Sclera; The White Part of Your Eye. This and other common eye care terms defined!

Amblyopia: Also called lazy eye. Decreased vision in one eye that leads to the use of the other eye as the dominant eye. A problem most commonly associated with children.

Astigmatism: An eye condition where the eye cannot focus light uniformly in all directions resulting from an irregular curvature of the cornea, the crystalline lens, or the eye itself. Astigmatism results in mild to moderately blurred vision and/or eyestrain.

Cataracts: A cataract is a clouding of the crystalline lens of the eye that makes it hard for light to pass through and be focused properly. In a normal eye, the crystalline lens is almost transparent, however injury, age or disease can cause the lens to eventually lose its clarity. When the lens becomes 'opaque,' it is called a cataract. Treatable by surgery.

Conjunctivitis (Pinkeye): An eye condition caused by the inflammation of the conjunctiva, or clear membrane covering the white part of the eye and lining of the eyelids. The eyes will often appear swollen and red while also feeling gritty. It is often viral and may be contagious. There are actually 20 different types of conjunctivitis – from fairly common strains that usually pose no long-term danger to you or your child's vision – to types that are resistant to antibiotics. Call or see your doctor to treat pinkeye.

Cornea: The transparent, multi-layered front part of the eye that covers the pupil and iris. It provides most of the eye’s optical power.

Floaters and Spots: A generalized term used to describe small specks moving subtly but noticeably in your field of vision. A floater or a spot is likely a tiny clump of gel or cells in the vitreous – the clear, jelly-like fluid inside your eye. Aging, eye injury and breakdown of the vitreous are the main causes of floaters and spots. If you notice a sudden increase in the number you see, call your eye care professional.

Fovea: A tiny spot in the center of the retina that contains only cone cells. This area is responsible for our sharpness of vision.

Glaucoma: A common cause of preventable vision loss when excessive pressure within the eye damages the optic nerve. Treatable by prescription drugs or surgery.

Hyperopia: A condition where distant objects are seen clearly, yet objects close up are seen less clearly. Also commonly referred to as “farsighted.”

Iris: The pigmented (colored) membrane that lies between the cornea and the crystalline lens that controls the size of the pupil.

Crystalline Lens: The eye’s natural lens located directly behind the iris. It has the ability to change shape to focus light rays onto the retina.

Macula: The part of the retina responsible for the sharp, central vision needed to read or drive.

Macular Degeneration: A group of conditions that include a deterioration of the macula causing a loss of central vision needed for sharp, clear eyesight. It is a leading cause of vision loss and blindness in those 65 years of age and older. Macular Degeneration is also called AMD or ARMD (age-related macular degeneration).

Myopia: A condition where distant objects appear less clearly and those objects up close are seen clearly. Also commonly referred to as “nearsighted.”

Nyctalopia: Commonly called “night blindness,” this is a condition that presents as impaired vision in dim light or darkness.

Optic Nerve: A bundle of nerve fibers that carries messages from the eyes to the brain.

Photophobia: Also called “light sensitivity”, this is a condition that can have many underlying causes, and can be prompted by many medications. Protection from bright light is critical for anyone with photophobia.

Pterygium: A raised growth on the eye that is most often directly related to over-exposure to the sun. Dry, dusty conditions may also contribute to development of these growths. Protecting your eyes from UV radiation is a critical preventive measure.

Pupil: The opening in the center of the iris that changes size to control how much light is entering the eye.

Pupillometer: An instrument used to measure the distance between pupils. This measurement is used to position the eyeglass prescription correctly in front of the eye.

Retina: Part of the rear two-thirds of the eye that converts images from the eye’s optical system into impulses that are transferred by the optic nerve to the brain. Consists of layers that include rods and cones.

Rods and cones: These are cells inside the eye used by the retina to process light. Rods are used for low light levels (night vision), cones are used for sharp visual acuity and color perception.

Sclera: The white part of the eye – composed of fibrous tissue that protects the inner workings of the eye.

Single-Vision: Types of lenses that correct one vision problem, like near or far-sightedness.

Snellen Chart: This is the commonly seen eye chart often topped by a large letter “E” used in eye examinations. This measures your eye’s visual acuity, or the ability to see sharp detail clearly.

Strabismus: Sometimes called “crossed eyes” in young children, this condition is the lack of coordination between the eyes, such as one or both eyes turning in, out, up or down.

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