Glossary of Terms

To increase your understanding of eye care, here are some terms that you may hear Family Eye Care optometrists use in their conversations with you and your family members.

A scan

An ultrasonic procedure to measure specific areas within the eye.

Acuity

The clarity of vision, usually measured on a chart.

Astigmatism

A warping of the curvature of the cornea so that light rays entering the eye do not meet in a single focal point, resulting in a distorted image.

B scan

Ultrasonic procedure used to check for abnormalities or locate foreign bodies within the eye.

Cataract

A disease that causes the lens or its capsule to become opaque. It can result in partially or severely decreased vision, but is usually removable and vision correctable by use of an implant.

Cornea

The clear front surface of the eye that covers the iris and pupil. Acts like the lens of a camera.

Diopter

A unit of measure of the refractive power of a lens, equal to the power of a lens with focal distance of one meter.

Glaucoma

A disease characterized by increased pressure within the eyeball, leading to gradual vision impairment and sometimes blindness if not diagnosed and treated.

Hyperopia

Farsightedness; a condition in which light rays are focused behind the retina so that distance objects are seen more clearly than near ones.

Intraocular lens implantation

Surgery to replace a cloudy lens (cataract) with a new, clear, artificial lens designed to eliminate the need for very thick, heavy glasses. This is usually done at the time of cataract extraction but may be done later as a secondary implant.

Keratometry

The measurement of the curvature of the cornea.

Myopia

Nearsightedness: a condition in which light rays from distance objects are focused in front of the retina instead of on it, so that distant objects are not seen clearly.

Phacoemulsification

Use of ultrasonic vibration to shatter and break up a cataract, making it easier to remove.

Retina

A layer of cells at the back of the eye that is sensitive to light and upon which the image formed by the lens is focused. The image is then carried to the brain by the optic nerve.

Secondary Implant

If no lens was placed in the eye at the time of initial cataract removal surgery, then a secondary procedure to implant a lens may be done months or years later.

Slit Lamp

A microscope using various magnifications combined with a strong light that can be focused into a slit for examining the eye.

Tonometry

The measurement of the tension or pressure inside the eyeball.

Ultrasound (A & B Scan)

A procedure using sound waves to measure certain portions or detect abnormalities within the eye.

Visual Field

A measurement of the vision level in all portions of the field of vision.

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