Sensory Function



Sensory Function


Sabrina Friedman, MSN, PhD, EdD, FNP, CNS




The senses connect the human body to the environment. They allow individuals to be aware of and interpret various stimuli, thus enabling interaction with the environment. Sensory changes can have a dramatic effect on the quality of life of older adults. Visual and hearing impairments may interfere with communication, social interactions, and mobility, leading to social isolation. Olfactory, gustatory, and tactile deprivations can lead to nutritional problems and safety hazards. It is important to understand the sensory changes associated with aging to help older adults adapt and function as independently as possible.


In the past, five senses were recognized: sight, hearing, taste, smell, and touch. Today, additional senses are recognized and categorized into two major groups: general and special. General senses include the senses of touch, pressure, pain, temperature, vibration, and proprioception (position sense). These have relatively simple receptors, which are located all over the body. These senses are further classified as somatic (those providing sensory information about the body and the environment) or visceral (those supplying information about the internal organs). Special senses are produced by highly localized organs and specialized sensory cells. These include the senses of sight, hearing, taste, smell, and balance.


Sensation is a conscious or unconscious awareness of external and internal stimuli. Perception is the interpretation of conscious sensations. The brain receives stimuli from both inside and outside the body. Conscious sensation occurs via action potentials generated by receptors that reach the cerebral cortex.



Vision


Vision plays an integral part in a person’s ability to function in the environment. Visual acuity (the ability to see clearly) is an important part of performing activities of daily living (ADLs); dressing, grooming, cooking, sewing, driving, and reading are all tasks that involve the use of eyesight (Fig. 31–1).




Age-Related Changes in Structure and Function


Normal age-related changes in the external and internal eye have been well documented. The eyelids lose tone and become lax, which may result in ptosis of the eyelids, redundancy of the skin of the eyelids, and malposition of the eyelids. Eyebrows may turn gray and become coarser in men, with outer thinning in both men and women. The conjunctiva thins and yellows in appearance. In addition, this membrane may become dry because of diminished quantity and quality of tear production. The sclera may develop brown spots. The cornea yellows and develops a noticeable surrounding ring, made up of fat deposits, called the arcus senilis. The pupil decreases in size and loses some of its ability to constrict. Changes related to aging that decrease the size of the pupil and limit the amount of light entering the eye also occur in the iris. The lens increases in density and rigidity, affecting the eye’s ability to transmit and focus light. Peripheral vision decreases, night vision diminishes, and sensitivity to glare increases (Roach, 2001; Brodie, 2003). The yellowing of the lens results in difficulty identifying certain colors, especially cool colors such as blue, green, and violet (Lueckenotte, 1998).


Ophthalmoscopic examination of the retina may reveal the following changes: blood vessels narrow and straighten; arteries seem opaque and gray; and drusen, localized areas of hyaline degeneration, may be noted as gray or yellow spots near the macula (Lueckenotte, 1998). Two common complaints of older adults, floaters and dry eyes, are discussed in the following section.



Common Complaints


Floaters and Flashers


Floaters appear as dots, wiggly lines, or clouds that a person may see moving in the field of vision. They become more pronounced when a person is looking at a plain background. Floaters occur more often after the age of 50 as tiny clumps of gel or cellular debris float in the vitreous humor in front of the retina. They are caused by degeneration of the vitreous gel and are more common in older adults who have undergone cataract operations or yttrium–aluminum–garnet (YAG) laser surgery.


In general, floaters are normal and harmless, but they may be a warning sign of a more serious condition, especially if they increase in number and if changes in the type of floater, light flashes, or visual hallucinations are noted. These symptoms may indicate a vitreous or retinal tear, which could lead to detachment. In addition, visual hallucinations have been associated with a brain tumor or cortical ischemia. Therefore any of these symptoms warrants a complete eye examination by an ophthalmologist.


Flashers occur when the vitreous fluid inside the eye rubs or pulls on the retina and produces the illusion of flashing lights or lightning streaks. Flashers that appear as jagged lines, last 10 to 20 minutes, and are present in both eyes are likely to be caused by a spasm of blood vessels in the brain called a migraine. These flashers commonly occur with advancing age, but they warrant prompt medical attention if they increase in number, if a large number of new flashers appears, or if partial loss of side vision is noted (Kollarits, 1998).


The nurse should refer a client who experiences any of the above symptoms to an ophthalmologist for a comprehensive eye examination. If no cause is found for the floaters and flashers, the nurse should teach the client about the condition and how to live with it. Clients should be taught to look up and down to get the floaters out of the field of vision. In addition, the nurse should provide the client with the printed information instruction sheet titled “Aging and Your Eyes” so he or she may learn more about floaters and flashers (Kollarits, 1998) (Box 31–1).



BOX 31–1   AGING AND YOUR EYES




1. Use bright light when performing tasks such as sewing, reading, and cooking; avoid fluorescent light.


2. Use a magnifying glass, if necessary, for close work.


3. See your health care provider regularly to detect health problems (e.g., diabetes, hypertension) that might affect your eyes.


4. Have your eyes examined and a glaucoma test performed by a qualified specialist every 1 to 2 years. Have your eyes examined more frequently if you have a disease or condition that is known to affect your vision.


5. Symptoms that require an immediate call to your health care provider or eye care specialist include pain, discharge, redness or swelling, and loss of vision (no matter how slight).


6. The use of a humidifier in the home or artificial tears may relieve dry eyes, which is a common condition. Check with your health care provider or eye care specialist before using any such over-the-counter preparations.


7. Excessive tearing can be a benign condition, or it may reflect a more serious problem. See your health care provider or eye care specialist if you are troubled by this problem.


8. Floaters, a common occurrence in older persons, are just spots or flecks that literally “float” across your field of vision. They usually occur gradually and are most noticeable in a brightly lit environment. If they occur in association with light flashes in your visual field, call your health care provider or eye care specialist.


9. Cataracts are a normal part of the aging process. They develop gradually and without pain. However, when tasks become increasingly difficult and fatiguing because of the vision changes that cataracts produce, see your health care provider or eye care specialist to discuss treatment options.


Data from US Department of Health and Human Services: Aging and your eyes, Bethesda, Md, 2009, National Institute on Aging.



Dry Eyes


Dry eyes result as the quantity and quality of tear production diminish with aging. Stinging, burning, scratchiness, and stringy mucus are some of the symptoms. Although this may seem surprising, increased tearing may be a symptom of dry eyes. If tear secretion is below normal, excess tears are produced by the lacrimal gland in response to irritation. If no foreign body is found, the condition is called dry eye syndrome. Tear production decreases with age, and menopausal women are most often afflicted. Also, dry eyes may be associated with arthritis and the use of certain medications.


Treatment consists of tear replacement or conservation. Tears can be replaced by instilling an over-the-counter artificial tear preparation to lubricate the eye and replace missing moisture. This type of preparation may be used as often as necessary, especially before activities that require significant eye movement. Solid inserts that gradually release lubricants throughout the day are also available. An ophthalmologist can conserve the naturally produced tears by temporarily or permanently closing the lacrimal drainage system. Other methods of conservation include use of a humidifier when the heat is on, wraparound glasses to reduce evaporation of eye moisture caused by wind, and avoidance of smoke (Kollarits, 1998).



Common Problems and Conditions


Common problems related to the aging eye include presbyopia, ectropion and entropion, blepharitis, glaucoma, cataracts, retinal disorders, eye injuries, and visual impairment. Presbyopia is a normal change that occurs with aging. The other problems are eye diseases that are more prominent in older adults.



Presbyopia


The most common complaint of adults older than 40 is a diminished ability to focus clearly on close objects (arm’s length), such as a newspaper. In presbyopia the lens loses its ability to focus on close objects. Accommodation is impaired as the lens thickens and loses its elasticity. The ciliary muscles weaken the lens’s ability to contract. Treatment involves wearing reading glasses or bifocals (two-part lenses that correct near and distant vision); there is an excellent prognosis for corrected vision.


Nursing care is aimed at encouraging the client to adjust to the glasses by wearing them and following up with a visit to the ophthalmologist every 2 years. Clients can be provided with an “Aging and Your Eyes” pamphlet (see Box 31–1) for information about presbyopia. Also, clients and their families can be taught eye health promotion and prevention techniques (see Health Promotion/Illness Prevention Box: The Eye).



Ectropion and Entropion


Ectropion and entropion are external eye conditions; specifically, they are malpositions of the lower lid, which irritate the eye. Both conditions are due to tissue laxity and scarring of the eyelids from infection. Ectropion (turning outward) prevents normal closure, affects tear drainage and production, and causes redness and tearing of the



eyeball. Entropion (turning inward) results in the eyelashes rubbing against the eye, causing corneal abrasion. The lower lashes may not be visible and can cause watering and redness of the eye. Both can be treated by minor same-day outpatient surgery performed by an ophthalmologist. The prognosis for complete recovery and cessation of symptoms is excellent (Brodie, 2003).



Blepharitis


Blepharitis is a chronic inflammation of the eyelid margins that is commonly found in older adults. It can be caused by seborrheic dermatitis or infection. The use of antihistamines, anticholinergics, antidepressants, and diuretics can exacerbate this condition because of the drying effects of the medications. In addition, the deficiency in tear production with aging can lead to infection. The symptoms include red, swollen eyelids, matting and crusting along the base of the eyelash at the margins, small ulcerations along the lid margins, and complaints of irritation, itching, burning, tearing, and photophobia. Treatment is aimed at removing the bacteria and healing the affected areas. Physicians may prescribe topical antibiotics or steroids. However, the nurse can play a large role in the treatment of this condition by teaching a client the following interventions.


The client must be taught scrupulous eye hygiene, including good hand washing habits. Mild soap (e.g., Ivory, Neutrogena) should be used. Contact lens wearers must be taught proper cleaning and storage techniques to prevent contamination of the eye, lens, lens solution, and lens case. Because cosmetics are a common source of bacterial contamination, eye makeup products should be replaced every 3 to 6 months to avoid bacterial growth. It is also important that clients know how to apply makeup with cotton balls and cotton-tipped applicators and understand the importance of discarding the applicators after each use. Mascara should be water resistant, free of lash-extending fibers, and not applied to the base of the lashes. Eyeliner should be a medium-hard pencil and not be applied to the inner margin of the eyelid. Clients should avoid the use of aerosol hairsprays because these can irritate the eyes. The inflammation caused by blepharitis and the client’s comfort level will improve after a week of these hygienic practices.



Glaucoma


Glaucoma is the second leading cause of blindness in the United States and the first cause of blindness among blacks. Although glaucoma can occur at any age, those most at risk are adults older than age 60 (Roach, 2001; Gohdes, Balamurugan, Larsen, & Maylahn, 2005). The most common form has few, if any, symptoms and may cause partial vision loss before it is detected. This major public health problem affects approximately 3 million older Americans and is associated with over 120,000 blind older adults (Ebersole, Touhy, Hess, et al, 2008).


Glaucoma results from a blockage in the drainage of the fluid (the aqueous humor) in the anterior chamber of the eye. Normally this fluid drains through Schlemm’s canal and is transported to the venous circulation system. If the fluid is formed in the eye faster than it can be eliminated, intraocular pressure (IOP) increases. Pressure is then transferred to the optic nerve, where irreparable damage, possibly even total blindness, can result. Three types of glaucoma are found in older adults: chronic open-angle glaucoma, closed-angle glaucoma, and secondary glaucoma.






Nursing Management


image Assessment


Clients with glaucoma may complain of dull eye pain, or they may experience no early symptoms. Visual field testing reveals a loss of peripheral vision (tunnel vision), and increased IOP is seen on ophthalmologic examination.





image Intervention


Nursing management is aimed at teaching the client that glaucoma is a chronic condition requiring lifelong medical treatment. Any current visual loss is permanent, but further loss can be prevented by following the care guidelines outlined in Box 31–2. If medication is unable to control rising IOP, surgical intervention may be necessary.



Trabeculoplasty is usually performed on an outpatient basis. It requires an IOP check 3 to 4 hours after surgery. A sudden rise in IOP can occur immediately after surgery. A 4-to 8-week wait is necessary to determine whether the procedure was effective. However, continual use of glaucoma medications is necessary.


Trabeculectomy requires overnight hospitalization. Postoperative nursing care for the client who has had a trabeculectomy includes (1) routine postanesthesia care, (2) protection of the operative eye with an eye patch or a shield, proper positioning of the client on the back or on the side of the inoperative eye, and the use of a call light and side rails, (3) administration of pain medications and cold eye compresses to maintain comfort, (4) monitoring of the eye for increased IOP, bleeding, or infection, and (5) assistance and teaching of safe, independent performance of ADLs (Monahan, 2006).



image Evaluation


Evaluation includes documentation of the achievement of the expected outcomes, no further vision loss, and the independent performance of ADLs. It is imperative that the client and family understand the chronic nature of this disease and its treatment. The client must be able to state the name and dosage of the prescribed eye medications and describe their daily use, even during periods of travel or hospitalization. The client must also be able to identify significant signs and symptoms so that they can be reported to the ophthalmologist.



Cataracts


Cataracts are the most common disorder found in the aging adult. The highest incidence is found in adults older than the age of 55; cataracts are found in virtually all adults older than 80.


A cataract is a clouding of the normally clear and transparent lens of the eye. The lens focuses light on the retina to produce a sharp image. When a cataract forms, the lens can become so opaque that light cannot be transmitted to the retina. Cataracts result from changes in the chemical composition of the lens; these changes can be caused by aging, eye injuries, certain diseases, and heredity. In addition, there are different types of cataracts. The normal aging process may cause the lens to harden and turn cloudy. These cataracts are called senile cataracts and can occur as early as age 40. Eye injuries, such as a hard blow, puncture, cut, or burn, can damage the lens and result in a traumatic cataract. Secondary cataracts can be caused by certain infections, drugs, or diseases (e.g., diabetes).


The size and location of a cataract determine the amount of interference with clear sight. A cataract located near the center of the lens produces more noticeable symptoms, such as



These symptoms develop slowly and at different rates in each eye.



Nursing Management


image Assessment


Subjective complaints include having trouble reading and the necessity of cleaning glasses (the vision difficulties are thought to be caused by dirty glasses). Lens opacity may be visible on external or internal eye examination.





image Intervention


Nursing management for a client with cataracts focuses mainly on preoperative and postoperative surgical care because surgery is the only method for treating cataracts. However, asymptomatic clients do not require referral. Most cataract surgery is performed as outpatient surgery with the administration of a local anesthetic; this makes preoperative teaching difficult because clients arrive just hours before surgery. Many ambulatory centers conduct preoperative assessment and teaching by phone a week before surgery. Preoperative care involves administering eye drops and a sedative as ordered. Postoperative care requires teaching the client and family home care procedures for the period after cataract surgery (see Client/Family Teaching Box: Home Care after Cataract Surgery), including the method for instilling eye drops. The home care instructions need to include special precautions recommended by the ophthalmologist based on the type of surgery performed. If a lens implant has not been inserted, clients need to wear contact lenses or cataract glasses. Clients wearing cataract glasses experience loss of depth perception and distorted peripheral and color vision. They need to be taught that objects are magnified by 25% and appear larger and closer than they really are; this requires home safety measures and the modification of dressing and cosmetic application after surgery (see Nursing Care Plan).



image Evaluation


Evaluation includes documentation of the achievement of the expected outcomes. Clients who have had successful cataract surgery will be free from complications and will have improved vision. Additionally, they will report performance of their usual daily activities with the use of lens implants, contact lenses, or




image NURSING CARE PLAN


Cataracts



Clinical Situation


Mrs. D is a 77-year-old retired nurse who has been admitted to the skilled nursing unit of a local hospital for rehabilitation therapy after repair of a right hip fracture. She is accompanied by her daughter. Mrs. D has no significant medical history, but a fall in her home resulted in the break in her hip. She states that she has been having trouble with her eyes, and she tripped on the stairs. Since her admission to the hospital, a vision screening detected cataracts in both eyes and surgery was recommended once she recovers. Mrs. D requires assistance with all ADLs except eating. She is unable to bear weight on her right leg, so assistance is needed to transfer to the toilet, chair, or bed. She also needs help bathing and dressing the lower half of her body because she cannot reach her legs or feet. Mrs. D states that her biggest concern is fear of falling again.





image INTERVENTIONS




Provide the client with the printed information sheet, “Aging and Your Eyes” (review Box 31–1) and the client education sheet “Home Care after Cataract Surgery” (see Client/Family Teaching Box).


Encourage the client and family member to speak with an ophthalmologist about the recommended surgery.


Explain preoperative and postoperative procedures related to the recommended surgery.


Provide a safe environment (e.g., bed in low position, side rails as needed, and call light and personal items in reach).


Assist with transfers until the client demonstrates safe transfer while unassisted.


Assess the client’s home for factors that hinder or support vision changes.


Administer pain medication as needed before helping the client to perform self-care.


Encourage the client to perform as much of her own care as possible to help restore independence.


Provide assistance, supervision, and teaching with the use of assistive devices as needed to perform self-care. Assess factors in the client’s home that support or hinder self-care.


Encourage expression of fears of falling.


Use therapeutic communication to gain insight into the client’s fears and give realistic feedback.


Increase attention to the client when she is feeling anxious.


From McFarland GK, McFarlane EA: Nursing diagnosis and intervention: planning for patient care, ed 3, St Louis, 1997, Mosby.


corrective glasses. The client and family will arrange assistance with ADLs for the first 24 to 48 hours after surgery, or they will notify the home health agency.



Retinal Disorders


Three common disorders that affect the retina of an older adult are macular degeneration, diabetic retinopathy, and retinal detachment.



Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness among older adults in the United States. It does not cause total blindness but results in loss of close vision. AMD is a poorly understood disease that causes damage to the macula, the key focusing area of the retina. The cells within the macula diminish in functional ability with age, and replacement of the damaged cells is decreased, causing irreversible damage to the macula (Roach, 2001). As a result, there is a decline in central visual acuity that makes daily tasks requiring close vision nearly impossible. Peripheral vision is retained. AMD is viewed as a disease that is becoming an epidemic among older adults (Bressler et al, 2004).


Types of AMD include



AMD is almost exclusively a disorder of whites and is more common in women than in men. Cases tend to cluster in families. Smoking, low dietary intake of antioxidant vitamins and zinc, and sun exposure are some modifiable risk factors (Taylor, 2002).


Symptoms of macular degeneration include






Nursing Management


image Assessment


There are no early symptoms of diabetic retinopathy and sometimes no symptoms with advanced retinopathy. Clients with macular degeneration may complain that they are unable to thread a needle or that the words on a page look blurred, which makes it difficult to read. Clients with retinal detachment notice flashes of light followed by floating spots before the eye with progressive loss of vision. The specific area of vision loss depends on where the detachment is located. When detachment occurs quickly and is extensive, the client may feel that a curtain has been drawn before the eyes.


Ongoing nursing assessment involves monitoring the client’s subjective statements about changes in vision and observing for signs of anxiety. All three retinal disorders are diagnosed by ophthalmoscopic examination.



image Diagnosis


Nursing diagnoses are determined by analysis of the client assessment. Possible nursing diagnoses for a client with a retinal disorder include


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