, or blue blindness. Color blindness in which all colors are perceived as gray is termed monochromasia. For people with the common, inherited, types of color deficiency there is no cure.
Computer Vision Syndrome (CVS)- the complex of eye and vision problems related to near work that are experienced during or related to computer use. Its symptoms include eyestrain, dry or burning eyes, blurred vision, headaches, double vision, distorted color vision, and neck and backaches. The condition is caused by various internal and external factors. Treatment options may include prescription glasses and/or vision therapy.
Cone a receptor cell which is sensitive to light and is located in the retina of the eye. It is responsible for color vision.
Conjunctivitis- an inflammation of the conjunctiva, the transparent layer covering the inner eyelid and the white portion (sclera) of the eyeball. Conjunctivitis can be caused by a virus, bacteria, or fungus (infectious conjunctivitis, or "pink eye", may be contagious); by allergies to pollen, fabrics, animals, or cosmetics (allergic conjunctivitis); or by air pollution or noxious fumes such as swimming pool chorine (chemical conjunctivitis). Symptoms include red or watery eyes, blurred vision, inflamed inner eyelids, scratchiness in the eyes, or (with infectious conjunctivitis) a puss like or watery discharge and matted eyelids. Conjunctivitis is usually treated with antibiotic eye drops and/or ointment.
Convergence- the ability to use both eyes as a team and to be able to turn the eyes inward to maintain single vision up close.
Convergence Excess (CE)- a clinical condition in which the eyes have a tendency to turn excessively inward when viewing an object at a near distance. Symptoms may include visual fatigue while reading or using a computer, occasional blurred or double vision, and inability to comprehend or concentrate while reading. Clinical signs include: greater esophoria at near than distance, high AC/A ratio, and a high lag of accommodation. Can be improved with vision therapy and/or glasses. (See "Esophoria")
Convergence Insufficiency (CI)- (clinical condition) the inability of the eyes to turn inward and/or sustain an inward turn. Symptoms include eye strain with reading and using a computer, headaches, loss of comprehension, difficulty concentrating, blurred or double vision, and eye fatigue. Vision therapy is an effective treatment option.
Cornea- the transparent, blood-free tissue covering the central front of the eye (over the pupil, iris, and aqueous humor) that initially refracts or bends light rays as light enters the eye. Contact lenses are fitted over the cornea. (See diagram of the eye)
Cover Test- a test of eyeball alignment in which each eye is covered with an occluder (eye cover) and then uncovered to observe eye movements.
Crystalline Lens- transparent disc located behind the iris which changes shape to focus on objects at different distances from the eye. (See diagram of the eye's lens)
Cylinder Lens- an ophthalmic lens that has at least one non-spherical surface. Used to correct astigmatism. The values are typically from -0.75 to -1.25. The cylinder measurement is given with a "-" sign. (Please note that the sign for myopia (nearsightedness) is also "-".)
Depth Perception- the ability to judge relative distances of objects. (See "Stereopsis")
Developmental Disorder- when a delay in an individuals normal development has occurred.
Diopter (D)- a measurement of the refractive (light bending) power of a lens or a prism (pd). The strength of prescription glasses and contacts are measured in these units. For example a lens that is 0.50 diopter (D) is very weak, where as a lens that is 10.0 diopter (D) is very strong.
Diplopia- a single object is perceived as two rather than one; double vision.
Direct Occlusion- covering the non-amblyopic eye. (See "Inverse Occlusion" and "Occlusion")
Distance Acuity- the eye's ability to distinguish an object's shape and details at a far distance such as 20 feet (6 meters).
Divergence- the ability to use both eyes as a team and be able to turn the eyes out toward a far object.
Divergence Excess (DE)- (clinical condition) the eye's tendency to drift out relative to the direction of a distant object being viewed. Symptoms include: double vision at distance, headaches, eyestrain, nausea, dizziness, and blurred vision. Can be improved with vision therapy.
Divergence Insufficiency (DI)- (clinical condition) the eye's tendency to turn more inward than necessary when viewing a distant object. Symptoms include: double vision, headaches, eyestrain, nausea, dizziness, and blurred vision. Treated with corrective lenses and vision therapy.
Dominant Eye- the eye that "leads" it partner during eye movements. Humans also have dominant hand, foot, eye, and side of the brain (not necessarily all on the same side).
Dyslexia a specific language-based disorder. The individual has difficulty with letter or word recognition, spelling, reading, writing, and sometimes naming pictures of objects. Dyslexia varies in degree from mild to very sever. It is caused by an inability of the brain's language centers to decode print or phonetically make the connection between the word's written symbols and their appropriate sounds. Dyslexia is not caused by a vision disorder. Children often are of normal or above normal intelligence. Dyslexia cannot be cured and will never be outgrown. Appropriate teaching methods can be taught to help those with dyslexia overcome their weakness.
Emmetropia- normal vision, no correction needed. (See diagram of the eye.)
Esophoria (Eso)- (clinical condition) a tendency of the eyes to want to turn more inward than necessary when an individual is viewing an object at near or at distance, which may cause the individual to experience eyestrain and other symptoms. Symptoms of basic esophoria include: eyestrain, headaches, blurred or double vision, apparent movement of print, and difficulty concentrating on and comprehending reading material. Sometimes esophoria is caused by a refractive error such as hyperopia (farsightedness), and glasses or contacts can correct the problem alone. However, sometimes vision therapy is needed to to help re-train the eyes to function more appropriately. (See "Convergence Excess" and "Divergence Insufficiency")
Esotropia (ET)- (clinical condition) a condition in which an eye is turned either constantly or intermittently inward toward the nose. Esotropia is a type of strabismus. It is caused by a reduction in visual acuity, reduced visual function, high refractive error, traumatic brain injury, oculomotor nerve lesion, or eye muscle injury. Treatment options may include one or more of the following: glasses or contacts, bi-focal lenses, prisms, vision therapy, surgery, or Botulinum Toxin Type A (Oculinum, Botox.) injections. In some cases, esotropia is caused by a refractive error such as hyperopia (farsightedness), and glasses or contacts alone may allow the eyes to straighten. Vision therapy is most appropriate when there are small degrees of misalignment. Surgery, to re-position or shorten the eye muscles, may be required for high degrees of misalignment. If surgery is required, a combination of surgery and vision therapy often yields the best results.
Exophoria (Exo)- (clinical condition) a tendency of the eyes to want to turn more outward than necessary when an individual is viewing an object at near or at distance, which may cause the individual to experience eyestrain and other symptoms. Symptoms of basic exophoria include: eyestrain, headaches, blurred or double vision, apparent movement of print, and difficulty concentrating on and comprehending reading material. Vision therapy is an effective treatment option. (See "Convergence Insufficiency" and "Divergence Excess")
Exotropia (XT)- (clinical condition) a condition in which an eye is either constantly or intermittently turned outward toward the ear. Exotropia is a type of strabismus. It may also be called divergent strabismus, wandering eye, or wall eye(s). It is caused by a reduction in visual acuity, reduced visual function, high refractive error, traumatic brain injury, oculomotor nerve lesion, or eye muscle injury. Treatment options may include one or more of the following: glasses or contacts, bi-focal lenses, prisms, vision therapy, surgery, or Botulinum Toxin Type A (Oculinum, Botox.) injections. Vision therapy is most appropriate when there are small degrees of misalignment. If surgery is required, a combination of surgery and vision therapy often yields the best results.
Extraocular Muscles- the muscles attached to the outside of the eyeball which control eye movement. Each eye has six muscles (lateral rectus, medial rectus, superior oblique, inferior oblique, superior rectus, and inferior rectus) that are coordinated by the brain.
Eye Hand Coordination- the ability of our eyes to guide our hands, also called visual motor integration.
Eye Tracking- the ability of the eyes to smoothly and effortlessly follow a moving target.
Fine Motor Skills- the ability to coordinate hand and finger movements.
Fixation- the ability to direct and maintain steady visual attention on a target. Fixations are a form of pursuits.
Fixation Disparity (FD)- over-convergence or under-convergence, or vertical misalignment of the eyes under binocular (both eyes) viewing conditions small
enough in magnitude so that fusion is present.
Floaters- also known as spots, are usually clouded or semi-opaque specks or particles within the eye that are seen in the field of vision. The eyes are filled with fluid which maintains the shape of the eye, supplies it with nutrition and aids in the focusing of light. Often, particles of protein or other natural materials are left floating or suspended in this fluid when the eye is formed before birth. If the particles are large or close together, they cast shadows which make them visible. This is particularly true when nearsightedness occurs or becomes more severe. In most cases this is normal but floaters can also be caused by certain injuries, eye disease or deterioration of eye fluid or its surrounding structures.
Fovea- center of the retina that can produce the sharpest eyesight and contains the most cones. (See diagram of the eye)
Fusion- the union of images from each eye into a single image. There are three degrees of fusion. 1st degree fusion is the superimposition of two dissimilar targets. 2nd degree fusion is flat fusion with a two-dimensional target. 3rd degree fusion is depth perception (stereopsis) with a three-dimensional target.
Fusion Test- determines the eyes ability to unite the images from each eye into a single image.
General Binocular Vision Disorder- inability to efficiently utilize and/or sustain binocular vision. Symptoms include eyestrain, headaches, decreased comprehension, inability to concentrate while reading, excessive tearing, and blurred vision. A patient will have difficulty with both base-in and base-out prisms. Vision therapy is an effective treatment option.
Hyperopia- farsightedness, an individual will have difficulty seeing clearly up close. Light entering the eye focuses behind the retina when the eye is at rest and is corrected with a plus lens. Vision therapy is not prescribed for hyperopia. Children, up to about the age of 8 years, are often farsighted.
Hyperphoria- a condition in which one eye has a tendency to point higher than the other eye, causing eyestrain. Sometimes improved by prisms in glasses.
Hypertropia- strabismus, one eye turned in an upward direction.
Hypophoria- a condition in which one eye has a tendency to point lower than the other eye. This condition may be observed when one eye is covered.
Hypotropia- strabismus, one eye turned in a downward direction.
Iris- the colored part of the eye located between the lens and cornea; it regulates the entrance of light. (See diagram of the eye)
Latent Hyperopia- hyperopia (farsightedness) is compensated by accommodation and the tonicity (tension) of the ciliary muscle; identified by cycloplegic refraction. In mild cases of hyperopia (farsightedness), the eyes are able to compensate without corrective lenses; otherwise a plus lens (glasses or contacts) is prescribed. Vision therapy is not prescribed. (See "Hyperopia")
Learning Disability (LD)- a disorder that affects people's ability to either interpret what they see and hear or to link information from different parts of the brain. Learning disabilities can be divided into five broad categories: speech and language disorders, reading disorder, arithmetic disorder, writing disorder, and attention disorders. The term learning disability does not include children who have learning problems that are primarily the result of visual, hearing, or motor disorders.
Lensometer- also called Verometer, is a device used to measure the refractive power of eyeglasses and contact lenses.
Macula- the most sensitive part of the retina that is about the size of a pinhead and is where our most detailed vision occurs. (See diagram of the eye)
Macular Degeneration a deterioration of the central portion of the retina known as the macula.
Malingering- a voluntary or intentional reduction in visual acuity or other examination data.
Minus (-) Lens- concave lens, stimulates focusing and diverges light. The lens is thinner in the center than the edges. It is used in glasses or contact lenses for people who are nearsighted (myopia).
Monocular Vision- only one eye having useful vision.
Myopia- nearsightedness, an individual will have difficulty seeing clearly at distance. Light entering the eye focuses in front of the retina when the eye is at rest and is corrected with a minus lens. A condition known as high myopia occurs when myopia is greater than 6 diopters. Typically, vision therapy is not prescribed for myopia.
Near Acuity- the eye's ability to distinguish an object's shape and details at a near distance such as 16 inches (40 cm).
Near Point of Convergence (NPC)- the closest point at which the two eyes can maintain a single united image.
Near Point of Convergence Test- measures the patients ability to point the eyes at an approaching object and to keep them fixed on the object as it reaches the patients nose. Normal range is 0 to 4 inches away from the nose.
Nystagmus- rhythmic oscillations or tremors of the eyes which occur independent of the normal eye movements. Generally nystagmus is not curable, but it is manageable. Treatments include prescription glasses or contact lenses, prisms, and vision therapy.
Occlusion- to block out light. An eye can be completely or partially blocked. This procedure is used to promote the use of one eye or both eyes. This therapy procedure may be used for people with amblyopia, strabismus, or closed head trauma. It may also be used in a vision therapy program for someone with amblyopia, eye focusing (accommodation) disorder, or poor eye tracking (oculomotor) skill. An eye patch, black contact, or another device may be used to block out light from an eye. (See "Direct Occlusion" and "Inverse Occlusion")
Ocular Motility- pertaining to binocular alignment and eye muscle movement. (See "Binocularity", "Strabismus")
Oculus Dexter (OD)- right eye.
Oculus Sinister (OS)- left eye.
Oculus Uterque (OU)- both eyes.
Ophthalmologist - a physician (doctor of medicine (M.D.) or doctor of osteopathy (D.O.) who specializes in the comprehensive care of the eyes and visual system in the prevention of eye disease and injury. The ophthalmologist has completed four or more years of college premedical education, four or more years of medical school, one year of internship, and three or more years of specialized medical and surgical training and experience in eye care. The ophthalmologist is a physician who is qualified by lengthy medical education, training and experience to diagnose, treat and manage all eye and visual system problems, and is licensed by a state regulatory board to practice medicine and surgery. The ophthalmologist is the medically trained specialist who can deliver total eye care: primary, secondary and tertiary care services (i.e., vision services, contact lenses, eye examinations, medical eye care and surgical eye care), and diagnose general diseases of the body. An ophthalmologist is not trained to provide vision therapy.
Ophthalmoscope- a device used to illuminate the inside of the eye and enlarge the image for examining the retina, optic nerve entrance, arteries, and veins.
Optic Nerve- is a bundle of nerve fiber that connects each eye to the brain and transmits images from the retina to the brain. (See diagram of the eye)
Optician- is a professional in the field of designing, finishing, fitting and dispensing of eyeglasses and contact lenses, based on an eye doctor's prescription. The optician may also dispense colored and specialty lenses for particular needs as well as low-vision aids and artificial eyes.
Optometrist - a health care professional who is state licensed to provide primary eye care service. These services include comprehensive eye health and vision examinations; diagnosis and treatment of eye disease and vision disorders; the detection of general health problems; the prescribing of glasses, contact lenses, low vision rehabilitation, vision therapy, and medications; the performing of certain surgical procedures; and the counseling of patients regarding their surgical alternatives and vision needs as related to their occupations, avocations and lifestyle. The optometrist has completed pre-professional undergraduate education in a college or university and four years of professional education at a college of optometry, leading to the doctor of optometry (O.D.) degree. Some optometrists complete a residency.
Perceptual Skills- includes the identification, discrimination, spatial awareness, and visual-sensory integration. These are visual cognitive skills used to processes visual information to the brain to be organized and interpreted. (See Visual Perceptual Disorder)
Peripheral Vision- the ability to see or be aware of what is surrounding us, our side vision. (See "Visual Field".)
Photophobia- unusual sensitivity to light.
Polaroid Lens- a lens used in sunglasses and sometimes 3D glasses which consists of two glass or plastic surfaces with a plastic lamination between the two surfaces, and designed to reduce reflected glare. In optometric vision therapy, these lens are used with 3D pictures such as vectograms and stereograms, which are also polarized.
Presbyopia- sometimes called the fourth refractive error, is not truly a refractive error. It is the natural process of the eye losing the ability to accommodate or change the shape of the natural crystalline lens inside the eye to see comfortably at near. This vision defect occurs with the advancement of age; the onset usually occurs between the ages of 40 to 45. Unlike the rest of the body, which stops growing by the age of twenty, the lens of the eye continues to grow throughout life. As the lens ages and grows, it becomes harder in consistency, loses its elasticity, and therefore is resistant to changes in shape. The result is a gradual reduction in accommodation (near eye focus), and a more dependence on reading glasses. A plus lens or multi-focal lens (such as a bifocal lens) is prescribed in the form of glasses or contact lenses. Vision therapy is not a treatment option.
Prism- a wedge-shaped lens which is thicker on one edge than the other. This plastic or glass lens bends light (opposite direction from its thicker end). Prisms can be used to measure an eye misalignment and/or treat a binocular dysfunction (eye teaming problem). A prism is sometimes added to glasses to help improve eyesight due to an eye misalignment or visual field loss. (See "Base-Down Prism", Base-In Prism, Base-Out Prism, "Base-Up Prism", "Yoked Prism")
Ptosis- droopy upper eyelid, causing the eye to remain partially closed.
Pupil- the opening at the center of the iris of the eye. It contracts (dilates) in the dark and when the eye is focused on a distant object. (See diagram of the eye)
Pupillary Distance (PD)- the distances between the pupils of the eyes, in millimeters -- a necessary measurement for proper lens prescription.
Refraction Test- determines the eye's refractive error and the best corrective lenses to be prescribed. There are several methods of performing refraction: Retinoscopy, Automated Refractor, and Subjective Refraction.
Refractive Error- defects in vision caused by the eyes inability to bend, or refract light and focus it clearly on the retina. Astigmatism, hyperopia, and myopia are common conditions of refractive error, also called ametropia.
Retina- the innermost layer of the eye, a neurological tissue, which receives light rays focused on it by the lens. This tissue contains receptor cells (rods and cones) that send electrical impulses to the brain via the optic nerve when the light rays are present. (See diagram of the eye)
Rod- a receptor cell which is sensitive to light and is located in the retina of the eye. It is responsible for night vision.
Saccades- the eye's ability to direct and coordinate movement as it quickly and voluntarily shift from one target to another.
Sclera- the white protective covering of the eye. (See the diagram of the eye)
Stereopsis- the ability to perceive a three dimensional depth which requires adequate fusion (union) of the images from each eye.
Strabismus- (clinical condition) turned eye (s), the eyes are misaligned. It is caused by a reduction in visual acuity, reduced visual function, high refractive error, traumatic brain injury, oculomotor nerve lesion, or eye muscle injury. In strabismus, the eyes send conflicting images to the brain, and the brain cannot combine these images as it would in normal vision. The brain compensates by ignoring one image in favor of the other, causing a loss of depth perception. Strabismus in more common in children, and affects four percent of all children (although it may also appear later in life).
Subconjunctival Hemorrhage a blood spot on the eye. It occurs when a small blood vessel under the conjunctiva (the transparent coating that covers the inner eyelid and the white of the eye) breaks and bleeds. A common condition caused spontaneously from coughing, heavy lifting, or vomiting. In some cases, it may develop following eye surgery or trauma. It tends to be more common among those with diabetes, hypertension, and taking blood thinners (including aspirin). A subconjunctival hemorrhage is essentially harmless. The blood naturally absorbs within one to three weeks and no treatment is required.
Suppression Test- determines if there is any tendency for the visual processing center of the brain to ignore or suppress visual data from one eye.
Tranaglyph- red/green targets used with red/green glasses to develop eye teaming skills.
Vision- the ability to take in information through our eyes and process the information so that it has meaning.
Visual Acuity- sharpness or clearness of eyesight.
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