Chapter 16
left 3rd nerve paralysis
A client with left 3rd nerve paralysis looks straight ahead.
Strabismus (or Tropia)
A constant malalignment of the eye axis, strabismus is defined according to the direction toward which the eye drifts and may cause amblyopia.
CORNEAL ABNORMALITIES
A corneal scar, which appears grayish white, usually is due to an old injury or inflammation.
What's a clinical tip about nystagmus?
A couple of oscillating movements of nystagmus at extreme lateral gaze is considered normal.
What are vision fields? What are the sections of vision fields?
A visual field refers to what a person sees with one eye. The visual field of each eye can be divided into four quadrants: upper temporal, lower temporal, upper nasal, and lower nasal (Fig. 16-6). The temporal quadrants of each visual field extend farther than the nasal quadrants. Thus, each eye sees a slightly different view but their visual fields overlap quite a bit. As a result of this, humans have binocular vision (" two-eyed" vision) in which the visual cortex fuses the two slightly different images and provides depth perception, or three-dimensional vision.
How to test accommodation of pupils? Normal and abnormal?
Accommodation occurs when the client moves his or her focus of vision from a distant point to a near object, causing the pupils to constrict. Hold your finger or a pencil about 12-15 in from the client. Ask the client to focus on your finger or pencil and to remain focused on it as you move it closer in toward the eyes. Normal: The norma pupillary response is constriction of the pupils and convergence of the eyes when focusing on a near object Abnormal: Pupils do not constrict; eyes do not converge
Performing eye examination, remember these key points:
Administer vision tests competently and record the results. Use the ophthalmoscope correctly and confidently. Recognize and distinguish normal variations from abnormal findings.
Miosis Weber, Janet R.; Kelley, Jane H. (2017-11-01). Health Assessment in Nursing (Kindle Location 10234). Wolters Kluwer Health. Kindle Edition.
Also known as pinpoint pupils, miosis is characterized by constricted and fixed pupils— possibly a result of narcotic drugs or brain damage.
Strabismus (or Tropia) Esotropia
An Eye turns inward
Strabismus (or Tropia) Exotropia
An Eye turns outwards
IRREGULARLY SHAPED IRIS
An irregularly shaped iris causes a shallow anterior chamber, which may increase the risk for narrow-angle (closed-angle) glaucoma.
Anisocoria
Anisocoria is pupils of unequal size. In some cases, the condition isnormal; in other cases, it is abnormal. For example, if anisocoria is greater in bright light compared with dim light, the cause may be trauma, tonic pupil (caused by impaired parasympathetic nerve supply to iris), and oculomotor nerve paralysis. If anisocoria is greater in dim light compared with bright light, the cause may be Horner syndrome (caused by paralysis of the cervical sympathetic nerves and characterized by ptosis, sunken eyeball, flushing of the affected side of the face, and narrowing of the palpebral fissure).
What are older adult considerations when it comes down to arcus senilis?
Arcus senilis, a normal condition in older clients, appears as a white arc around the limbus. The condition has no effect on vision.
How to inspect the lacrimal apparatus? Normal and abnormal finding?
Assess the areas over the lacrimal glands (lateral aspect of upper eyelid) and the puncta (medial aspect of lower eyelid) Normal: No swelling or redness should appear over areas of the lacrimal gland. The puncta is visible without swelling or redness and is turned slightly toward the eye. Abnormal: Swelling of the lacrimal gland may be visible in the lateral aspect of the upper eyelid. This may be caused by blockage, infection or an inflammatory condition. Redness or swelling around the puncta may indicate an infectious or inflammatory condition. Excessive tearing may indicate nasolacrimal sac obstruction.
What is the point of cardinals fields of gaze test? How to do it? Normal and abnormal?
Assesses eye muscle strength and cranial nerve function. Instruct the client to focus on an object you are holding (12 inches away). Move the object through the six cardinal positions of gaze in a clockwise position and observe the client's eye movements. Normal: eye movement should be smooth and symmetric throughout all six directions. Abnormal: Failure of eyes to follow movement symmetrically in any or all directions indicates a weakness in one or more extra-ocular muscles or dysfunction of the cranial nerve that innervates the particular muscle.
What are some do's?
Begin about 10 to 15 in from the client at a 15-degree angle to the client's side. Pretend that the ophthalmoscope is an extension of your eye. Keep focused on the red reflex as you move in closer, then rotate the diopter setting to see the optic disk.
Describe collecting subjective data: the nursing health history?
Beginning when the nurse first meets the client, assessment of vision provides important information about the client's ability to interact with the environment. Changes in vision are often gradual and go unrecognized by clients until a severe problem develops. Therefore, asking clients specific questions about their vision may help with early detection of disorders. With recent advances in medicine and surgery, early detection and intervention are increasingly important.
What are the cultural considerations with sclera?
Dark skinned clients may have sclera with yellow or pigmented freckles
Mydriasis
Dilated and fixed pupils, typically resulting from central nervous system injury, circulatory collapse, or deep anesthesia.
What are some don'ts?
Do not use your right eye to examine the client's left eye or your left eye to examine the client's right eye (your noses will bump). Do not move the ophthalmoscope around; ask the client to look into light to allow you to view the fovea and macula. Do not get frustrated— the ophthalmologic examination requires practice.
What are some examples of actual diagnoses?
Dry eye related to decreased tear production, inadequate intake of nutrients and advancing age I Ineffective Health Maintenance related to lack of knowledge of necessity for eye examinations Self-Care Deficit (specify) related to poor vision Acute Pain related to injury from eye trauma, abrasion, or exposure to chemical irritant Social Isolation related to inability to interact effectively with others secondary to vision loss
What are the older considerations with entropion and ectropion?
Entropion and ectropion are common in older clients
What is the second step to the procedure of inspecting palpebral conjunctiva? What is normal and abnormal findings to find?
Evert the upper eyelid. Ask the client to look down with his or her eyes slightly open. Gently grasps the client's upper eyelashes and pull the lid downward. Normal: Palpebral conjunctiva is free of swelling, foreign bodies or trauma Abnormal: A foreign body or lesion may cause irritation burning, pain, and/ or swelling of the upper eyelid
How to prepare the client?
Explain each vision test thoroughly to guarantee accurate results. For the eye examination, position the client to be seated comfortably. During examination of the internal eye with the ophthalmoscope, you will move very close to the client's face to view the retina and internal structures. Explain to the client that this may be slightly uncomfortable. To ease any client anxiety, explain in detail what you will be doing and answer any questions the client may have.
External Structures: What are the eyelashes?
Eyelashes are projections of stiff hair curving outward along the margins of the eyelids that filter dust and dirt from air entering the eye.
In the subjective data, what to do first?
First, gather data from the client about his or her current level of eye health. Also discuss any personal and family history problems that are related to the eye. Collecting data concerning environmental influences on vision as well as how any problems are influencing or affecting the client's usual activities of daily living is also important. Answers to these types of questions help to evaluate a client's risk for vision loss and, in turn, present ways that the client may modify or reduce the risk of eye problems. The following questions provide guidance in conducting the interview.
Assessing eye trauma: in the event of an eye trauma in which the client is experiencing eye pain, discomfort, or feels something is in the eye, observe for; What is normal? What if you find something abnormal?
Foreign body that remains after gentle washing Perforated globe Blood in eye No foreign body is observed. the eye globe is intact with no indication of blood in eye. Bad: Refer the client to an eye doctor quickly if a foreign body cannot be removed with gentle washing, there is perforation of globe, blood in eye and/or client has impaired vision.
What do you do when inspecting the bulbar conjunctiva and sclera? Abnormal and normal?
Have the client keep the head straight while looking from side to side then up toward the ceiling. Observe clarity, color and texture Normal: Bulbar conjunctiva is clear, moist and smooth. Underlying structures are clearly visible. Sclera is white. Abnormal: generalized redness of the conjunctiva suggests conjunctivitis (pink eye). Areas of dryness are associated with allergies or trauma. Epicleritis is a local, noninfectious inflammation of the sclera. The condition is usually characterized by either a nodular appearance or by redness with dilated vessels. Yellow sclera occurs when the client has jaundice or icterus. Bright red areas on the sclera indicate a subconjunctival hemorrhage. There are often caused by sneezing, coughing or vomiting which may break a blood vessel. This may lead to accumulation of trapped blood, which is not quickly absorbed . It is harmless and disappears in 1-2 weeks.
What are the two clinical tips for observing the internal eye structures?
Hold the ophthalmoscope in your right hand, to your right eye, to inspect the client's right eye. Hold the ophthalmoscope in your left hand, to your left eye, to inspect the client's left eye. Visualization of the eye grounds requires practice. Only approximately 1/9 of the image of the total eye grounds will be visible to the examiner in an undilated eye
What is the E chart?
If the client cannot read or has a handicap that prevents verbal communication, the E chart is used. The E chart is configured just like the Snellen chart but the characters on it are only Es, which face in all directions. The client is asked to indicate by pointing which way the open side of the E faces. If the client wears glasses, they should be left on, unless they are reading glasses
What is the clinical tip for test distant visual acuity?
If the client wears glasses, they should be left on unless they are reading glasses. (reading glasses blur distance vision)
How to inspect the retinal vessels? Note color and diameter of the arterioles? Observe the arteriovenous ratio? Look at AV crossings? Normal findings and abnormal findings of each?
Inspect sets of retinal vessels by following them out to the periphery of each section of the eye. Note the number of arterioles and venules. Normal: Four sets of arterioles and venules should pass through the optic disc. Abnormal: changes in the blood supply to the retina may be observed in constricted arterioles, dilated veins or absence of major vessels. Normal: Arterioles are bright red and progressively narrow as they move away from the optic disc. Arterioles have a light reflex that appears as a thin, white line in the center of the arteriole. Venules are darker red and larger than arterioles. They are also narrow as they move away from optic discs. Abnormal: hypertension may cause widening of the arterioles' light reflex and the arterioles take on a copper color. With long-standing hypertension, arteriole walls thicken and appear opaque and silver Normal: the ratio of arteriole to vein diameter is 2:3 or 4:5. Normal: In a normal AV crossing, the vein passing underneath the arteriole is seen right up to the column of blood on either side of the arteriole. Abnormal: Arterial nicking, tapering, and banking are abnormal AV crossings caused by hypertension or arteriosclerosis.
How to inspect the iris and pupil? Normal and abnormal findings?
Inspect shape and color of iris and size and shape of pupil. Measure pupils against a gauge if they appear larger or smaller than normal or if they appear to be two different sizes. Normal: The iris is typically round, flat and evenly colored. The pupil, round with a regular border, is centered in the iris. Pupils are normally equal in size. An in equality in pupil size of less than 0.5 mm occurs in 20% of clients. This condition is called anisocoria, is normal. Abnormal: Typical abnormal findings include irregularly shaped irises, miosis, mydriasis and anisocoria. If the difference in pupil size changes throughout pupillary response tests, the inequality of size is abnormal.
What are cultural consideration to consider with vision acuity?
It varies by race in US population. Japanese and Chinese americans have the poorest corrected visual acuity (especially myopia) followed by blacks and hispanics. Native Americans and Caucasians have the best-corrected visual acuity. Eskimos are undergoing an epidemic of myopia.
How do you inspect the optic disc? Normal and abnormal finding?
Keep the light beam focused on the pupil and move closer to the client from a 15 degree angle. You should be very close to the client's eye, almost touching the eyelashes. Rotate the diopter setting to bring the retinal structures into sharp focus. The diopter should be 0 if neither the examiner nor the client has refractive errors. Note shape, color, size and physiologic cup. Normal: The optic discs should be round to oval with sharp, well defined borders. Nasal edge of disc is normally creamy, yellow-orange to pink. Abnormal: Papilledma or swelling of the optic disc appears as a swollen disc with blurred margins, a hyperemic appearance, more visible and more numerous disc vessels and lack of visible physiologic cup. The condition may result from hypertension or increased intracranial pressure. The intraocular pressure associated with glaucoma interferes with the blood supply to optic structures. Optic atrophy is evidenced by the disc being white in color and a lack of disc vessels. This condition is caused by the death of optic nerve fibers.
In the case of blunt eye trauma, observe for: What's normal? What's abnormal?
Lids swollen shut Blood in anterior chamber White/hazy cornea Irregularly shaped, fixed, dilated or constricted pupil Normal: There is no swelling of eye, no blood in anterior chamber, cornea is clear, pupils equal and reactive too light. Abnormal: Refer client to eye doctor quickly if eye is swollen, blood is observed in anterior chamber, cornea is hazy, or pupils are irregularly shaped, fixed, dilated or constricted.
ABNORMALITIES OF THE PUPILS
Miosis Anisocoria Mydriasis
What is the Jaegar test?
Near vision is assessed in clients over 40 years of age by holding the pocket screener (Jaeger test) or newspaper print 14 in from the eye. Clients who have decreased accommodation to view closer print will have to move the card or newspaper further away to see it.
What are the normal and abnormal findings when observing redness, swelling, discharge or lesions?
Normal: Skin on both eyelids is without redness, swelling or lesions. Abnormal: Redness and crusting along the lid margins suggest seborrhea or blepharitis, an infection caused by Staph aureus. Hordeolum, a hair follicle infection, causes local redness, and pain. A chalazion, an infection of the meibomian gland, may produce extreme swelling of the lid, moderate redness, but minimal pain.
What is the normal and abnormal findings to assess ability of eyelids to close?
Normal: The upper and lower lids close easily and meet completely when closed Abnormal: Failure of lids to close completely puts client at risk for corneal damage
How to inspect retinal background? Norma and abnormal?
Normal: background appears consistent in texture. The red orange color of the background is lighter near the optic disc. Abnormal: Cotton wool patches and hard exudates from diabetes and hypertension appear as light colored spots on the retinal background. Hemorrhages and microanneurysms appear as red spots and streaks on the retinal background
What are the normal and abnormal findings when you observe the position and alignment of the eyeball in the eye socket?
Normal: symmetrically aligned in sockets without protruding or sinking Abnormal: Protrusion of the eyeballs accompanied by retracted eyelid margins is termed exophathalmos and is characteristic of Graves disease. A sunken appearance of the eyes may be seen with severe dehydration or chronic wasting illnesses.
What are the normal and abnormal findings to assess the position of the eyelids in comparison with the eyeballs?
Normal: the lower eyelid is upright with no inward or outward turning. Eyelashes are evenly distributed and curse outward along the lid margins. Xanthelasma raised yellow plaques located most often near the inner canthus, are a normal variation associated with increasing age and high lipid levels. Abnormal: An inverted lower lid is a condition called an entropion, which may cause pain and injure the cornea as the eyelash brushes against the conjunctiva and cornea. Ectropian: an everted lower eyelid, results in exposure and drying of the conjunctiva. Both conditions interfere with normal tear drainage.
What should the nurse pay attention to when testing the clients?
Note behaviors like leaning forward, head tilting or squinting) that could be unconscious attempts to see better.
When inspecting the eyelids and eyelashes, what do you note, asses, and observe
Note width and position of palpated fissures Assess ability of eyelids to close Note the position of the eyelids in comparison with the eyeballs, Also not any unusual: turnings, color, swelling, lesions, and discharge. Observe for redness, swelling, discharge or lesions Observe the position and alignment of the eyeball in the eye socket
Phoria (Mild Weakness)
Noticeable only with the cover test, phoria is less likely to cause amblyopia than strabismus. Esophoria is an inward drift and exophoria an outward drift of the eye. The uncovered eye is weaker; when the stronger eye is covered, the weaker eye moves to refocus. When the weaker eye is covered, it will drift to a relaxed position. Once the eye is uncovered, it will quickly move back to reestablish fixation.
Paralytic Strabismus
Noticeable with the positions test, paralytic strabismus is usually the result of weakness or paralysis of one or more extraocular muscles. The nerve affected will be on the same side as the eye affected (for instance, a right eye paralysis is related to a right-side cranial nerve). The position in which the maximum deviation appears indicates the nerve involved.
LENS ABNORMALITIES
Nuclear cataracts appear gray when seen with a flashlight; they appear as a black spot against the red reflex when seen through an ophthalmoscope.
What are the types of abnormal conditions that you can find out with cardinal fields of gaze test?
Nystagmus: an oscillating (shaking) movement of the eye--may be associated with an inner ear disorder, multiple sclerosis, brain lesions or narcotics
What are cultural considerations with optic discs?
Optic discs are larger in African American, which is thought to be associated with the higher rate of glaucoma in this group
Characteristic abnormal findings during an ophthalmoscopic examination Optic Disc
PAPILLEDEMA GLAUCOMA OPTIC ATROPHY
What are the abnormal findings of the extraocular muscles? POSITIVE TEST ABNORMALITIES
Paralytic Strabismus 6th nerve paralysis: 4th nerve paralysis: 3rd nerve paralysis
What are the abnormal findings of the extraocular muscles? COVER TEST ABNORMALITIES
Phoria (Mild Weakness)
What are the types of abnormal findings an be found in the cover test?
Phoria: describes misalignment that occurs only when fusion reflex is blocked Strabismus is constant malalignment of the eyes. Tropia: specific type of misalignment: esotropia is an inward turn of the eye and exotropia is an outward turn of the eye
What are the last three steps to the procedure of inspecting palpebral conjunctiva?
Place a cotton tipped applicator approximately 1 cm above the eyelid margin and push down the applicator while still holding the eyelashes Hold the eyelashes against the upper ridge of the body orbit just below the eyebrow to maintain the everted position of the eyelid. Examine the palpebral conjunctiva for swelling, foreign bodies or trauma. Return the eyelid to normal by moving the lashes forward and asking the client to look up and blink. The eyelid should return to normal.
What's the clinical tip for testing a consensual response?
Place your hand or another barrier to light between the client's eyes to avoid an inaccurate finding.
How to test distant visual acuity? Normal and abnormal?
Position the distant 20 feat from the snellen or e chart and ask her to read each line until she cannot decipher the letters or their direction. Normal: vision acuity 20/20 with or without corrective lenses. This means that the client can distinguish what the person with normal vision can distinguish from 20 ft away. Abnormal: Myopia (impaired far vision) is present when the second number in the test result is larger than the first (20/40). The higher the second number, the poorer the vision. A client is considered legally blind when vision in the better eye with correctuve lenses is 20/200 or less. Refer any client worse than 20/30 for further evaluation.
What are older adult considerations for near vision? abnormal
Presbyopia is a common condition in clients over 45 years of age
What are the abnormal findings of the extraocular muscles? (CORNEAL LIGHT REFLEX TEST ABNORMALITIES)
Pseudostrabismus Strabismus (or Tropia) Esotropia (eye turns inward). Exotropia (eye turns outward).
Pseudostrabismus
Pseudostrabismus Normal in young children, the pupils will appear at the inner canthus (due to the epicanthic fold).
How to palpate the lacrimal apparatus? Normal and abnormal finding?
Put on disposable gloves to palpate the nasolacrimal duct to assess for blockage. Use one finger and palpate just inside the lower orbital rim. Normal: No drainage Abnormal: Expressed drainage from the puncta on palpation occurs with duct blockage
What is the first step to the procedure of inspecting palpebral conjunctiva? What is normal and abnormal findings to find?
Put on gloves for this assessment procedure. First inspect the palpebral conjunctiva of the lower eyelid by placing your thumbs bilaterally at the level of the lower bony orbital rim and gently pulling down to exposure the palpebral conjunctiva. Avoid putting pressure on the eye. Ask the client to look up as you observe the exposed areas. Normal: The lower and upper palpebral conjunctivae are clear and free of swelling or lesions Abnormal: Cyanosis of lower lid suggests a heart or lung disorder
Following is a list of collaborative problems that may be identified when assessing the eye. These problems are worded as Risk for Complications (RC), followed by the problem.
RC: Increased intraocular pressure RC: Corneal ulceration or abrasion
Examples of Health Promotion Diagnoses?
Readiness for enhanced knowledge: improved visual integrity
What are some examples of the risk diagnosis?
Risk for Eye Injury related to hazardous work area or participation in high-level contact sports Risk for Injury related to impaired vision secondary to the aging process Risk for Eye Injury related to decreased tear production secondary to the aging process Risk for Self-Care Deficit (specify) related to vision loss
How to inspect anterior chamber? Normal and abnormal?
Rotate the lens wheel slowly to +10, +12 or higher to inspect the anterior chamber of the eye Normal: The anterior chamber is transparent. Abnormal: Hyphemia: occurs when injury causes red blood cells to collect in the lower half of the anterior chamber Hypopyon: usually results from an inflammation response in which white blood cells accumulate in the anterior chamber and produce cloudiness in front of the iris
How to inspect the cornea and lens? Normal and abnormal findings?
Shine a light from the side of the eye for an oblique view. Look through the pupil to inspect the lens. Normal: The cornea is transparent, with no opacities. The oblique view shows a smooth and overall moist surface; the lens is free of opacities Abnormal: Areas of roughness or dryness on the cornea are often associated with injury or allergic responses. Opacities of the lens are seen with cataracts.
How to inspect fovea (sharpest area of vision) and macula? Normal and abnormal?
Shine the light beam toward the side of the eye or ask the client to look directly into the light. Observe the fovea and the macula that surrounds it. Normal: the macula is the darker area, one disc diameter in size, located to the temporal side of the optic disc. Within this area is a star-like light reflex called the fovea Abnormal: Excessive clumped pigment appears with detached retinas or retinal injuries. Macular degeneration may be due to hemorrhages, exudates or cysts.
What are the equipments needed for the eye assessment?
Snellen or E chart (see Assessment Guide 16-1) Hand-held Snellen card or near-vision screener Penlight Opaque cards Ophthalmoscope (Assessment Guide 16-2) Disposable gloves (wear as needed to prevent spreading infection or coming in contact with exudate)
PAPILLEDEMA
Swollen optic disc Blurred margins Hyperemic appearance from accumulation of excess blood Visible and numerous disc vessels Lack of visible physiologic cup
How to test pupillary reaction to light? Normal and abnormal?
Test for direct response by darkening the room and asking the client to focus on a distant object. To test direct pupil reaction,shine a light obliquely into one eye and observe the pupillary reaction. Shining the light obliquely into the pupil and asking the client to focus on an object in the distance ensures that pupillary constriction is a reaction to light and not a near reaction Normal: Constriction Abnormal: Monocular blindness can be detected when light directed to the blind eye results in no response in either pupil. When light is directed into the unaffected eye, both pupils constrict Assess consensual response at the same time as direct response b shining a light obliquely into one eye and observing the pupillary reaction in the opposite eye Normal: Constriction Abnormal: Pupils do not react at all.
Internal structures: describe the choroid layer?
The choroid layer contains the vascularity necessary to provide nourishment to the inner aspect of the eye and prevents light from reflecting internally. Anteriorly, it is continuous with the ciliary body and the iris.
What's the clinical tip for test near visual acuity?
The client who wears glasses should keep them on for this test,
External Structures: What's the conjunctiva? Describe it and the two portions?
The conjunctiva is a thin, transparent, continuous membrane that is divided into two portions: a palpebral and a bulbar portion. The palpebral conjunctiva lines the inside of the eyelids, and the bulbar conjunctiva covers most of the anterior eye, merging with the cornea at the limbus. The point at which the palpebral and bulbar conjunctivae meet creates a folded recess that allows movement of the eyeball. This transparent membrane allows for inspection of underlying tissue and protects the eye from foreign bodies.
What is the point of the cover test? How to do it? Normal and abnormal?
The cover tests detects deviation in alignment or strength and slight deviations in eye movement by interrupting the fusion reflex that normally keeps the yes parallel. Ask the client to stare straight ahead and focus on a distant object. Cover one of the client's eyes with an opaque card. As you cover the eye, observe the uncovered eye for movement. Now remove the opaque card and observe the previously covered eye for any movement. Repeat test on the opposite eye. Normal: The uncovered eye should remain fixed straight ahead. The covered eye should remain fixed straight ahead after being uncovered. Abnormal: The uncovered eye will move to establish focus when the opposite eye is covered. When the covered eye is uncovered, movement to reestablish focus occurs. These indicates deviations in alignment of the eye and muscle weakness.
External structures: Describe the extraocular muscles and what are they innervated by?
The extraocular muscles are the six muscles attached to the outer surface of each eyeball (Fig. 16-3). These muscles and associated nerves control six different directions of eye movement. There are four rectus muscles (superior, inferior, lateral, and medial) and two oblique muscles (superior and inferior) that are responsible for moving the eye in the direction controlled by that muscle. Each muscle coordinates with a muscle in the opposite eye. This allows for parallel movement of the eyes and thus the binocular vision characteristic of humans. Innervation for these muscles is supplied by three cranial nerves: the oculomotor (III), trochlear (IV), and abducens (VI).
4th nerve paralysis:
The eye cannot look down when turned inward.
6th nerve paralysis:
The eye cannot look to the outer side. In left 6th nerve paralysis, the client tries to look to the left. The right eye moves left, but the left eye cannot move left.
What is the main function, structure, location with the eyeball?
The eye transmits visual stimuli to the brain for interpretation and, in doing so, functions as the organ of vision. The eyeball is located in the eye orbit, a round, bony hollow formed by several different bones of the skull. In the orbit, a cushion of fat surrounds the eye. The bony orbit and fat cushion protect the eyeball.
What are the chambers the eyeball contains and what are they filled with and what structures compose them?
The eyeball contains several chambers that maintain structure, protect against injury, and transmit light rays. The anterior chamber is located between the cornea and iris; the posterior chamber is the area between the iris and the lens. These chambers are filled with aqueous humor, a clear liquid substance produced by the ciliary body. Aqueous humor helps to cleanse and nourish the cornea and lens as well as maintain intraocular pressure. The aqueous humor filters out of the eye from the posterior to the anterior chamber then into the canal of Schlemm through a filtering site called the trabecular meshwork. Another chamber, the vitreous chamber, is located in the area behind the lens to the retina. It is the largest of the chambers and is filled with a vitreous.humor that is clear and gelatinous.
Internal structures of the eye: Describe the eyeball? The structures? What does it compose? What are the functions? What are the layers?
The eyeball is composed of three separate coats or layers (Fig. 16-4). The external layer consists of the sclera and cornea. The sclera is a dense, protective, white covering that physically supports the internal structures of the eye. It is continuous anteriorly with the transparent cornea (the "window of the eye"). The cornea permits the entrance of light, which passes through the lens to the retina. It is well supplied with nerve endings, making it responsive to pain and touch.
External structures: What are the eyelids? What is the main purpose of the eyelids? What's significant about the upper eyelid? How are the eyelids joined? What are the functions?
The eyelids (upper and lower) are two movable structures composed of skin and two types of muscle: striated and smooth. Their purpose is to protect the eye from foreign bodies and limit the amount of light entering the eye. In addition, they serve to distribute tears that lubricate the surface of the eye (Fig. 16-1). The upper eyelid is larger, more mobile, and contains tarsal plates made up of connective tissue. These plates contain the meibomian glands, which secrete an oily substance that lubricates the eyelid. The eyelids join at two points: the lateral (outer) canthus and medial (inner) canthus. The medial canthus contains the puncta, two small openings that allow drainage of tears into the lacrimal system, and the caruncle, a small, fleshy mass that contains sebaceous glands. The white space between open eyelids is called the palpebral fissure. When closed, the eyelids should touch. When open, the upper lid position should be between the upper margin of the iris and the upper margin of the pupil. The lower lid should rest on the lower border of the iris. No sclera should be seen above or below the limbus (the point where the sclera meets the cornea).
What are the cultural considerations when you observe the position and alignment of the eyeball in the eye socket?
The eyes of African Americans protrude slightly more than those of Caucasians and those of Hispanics protrude less. Eyes of African Americans of both sexes may have eyes protruding beyond 21 min. A difference of more than 2mm between the two eyes is normal.
Internal structure: describe the iris?
The iris is a circular disc of muscle containing pigments that determine eye color. The central aperture of the iris is called the pupil. Muscles in the iris adjust to control the pupil's size, which controls the amount of light entering the eye. The muscle fibers of the iris also decrease the size of the pupil to accommodate for near vision and dilate the pupil when far vision is needed.
External structures: What's the lacrimal apparatus? What's the lacrimal gland? Locations
The lacrimal apparatus consists of glands and ducts that lubricate the eye (Fig. 16-2). The lacrimal gland, located in the upper outer corner of the orbital cavity just above the eye, produces tears. As the lid blinks, tears wash across the eye then drain into the puncta, which are visible on the upper and lower lids at the inner canthus. Tears empty into the lacrimal canals and are then channeled into the nasolacrimal sac through the nasolacrimal duct. They drain into the nasal meatus.
Internal structure: describe the lens?
The lens is a biconvex, transparent, avascular, encapsulated structure located immediately posterior to the iris. Suspensory ligaments attached to the ciliary body support the position of the lens. The lens functions to refract (bend) light rays onto the retina. Adjustments must be made in refraction depending on the distance of the object being viewed. Refractive ability of the lens can be changed by a change in shape of the lens (which is controlled by the ciliary body). The lens bulges to focus on close objects and flattens to focus on far objects.
Internal structure: describe the middle layer?
The middle layer contains both an anterior portion, which includes the iris and the ciliary body, and a posterior layer, which includes the choroid. The ciliary body consists of muscle tissue that controls the thickness of the lens, which must be adapted to focus on objects near and far away.
Describe the ophthalmoscope?
The ophthalmoscope is a hand-held instrument that allows the examiner to view the fundus of the eye by the projection of light through a prism that bends the light 90 degrees. There are several lenses arranged on a wheel that affect the focus on objects in the eye. The examiner can rotate the lenses with the index finger. Each lens is labeled with a negative or positive number, a unit of strength called a diopter. Red numbers indicate a negative diopter and are used for myopic (nearsighted) clients. Black numbers indicate a positive diopter and are used for hyperopic (farsighted) clients. The zero lens is used if neither the examiner nor the client has refractive errors.
Internal structures: describe the optic disc?
The optic disc is a cream-colored, circular area located on the retina toward the medial or nasal side of the eye. It is where the optic nerve enters the eyeball. The optic disc can be seen with the use of an ophthalmoscope and is normally round or oval in shape, with distinct margins. A smaller circular area that appears slightly depressed is referred to as the physiologic cup. This area is approximately one third the size of the entire optic disc and appears somewhat lighter/ whiter than the disc borders.
What are the visual reflexes and what do they do?
The pupillary light reflex causes pupils immediately to constrict when exposed to bright light. This can be seen as a direct. reflex, in which constriction occurs in the eye exposed to the light, or as an indirect or consensual reflex, in which exposure to light in one eye results in constriction of the pupil in the opposite eye (Fig. 16-7). These protective reflexes, mediated by the oculomotor nerve, prevent damage to the delicate photoreceptors by excessive light. Accommodation is a functional reflex allowing the eyes to focus on near objects. This is accomplished through movement of the ciliary muscles, causing an increase in the curvature of the lens. This change in shape of the lens is not visible. However, convergence of the eyes and constriction of the pupils occur simultaneously and can be seen.
What is the clinical tip with the sclera?
The sclera of the eye, which is normally white, is an excellent place to look for signs of jaundice or icterus.
What are normal and abnormal findings when noting width and position of peripheral fissures?
The upper lid margin should be between the upper margin of the iris and the upper margin of the pupil. The lower lid margin rests on the lower border of the iris. No white sclera is seen above or below the iris. Palpebral fissures may be horizontal. Abnormal: Drooping of the upper lid is called ptosis. May be attributed to oculomotor nerve damage, myasthenia gravis, weakened muscle or tissue, or a congenital disorder. Retracted lid margins, which allow for viewing of the sclera when eyes are open, suggest hyperthyroidism.
How to perform the corneal light reflex test? What does it assess? Normal and abnormal?
This test assesses parallel alignment of the eyes. Hold a penlight approximately 12 in from the client's face. Shine the light towards the bridge of the nose while the client stares straight ahead. Note the light reflected on the corneas. Normal: The reflection of light on the corneas should be in the exact same spot on each eye, which indicates parallel alignment Abnormal: Asymmetric position of the light reflex indicates deviated alignment of the eyes. This may be due to muscle weakness or paralysis.
How to test visual fields for gross peripheral vision? What's normal and what's abnormal?
To perform the confrontation test, position yourself approximately 2ft away from the client at eye level. Have the client cover the left eye, while you cover your right eye. Look directly at each other with your uncovered eyes. Next, fully extend your left arm at midline and slowly move one finger upward from below until the client sees your finger. Test the remaining three visual fields of the client's right eye (superior, temporal and nasal). Repeat the test for the opposite eye. Normal: the client should see the examiner's finger at the same time the examiner sees it. Normal visual field degrees are approximately as follows: Inferior: 70 degrees Superior: 50 degrees Temporaal: 90 degrees Nasal: 60 degrees Abnormal: a delayed or absent perception of the examiner's finger indicates reduced peripheral vision. Refer the client for further evaluation.
Basics of Operation?
Turn the ophthalmoscope "on" and select the aperture with the large round beam of white light. The small round beam of white light may be used if the client has smaller pupils. There are other apertures, but they are not typically used for basic ophthalmologic screening. Ask the client to remove any eyeglasses but to keep contact lenses in place. You can rotate the lenses to accommodate for any refractive errors. However, if the client has severe refractive errors, glasses should be left on. If you are wearing glasses, you should remove them, but you should keep contact lenses in place. Removing the client's and your glasses enables you to get closer to the client's eye, allowing for a more accurate inspection. Ask the client to fix his or her gaze on an object that is straight ahead and slightly upward. Darken the room to allow pupils to dilate. For a more thorough examination, optometrists or ophthalmologists may use mydriatic eye drops to dilate the pupils to view the posterior eye structures. However, mydriatic drops may precipitate acute angle closure glaucoma. Clients with a history of glaucoma or extreme farsightedness are at risk. Hold the ophthalmoscope in your right hand with your index finger on the lens wheel and place it to your right eye (braced between the eyebrow and the nose) if you are examining the client's right eye. Use your left hand and left eye if you are examining the client's left eye. This allows you to get as close to the client's eye as possible without bumping noses with the client. Weber, Janet R.; Kelley, Jane H. (2017-11-01). Health Assessment in Nursing (Kindle Locations 10040-10049). Wolters Kluwer Health. Kindle Edition.
Describe test near visual acuity? and how to do this test? normal and abnormal?
Use this tests for middle aged clients and others who have difficulty with near vision or with reading. Give the client a hand-held vision chart to hold 14 in from the eyes. Have the client cover one eye with an opaque card before reading top (largest print) to bottom (smallest print) Repeat test for other eye. Normal: normal near visual acuity is 14/14. This means that the client can read what the normal eye can read from a distance of 14 in. Abnormal: Presbyopia (impaired near vision) is indicated when the client moves the chart away from the eyes to focus on the print. It is caused by decreased accommodation.
What is the Snellen Chart?
Used to test distant visual acuity, the Snellen chart consists of lines of different letters stacked one above the other. The letters are large at the top and decrease in size from top to bottom. The chart is placed on a wall or door at eye level in a well-lighted area. The client stands 20 ft from the chart and covers one eye with an opaque card (which prevents the client from peeking through the fingers). Then the client reads each line of letters until he or she can no longer distinguish them.
What is visual perception? How does light pass through? How are images projected?
Visual perception occurs as light rays strike the retina, where they are transformed into nerve impulses, conducted to the brain through the optic nerve, and interpreted. In the eye, light must pass through transparent media (cornea, aqueous humor, lens, and vitreous body) before reaching the retina. The cornea and lens are the main eye components that refract (bend) light rays on the retina. The image projected on the retina is upside down and reversed right to left from the actual image. For example, an image from the lower temporal visual field strikes the upper temporal quadrant of the retina. At the point where the optic nerves from each eyeball cross— the optic chiasma— the nerve fibersfrom the nasal quadrant of each retina (from both temporal visual fields) cross over to the opposite side. At this point, the right optic tract contains only nerve fibers from the right side of the retina and the left optic tract contains only nerve fibers from the left side of the retina. Therefore, the left side of the brain views the right side of the world.
What are the older adult considerations for the bulba conjunctiva?
Yellowish nodules on the bulbar conjunctiva are called pingquecula. These harmless nodules are common in older clients and appear first on the medial side of the iris and then on the lateral side.
Internal structures: describe retinal vessels? The structures it contains?
lighter/ whiter than the disc borders. The retinal vessels can be readily viewed with the aid of an ophthalmoscope. Four sets of arterioles and venules travel through the optic disc, bifurcate, and extend to the periphery of the fundus. Venules are dark red and grow progressively narrower as they extend out to the peripheral areas. Arterioles carry oxygenated blood and appear brighter red and narrower than the veins. The general background, or fundus (Fig. 16-5), varies in color, depending on skin color. A retinal depression known as the fovea centralis is located adjacent to the optic disc in the temporal section of the fundus. This area is surrounded by the macula, which appears darker than the rest of the fundus. The fovea centralis and macular area are highly concentrated with cones and form the area of highest visual resolution and color vision.
