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February 10, 2012

Eyeglasses, Sunglasses, and Magnifying Glasses Glossary of Terms

The following are health and medical definitions of terms that appear in the Eyeglasses, Sunglasses, and Magnifying Glasses article.

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).

Aging: The process of becoming older, a process that is genetically determined and environmentally modulated.
See the entire definition of Aging

Basal cell carcinoma: The most common type of skin cancer, a disease in which the cancer cells resemble the basal cells of the epidermis, the outer layer of the skin.
See the entire definition of Basal cell carcinoma

Carcinoma: Cancer that begins in the skin or in tissues that line or cover body organs. For example, carcinoma can arise in the breast, colon, liver, lung, prostate, and stomach.

Cataract: A clouding or loss of transparency of the lens in the eye as a result of tissue breakdown and protein clumping. There are many causes of cataracts, including aging, cortisone medication, trauma, diabetes, and other diseases. Cataracts affect most people who live into an old age. Symptoms include double or blurred vision and sensitivity to light and glare. A physician can diagnose cataracts by examining the eyes with a viewing instrument. Sunglasses can help to prevent cataracts.
See the entire definition of Cataract

Cell: The basic structural and functional unit in people and all living things. Each cell is a small container of chemicals and water wrapped in a membrane.
See the entire definition of Cell

Conjunctiva: A thin clear moist membrane that coats the inner surfaces of the eyelids and the outer surface of the eye.
See the entire definition of Conjunctiva

Conjunctival: Pertaining to the conjunctiva, the clear moist membrane that covers the inner surfaces of the eyelids and the front of eyeball.

Cornea: The clear front window of the eye that transmits and focuses light into the eye.
See the entire definition of Cornea

Dilate: To stretch or enlarge. It comes from the Latin verb "dilatare" meaning "to enlarge or expand."

Excision: 1. Surgical removal, as in the excision of a tumor. 2. The removal as if by surgery, as in base excision repair.
See the entire definition of Excision

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.

Fatigue: A condition characterized by a lessened capacity for work and reduced efficiency of accomplishment, usually accompanied by a feeling of weariness and tiredness. Fatigue can be acute and come on suddenly or chronic and persist.
See the entire definition of Fatigue

Focal: Pertaining to a focus which in medicine may refer to:
1. The point at which rays converge as, for example, in the focal point.
2. A localized area of disease. A focal cancer is limited to one specific area.

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.
See the entire definition of Lens back to top

Macular: Pertaining to the macula. A macula is a small spot. A macula on the skin is a small flat spot while the macula in the eye is a small spot where vision is keenest in the retina.


See the entire definition of Macular

Macular degeneration: A disease that progressively destroys the macula, the central portion of the retina, impairing central vision. Macular degeneration rarely causes blindness because only the center of vision is affected. However, injury to the macula in the center of the retina can impair the ability to see straight ahead clearly and sometimes make it difficult to read, drive, or perform other daily activities that require fine central vision.
See the entire definition of Macular degeneration

Membrane: A very thin layer of tissue that covers a surface.

Pigment: A substance that gives color to tissue. Pigments are responsible for the color of skin, eyes, and hair.

Presbyopia: The loss of the eye's ability to change focus to see near objects. The reasons for this loss of the power of accommodation are not yet fully known. It is conventionally said to be due to the lens becoming less elastic with time.
See the entire definition of Presbyopia

Prescription: A physician's order for the preparation and administration of a drug or device for a patient. A prescription has several parts. They include the superscription or heading with the symbol "R" or "Rx", which stands for the word recipe (meaning, in Latin, to take); the inscription, which contains the names and quantities of the ingredients; the subscription or directions for compounding the drug; and the signature which is often preceded by the sign "s" standing for signa (Latin for mark), giving the directions to be marked on the container.

Progressive: Increasing in scope or severity. Advancing. Going forward. In medicine, a disease that is progressive is going from bad to worse.

Pterygium: A winglike triangular membrane. Although a pterygium can be anywhere, including behind the knee, it commonly refers to a winglet of the conjunctiva. This pterygium may extend across the white of the eye toward the inner corner of the eye. It is caused by prolonged exposure of the eyes to wind and weather, or can be an inherited disorder caused by a single gene.

Pupil: The opening of the iris. The pupil may appear to open (dilate) and close (constrict) but it is really the iris that is the prime mover; the pupil is merely the absence of iris. The pupil determines how much light is let into the eye. Both pupils are usually of equal size. If they are not, that is termed anisocoria (from "a-", not + "iso", equal + "kore", pupil = not equal pupils).
See the entire definition of Pupil

Resistance: Opposition to something, or the ability to withstand it. For example, some forms of staphylococcus are resistant to treatment with antibiotics.

Retina: The retina is the nerve layer that lines the back of the eye, senses light, and creates impulses that travel through the optic nerve to the brain. There is a small area, called the macula, in the retina that contains special light-sensitive cells. The macula allows us to see fine details clearly.
See the entire definition of Retina

Sclera: The tough white outer coat over the eyeball that covers approximately the posterior five-sixths of its surface. The sclera is continuous in the front of the eye with the cornea and in the back of the eye with the external sheath of the optic nerve.
See the entire definition of Sclera

Squamous cell carcinoma: Cancer that begins in squamous cells -- thin, flat cells that look under the microscope like fish scales. Squamous cells are found in the tissue that forms the surface of the skin, the lining of hollow organs of the body, and the passages of the respiratory and digestive tracts. Squamous cell carcinomas may arise in any of these tissues.
See the entire definition of Squamous cell carcinoma

Strain: 1. An injury to a tendon or muscle resulting from overuse or trauma. 2. A hereditary tendency that originated from a common ancestor. 3. To exert maximum effort. 4. To filter.

Tumor: An abnormal mass of tissue. Tumors are a classic sign of inflammation, and can be benign or malignant (cancerous). There are dozens of different types of tumors. Their names usually reflect the kind of tissue they arise in, and may also tell you something about their shape or how they grow. For example, a medulloblastoma is a tumor that arises from embryonic cells (a blastoma) in the inner part of the brain (the medulla). Diagnosis depends on the type and location of the tumor. Tumor marker tests and imaging may be used; some tumors can be seen (for example, tumors on the exterior of the skin) or felt (palpated with the hands).
See the entire definition of Tumor back to top

Visual acuity: The clarity or clearness of the vision, a measure of how well a person sees. The ability to distinguish details and shapes of objects; also called central vision.
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  • Related Diseases & Conditions

    • Cataracts
      • A cataract is an eye disease that causes the eye's lens to become cloudy and opaque with decreased vision. Causes of cataracts include diabetes, hypothyroidism, certain genetic illnesses, hyperparathyroidism, atopic dermatitis, and certain medications. Symptoms and signs include a decrease in vision and a whitish color to the affected eye. Treatment depends upon the patient's specific visual needs and may involve cataract surgery.
    • Eye Strain
      • Eye strain is a symptom caused by looking at something for a long time. Symptoms and signs include redness, light sensitivity, headaches, and blurred vision. Symptoms may be treated by closing the eyes and taking a break from the visual task.
    • Eye Care
      • Many common eye disorders resolve without treatment and some may be managed with over-the-counter (OTC) products. It's important to visit a physician or ophthalmologist is the problem involves the eyeball itself or the condition hasn't improved after 72 hours of use of an eye-care OTC product.
    • Astigmatism
      • Astigmatism is a common eye condition that's easily corrected by eyeglasses, contact lenses, or surgery. Symptoms of astigmatism are headaches, fatigue, eyestrain and blurred vision.
    • Blindness
      • Blindness is the state of being sightless. Causes of blindness include macular degeneration, stroke, cataract, glaucoma, infection and trauma. Symptoms and signs may include eye pain, eye discharge, or the cornea or pupil turning white. Treatment of blindness depends upon the cause of the blindness.
    • Macular Degeneration
      • Age-related macular degeneration (AMD) is a disease that gradually destroys the central vision. In people over 60, AMD is a leading cause of vision loss. Wet AMD occurs when abnormal blood vessels behind the retina start to grow under the macula, leaking blood and fluid and causing rapid vision loss. In dry AMD, light-sensitive cells slowly break down in the macula, resulting in gradual vision loss. Pain is not associated with either form of AMD.
    • Presbyopia
      • Presbyopia is the age-related loss of the ability to focus on objects that are close up. The condition generally affects people over 45 years of age and causes blurred vision, headaches, and the need to hold reading material at arm's length. Presbyopia cannot be cured. Prescription contact lenses and glasses can help those who have presbyopia to see more clearly.
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Eyeglasses, Sunglasses, and Magnifying Glasses

Introduction

Presbyopia is part of the natural aging process of the eye, and can be easily corrected. Technically, presbyopia is the loss of the eye's ability to change its focus to see objects that are near. It is not a disease. It's as natural as wrinkles, and it affects everybody at some point in life. Presbyopia generally starts to appear around age 45.

Presbyopia is often confused with farsightedness , but the two are different. Presbyopia occurs when the eye's lens loses flexibility. Farsightedness occurs as a result of the shape of the eyeball, which causes light rays to bend incorrectly once they have entered the eye.

What Are the Symptoms of Presbyopia?

Symptoms of presbyopia include:

  • Blurred vision at a normal reading distance
  • The need to hold reading material at arm's length
  • Headaches from doing ...

Read the Presbyopia article »


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