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94 Cards in this Set
- Front
- Back
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What is Scotoma?
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Retinal defect, Blind spot in the visual field most commonly resulting from an inflammatory lesion of the optic nerve in MS pts.
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What is the etiology of Scotoma?
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Exact mechanism is unknown, can result from; optic nerve compression, retroorbital tumor, & inflammation of the optic nerve, pernicious anemia, toxic or metabolic causes; alcohol poisoning & tabacco use, local retinal damage & other localized pathologies (DM, abn carbohydrate metabolism)
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With Scotoma if the damage is @ the retinal or optic nerve level what happens?
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Only monocular field of the damaged eye becomes a problem.
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Are Scotoma pts usually aware that they have a blind spot?
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No, pts may find that a part of a printed page appears or disappears.
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Explain the reasons that Scotoma can be dangerous?
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The unawareness of the defect & absences near or in the center of the bilateral visual field, & defects in the peripheral visual field, including nonocular fields are less annoying but more dangerous.
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What type of lesion involving Scotoma can lead to eyestrain during reading?
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A lesion affecting the central foveal vision of one eye.
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What types of localized damage can lead to Scotoma?
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To the optic tracts, LGN, optic radiation or primary visual cortex affects corresponding parts of the visual fields of both eyes.
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What is the management of Scotoma?
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Careful eduaction, pt can learn to shift the gaze constantly to obtain visual coverage of important parts of the visual field.
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What is a Cataract?
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An alteration in the lens from normally clear to cloudy or opaque area → to vision loss.
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Cataract Epidemiology;
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13 million people in the US >40yrs are disabled due to cataract, most common age related cause of vision loss in the world, 50% in 65-74yrs & 70% >75yrs.
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What are the causes of cataract?
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multifactorial, pathogenesis not completely understood, metabolically induced (DM), Lowe's syndrome (synthesis of lens protein)
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What are the proposed risk factors for cataract?
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Long-term exposure to sunlight & heavy smoking, developmental defects, drugs (phenothyazine, corticosteroids)
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What are the types of cataracts?
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Traumatic,
Congenital, Senile. |
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What is the pathophysiologic process of traumatic cataract caused by foreign body ingury to the lens?
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Interrupts the lens capsule allowing the aqueous & vitreous humor to enter the lens & initiate cataract formation.
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What is the pathophysiologic process of traumatic cataract caused by overexposure to heat?
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Radiation dose causing cataract varies w/amt & type of energy, younger lenses are most vunerable.
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What are the causes of Congenital cataracts?
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(Present @ birth), Toxic environmental agents(Lead poisoning, drugs) & viruses (rubella 1st trimester), may occur in children of diabetic mothers.
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What is the pathophysiologic process of congenital cataract?
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These defects of the ocular apparatus depend on the total dose & the embryonic stage @ time of exposure, most are not progressive & are not dense enough to cause significant visual impairment.
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(cataract, malformation)
During the last trimester of pregnancy what in occur)? |
Genetically or environmentally influenced malformation of the superficial lens fibers.
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What is the Pathophysiologic process of Senile Cataract?
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Normal aging of the nucleus & cortex, metabolic ▲s occur, early stages-yellow pigment & vacuoles accumulate in the lens fibers. Unfolding of protein molecules, cross-link w/sulfhydryl groups & convert soluble to insoluble proteins→loss of lens transparency, pupillary colour may ▲ to yeloow, gray or white.
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With Senile Cataract as the lens becomes opaque, what sx will pt experience?
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Glare, poor night vision, & blurred vision.
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What is Papilledema?
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Optic disc swells where the optic nerve leaves the eye & enters the brain, obstruction to venous return from the retina→papilledema.
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What are the 3 principal causes of Papilledema?
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↑ ICP, retrobulbar neuritis (swellin of the optic disc), ▲s in retinal blood vessels.
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What is the pathophysiologic process of papilledema?
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Distension of retinal vein initially, obliteration of the physiologic cup follows, optic disc becomes raised above the level of the surrounding retina, & the margins become blurred & indistinct, severe swelling→hemorrhage & white exudate patches around disc margins.
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What is dark adaptation?
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Visual adjustment occurring under reduced illumination in which the retinal sensitivity to light is ↑.
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How is the ability to adaptat to the dark affected in the elderly?
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▲s in the quality & quantity of rhodopsin → decreased dark adaptation, Vit A defieiency can cause it @ any age.
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Glaucoma epidemiology;
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Is the 2nd leading cause of blindness among the elderly, & the leading cause of preventable blindness in the US.
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What is Glaucoma?
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Dz of the eye associated w/↑ IOP & excavation & atrophy of the optic nerve, produces visual field defects→to blindness. Can be open or closed, primary or 2ndary, & congenital closure.
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What are the risk factors of Glaucoma?
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↑ w/age, Black (genetic; sex link recessive, ♂), DM, Eye trauma, Long-term steroid use.
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What is the pathophysiologic processes & manifestations of angle closure glaucoma?
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Aqueous humor is unable to drain out of the eye, pressure builds up & is referred to the eye's posterior chamber, the iris flattens out & may obstruct the outflow of A/H form the trabecular system (canal or schlemm) & venous plexus.
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What is the pathophysiologic process of open-angle glaucoma?
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Most common form, trabecular network becomes clogged → IOP, usually asymptomatic → to difficulty dx → visual field ▲s & significant optic nerve damage.
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What are the clinical manifestations of open-angle glaucoma?
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Typically bilateral, mild aching in the eye, loss of peripheral vision, halors around lights, ↓ visual acculity.
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What are the clinical manifestations of acute-angle glaucoma?
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Usually unilateral, Red painfuld eye, Sensation of pressure, Cloudy cornea, Blurring & ↓ visual acuity, Photophobia, Halos around lights, Nausea & vomiting.
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What is retinal detachment?
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Separation of the retina from the posterior part of the eye, threatens vision, rhegmatogenous detachment (sm breaks in the sensory pathway)
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What is the most common cause of retinal detachment?
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Trauma (tears), age related degenerative ▲s, & vascular or metabolic dz are also causes.
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What is rhegmatogenous?
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Caused by or pert. to a tear. The term refers almost exclusively to retinal disease.
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How are ▲s in vitreous humor related to retinal detachment?
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W/age vitrous humor's acid concentration ▲s & liquifies the part that maintains the eye's shape & holds its structures together → posterior structures in the eye can move forward tearing the retina.
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What is the pathophysiology of retinal detachment?
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Neural retinal detachment from the retinal pigment layer separates the receptors form their major blood supply, continuous detachment → permanent destruction & blindness (bipolar & ganglion cells may survive, blood supply is not interupted) w/out receptors their is no visual function.
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What are the symptoms of retinal detachment?
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Loss of vision, flashing lights or sparks, no pain @ this time, perception of dark curain, initial visual distrubances may involve only quadrant of the visual field, lg peripheral detachment may be w/out macula involvement → unaffected visual acuity.
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What is Age-related macular degeneration?
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Atrophy or degeneration of the macula disc, usually bilateral.
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What is the most common cause of legal blindness in adults?
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Age-related macular degeneration
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What are the 2 types of Age-related macular degeneration?
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Dry or atrophic (mild vision loss)
Wet or exudative (subretinal formation of new blood vessels) |
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What is the cause of Age-related macular degeneration?
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It is unknown.
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What is the over-all pathophysiology of Age-related macular degeneration?
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Retinal arteries become hard or obstructed, neurovascularization in the macular area obscures central vision.
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What is the pathophysiology of Age-related macular degeneration Dry form?
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Yellow extracellular deposits or drusen accumulate beneath the pigment epithelium of the retina & may be prominent in the macula, visual loss occurs as the retinal pigment epithelium detaches & becomes atrophic.
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What are drusen?
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Small, hyaline, globular pathological growths on the optic papilla or on Descemet's membrane. Common in the elderly & over time become more numerous.
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What is the pathophysiology of Age-related macular degeneration Wet form?
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New blood vessels in the choroids project through abnormalities via Brunch's memvrane & invade the potential space underneath the retinal epithelium, as they leak, fluid in the retinal pigment epithelium ↑ → blurry vision.
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What causes aleterations in accommodation?
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Presbyopia
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What is Presbyopia?
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The permanent loss of accommodation of the crystalline lens of the eye that occurs when people are in their mid-40s, marked by the inability to maintain focus on objects held near to the eye
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What causes alterations in refraction?
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Myopia,
Hyperopia, Astigmatism |
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What is Myopia?
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An error in refraction in which light rays are focused in front of the retina, enabling the person to see distinctly for only a short distance.
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What is hyperopia?
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Farsightedness; a defect which parallel rays come to a focus behind the retina as a result of flattening of the globe of the eye or of an error in refraction. Symptoms include ocular fatigue and poor vision.
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What is astigmatism?
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A form of ametropia in which the refraction of a ray of light is spread over a diffuse area rather than sharply focused on the retina. It is due to differences in the curvature in various meridians of the cornea and lens of the eye. The exact cause is unknown. Some types show a familial pattern.
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How does accommodation occur?
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The thickness of the eye lens ▲s to maintain visual acuity.
(problems may be caused by pressure, inflammation, aging, disorders affecting CN-III) |
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What can impaired accommodation cause?
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Diplopia, prebypia, blured vision or HA
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What is Diplopia?
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Double vision
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How does the lens accomodate for near vision?
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The cilliary muscle contracts & relaxes the zonules, the lens becomes sperical, the pupil constricts & the eyes converge.
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How does the lens accomodate for far vision?
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The cillary body relaxes the zonules tighten , the lens becomes flatter, the eyes straighten, & the pupils dilate.
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How does the brain control accommondation?
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CN-III & coordinated brainstem pathways.
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What causes accommodation loss affect older adults?
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The ocular lens is larger & firmer w/less elasticity, near vision is diminished so reading material is held @ a distance.
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What is refraction?
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Process of bending light rays so that they fall on the retina.
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What causes alterations in refraction?
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(inproperly focused light), abn corneal curvature, abn lens focus, & abn eye length.
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What is the physiology of myopia?
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(nearsightness) light rays are focused in front of the retina, near objects are clearly seen, distant objects are blurred.
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What are causes of myopia?
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Eye too long, the refractive power of the cornea or lens is too great, hyperglycemia of uncontrolled DM → lens swelling (corrected by concave lens)
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What is the physiology of hyperopia?
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(farsightedness) light rays are focused behind the retina, distant objects appear clear, near objects are blurred.
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What are causes of hyperopia?
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Eye too short, refractive power of cornea or lens too low, (corrected by convex lens)
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What is the physiology of astigmatism?
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Occurs when unequal curvature of the cornea or eyeball causes light rays to focus on different points on the retina → distorted images, corrected w/cylinder lens.
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How is color vision affected by age?
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Normal sensitivity to color is diminished due to the progressive yellowing of the lens.
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What is the most common variety of color vision defect or blindness?
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The ability to distinguish between red & green.
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What is the physiology of color vision?
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Cones are responsible for color vision, each one contains 1 of 3 different visual pigments (red, green & blue) that absorb light waves of different wavelengths.
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How is color blindness inherited?
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On the X chromosome & so usually affects ♂
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What is the cause of acquired color blindness?
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DM, bilateral strokes or dz of the optic nerve or macula.
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How is color vision of older adults usually impaired?
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Blue & green ranges, yelowing of the aging lens also impairs color vision.
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Why do eyes constantly move to keep objects being viewed on the fovea?
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It contains only cones & is responsible for the best peripheral visual acuity.
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What cranial nerves innervate the six extra ocular muscles?
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CN-III, CN-IV, & CN-VI
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Alterations in ocular movement include what disorders?
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Strabismus,
Diplopia, Nystagmus |
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What is the physiology of strabismus?
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It occurs when one eye deviates from its normal position due to the absence of normal, parallel, or coordinated movement. The eye may have an uncoordinated appearance & the person may experience diplopia.
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What are the types of strabismus that occur in peds?
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Concomitant (harmony between degree of vision & degree of gaze)
Nonconcomitant (degree of vision varies from degree of gaze), Congenital (evident w/in 1st 6mos), Acquired (evident w/in 2.5yrs), Latent, Constant. |
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What are the types of tropias?
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Esotropia (inward)
Exotropia (outward) Hypotropia (downward) Hypertropia (upward) |
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What is the eitology of strabismus?
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Is frequently inherited, cause unknown, adults-may result from trauma, incidence ↑ in pts w/ CNS disorders, Muscle inbalance may be corrected by glasses, patching or surgery. Residual defects in vision & ocular muscle alignment may persist even p tx.
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What is strabismic amblyopia characterized by?
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Loss of central vision in 1 eye,
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What causes strabismic amblyopia?
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Usually esotropia, may result from hyperopia or anisometropia.
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What is the cause of esotropia?
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Muscle imbalance & may be congenital or acquired.
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What is esotropia?
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Marked turning inward of the eye; crossed eyes.
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What is anisometropia?
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Condition in which the refractive power of the eyes is unequal.
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What is the phisiology of diplopia?
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Extraocula muscles fail to work together & images fall on non-corresponding parts of the retinas, usually begins intermittently or affects near or far vision exclusively.
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What are the 2 types of Diplopia?
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Monocular (persists when 1 eye is covered)
Binocular (more common, clears when 1 eye is covered. |
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What can cause Monocular Diplopia?
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Early cataract, retinal edema or scarring, iridolysis, subluxated lens, poorly fitting contact lens, uncorrected refractive error.
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What can cause Binocular Diplopia?
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Ocular deviation or displacement, Extraocular muscle palsies, psychoneurosis, post retinal surgery, infection, neoplastic dz, metabolic disorders, degenerative dz, inflammatory disorders, vascular dz.
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What is nystagmus?
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Involuntary oscillations or alternating movements of 1 or both eyes.
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What are the 2 classifications of nystagmus?
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Pendular or Jerk
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Describe the differences in the oscillations & movementsof nystagmus?
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Rhythmic & may be horizontal, vertical or rotary, may be transient or sustained & may occur spontaneously or on deviation or fixation, have a fast & slow component, direction is given by the fast component.
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What is the physiology of nystagmus?
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A supranuclear ocular palsy resulting from pathology in the visual perceptual area, vestibular system or cerebellum.
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What can cause nystagmus?
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Brain stem or cerebellar lesions, Labyrinthine dz, Stroke, Encephalitis, meniere's dz, MS, Alcohol toxicity, & barbituates, phenytoin or carbamazepine toxicity.
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What is amblyopia?
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Severely ↓ visual acuity or virtual blindness in a structurally intact eye, may be caused by toxins, may accompany systemic dz (DM, Renal failure)
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