What are the structures of the eye?

What are the Functions of the Eye Structures?

Eye Disorders

There are two general kinds of patients with impaired vision: those who were born blind, and those who develop some degree of visual impairment later in life. This chapter focuses on the latter type of visually handicapped patient.

Eye disorders are caused by injury or disease, or are disorders for which there is a genetic predisposition. Diabetes mellitus and hypertension contribute greatly to visual loss in the United States. Untreated glaucoma causes blindness. Macular degeneration is another major cause of impaired vision. It is now known that smoking has a direct link to the incidence of macular degeneration. Cataracts eventually cause blindness, if they are not removed.

There are approximately 15 million visually impaired or blind people in the United States. Of those, 7.3 million are over 65 years of age (Braille Institute of America, 2010). There are many new surgical techniques and medical treatments that offer hope for eyesight preservation to increasing numbers of people. Efforts also have been made to educate the public about eye care, prevention of eye disease, and periodic examinations to detect eye disorders in their earliest and treatable stages.

Basic Eye Care

To prevent eye strain, rest the eye muscles periodically when working at the computer, watching television, doing needlework, or performing any activity that demands intensive visual effort. If the eyes tire easily or if there is headache or burning, itching, or redness of the eyes, the eyes should be examined. Good nutrition is important to eye health, and certain nutrients such as lutein and zeaxanthin are especially beneficial to vision.

Normal secretions of the conjunctiva and tear glands should be sufficient to lubricate the eye and wash away small particles of dust. Accumulations of purulent material or excessive tearing usually indicate the need for an eye examination. Dry eye syndrome in people younger than 60 years could be symptomatic of underlying disease.

Adults should have an eye examination once between ages 20 and 29, twice between ages 30 and 39, and a baseline screening at age 40. After age 65, eyes should be examined by an eye specialist every 2 years (Eyecareamerica, 2010). It is particularly important to test for glaucoma because this disease usually is asymptomatic until damage to vision has occurred. People with a family history of glaucoma should be especially careful to have their eyes tested frequently for increased pressure within the eyeball, as this is the basic pathology of glaucoma, and the disorder tends to be hereditary.

Prevention of Eye Injury

Accidental injury to the eye is a major cause of diminished or total loss of vision. Adults should be cautioned to wear protective eyewear when engaging in sports such as racquetball and squash, in which small balls travel at high speeds. Protective eyewear should be worn when using machinery that might cause debris to fly into the eye, such as lawn mowers, weed trimmers, sanders, or power saws.

The rate of occupational accidents has gone down since the establishment and enforcement of rules for wearing goggles and other protective devices by people working in a hazardous environment. The National Institute of Occupational Safety and Health (NIOSH) in Rockville, Maryland, provides information about eye safety and hazards in the workplace.

Cosmetics for the eyelids, eyelashes, and eyebrows can be a source of infection and allergy. Eye makeup should be discarded every 6 months to help prevent infection. Most dyes used for hair on the scalp are not intended for use on the eyelashes and eyebrows.

Saliva should not be used to moisten eye pencils, eye shadow, or mascara, as it may contain organisms that can cause eye infection. Apply eye cosmetics with

a steady hand to avoid accidentally scratching the cornea and eyelids. Cosmetics should never be shared, as this can transmit organisms.

Prevention of Visual Loss

Diabetes mellitus and hypertension are chronic diseases that—when uncontrolled—may cause visual loss. Patients with these disorders are more susceptible to retinopathy. Nurses should encourage good control over these diseases.

To help prevent infections that might cause corneal scarring and loss of vision, encourage people who experience an accident causing a corneal abrasion to seek medical attention quickly. Promptly seeking medical attention when the eye is inflamed, is secreting purulent discharge, or is sore assists in treatment of infection that may cause a residual visual loss.

Nurses must be aware that there are many types of visual loss. Some may affect only one area of the field of vision in one eye, whereas others affect parts of the field of vision in both eyes. The degree of visual impairment varies greatly.

Nursing Management of Eye Problems

The nursing care of patients with severe visual handicaps demands a special awareness of the unique problems encountered by someone who has either a partial or a total loss of vision. You must be sensitive to these patients’ special needs. Patient education is especially important to these patients’ acceptance of their visual disorder, their participation in diagnostic and therapeutic measures, and their adjustment to their new surroundings when they are hospitalized or admitted to a long-term care facility.