Jarvis chapter 15 clinical lab questions PDF

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Lab questions at the end of the book including chapter review questions...

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Chapter 15 1. Name the 6 sets of extraocular muscles and the cranial nerve that innervates each one. ● Superior oblique ● Medial rectus ● Superior rectus ● Lateral rectus ● Inferior oblique ● Inferior rectus 2. Name and describe the 3 concentric coats of the eyeball.

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● The outer fibrous sclera is a tough, protective, white covering that is continuous anteriorly with the smooth, transparent cornea. ● The middle vascular choroid delivers blood to the retina. Anteriorly, the choroid is continuous with the ciliary body and the iris. ● The inner nervous retina is the visual receptive layer of the eye in which light waves are changed into nerve impulses. Name the functions of the ciliary body, the pupil, and the iris. ● Ciliary body: the muscles of the ciliary body control the thickness of the lens. ● Pupil: controls the amount of light admitted into the retina. ● Iris: functions as a diaphragm, varying the opening of the pupil. Describe the anterior chamber, the posterior chamber, and the vitreous body. ● The anterior chamber is posterior to the cornea and in front of the iris and lens. ● The posterior chamber lies behind the iris to the sides of the lens. These contain the clear, watery aqueous humor that is produced continually by the ciliary body. ● The continuous flow of fluid serves to deliver nutrients to the surrounding tissues and drain metabolic wastes. ● Intraocular pressure is determined by a balance between the amount of aqueous produced and resistance to its outflow at the angle of the anterior chamber. Describe how an image formed on the retina compares with its actual appearance in the outside world. ● The image formed on the retina is upside down and reversed from its actual appearance in the outside world. Describe the lacrimal system. ● The lacrimal apparatus provides constant irrigation to keep the conjunctiva and cornea moist and lubricated. The lacrimal gland secretes tears, which wash across the eye, and then eventually drain into the puncta at the inner canthus. Define the pupillary light reflex, fixation, and accommodation.

● Pupillary light reflex: the normal constriction of the pupils when bright light shines on the retina. Can be direct or consensual. ● Fixation: a reflex direction of the eye toward an object attracting a person’s attention. The image is fixed in the center of the visual field, the fovea centralis. ● Accommodation: the adaptation of the eye for near vision. Movement of the ciliary muscles increases the curvature of the lens. Accommodation is observed through convergence (motion toward) of the axes of the eyeballs and constriction of the pupils. 8. Concerning the pupillary light reflex, describe and contrast a direct light reflex with a consensual light reflex. ● Direct light reflex of the pupil occurs when one eye is exposed to bright light and its pupil constricts. ● Consensual light reflex of the pupil occurs when one eye is exposed to light and the other eye’s pupil constricts simultaneously. 9. Identify common age-related change in the eye. ● Cataract formation: a clouding of the crystalline lens partly due to ultraviolet radiation. This is curable with lens replacement surgery, which the older person can consider when vision changes interfere with daily activities ● Glaucoma: an optic nerve neuropathy characterized by loss of peripheral vision, caused by increased intraocular pressure. ● Age-related macular degeneration (AMD): a loss of central vision caused by yellow deposits (drusen) and neovascularity in the macula. ● Diabetic retinopathy: the leading cause of blindness in adults 25 to 74 years of age. This vision impairment results in difficulty driving, reading, managing diabetes treatment, and other self-care. 10. Discuss the most common causes of decreased visual function in the older adult. ● Decreased visual changes in the older adult occur in cataract formation, glaucoma, and macular degeneration. 11. Explain the statement that normal visual acuity is 20/20. ● Normal visual acuity of 20/20: the top number indicates the distance the person is standing from the chart, and the bottom number gives the distance at which a normal eye could have read a particular line on a chart. 20/20 means that one can read at 20 feet what the normal eye could have read at 20 feet. 12. Describe the method of testing for presbyopia. ● To test for presbyopia: use a handheld vision screener with various sizes of print. Hold the card, while in good light, about 14 inches from the eye,

this distance equals the print size on the 20-foot chart. Test each eye separately, with glasses on. If no vision screening card is available, ask the person to read from a magazine or newspaper. 13. To test for accommodation, the person focuses on a distant object and then shifts the gaze to a near object about 6 inches away. At near distance, you would expect the pupils to constrict and the axes of the eye to converge. 14. Concerning malalignment of the eye axes, contrast phoria with tropia. ● Phoria: a mild weakness noted when fusion is blocked. ● Tropia: more severe than phoria, a constant malalignment of the eyes. 15. Describe abnormal findings of tissue color that are possible on the conjunctiva and sclera, and describe their significance. ● Conjunctiva: General reddening may indicate conjunctivitis, a bacterial or viral infection, allergic reaction, or chemical irritation. Cyanosis of the lower lids may indicate hypoxemia. Pallor near the outer canthus of the lower lid may indicate anemia. ● Sclera: scleral icterus is an even yellowing of the sclera that extends up to the cornea, indicating jaundice. 16. Describe the method of everting the upper eyelid for examination. ● This maneuver is not part of the normal examination, but it is useful when you must inspect the conjunctiva of the upper lid, as with eye pain or suspicion of a foreign body. Most people are apprehensive of any eye manipulation. Enhance their cooperation by using a calm and gentle, yet deliberate, approach. 17. Contrast pinguecula with pterygium. ● Pingueculae, nodules on the sclera, are yellowish elevated nodules that are due to a thickening of the bulbar conjunctiva from exposure to sun, wind, and dust. They appear at the 3 and 9 o’clock positions, first on the nasal side, then on the temporal side. ● Pterygium is a triangular, opaque wing of bulbar conjunctiva that grows toward the center of the cornea. It usually develops from the nasal side, and may obstruct vision if it covers the pupil. It is caused by chronic exposure to a hot, dry, sandy climate, which stimulates the growth of a pinguecula into a pterygium. 18. Contrast the use of the negative diopter or red lens settings with the positive diopter or black lens settings on the ophthalmoscope. ● The ophthalmoscope contains a set of lenses that control the focus. The unit of strength of each lens is called the diopter. The black numbers indicate a positive diopter and focus on objects nearer in space to the ophthalmoscope. The red numbers show a negative diopter and are used for focusing on objects farther away.

19. Explain the rationale for testing for strabismus during early childhood. ● Testing for strabismus (squint) is an important screening measure during early childhood years because diagnosis after age 6 has a poor prognosis for correction. Early recognition and treatment are essential for restoration of binocular vision. 20. Describe these findings, and explain their significance: epicanthal fold; pseudostrabismus; ophthalmia neonatorum; Bushfield spots. ● Epicanthal fold: an excess skinfold extending over the inner corner of the eye, partly or totally overlapping the inner canthus. It occurs frequently in Asian children and in 20% of whites, and eventually disappears in non-Asian children with growth. ● Pseudostrabismus: the presence of epicanthal folds gives a false appearance of malalignment, termed pseudostrabismus, but the corneal light reflex is normal. ● Ophthalmia neonatorum: (conjunctivitis of the newborn) is a purulent discharge due to a chemical irritant or bacterial or viral agent from the birth canal. ● Brushfield’s spots: white specks noted around the edge of the iris, may occasionally be normal but usually suggest Down syndrome. 21. Describe the following 4 types of red-eye and explain their significance. Conjunctivitis, subconjunctival hemorrhage, iritis, acute glaucoma. ● Conjunctivitis: Infection of the conjunctiva, “pink eye,” has red, beefy-looking vessels at periphery but is usually clearer around iris, commonly from viral or bacterial infection, allergy, or chemical irritation. ● Subconjunctival hemorrhage: A red patch on the sclera, subconjunctival hemorrhage looks alarming but is usually not serious. The red patch has sharp edges like a spot of paint, although here it is extensive. It occurs from increased intraocular pressure from coughing, vomiting, weight lifting, labor during childbirth, straining at stool, or trauma. ● Iritis: There is a deep, dull red halo around the iris and cornea. ● Acute glaucoma: Acute narrow-angle glaucoma shows circumcorneal redness around the iris, with a dilated pupil. Pupil is oval, dilated; cornea looks “steamy”; and anterior chamber is shallow....