Primary Congenital Glaucoma Glossary of Terms
The following are health and medical definitions of terms that appear in the Primary Congenital Glaucoma article.
Ablation: Removal or excision. Ablation is usually carried out surgically. For example, surgical removal of the thyroid gland (a total thyroidectomy) is ablation of the thyroid. The word ablation comes from the Latin ablatum meaning to carry away. Abnormal: Not normal. Deviating from the usual structure, position, condition, or behavior. In referring to a growth, abnormal may mean that it is cancerous or premalignant (likely to become cancer). Amblyopia: Partial or complete loss of vision in one eye caused by conditions that affect the normal development of vision. These conditions include strabismus, in which the eyes are crossed inward (esotropia) or turned outward (exotropia) and anisometropia, in which there is a major difference in refractive error between the two eyes from nearsightedness, farsightedness, or astigmatism. Less common causes of amblyopia include ptosis (drooping) of one eyelid, disease of the cornea (preventing light from entering the eye), congenital cataract, and injury to the eye of a young child. Anesthesia: Loss of feeling or awareness. A general anesthetic puts the person to sleep. A local anesthetic causes loss of feeling in a part of the body such as a tooth or an area of skin without affecting consciousness. Regional anesthesia numbs a larger part of the body such as a leg or arm, also without affecting consciousness. The term "conduction anesthesia" encompasses both local and regional anesthetic techniques. Many surgical procedures can be done with conduction anesthesia without significant pain. In many situations, such as a C-section, conduction anesthesia is safer and therefore preferable to general anesthesia. However, there are also many types of surgery in which general anesthesia is clearly appropriate. Anterior: The front, as opposed to the posterior. The anterior surface of the heart is toward the breast bone (the sternum). Anterior chamber: The space in the eye that is behind the cornea and in front of the iris. Aqueous humor: In medicine, humor refers to a fluid (or semifluid) substance. Thus, the aqueous humor is the fluid normally present in the front and rear chambers of the eye. It is a clear, watery fluid that flows between and nourishes the lens and the cornea; it is secreted by the ciliary processes. Bilateral: Having, or relating to, two sides. Bilateral is as opposed, for example, to unilateral (which means having, or relating to, one side). Blepharospasm: Involuntary forcible closure of the eyelids. The first symptom may be uncontrollable blinking. Only one eye may be affected initially, but eventually both eyes are usually involved. The spasms may leave the eyelids completely closed causing functional blindness even though the eyes and vision are normal. Blepharospasm is a form of focal dystonia. Blind: 1. Unable to see. Without part or all of the sense of sight. Blindness: Loss of useful sight. Blindness can be temporary or permanent. Damage to any portion of the eye, the optic nerve, or the area of the brain responsible for vision can lead to blindness. There are numerous (actually, innumerable) causes of blindness. The current politically correct terms for blindness include visually handicapped and visually challenged. Choroid: In the eye, a thin vascular layer between the sclera and the retina. The choroid supplies blood to the retina and conducts arteries and nerves to other structures in the eye. Ciliary body: Part of the eye, the ciliary body is a thin vascular (blood vessel-filled) middle layer of the eye that is situated between the sclera (the white of the eye) and the retina (the nerve layer that lines the back of the eye, senses light, and creates impulses that travel through the optic nerve to the brain). Congenital: Present at birth. A condition that is congenital is one that is present at birth. There are numerous uses of "congenital" in medicine. There are, for example, congenital abnormalities. (For more examples, see below.) Cornea: The clear front window of the eye that transmits and focuses light into the eye. Corneal: Pertaining to the cornea, the clear front window of the eye that transmits and focuses light into the eye. Cure: 1. To heal, to make well, to restore to good health. Cures are easy to claim and, all too often, difficult to confirm. Dilation: The process of enlargement, stretching, or expansion. The word "dilatation" means the same thing. Both come from the Latin "dilatare" meaning "to enlarge or expand." Disc: Shortened terminology for an intervertebral disc, a disk-shaped piece of specialized tissue that separates the bones of the spinal column. Drain: A device for removing fluid from a cavity or wound. A drain is typically a tube or wick. As a verb, to allow fluid to be released from a confined area. Eyelid: The lid or cover of the eye, a movable fold of skin and muscle that can be closed over the eyeball or opened at will. Each eye has an upper and a lower lid. An eyelid is also called a palpebra. Fundus: Latin word for the bottom. In medicine, fundus refers to the bottom or base of an organ. Glaucoma: A common eye condition in which the fluid pressure inside the eyes rises because of slowed fluid drainage from the eye. If untreated, it may damage the optic nerve and other parts of the eye, causing the loss of vision or even blindness. Humor: In medicine, humor refers to a fluid (or semifluid) substance. Thus, the aqueous humor is the fluid normally present in the front and rear chambers of the eye. The humors ran through an ancient theory that held that health came from balance between the bodily liquids. These liquids were termed humors. Disease arose when there was imbalance between these humors. Implant: 1. To embed; to set in firmly. In embryology, the fertilized egg implants in the uterine lining 6 or 7 days after conception (fertilization). In medicine today, many things may be implanted. Incision: A cut. When making an incision, a surgeon is making a cut. Indicate: In medicine, to make a treatment or procedure advisable because of a particular condition or circumstance. For example, certain medications are indicated for the treatment of hypertension during pregnancy while others are contraindicated. Infant: A child up to 2 years (24 months) of age. Infection: The growth of a parasitic organism within the body. (A parasitic organism is one that lives on or in another organism and draws its nourishment therefrom.) A person with an infection has another organism (a "germ") growing within him, drawing its nourishment from the person. Inflammation: A basic way in which the body reacts to infection, irritation or other injury, the key feature being redness, warmth, swelling and pain. Inflammation is now recognized as a type of nonspecific immune response. Intraocular: In the eye. The intraocular pressure is the pressure within the eye. Intraocular pressure: The pressure created by the continual renewal of fluids within the eye. The intraocular pressure is increased in glaucoma. Iris: The iris is the circular, colored curtain of the eye. Its opening forms the pupil. The iris helps regulate the amount of light that enters the eye. Laser: A powerful beam of light that can produce intense heat when focused at close range. Lasers are used in medicine in microsurgery, cauterization, for diagnostic purposes, etc. For example, lasers are employed in microsurgery to cut tissue and remove tissue. Lazy eye: An eye that diverges in gaze. A lazy eye is formally called strabismus. A lazy eye (strabismus) can be due to esotropia (cross-eyed) or to exotropia (wall-eyed). The danger of the condition is that the brain comes in time to rely more on one eye than the other and that part of the brain circuitry connected to the less-favored eye fails to develop properly, leading to amblyopia (blindness) in that eye. Lens: The transparent structure inside the eye that focuses light rays onto the retina (the nerve layer that lines the back of the eye, senses light and creates impulses that go through the optic nerve to the brain). The lens was named after the lentil bean because it resembled it in shape and size. Membrane: A very thin layer of tissue that covers a surface. Nerve: A bundle of fibers that uses chemical and electrical signals to transmit sensory and motor information from one body part to another. See: Nervous system. Nystagmus: Rapid rhythmic repetitious involuntary (unwilled) eye movements. Nystagmus can be horizontal, vertical or rotary. Operating room: A facility equipped for performing surgery. Abbreviated OR. Ophthalmologist: An eye doctor. A physician practicing ophthalmology. An ophthalmologist is an M.D. Ophthalmology: The art and science of eye medicine. Ophthalmoscopy: Examination of the interior of the eye, including the lens, retina and optic nerve, by indirect or direct ophthalmoscopy. Optic: Having to do with vision. Optic disc: The circular area in the back of the inside of the eye where the optic nerve connects to the retina. Also called the optic nerve head. Optic nerve: The optic nerve connects the eye to the brain. The optic nerve carries the impulses formed by the retina, the nerve layer that lines the back of the eye and senses light and creates impulses. These impulses are dispatched through the optic nerve to the brain, which interprets them as images. Using an ophthalmoscope, the head of the optic nerve can be easily seen. It can be viewed as the only visible part of the brain (or extension of it). Pharmacy: A location where prescription drugs are sold. A pharmacy is, by law, constantly supervised by a licensed pharmacist. Photophobia: Painful oversensitivity to light. For example, there is photophobia in measles (rubeola). Keeping the lights dim or the room darkened may be useful. Sunglasses may also help. Probe: (1) In surgery, a probe is a slender flexible rod with a blunt end used to explore, for example, an opening to see where it goes. (2) In molecular genetics, a probe is a labeled bit of DNA or RNA used to find its complementary sequence or locate a particular clone like homing in on a needle in a haystack. Prognosis: 1. The expected course of a disease. Recur: To occur again. To return. Any symptom (such as fatigue), any sign (such as a heart murmur), or any disease can recur. Resistance: Opposition to something, or the ability to withstand it. For example, some forms of staphylococcus are resistant to treatment with antibiotics. Rule out: A term much used in medicine, meaning to eliminate or exclude something from consideration. The ACB (albumin cobalt binding) test helps rule out a heart attack in the differential diagnosis of severe chest pain. Sensitivity: 1. In psychology, the quality of being sensitive. As, for example, sensitivity training, training in small groups to develop a sensitive awareness and understanding of oneself and of ones relationships with others. 2. In disease epidemiology, the ability of a system to detect epidemics and other changes in disease occurrence. 3. In screening for a disease, the proportion of persons with the disease who are correctly identified by a screening test. 4. In the definition of a disease, the proportion of persons with the disease who are correctly identified by defined criteria. Shunt: 1) To move a body fluid, such as cerebrospinal fluid, from one place to another. 2) A catheter (tube) that carries cerebrospinal fluid from a ventricle in the brain to another area of the body. A shunt may be placed to relieve pressure from hydrocephalus, for example. Surgeon: A physician who treats disease, injury, or deformity by operative or manual methods. A medical doctor specialized in the removal of organs, masses and tumors and in doing other procedures using a knife (scalpel). The definition of a "surgeon" has begun to blur in recent years as surgeons have begun to minimize the cutting, employ new technologies that are "minimally invasive," use scopes, etc. Surgery: The word "surgery" has multiple meanings. It is the branch of medicine concerned with diseases and conditions which require or are amenable to operative procedures. Surgery is the work done by a surgeon. By analogy, the work of an editor wielding his pen as a scalpel is s form of surgery. A surgery in England (and some other countries) is a physician's or dentist's office. Tear: A drop of the salty secretion of the lacrimal glands which serves to moisten the conjunctiva and cornea. Tonometry: A standard eye test that determines the fluid pressure inside the eye. Increased pressure is a possible sign of glaucoma, a common and potentially very serious eye problem if not detected and treated promptly. It is recommended that adults over age 40 have tonometry for glaucoma every 3 to 5 years by having their eye pressures measured. Trauma: Any injury, whether physically or emotionally inflicted. "Trauma" has both a medical and a psychiatric definition. Medically, "trauma" refers to a serious or critical bodily injury, wound, or shock. This definition is often associated with trauma medicine practiced in emergency rooms and represents a popular view of the term. In psychiatry, "trauma" has assumed a different meaning and refers to an experience that is emotionally painful, distressful, or shocking, which often results in lasting mental and physical effects. Ultrasound: High-frequency sound waves. Ultrasound waves can be bounced off of tissues using special devices. The echoes are then converted into a picture called a sonogram. Ultrasound imaging, referred to as ultrasonography, allows physicians and patients to get an inside view of soft tissues and body cavities, without using invasive techniques. Ultrasound is often used to examine a fetus during pregnancy. There is no convincing evidence for any danger from ultrasound during pregnancy. Uvea: Part of the eye, consisting collectively of the iris, the choroid of the eye, and the ciliary body Uveitis: Inflammation of the uvea, the part of the eye that collectively refers to the iris, the choroid of the eye, and the ciliary body. The uvea provides most of the blood supply to the retina. Uveitis as a rule signifies inflammation involving the iris, choroid, and ciliary body -- all three components of the uveal tract. Visual field: The entire area that can be seen when the eye is directed forward, including that which is seen with peripheral vision. |
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Primary Congenital Glaucoma
What is glaucoma?
Glaucoma is usually high pressure inside the eye that damages the optic nerve and can result in permanent vision loss. Not all 3 criteria (that is, high pressure inside the eye, optic nerve damage, and vision loss) are required to diagnose glaucoma; however, a diagnosis of glaucoma is certain when all 3 criteria are present.
What causes high pressure inside the eye?
High pressure inside the eye is caused by an imbalance in the production and drainage of fluid in the eye (aqueous humor). The channels that normally drain the fluid from inside the eye do not function properly or are blocked. More fluid is continually being produced but cannot be drained because of the improperly functioning or blocked drainage channels. This results in an increased amount of fluid inside the eye, thus raising the pressure.
Another way to think of high pressure inside the eye is to imagine a water balloon. The more water tha...
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