T
The following list provides a brief description of several of the most common eye disorders.
ACCOMMODATION The ability of the visual system to see clearly distant and close. ACCOMMODATION, MUSCLES OF (See CILIARY MUSCLE)
AMBLYOPIA (LAZY EYE) Reduced vision uncorrectable by glasses. It occurs when the brain 'switches off' the messages coming from a particular eye. This eye sometimes turns to one side or the other.
ASTIGMATISM is a visual defect which is caused by an irregularity in the surface of either the cornea or the crystalline lens.
AUTONOMIC NERVOUS SYSTEM The part of our nervous system that functions automatically and is in charge of maintaining a stable internal environment.
BATES SYSTEM Techniques for relaxing and mobilising the whole visual system devised by American ophthalmologist William H Bates. This method emphasized the connection between the body and mind and gave individuals a way to improve their sight without depending on glasses.
BEHAVIOURAL OPTOMETRY A specialized branch of optometry which recognizes the influence of environment, posture and general health on eyesight. The treatment is a combination of training lenses and eye exercises.
BINOCULAR VISION is vision in which both eyes are used together.
BLOODSHOT EYES If your eyes are chronically bloodshot, it may be that the delicate capillaries in your eyes are trying to tell you something.
CATARACT is a condition in which the lens of the eye becomes dense or opaque and does not properly transmit light.
CHI The Chinese term for universal life energy.
CHIROPRACTIC A system of healing based upon the theory that disease results from a lack of normal nerve function. Treatment consists of manipulation and specific adjustments of body structures, especially the spinal column.
CILIARY MUSCLE The muscle which encircles the lens of the eye. It contracts and releases, changing the shape of the lens thus producing accommodation.
CONE CELLS Specialised nerve cells on the retina which produce colour and detail vision.
CONCAVE LENSES a lens which curves inward, used to compensate for myopia. This. lens makes things look smaller.
CONJUNCTIVITIS, sometimes called pink eye, is an inflammation of the blood vessels in the conjunctiva, the membrane that covers the sclera and inside of the eyelids. Conjunctivitis may be caused by bacteria or viruses, making it very contagious.
CONVERGENCE INSUFFICIENCY is a common condition that is characterized by a person's inability to maintain proper binocular eye alignment on objects as they approach from distance to near.
CONVEX LENSES a lens which curves outward, used to compensate for hyperopia. This lens magnifies.
CORNEA The transparent front of the eye that covers the iris and pupil.
CROSSED EYES is also known as Squint or Strabismus. It describes the situation where the eyes move out of the aligned state when they are dissociated.
DIOPTER The measurement unit used for describing refractive error on prescriptions. One diopter is the refractive power of a lens needed to focus a point of light at one metre's distance.
DIVERGENCE Moving away from a central point or line. A term used to describe eyes that turn outward. (See STRABISMUS)
DOMINANT Commanding or controlling. This term is used to describe the sides of the brain and body which are used first, ie each individual is either right or left brain dominant, dictating their particular tendancies even when they are using both sides. (See RIGHT & LEFT BRAIN.) A 'right-handed' individual can be described as 'right hand dominant'.
DRY EYE occurs when there is not enough moisture in the eye, causing it to feel dry, hot, sandy, and gritty. Dry eye may be caused by low humidity, smoke, aging, certain diseases, and certain medications (i.e., antihistamines, decongestants).
EMMETROPIA Normal refractive condition of the eye.
ENZYMES Chemicals created by living cells that catalyse processes in the body. The most well known enzymes are those used by the body for digesting foods. Digestive enzymes are essential for the breaking down of foods into their nutrient components for use by the body.
ESOTROPIC This describes an eye that turns inward (cross-eyed) (See PHORIA).
EXOTROPIC This describes an eye that turns outward (wall-eyed): (See PHORIA) FOVEA
EYE ALLERGIES Up to 50 million Americans suffer from the miseries of allergies, with allergic reactions involving the eyes being a common complaint. An allergic reaction that affects the conjunctiva, a clear layer of skin overlying the eyes, is commonly referred to as allergic conjunctivitis.
EYE ANATOMY The human eye is one of the most important organs and probably the most useful of various sense organs of our body.
CENTRALIS The point of keenest vision in the eye, located inside the macula lutea. In this area a very large number of cone cells are massed tightly together. When light enters the lens and is cast directly on the fovea centralis, sharp, detailed images will result.
FLOATERS
Nearsighted people almost always have a certain number of floaters because of the shape of their eyes. In older people, the vitreous transforms from a gel to a more liquid form ...
FOVEAL VISION Sharp, clear vision acheived by the fovea centralis. Also called 'nuclear' and 'central' vision. (See NUCLEAR VISION).
FUSION The brain and mind's ability to create one image from the messages coming from both eyes.
FUSIONAL RESERVE A reserve of strength and energy in the visual system which allows clear vision and fusion to take place through periods of strain. This reserve lasts for a certain period and can be 're-charged', but will not be maintained through long periods of constant stress.
'GATE' The appearance of two fingers that arises when one finger is held up close in front of the eyes and the attention is in the distance. This double-image shows that fusion is happening in the visual system.
GLAUCOMA is a disease that impairs vision when fluid and pressure build up in the eye and damage the optic nerve.
'GREAT WHITE GLOW' The white aura seen around letters and words when viewing black print on white paper with a relaxed mind.
HYPEROPIA (LONG-SIGHTEDNESS) A state in which images of close objects fall behind the retina rather than on it, resulting in visual blur. The physical aspect is an abnormally short eyeball. The emotional aspect is discomfort with closeness, intimacy, details. Usually compensated for by prescribing of magnifying or 'plus' lenses.
INTEGRATION The merging and blending of abilities and characteristics. The act of unifying rather than isolating. Denotes a state of high human ability.
LAZY EYE (Also known as Amblyopia) is the natural consequence of long-term disuse or suppression of an eye. It should be noted that severe congenital visual defects in both eyes, if not corrected in time, may result in laziness of both the eyes.
LENS The transparent layered curved structure that sits between the pupil and vitreous humor. The lens gently bends entering light and helps bring it to a point on the retina.
MACULAR DEGENERATION is the breaking down, or degeneration, of the macula area of the retina of the eye.
MACULA LUTEA A small area on the retina in a direct line back from the lens of the eye. It has a higher concentration of the cone receptor cells than the rest of the retina.
MELANIN A pigment in human skin. It helps to protect the skin from overexposure to sunlight.
MYOPIA (SHORT-SIGHTEDNESS) A state of the visual system in which images of distant objects fall in front of rather than on the retina, resulting in blur. Physically, the eyeball is too long. Emotionally, myopes usually have difficulty wanting to see or open up to the larger world. Usually compensated for by prescribing of contractive 'minus' lenses.
OCULAR ANAESTHESIA Anaesthesia used on the eye so that surgery can be performed.
OPTIC CHIASM The intersection of the optic nerves from the two eyes. At this point in the brain the optic nerve fibres divide, half from each eye crossing over to join half from the other eye.
OPHTHALMOLOGIST A medical doctor specializing in examining eyes and prescribing glasses, diagnosing and treating eye dis.eases. Performs optional surgeries for strabismus and myopia.
OPTOMETRIST Examines eyes and prescribes glasses. Diagnoses but usually refers eye diseases. Behavioural optometrists also give eye exercises.
ORTHOPTICS A medically accepted method of exercising eye muscles to correct crossed eyes and muscular weakness. Commonly used for a short period after surgery.
OSTEOPATH A practitioner of osteopathy.
OSTEOPATHY A system of medical treatment based on the theory that diseases are chiefly due to the loss of structural integrity in the tissues of the body. Treatment consists of body manipulation (adjustments) surgery, drugs, and diet.
PALMING Gently placing the cupped palms of the hands over closed eyes to relax by visualising pleasant images.
PATCHING Covering one eye with an obscuring material to encourage the uncovered eye to wake up, perceive and strengthen.
PHORIA The tendency of lines of vision to deviate from the normal. Esophoria is the tendency of eyes to deviate (turn) inward (towards the nose). Exophoria is the tendency of eyes to deviate in an outward direction.
PINK EYE, also known as Conjunctivitis, is an inflammation of the blood vessels in the conjunctiva, the membrane that covers the sclera and inside of the eyelids. Conjunctivitis may be caused by bacteria or viruses, making it very contagious.
PRESBYOPIA is an eye condition that typially occurs after the age of forty. Loss of elasticity in the lens of the eyes is the main cause of Presbyopia.
PTERYGIUM A fleshy mass of conjunctiva which usually occurs at the inner side of the eyeball, covering part of the cornea. Pterygiums can cause a disturbance of vision by growing across the pupil.
REFRACTIVE ERROR A deviation in the eye's ability to bend incoming light to create a clear image. Variations are labeled as hyperopia, myopia, presbyopia ('old-age sight') and astigmatism.
REM (RAPID EYE MOVEMENT) Prior to going into deep sleep an individual's eyes make many rapid small movements behind closed lids.
RETINA The responsive layer of specialised nerve cells at the back of the eye which change light into electrical impulses.
RETINOSCOPE An optical instrument that casts a beam of light into the eye revealing whether it is in a state of refractive error.
RETINOSCOPY Objective examination of the refractive powers of the eye by observation with a retinoscope.
ROD CELLS Nerve cells in the retina which register light and dark. They are stimulated in dim light and do not register colour.
SACCADES Quick, small movements that enable the eyes to pick up details and to move from one object of interest to another.
SQUINT is also known as crossed eyes or Strabismus. It describes the situation where the eyes move out of the aligned state when they are dissociated.
STRABISMUS (SEE SQUINT)
SUNNING Relaxing for short periods in the sunlight with eyes closed. Sunning allows body and eyes to absorb the small amount of UV light essential to human health.
SUPPRESSION The vision of a person with suppression in one eye could be thought of as one dimensional. He finds it difficult to judge the location of an object in space correctly.
SWING Moving attention and body to relax and to activate rapid saccadic movement in the eyes.
ULTRA-VIOLET (UV) That part of the sun's rays with slightly greater frequency than violet. It is also emitted by artificial lamps that are used for healing, growing plants and forming vitamins. Ultra-violet is said to be necessary for human health as it stimulates the pituitary gland.
VISUAL CORTEX A part of the cerebral cortex in the brain, primarily responsible for interpreting visual impulses from the eyes. Also called the visual brain.
