Accommodation:  The ability of the eye to focus on objects that are closer than optical infinity, approx. 20 ft (6 m)

Age Related Macular Degeneration:  (ARMD) diseases in which sensory cells of the macula decrease resulting in a loss of central vision: affects older people

Amblyopia:  “Lazy eye” a unilateral or occasionally bilateral condition in which the best corrected vision is poorer than 20/20 (6/6) in the absence of any obvious structural abnormalities or ocular disease

Anterior Chamber:  The small compartment between the cornea and the iris that is filled with clear, transparent fluid called aqueous humor

Anterior Chamber Angle:  The junction of the cornea and the iris, from which aqueous leaves the eye.  Also called filtration angle

Applanation:  A form of tonometry in which the force required to flatten a small area of the central cornea is measured

A-scan Ultrasonography:  A diagnostic procedure in which sound waves traveling in a line are used to reveal the position of, and distances between structures within the eye orbit.  Also called A-mode ultrasonography

Astigmatism:  A refractive anomaly caused by unequal refraction of light in different meridians, resulting in a distorted and blurred image

Cataract:  an opacified or clouded change in the structure of the crystalline lens which results in loss of light and therefore images transmission to the retina

Chalazion:  A non-tender lump that may become visible on the outer lid; due to long term inflammation and infection of a meibomian gland

Conjunctiva:  The thin transparent membrane lining the exposed eyeball and inside surface of the eyelid

Conjunctivitis: Inflammation of the conjunctiva.  May be caused by bacteria, virus, allergens or chemical or UV exposure

Cornea:  The front-most surface of the eye.  The transparent window and primary focusing lens of the eye

Diabetes Mellitus:  A chronic metabolic disorder characterized by the lack of insulin secretion and/ or increased cellular resistance of insulin, resulting in elevated blood levels of simple sugars (glucose) and including complications involving damage to the eyes, kidneys, nervous system and vascular system

Diabetes Type I:  IDDM insulin dependent, resulting from destruction of the insulin producing pancreatic islet cells

Diabetes Type II:  NIDDM non-insulin dependent, resulting from tissue resistance of insulin

Diabetic Retinopathy:  A progression of pathologic changes in the retina; produced by standing diabetes mellitus

Esotropia:  A condition in which the eye is turned inwards

Exotropia:  A condition in which the eye is turned outwards

Floaters:  Small particles of dead cells or other debris that become suspended in the vitreous or particles of the vitreous itself that degenerate in the normal aging process;  they cast shadows on the retina and appear as spots or cobwebs

Fluorescein Angiography:  A diagnostic photography of retinal vessels that require injection of fluorescein dye

Fundus:  A collective term for the retina, optic disc, and macula

Glaucoma: Abnormally increased intraocular pressure resulting in optic nerve damage and loss of visual field

Goldmann Tonometer:  An applanation tonometer that measures corneal flattening to determine the intraocular pressure

Gonioscopy:  A viewing procedure utilizing a mirror/lens device placed directly upon the cornea that is used to view the drainage area called “the angle” through which aqueous fluid exits the eyeball

Hyperopia:  Farsightedness, long-sight (UK):  a refractive condition in which light entering the eye is focused virtually behind the retina, resulting in a blurred image in the non-accommodated eye

Iritis:  An inflammation of the iris that may cause pain, tearing, blurred vision, small pupils and a red congested eye (uveitis)

Keratoconus:  A rare degenerative corneal disease in which the center of the cornea thins and assumes the shape of a cone, seriously affecting the vision

Legal Blindness:  A best corrected visual acuity of 20/200 or less or a visual field reduction of 20° or less in the better-seeing eye

Lens:  Part of the optical focusing system of the eye, immediately behind the iris.  Also
crystalline lens

Lensmeter: An instrument for measuring the prescription of the eyeglass lenses or the power or rigid contact lenses

Macula:  The specialized area of the retina closed to the center of the back of the eye that provides detailed central vision

Meibomian Gland:  A specialize gland that secretes the oily part of the tear film that lubricates the outer surface of the globe; located on the inner margin of the eyelid (the edge closest to the globe)

Myopia:  Nearsightedness, short-sighted (UK) a refractive condition in which light entering the eye is focused short of the retina, resulting in a blurred image

Ophthalmologist:  A medical doctor (MD or DO) who specializes in prevention, diagnosing and medical and well as surgical treatment of vision problems and diseases with the eye

Optic Nerve:  The nerve that carries electric impulses to the brain’s visual cortex, where they are integrated to produce the sensation of sight

Optometrist:  An independent practitioner trained in the prescription of eyeglasses and contact lenses as well as in the detection of eye diseases

Presbyopia:  A condition in which the accommodative system fails to allow for the focusing of near objects, resulting from age-related changes in the crystalline lens or ciliary muscle

Ptosis: Drooping of an inability to raise the upper eyelid, caused by the levator

Pterygium: An abnormal wedge-shaped growth on the bulbar conjunctiva that could gradually advance to the cornea and require surgical removal.  Most likely related to sun irritation

Pupil: The center hole in the iris through which light must pass to reach the back of the eye

Refraction: In eye care, the process of measuring a patient’s refractive error and the clinical judgement to determine the optical correction needed

Refractive Surgery:  A type of corneal surgery that modifies the shape of the cornea to correct some types of myopia, hyperopia and astigmatism

Retina: The inner lining of the eyeball; consists of a layer of light-sensitive cells that convert images from the optical system into electric impulses sent along the optic nerve for transmission to the brain

Strabismus:  A misalignment of the eyes that may cause vision to be disturbed; occurs when the extraocular muscles do not work in a coordinated manner

Tonometry: A procedure for the measurement of intraocular pressure.  One of the tests for glaucoma

Vertex Distance:  The distance from the back surface of an eyeglass lens to the front of the cornea

Visual Field:  The height and breadth of space seen by the eye when the gaze is fixated ahead