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Anatomy
Conjunctiva: A tissue-paper thin membrane that is on the surface of
the white part of the eye. It contains many tiny blood vessels which dilate
when irritated and cause the eye to be red (see pink eye).
Cornea: The clear front surface of the eye.
Iris: The colored part of the eye, usually blue, brown or hazel.
Lens: The part of the eye that changes the focus of the eye by changing
its shape.
Optic nerve: The nerve that carries information from the retina to the
brain.
Pupil: An opening in the iris that can change size depending on lighting
conditions.
Retina: The lining of the eye which, like film in a camera or a movie
screen, records the image you see.
Sclera: The white outer shell of the eye seen beneath the thin conjunctiva.
It is a tough protective layer of tissue.
Visual field: The entire area that is seen, including central vision
(for reading) and peripheral or side vision.
Vitreous: A jelly-like substance that fills the inside of the eye.
Conditions
Astigmatism: A common finding relating to the shape of the cornea (the
front surface of the eye). The cornea's curve vertically is different than its
curve horizontally, like the bowl of a spoon.
Farsightedness (Hyperopia): The ability to see distant and near objects
with changes in focusing of the lens; a common condition that usually does not
require glasses until a person is in their 40's or 50's.
Nearsightedness (Myopia): The ability to see near objects clearly with
or without glasses, but distant objects are blurred without glasses.
Presbyopia: Literally "elder vision", this is a gradual loss
of the ability to focus on near objects. This is a normal change that happens
to everyone and it is corrected by reading glasses or bifocals.
Diseases
Amblyopia or lazy eye: Poor vision in one eye due to 1) abnormal alignment
of the two eyes, or 2) a significant difference in the refraction (need for
glasses) in the two eyes, or 3) blockage of a good image from cataract, corneal
scar, droopy eye lid, etc.
Cataract: A haze or clouding of the lens of the eye due to normal aging
changes. Cataracts blur vision but do no permanent damage to the eyes.
Detached retina: A problem in which the inner lining of the eye (the
retina) separates from the back of the eye, usually accompanied by flashing
lights, floaters and blurring of vision or loss of side vision.
Diabetic retinopathy: Abnormal blood vessels formed in response to chronically
abnormal blood sugar. These blood vessels tend to break and cause bleeding,
swelling and scar tissue in the retina.
Esotropia: A condition in which one eye turns in as if looking toward
the nose, usually due to a weak eye muscle, poor vision in one eye, or abnormal
innervation to the eye muscles.
Exotropia: An eye condition in which one eye turns out due to a weak
eye muscle, abnormal innervation to the eye muscle, or lack of coordination
of eye movements.
Floaters: Small dots, irregular lines, blobs, or spider web appearing
objects that float or wander across your visual field; these are usually due
to small pieces of vitreous gel or blood in the eye. They are usually not a
problem, but may rarely provide warning of a retinal detachment.
Glaucoma: An eye condition in which the main nerve of the eye (the optic
nerve) is damaged due either to intolerance of the eye pressure and/or to poor
circulation around the nerve.
Iritis: An irritation of the colored part of the eye that causes redness,
pain and light sensitivity.
Keratoconus: A condition in which the cornea is thin and bulges forward
irregularly causing poor vision.
Lazy eye: A term used for a poor vision eye (as noted under amblyopia),
for an eye that wanders in or out, or for an eye that has a droopy eye lid.
Macular degeneration: Decrease or loss of reading vision due to damage
to the central retina from abnormal circulation and/or nutritional factors.
Nystagmus: Irregular, uncontrollable jerking or wobbling movements of
the eyes usually seen in very poor vision eyes.
Optic Atrophy: A degeneration of the main nerve of the eye that carries
the image to the brain.
Pink eye: A red color of the lining of the eye that is due to infection
(bacterial or viral) inflammation (allergy, dryness, pollution or smoke) or
bleeding (broken blood vessels).
Posterior capsular opacity: A film that may develop behind the intraocular
lens, that may cause blurring of vision; this film may form months to years
after cataract surgery.
Pterygium: A thickened or fleshy tissue on the white part of the eye
that grows onto the cornea covering the colored part of the eye (the iris).
Ptosis: A droopy eye lid due to weakness of the muscle that lifts the
lid or to excess skin that covers the eye; this may be in one or both eyes.
Sty: A localized infection of an oil gland in the eyelid, like a pimple.
Sub-conjunctival hemorrhage: A red spot on the white of the eye due
to a broken blood vessel; it is like a bruise and may vary in size.
Optical Terms
Bifocal: Glasses with lenses that focus at two different distances;
near for reading and far for driving or watching TV.
Progressive bifocal: "no line" bifocals that focus at multiple
distances.
Refraction: The process of determining the lens power that will correct
an eye that is nearsighted, farsighted or has astigmatism and allow that eye
to see its best.
Trifocal: Glasses with lenses that focus at three different distances;
near for reading, far for driving, and at arm's length for computer use, piano
playing, etc.
Surgery
Intraocular lens: A plastic lens (similar in shape to a contact lens,
but smaller) that is placed in the eye after cataract surgery to correct the
patient's vision.
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