COA key terms

A condition in which the eye does not bend light correctly onto the retina, causing blurred vision. Myopia, hyperopia, and astigmatism are the common types.

Nearsightedness. Distant objects appear blurry because light focuses in front of the retina, usually when the eye is too long relative to its focusing power.

Farsightedness. Near objects are blurry because light would focus behind the retina, often because the eye is too short or the cornea is too flat.

A refractive error caused by an irregularly curved cornea or lens, so light focuses at different points and vision is distorted or blurry at all distances.

Age-related loss of the ability to focus on near objects, caused by stiffening of the lens. It typically becomes noticeable in the early to mid-forties.

The unit of optical power for a lens or the eye. It equals the reciprocal of the focal length measured in meters, so a 2-diopter lens focuses at half a meter.

The eye's ability to increase its focusing power for near vision by contracting the ciliary muscle, which makes the lens rounder and thicker.

The gap between the back surface of a spectacle lens and the front of the cornea. It matters for high-power lenses because changing it alters the effective power at the eye.

A measurement of the curvature and power of the central cornea, usually reported in diopters and used to fit contact lenses and plan refractive surgery.

A wall chart of letters arranged in decreasing size, used to measure distance visual acuity. The result is recorded as a fraction such as 20/20 or 20/40.

The sharpness of central vision, measured by the smallest letters or symbols a patient can identify at a set distance. It is recorded for each eye separately.

A quick check in which the patient looks through a tiny hole. If vision improves, the blur is likely from a refractive error rather than a disease of the eye.

A simple bedside screening in which the examiner faces the patient and moves a target inward from the side to compare the patient's side vision with their own.

The automatic narrowing of the pupil when light shines into the eye. Comparing both pupils helps detect nerve or brain problems and is part of a basic eye exam.

The patient's main reason for the visit, recorded in their own words. It guides the rest of the history and the focus of the examination.

A detailed account of the current problem, including when it started, how it has changed, what makes it better or worse, and any treatments tried.

A set of questions about symptoms across the body's systems, used to uncover problems the patient has not mentioned and to spot conditions that affect the eyes.

The clear front window of the eye. It is the main focusing surface and contains many nerve endings, so injuries and foreign bodies are painful.

The fluid-filled space between the cornea and the iris. The fluid inside, called aqueous humor, nourishes nearby structures and helps maintain eye pressure.

A ring of tissue behind the iris that produces aqueous humor and contains the muscle controlling the shape of the lens for focusing.

The pressure inside the eye, kept in balance by fluid production and drainage. Raised pressure is a major risk factor for glaucoma.

The measurement of pressure inside the eye. Common methods briefly touch the anesthetized cornea or use a puff of air.

The thin, clear membrane covering the white of the eye and lining the inside of the eyelids. It protects the eye and can become inflamed in infection or allergy.

Inflammation of the conjunctiva, causing redness, discharge, and irritation. It can be caused by infection, allergy, or irritation, and some forms spread easily.

A drug that enlarges the pupil. Mydriatics are used to allow a wider view of the inside of the eye and often blur near vision for several hours.

A drug that constricts the pupil. Miotics may be used to treat certain types of glaucoma or to reverse the effects of pupil-dilating drops.

Numbing drops placed on the eye surface to block pain during procedures such as pressure measurement or foreign body removal. They are not sent home for pain relief.

The small opening in the inner corner of each eyelid where tears drain into the tear duct system. It is also the target for punctal plugs.

Blocking the tear drainage openings to keep lubricating or medicated drops on the eye longer. It can be done by pressing on the inner corner or with small plugs.

Placing drops or ointment into the eye. The lower lid is pulled down to form a pouch, and the tip of the container must not touch the eye or lashes.

Cleaning the hands with soap and water or alcohol rub. It is the single most important step for preventing the spread of infection in an eye clinic.

Barriers such as gloves, masks, and eye protection worn to prevent contact with body fluids. The items chosen should match the task and the risk of exposure.

A work area kept free of all microorganisms during a procedure. Only sterile items may touch it, and items that contact a non-sterile surface are considered contaminated.

Treating all blood and body fluids as if they carry infection, so protective measures are used with every patient regardless of known diagnosis.

A microscope with a narrow beam of light used to examine the front of the eye in detail. The patient rests their chin and forehead against supports during viewing.

An instrument with a light and lenses used to view the back of the eye, including the retina and optic nerve, usually through a dilated pupil.

The inner back surface of the eye, including the retina, optic disc, and blood vessels. It is examined to detect disease such as diabetic changes or glaucoma damage.

A grid of straight lines the patient looks at to check central vision. Wavy, missing, or distorted lines can signal problems in the macula.

The patient's voluntary agreement to a test or procedure after understanding its purpose, risks, benefits, and alternatives. It must be documented according to clinic policy.

The legal document of a patient's care, including history, test results, and treatments. Entries must be accurate, dated, and kept private.