COA Certified Ophthalmic Assistant key terms

A measurement of central distance vision in which the patient reads letters of decreasing size from a chart placed 20 feet (6 meters) away; the result compares the patient's performance with that of a standard observer.

A quick screening technique in which the patient views the chart through a small aperture; if vision improves, the cause is likely an uncorrected refractive error rather than disease of the retina or optic nerve.

The sharpest vision a patient can achieve while wearing the most accurate spectacle or contact lens prescription, determined by refraction or by testing with a pinhole; it is the benchmark for detecting later vision loss.

A handheld card printed with blocks of text in graduated sizes, used to estimate near vision at a customary reading distance of about 14 inches; results are recorded as a J number.

A bedside screening test in which the examiner faces the patient and moves a target or wiggling fingers in from the periphery to compare the patient's field with the examiner's own; it detects large field defects only.

A grid of straight lines used at near to screen for central visual field distortion or blind spots; the patient reports missing, wavy, or bent lines, which may indicate macular disease such as age-related macular degeneration.

Perimetry in which the patient responds to light stimuli at various locations to map the area of vision; it documents peripheral loss from glaucoma, stroke, or neurologic disease and tracks change over time.

The fluid pressure inside the eye, usually measured with a tonometer and reported in millimeters of mercury; elevated pressure is a major modifiable risk factor for glaucoma, though glaucoma can occur with normal pressure.

A method that estimates intraocular pressure by measuring the force needed to flatten a fixed area of the cornea; corneal thickness and curvature affect the reading, so results must be interpreted with those factors in mind.

A slit-lamp-mounted instrument that measures intraocular pressure by applanation after the cornea is anesthetized and stained with fluorescein; the blue light and tear film allow the examiner to align the mires accurately.

The automatic constriction of the pupil when light enters the eye; the direct response occurs in the stimulated eye and the consensual response in the fellow eye, and comparing both helps localize nerve or brain injury.

A reduced pupillary response when light is swung from the healthy eye to the affected eye, indicating asymmetric damage to the optic nerve or extensive retina; it is tested with the swinging flashlight test.

The process of determining the lens power that brings light to a sharp focus on the retina; it may be done objectively with a retinoscope or autorefractor and refined subjectively with trial lenses.

An objective technique in which the examiner shines a streak of light into the eye and observes the movement of the reflected glow to estimate refractive error, especially useful in children and noncommunicative patients.

A mismatch between the eye's focusing power and its length that blurs vision; the main types are myopia, hyperopia, and astigmatism, and all are usually correctable with glasses or contact lenses.

Nearsightedness, in which parallel light rays focus in front of the retina, usually because the eye is too long; distance vision is blurred while near vision is relatively clear, and risk of retinal detachment is increased.

Farsightedness, in which unaccommodated light focuses behind the retina, usually because the eye is too short; young patients may see clearly by accommodating, which can cause eye strain or fatigue.

A refractive condition in which the cornea or lens has unequal curvature in different meridians, so light is focused at more than one point; patients report blurred or distorted vision at all distances.

The eye's ability to increase its focusing power for near tasks by contracting the ciliary muscle, which lets the crystalline lens become rounder; it declines with age, producing presbyopia.

The age-related loss of near focusing ability, typically noticed in the early to mid-forties, caused by stiffening of the crystalline lens; it is managed with reading glasses, bifocals, or multifocal contact lenses.

The clear, dome-shaped front window of the eye that provides most of its focusing power; it has no blood vessels, receives nutrients from tears and aqueous humor, and is highly sensitive to touch.

A progressive thinning and bulging of the cornea into a cone shape, causing irregular astigmatism and reduced vision; rigid contact lenses often restore vision, and corneal crosslinking can slow progression.

The pigmented, muscular ring behind the cornea that controls pupil size; its sphincter and dilator muscles adjust the amount of light entering the eye, and its color comes from pigment content.

The ring of tissue behind the iris that produces aqueous humor and contains the ciliary muscle; contraction of this muscle changes lens shape for focusing, and the fluid it makes maintains intraocular pressure.

The clear fluid produced by the ciliary body that fills the front chamber of the eye, nourishes the cornea and lens, and drains through the trabecular meshwork; impaired drainage raises intraocular pressure.

The light-sensitive inner layer at the back of the eye containing rods and cones and neurons that convert light into nerve signals; its central macula provides sharp vision and its periphery serves dim light and motion.

The small central area of the retina responsible for sharp, detailed, color vision; its center, the fovea, contains only cones and is vulnerable to diseases such as age-related macular degeneration and diabetic edema.

The bundle of nerve fibers that carries visual signals from the retina to the brain; its head is visible with the ophthalmoscope, and swelling or pallor can signal glaucoma, raised intracranial pressure, or optic neuropathy.

A group of optic neuropathies characterized by progressive loss of optic nerve fibers, often with elevated intraocular pressure; peripheral vision is lost first, so early detection by pressure checks and field testing matters.

Examination of the inside of the eye, especially the optic nerve head and retina, using a handheld ophthalmoscope or a slit-lamp lens; the pupil is often dilated first for a better view.

An eye drop that widens the pupil, commonly tropicamide or phenylephrine, used to allow examination of the retina and optic nerve; patients should be warned about glare, blur, and driving restrictions until it wears off.

An orange dye used in eye care to stain damaged corneal tissue for detection under blue light and to outline the tear film during applanation tonometry; it is also used in angiography to image retinal blood vessels.

A drop such as proparacaine or tetracaine that numbs the surface of the eye for brief procedures like tonometry or foreign body removal; it must never be given to patients for home use because it impairs healing.

The structured interview covering the reason for the visit, current eye symptoms, past eye disease and surgery, medications, allergies, and family eye history; it directs the examination and flags conditions needing urgent attention.

The patient's main reason for seeking care, recorded in the patient's own words along with duration and severity; it focuses the visit and is the first element of the history of present illness.

A systematic set of questions about symptoms across body systems, such as headache, joint pain, or diabetes, that may relate to eye findings; it helps uncover systemic disease affecting vision.

The process of explaining a procedure's purpose, risks, benefits, and alternatives so the patient can decide voluntarily whether to proceed; the ophthalmic assistant confirms understanding and documents the discussion.

Infection-control practices applied to all patients, including hand hygiene, gloves, and eye protection when exposure to blood or tears is likely; they reduce transmission of organisms in the clinic.

A binocular microscope combined with an adjustable light beam used to examine the front of the eye and, with lenses, the retina; the narrow beam shows depth, and the joystick controls focus and position.

Recording each eye's vision separately with the chart distance, correction status, and pinhole result if used, so that later measurements can be compared fairly; missing details make change hard to interpret.