Lewis: Medical-Surgical Nursing, 8th Edition

Chapter 21: Nursing Assessment: Visual and Auditory Systems

Key Points – Printable

Structures and Functions OF VISUAL SYSTEM
•	The visual system includes external tissues and structures surrounding the eye. 
o	External structures that play an important role in protecting the eye include the eyebrows, eyelids, eyelashes, lacrimal system, conjunctiva, and sclera. The cornea and extraocular muscles play an important role in vision.
o	Internal structures include the iris, lens, ciliary body, choroid, and retina.
•	The cornea, aqueous humor, lens, and vitreous must all remain clear for light to reach the retina and stimulate the photoreceptor cells. Excess production or decreased outflow of aqueous humor can elevate intraocular pressure.
•	Refraction is the ability of the eye to bend light rays so that they fall on the retina. When light does not focus properly, it is called refractive error.
o	Types of refractive errors are myopia (nearsightedness) and hyperopia (farsightedness).
o	Astigmatism is caused by corneal unevenness, resulting in visual distortion.
o	Presbyopia is a loss of accommodation resulting in an inability to focus on near objects.
•	The retina contains specialized nerve cells that are responsible for color vision and translating visual images into stimuli that the brain can interpret.
•	Every structure of the visual system is subject to changes with aging.

ASSESSMENT OF VISUAL SYSTEM
•	Assessment of the visual system depends on the needs of the patient. For routine ophthalmic care, focus your assessment of functional patterns on health promotion. For a recognized problem, direct the assessment to issues related to the specific problem.
•	The patient’s nonocular history can be significant in assessing and treating ophthalmic conditions. Patient information obtained should include past eye health and family history. History should also include specific diseases and medications known to cause vision problems. Past history of visual tests and head/eye trauma is also noted.
•	Visual assessment determines visual acuity, color vision, ability to judge closeness and distance, extraocular muscle function, evaluation of visual fields and pupil function, stereopsis, and intraocular pressure measurement.
•	Visual structures are assessed by inspection for symmetry and deformity. Some eye structures must be visualized with an ophthalmoscope.

DIAGNOSTIC STUDIES OF VISUAL SYSTEM
•	Diagnostic studies provide important information in monitoring the patient’s condition and planning appropriate interventions.
•	Commonly used tests include refractometry, ultrasound, fluorescein angiography, and the Amsler grid test.

STRUCTURES AND FUNCTIONS OF AUDITORY SYSTEM
•	The auditory system consists of peripheral and central systems. 
o	Peripheral system includes the external, middle, and inner ear and is involved with sound reception and perception.
o	The central system (brain and its pathways) integrates and assigns meaning to what is heard.
•	External and middle ear portions conduct and amplify sound waves from the environment. Problems located in these areas cause conductive hearing loss with changes in sound perception/sensitivity. 
•	The inner ear functions in hearing and balance. Problems located in this area or along the nerve pathway from the brain can cause sensorineural hearing loss with changes in tone perception/sensitivity.
•	Central auditory system problems cause central hearing loss with difficulty in understanding the meaning of words.
•	The vestibular apparatus in the inner ear is critical to maintaining position sense and equilibrium.
•	Presbycusis (hearing loss) can result from aging or insults from a variety of sources. Tinnitus (ringing in the ears) may accompany the hearing loss that results from the aging process.
•	Age-related changes of the auditory system can result in impaired hearing, which can have serious implications for quality of life, including psychosocial and physical dysfunction.

Assessment OF AUDITORY SYSTEM
•	Because many ear problems are related to childhood illnesses or problems with adjacent organs, a careful health history is important. Patient information obtained should include specific diseases and medications known to cause hearing problems. Past history of auditory tests and ear trauma are also noted.
•	Because hearing problems can impact all aspects of a person’s life, a functional health pattern assessment is useful for assessing the impact of hearing loss.
•	Assessment of the auditory system should include assessment of hearing and equilibrium, since problems with balance may present as nystagmus or vertigo. 
•	Auditory assessment notes head posturing and appropriateness of responses when speaking to the patient. 
•	External structures of the ear are assessed by inspection for symmetry and deformity. An otoscope is used for further assessment of the tympanum and auditory canal.

DIAGNOSTIC STUDIES OF AUDITORY SYSTEM
•	Tests involving whispered and spoken voice can provide general screening information. Audiometric testing provides more detailed information used in the diagnosis and treatment of various disorders.
•	Tuning fork tests aid in distinguishing between conductive and sensorineural hearing loss.
•	The most common test performed by an audiologist is pure-tone audiometry. Evoked potential studies, CT, and MRI scans may also be used.