N307 - Chapter 15: Eyes

When examining the eye, the nurse notices that the patients eyelid margins approximate completely. The nurse recognizes that this assessment finding:

• Is expected

• May indicate a problem with extraocular muscles

• May result in problems with tearing

• Indicates increased intraocular pressure

Answer explanation

The palpebral fissure is the elliptical open space between the eyelids, and, when closed, the lid margins approximate completely, which is a normal finding

During ocular examinations, the nurse keeps in mind that movement of the extraocular muscles is

• Decreased in the older adult

• Impaired in a patient with cataracts

• Stimulated by cranial nerves (CNs) I and II

• Stimulated by CNs III, IV, and VI

Answer explanation

Movement of the extraocular muscles is stimulated by three CNs: III, IV, and VI.

The nurse is performing an external eye examination. Which statement regarding the outer layer of the eye is true?

• The outer layer of the eye is very sensitive to touch.

• The outer layer of the eye is darkly pigmented to prevent light from reflecting internally.

• The trigeminal nerve (CN V) and the trochlear nerve (CN IV) are stimulated when the outer surface of the eye is stimulated.

• The visual receptive layer of the eye in which light waves are changed into nerve impulses is located in the outer layer of the eye.

Answer explanation

The cornea and the sclera make up the outer layer of the eye. The cornea is very sensitive to touch. The middle layer, the choroid, has dark pigmentation to prevent light from reflecting internally. The trigeminal nerve (CN V) and the facial nerve (CN VII) are stimulated when the outer surface of the eye is stimulated. The retina, in the inner layer of the eye, is where light waves are changed into nerve impulses

When examining a patients eyes, the nurse recalls that stimulation of the sympathetic branch of the autonomic nervous system:

• Causes pupillary constriction

• Adjusts the eye for near vision

• Elevates the eyelid and dilates the pupil

• Causes contraction of the ciliary body

Answer explanation

Stimulation of the sympathetic branch of the autonomic nervous system dilates the pupil and elevates the eyelid. Parasympathetic nervous system stimulation causes the pupil to constrict. The muscle fibers of the iris contract the pupil in bright light to accommodate for near vision. The ciliary body controls the thickness of the lens.

The nurse is reviewing causes of increased intraocular pressure. Which of these factors determines intraocular pressure?

• Thickness or bulging of the lens

• Posterior chamber as it accommodates increased fluid

• Contraction of the ciliary body in response to the aqueous within the eye

• Amount of aqueous produced and resistance to its outflow at the angle of the anterior chamber

Answer explanation

Intraocular pressure is determined by a balance between the amount of aqueous produced and the resistance to its outflow at the angle of the anterior chamber. The other responses are incorrect.

The nurse is conducting a visual examination. Which of these statements regarding visual pathways and visual fields is true?

• The right side of the brain interprets the vision for the right eye

• The image formed on the retina is upside down and reversed from its actual appearance in the outside world

• Light rays are refracted through the transparent media of the eye before striking the pupil

• Light impulses are conducted through the optic nerve to the temporal lobes of the brain

Answer explanation

The image formed on the retina is upside down and reversed from its actual appearance in the outside world. The light rays are refracted through the transparent media of the eye before striking the retina, and the nerve impulses are conducted through the optic nerve tract to the visual cortex of the occipital lobe of the brain. The left side of the brain interprets vision for the right eye.

The nurse is testing a patients visual accommodation, which refers to which action?

• Pupillary constriction when looking at a near object

• Pupillary dilation when looking at a far object

• Changes in peripheral vision in response to light

• Involuntary blinking in the presence of bright light

Answer explanation

The muscle fibers of the iris contract the pupil in bright light and accommodate for near vision, which also results in pupil constriction. The other responses are not correct.

A patient has a normal pupillary light reflex. The nurse recognizes that this reflex indicates that:

• The eyes converge to focus on the light

• Light is reflected at the same spot in both eyes

• The eye focuses the image in the center of the pupil

• Constriction of both pupils occurs in response to bright light

Answer explanation

The pupillary light reflex is the normal constriction of the pupils when bright light shines on the retina. The other responses are not correct.

A mother asks when her newborn infants eyesight will be developed. The nurse should reply:

• Vision is not totally developed until 2 years of age

• Infants develop the ability to focus on an object at approximately 8 months of age

• By approximately 3 months of age, infants develop more coordinated eye movements and can fixate on an object

• Most infants have uncoordinated eye movements for the first year of life

Answer explanation

Eye movements may be poorly coordinated at birth, but by 3 to 4 months of age, the infant should establish binocularity and should be able to fixate simultaneously on a single image with both eyes.

The nurse is reviewing in age-related changes in the eye for a class. Which of these physiologic changes is responsible for presbyopia?

• Degeneration of the cornea

• Loss of lens elasticity

• Decreased adaptation to darkness

• Decreased distance vision abilities

Answer explanation

The lens loses elasticity and decreases its ability to change shape to accommodate for near vision. This condition is called presbyopia.