15.8 Glossary

Amblyopia (am-blē-Ō-pē-ă): Often called “lazy eye,” a vision development disorder where an eye fails to achieve normal visual acuity. (Chapter 15.5)

Anosmia (a-NŌZ-mē-ă): Loss or impairment of the sense of smell, which can be temporary or permanent. (Chapter 15.5)

Astigmatism (ă-STIG-mă-tizm): A vision condition that causes blurred vision due to the irregular curvature of the cornea or lens. (Chapter 15.5)

Audiogram (AW-dē-ō-gram): A graphic record of the results of a hearing test, typically showing hearing sensitivity at different frequencies. (Chapter 15.6)

Audiologists (aw-dē-OL-ŏ-jĭsts): Health care professionals specializing in diagnosing, managing, and treating hearing or balance problems. (Chapter 15.6)

Audiology (aw-dē-OL-ŏ-jē): The study of hearing. (Chapter 15.6)

Audiometer (aw-dē-OM-ĕt-ĕr): An electronic device used in audiometry to generate pure tones of controlled intensity for hearing testing. (Chapter 15.6)

Audiometry (aw-dē-OM-ĕ-trē): The testing of a person’s hearing ability, usually by producing sounds of different frequencies and intensities. (Chapter 15.6)

Auricle (AW-rĭ-kl): The large fleshy structure on the lateral aspect of the head, directing sound waves into the ear canal. (Chapter 15.4)

Cataract (KAT-ă-rakt): A progressive disease of the lens causing cloudiness and lack of transparency, leading to vision impairment. (Chapter 15.5)

Cerumen impaction (sĕ-ROO-mĕn Im-PĂK-shŭn): The buildup of earwax (cerumen) in the ear canal, which can lead to symptoms such as hearing loss, tinnitus, or discomfort. (Chapter 15.5)

Cochlea (KŎK-lē-ă): A part of the inner ear involved in hearing; it converts sound waves into neural signals. (Chapter 15.4)

Conductive hearing loss (kŏn-DUC-tĭv HĒR-ing LŎS): Hearing loss caused by problems with the ear canal, eardrum, or middle ear and its little bones (the malleus, incus, and stapes). (Chapter 15.5)

Conjunctiva (kŏn-jŭnk-TI-va): The inner surface of each lid, a thin membrane that extends over the white areas of the eye called the sclera, connecting the eyelids to the eyeball. (Chapter 15.4)

Conjunctivitis (kŏn-jŭnk-tĭ-VĪT-ĭs): An infection or inflammation of the conjunctiva, causing redness, swelling, and often discharge in the eye. (Chapter 15.5)

Cornea (KOR-nē-ă): The transparent front part of the eye covering the iris, pupil, and anterior chamber, playing a key role in focusing vision. (Chapter 15.4)

Diabetic retinopathy (ret-ĭn-OP-ă-thē): A complication of diabetes mellitus causing fluid leakage from blood vessels in the retina, leading to vision impairment. (Chapter 15.5)

Eustachian tube (yōō-STĀ-shən tūb): A tube connecting the middle ear to the pharynx, helping equalize air pressure across the tympanic membrane. (Chapter 15.4)

Glaucoma (glăw-KŌ-mă): A group of eye conditions that damage the optic nerve, often caused by abnormally high pressure in the eye. (Chapter 15.5)

Hyperopia (hī-pĕr-Ō-pē-ă): Also known as farsightedness, a condition where distant objects can be seen more clearly than close ones. (Chapter 15.5)

Incus (ĬN-kŭs): A small anvil-shaped bone in the middle ear, connecting the malleus to the stapes. (Chapter 15.4)

Inner ear (IN-er ĒR): The part of the ear that includes the cochlea, vestibule, and semicircular canals, responsible for processing sound and maintaining balance. (Chapter 15.4)

Iris (IR-ĭs): The colored part of the eye, a smooth muscle that controls the diameter and size of the pupil. (Chapter 15.4)

Lacrimal gland (LAK-rĭ-măl glănd): A gland located beneath the lateral edges of the nose that produces tears. (Chapter 15.4)

Legal blindness (LĒ-găl BLĪND-nĕss): A defined level of visual impairment that has been established as a threshold for eligibility for governmental disability benefits; typically, visual acuity of 20/200 or less in the best-corrected eye. (Chapter 15.5)

Low vision (LŌ VIZH-ŭn): A condition where an individual has significant visual impairment that cannot be fully corrected with standard glasses, contact lenses, medicine, or surgery, and which interferes with daily activities. (Chapter 15.5)

Macular degeneration (MĂK-yŭ-lăr Dĕ-gĕn-ĕ-RĀ-shŭn): A common eye condition among older adults that leads to loss of vision in the center of the visual field (the macula) due to damage to the retina. (Chapter 15.5)

Malleus (MĂL-ē-ŭs): A small bone in the middle ear attached to the tympanic membrane, resembling a hammer. (Chapter 15.4)

Myopia (mī-Ō-pē-ă): Also known as nearsightedness, a common vision condition where distant objects appear blurry. (Chapter 15.5)

Myringotomy (mĭr-ĭn-GŎT-ō-mē): A surgical procedure where a small incision is made in the eardrum to relieve pressure or drain fluid. (Chapter 15.5)

Nyctalopia (nik-ta-LŌ-pē-ă): Poor vision at night or in dimly lit environments, commonly known as night blindness. (Chapter 15.5)

Nystagmus (nĭs-TĂG-mŭs): Involuntary rhythmic movement of the eyes, which can impair vision and affect balance. (Chapter 15.5)

Ophthalmologist (ŏp-thăl-MŎL-ō-jĭst): A physician who specializes in diagnosing and treating eye disorders and performing eye surgery. (Chapter 15.6)

Ophthalmoscope (op-THAL-mŏ-skōp): An instrument used to examine the interior structures of the eye. (Chapter 15.6)

Ophthalmoscopy (op-thal-MOS-kŏ-pē): The examination of the interior of the eye, particularly the retina, using an ophthalmoscope. (Chapter 15.6)

Optic nerve (OP-tik nerv): The nerve that transmits visual information from the retina to the brain. (Chapter 15.4)

Opticians (ŏp-TĬSH-ăns): Technicians who design, verify, and fit eyeglass lenses and frames, contact lenses, and other devices to correct eyesight. (Chapter 15.6)

Optometrist (ŏp-TŎM-ĕ-trĭst): A health care professional who examines eyes for vision and health problems and prescribes corrective lenses. (Chapter 15.6)

Otitis externa (ō-TĪ-tĭs eks-TUR-nă): Inflammation or infection of the outer ear canal, often referred to as “swimmer’s ear.” (Chapter 15.5)

Otitis media (ō-TĪ-tĭs MĒ-dē-ă): Inflammation or infection of the middle ear, common in children and often associated with upper respiratory infections. (Chapter 15.5)

Otolaryngologist (ō-tō-lăr-ĭn-GŎL-ō-jĭst): A physician who specializing in ear, nose, and throat disorders, also known as an ENT doctor. (Chapter 15.6)

Otology (ō-TŎL-ō-jē): The study of the ear and its diseases. (Chapter 15.6)

Otosclerosis (ō-tō-sklĕ-RŌ-sĭs): A hearing loss condition caused by abnormal bone growth in the middle ear. (Chapter 15.5)

Otoscope (Ō-tō-skōp): An instrument used for visual examination of the ear canal and tympanic membrane. (Chapter 15.5, Chapter 15.6)

Otoscopy (ō-TŎS-kō-pē): The examination of the ear canal and eardrum with an otoscope. (Chapter 15.6)

Pinna (PĬN-ă): Another term for the auricle, the visible part of the ear that resides outside of the head. (Chapter 15.4)

Presbycusis (prez-bĭ-KŪ-sĭs): Age-related hearing loss, often due to gradual nerve degeneration and other changes in the inner ear. (Chapter 15.5)

Presbyopia (prez-bī-Ō-pē-ă): An age-related condition in which the ability to focus on close objects decreases over time. (Chapter 15.5)

Pupil (PŪ-pĭl): The hole at the center of the eye that allows light to enter, its size is controlled by the iris. (Chapter 15.4)

Retina (RĔT-ĭ-nă): The innermost layer of the eye, containing photoreceptors and nerve cells for initial processing of visual stimuli. (Chapter 15.4)

Sclera (sklĕr-ă): The white, outer layer of the eyeball that extends from the cornea to the optic nerve at the back of the eye. (Chapter 15.4)

Sensorineural hearing loss (sĕn-sō-rē-NOOR-ăl HĒR-ing LŎS): A type of hearing loss resulting from damage to the inner ear (cochlea) or to the nerve pathways from the inner ear to the brain. (Chapter 15.5)

Stapedectomy (stā-pĕ-DEK-tŏ-mē): A surgical procedure to remove part or all of the stapes bone and replace it with a prosthesis to improve hearing. (Chapter 15.5)

Stapes (STĀ-pēz): A stirrup-shaped bone in the middle ear, attached to the inner ear where sound waves are converted into neural signals. (Chapter 15.4)

Strabismus (stră-BĬZ-mŭs): A condition where the eyes do not properly align with each other when looking at an object. (Chapter 15.5)

Stye (STĪ): An infection of an oil gland in the eyelid, leading to a painful, red swelling on the eyelid. (Chapter 15.5)

Tinnitus (tĭ-NĪ-tŭs): A condition characterized by hearing ringing, buzzing, or other noises in the ear in the absence of external sound. (Chapter 15.5)

Total blindness (TŌ-tăl BLĪND-nĕss): The complete absence of visual perception, characterized by the inability to perceive light or discern any visual images. (Chapter 15.5)

Tympanic membrane (tĭm-PĂN-ik MEM-brān): Also known as the eardrum, it vibrates in response to sound waves. (Chapter 15.4)

Vertigo (VUR-tĭ-gō): A sensation of spinning or dizziness, often caused by issues with the inner ear or vestibular system. (Chapter 15.4, Chapter 15.5)

Vestibule (ves-tĭ-būl): A part of the inner ear that contributes to balance and spatial orientation. (Chapter 15.4)

Vestibulocochlear nerve (vĕs-tĭ-būl-ō-KŌ-klē-ăr nerv): The nerve that carries auditory and balance information from the inner ear to the brain. (Chapter 15.4)

Visual acuity (VIZH-u-ăl ă-KŪ-ĭt-ē): The sharpness or clearness of vision, typically measured with a Snellen chart. (Chapter 15.5, Chapter 15.6)

Visual impairment (VIZH-ŭ-al Im-PĀR-mĕnt): A decrease in the ability to see to a significant degree, which may cause problems not fixable by usual means, such as glasses or medication. (Chapter 15.5)