פרק 12 Chapter 12: Disturbances of Vision Flashcards
Table 12-3
CAUSES OF UNILATERAL AND BILATERAL OPTIC NEUROPATHY
8 main causes
- Demyelination (2)
- Ischemic (4)
- Parainfectious (2)
- Toxins & drugs (11)
- Deficiency states (3)
- Heredofamillial & developmental (4)
- Compressive & infiltrative (10)
- Radiation induced optic neuropathy
מתנול
Impairment of vision because of methyl alcohol intoxication
(methanol) is abrupt in onset and characterized by
large symmetrical central scotomas as well as symptoms
of acidosis. Treatment is directed mainly to correction of
the acidosis and possibly, the administration of fomepizole.
The same may occur with ethylene glycol ingestion.
The subacute development of central field defects is
attributable to other toxins and to the chronic administration
of certain therapeutic agents, notably halogenated
hydroxyquinolines (clioquinol), chloramphenicol, ethambutol,
linezolid, isoniazid, streptomycin, chlorpropamide
(Diabinese), infliximab, and various ergot preparations.
בן 62 שם לב לירידה בחדות הראיה בעין שמאל. שולל כאבים בהנעת העין, שולל כאב ראש. בבדיקה
חדות הראיה 06/30 משמאל ו- 6/7 מימין . חסר בשדה הראיה התחתון בעין שמאל
RAPD חיובי משמאל,
הדיסקה בעין שמאל תפוחה עם גודש של כלי הדם.
שקיעת דם 15 ו CRP . 0.5
מה הסיבה לאובדן הראיה בעין שמאל ?
א. Retrobulbar optic neuritis
ב. Branch retinal artery occlusion
ג. Acute ischemic optic neuropathy
ד. Papilledema
AION
סיבות לקטרקט
Idiopathic
Diabetic
Galactasemia
Hypoparathyroidism
Corticosteroids
Radiation
Downs syndrome
Oculocerebrorenal syndrome
Spinocerebellar ataxia with oligophrenia
Atopic dermatitis
Ichthyosis
Myotonic dystrophy
Wilson’s
Usher syndrome Pelizaeus Merzbacher disease
Cerebrohepatorenal disease
Aspartylglycosaminuria
Cockayne syndrome
CTX – cerebrotendinous xanthomatosis
Fabry
NFT2
Congenital Rubella
Refsum
Quetiapine
מהי
Achromatopsia
Achromatopsia – עוורון צבעים נרכש
Bilateral Occipitalנגרם בגלל פגיעה ב-
Acquired color blindness caused by a cerebral lesion, with retention of form vision, is referred to as central achromatopsia . Here the disturbance is one of hue discrimination; the patient cannot sort a series of colored wools according to hue (Holmgren test) and may complain that colors have lost their brightness or that everything looks gray. involvement of the inferomedial occipital, and temporal lobe(s) and the lower part of the striate cortex or optic radiation
מהי VISUAL AGNOSIA
In distinction to these forms of blindness, there is a less-common category of visual impairment in which the patient cannot understand the meaning of what he sees, i.e., visual agnosia. Primary visual perception is more or less intact, and the patient may accurately describe the shape, color, and size of objects and draw copies of them. Despite this, he cannot identify the objects unless he hears, smells, tastes, or palpates them. The failure of visual recognition of words alone is called visual verbal agnosia, or alexia. Visual-object agnosia rarely occurs as an isolated finding: as a rule, it is combined with visual verbal agnosia, homonymous hemianopia, or both.
These abnormalities arise from lesions of the dominant occipital cortex and adjacent temporal and parietal cortex (angular gyrus) or from a lesion of the left calcarine cortex combined with one that interrupts the fibers crossing from the right occipital lobe (see Fig. 22-6). In the latter case, fibers responsible for writing are spared, and the patient remains with a syndrome of alexia without agraphia
visual object agnosia is usually associated with visual verbal agnosia (alexia) and homonymous hemianopia. Prosopagnosia is also present in most cases.
The underlying lesions are usually bilateral, although also reported with a restricted lesion of the left occipitotemporal region (by MRI).
bitemporal hemianopsia
**The optic chiasm lies just above the pituitary gland and
also forms part of the anterior wall of the third ventricle;
hence the crossing fibers may be compressed from below
by a pituitary tumor, a meningioma of the tuberculum
sellae, or an aneurysm, and from above by a dilated third
ventricle or craniopharyngioma.
The resulting field defect is bitemporal (“bitemporal hemianopia”);
If the lesion has an anterior extension to the junction with
one optic nerve there is a loss of full-field vision in that
eye and a partial loss in the other (“functional scotoma”).
Optic tract lesions are relatively rare and cause a full contralateral
hemianopia
מה יגרום לכל אחת מהפרעות הראייה שבתמונה?
A. Complete blindness in left eye
from an optic nerve lesion.
B. A left “junctional scotoma” with vision loss in the left eye coupled with a superotemporal defect in the right eye.
C. Chiasmatic lesion causing bitemporal hemianopia.
D. Right homonymous hemianopia from optic tract lesion.
E and F. Right superior and inferior quadrant hemianopia from interruption of visual radiations.
G. Right homonymous hemianopia caused by lesion of occipital striate cortex.
H. Hemianopia with macular sparing, typically from posterior cerebral artery infarction.
טמפורלי
Pie in the sky
מהו המסלול שהאינפורמציה הראייתית מבצעת לאחר הכיאזמה?
Optic tract – 80% of fibers terminate in LGB – a thalamic nucleus
Synapse with the six laminae of its neurons – crossed nasal fibers synapse on laminae
1,4,6 – dorsal nuclei
2,3,5 – uncrossed temporal fibers from ipsilateral eye.
Occlusion of blood to LGN (anterior and posterior choroidal arteries) causes a multiple sectoral field defect.
Other fibers terminate in pretectum nuclei (Edinger Westphal) and in suprachiasmatic nuclei of hypothalamus (circadian rhythms)
The fibers course through the temporal lobes –
Fibers from lower and upper quadrants diverge -
Lower ones around anterior pole of temporal horn of lateral ventricle and then turn posteriorly, the other more direct through white matter of uppermost part of temporal lobe.
Wilbrand’s knee:
Wilbrand’s knee:
Lesions at the junction of the
optic nerve and chiasm,
AKA Wilbrand’s knee: Inferonasal fibres of the optic nerve which go into the contralateral optic nerve 4 mm before crossing over to the opposite optic tract.
generally compressive in nature,
may cause a small contralateral superotemporal quadrantic
defect in addition to the expected central scotoma
in the ipsilateral eye (“junctional scotoma”). The finding is explained by the compression of the tract and the nerve on the same side
יכול להגרם גם בגלל אדנומה היפופיזרית
under what conditions is the patient with homonymous hemianopia still able to see and function?
a. macular sparing
b. temporal cresent
If the entire optic tract or calcarine cortex on one side
is destroyed, the homonymous hemianopia is complete.
But often that part of the field subserved by the macula is spared, i.e., there is a 5- to 10-degree island of vision around the fixation point on the side of the hemianopia (sparing of fixation, or macular sparing). With infarction of the occipital lobe as a result of occlusion of the posterior
cerebral artery, the macular region, represented in the most posterior part of the striate cortex, may be spared by virtue of collateral circulation from branches of the
middle cerebral artery.
In yet other instances of complete homonymous hemianopia,** the patient may be little disabled by visual field loss**. This is because of preservation of vision in a small monocular part of the visual field known as the temporal crescent. The latter is a peripheral unpaired portion of the visual field, between 60 and 100 degrees from the fixation point, and is represented in the most anterior part of the visual striate cortex. In particular, the
temporal crescent is sensitive to moving stimuli, allowing the patient to avoid collisions with people and objects.
הפרעה לא אורגנית!
Marked constriction of the visual fields of unvarying degree, regardless of the distance of the
visual stimulus from the eye (“gun-barrel” or “tunnel” vision), however, is a sign of hysteria.
With organic disease, the constricted visual field naturally enlarges as the
distance between the patient and the test object increases.
Table 12-2
CAUSES OF OPTIC DISC SWELLING
בת 72, סוכרת, HTN, במיון עקב טשטוש ראיה עין שמאל. בבדיקת חדות ראיה 6/9. בקרקעית העין משמאל (תמונה……) אבחנה סבירה:
Retinal Vein Occlusion
The veins are engorged and tortuous, and there are multiple diffuse “dot-and blot” and streaky linear retinal hemorrhages.
Retinal vein thrombosis is observed most frequently with diabetes mellitus, hypertension, and leukemia; less
frequently with sickle cell disease; and rarely with multiple myeloma, and Waldenstrom macroglobulinemia in relation to the hyperviscosity that these two diseases
cause. Sometimes, no associated systemic disease can be identified, in which case the possibility of an orbital mass (e.g., optic nerve glioma) should always be considered. In
retinal vein thrombosis, visual loss is variable and there may be recovery of useful vision.
מה הגורם לתמונה הבאה?
Hollenhorst plaques-
glistening, white-yellow atheromatous particle as a cause of CRAO
CRAO
Most often, ischemia of the retina can be traced to occlusion of the central retinal artery or its branches by thrombi or emboli - Central
retinal artery occlusion (abbreviated CRAO). Occlusion is attended by sudden painless blindness. The retina becomes opaque and has a gray-yellow appearance; the arterioles are narrowed, with segmentation of columns of blood and a cherry-red appearance of the fovea
one may be able to see the occluding material.
Most frequently observed are Hollenhorst plaques- glistening, white-yellow atheromatous Particles seen in 40 of 70 cases of retinal embolism but are as often an asymptomatic manifestation of carotid or aortic atherosclerosis. The particles may alternatively
have the appearance white calcium from calcified aortic or mitral valves or atheroma of the great vessels, and red or white fibrin-platelet emboli from a number of sources, mostly undefined, or perhaps from the heart or its valves.
Emboli to retinal artery branches may be difficult to see without fluorescein retinography; furthermore, most of these emboli soon disappear.
** Central and branch retinal artery occlusions also occur as a consequence of hypercoaguable states, including anti-phospholipid antibody syndrome. Central retinal artery occlusion also occurs as a consequence of giant cell arteritis;** patients who are in their 50s or older should be screened for this condition.
treatments are generally aimed at lowering intraocular pressure (acetazolamide, inhalation of carbon dioxide;
paracentesis of the anterior chamber, ballottement), to dilate the vessels, and reestablish flow
Altitudinal defect
(NAION/AION)
In persons older than 50 years of age, ischemic infarction of the optic nerve head is the most common cause of a persistent monocular loss of vision. The onset is abrupt and painless, but on occasion the visual loss is progressive for several days. The field defect is often altitudinal and involves the area of central fixation, accounting for a severe loss of acuity. Swelling of the optic disc, extending for a short distance beyond the disc margin,
and associated small, flame-shaped hemorrhages, is typical;
A relationship has been observed between ischemic optic neuropathy and the use of nitric oxide inhibitors, such as sildenafil, for erectile dysfunction. The visual loss has occurred within 24 h of taking the drug and is usually unilateral.
As to the pathogenesis of nonarteritic anterior ischemic optic neuropathy, it has been attributed to insufficiency of the posterior ciliary artery circulation and more specifically to occlusion of the branches of the peripapillary choroidal arterial system. A “crowded” optic disc, with small cup-to-disc ratio, is a risk factor. Most cases occur on a background of hypertensive vascular disease and diabetes, Nocturnal hypotension may be a contributing factor, and patients are often counseled to avoid medications that could cause the blood pressure to decline overnight. Nonarteritic anterior ischemic optic neuropathy may also complicate intraocular surgery.
Massive blood loss or intraoperative hypotension,
particularly in association with the use of cardiac surgery with a bypass pump, may also produce visual loss, and ischemic infarction of the retina and optic nerve.
A remarkable unilateral or bilateral optic neuropathy, which we have observed and which is also presumably ischemic in nature, occurs after prolonged laminectomy Operations that are performed with the patient in the prone position. Obese individuals and those with small optic cups are seemingly at risk for this complication.
Some recovery is possible after many weeks but most patients remain blind from infarction of the optic nerve heads.
Blood loss of greater than 1 L, and surgery longer than 6 hours seem to be common to most cases.
Temporal, or giant cell, arteritis is another important cause of AION or NAION
A monocular altitudinal hemianopia, is almost invariably an ischemic optic neuropathy that arises from occlusion of the posterior ciliary vessels
- AION/NAOIN – caused by ischaemic infarction of the optic nerve head. disease of posterior ciliary vessels –field defect is often altitudinal. Swelling of optic disc along with associated flame-shaped haemorrhages is typical.
- CRVO: veins engorged and tortuous, multiple dot and blot hemorrhages. Associated with hyperviscosity, DM, HTN, Leukemia. Visual loss variable.
- CRAO: sudden painless blindness. Retina opaque with gray-yellow appearance, cherry red fovea, Hollenhurst plaques.
- Opthalmic artery – divides into the Central Retinal Artery and posteiror ciliary artery – therefore occlusion will cause diffuse visual loss
פפיליטיס
The optic disc and retina appear normal in the majority of cases, in which the condition is of the more common retrobulbar variety. However, if the inflammation is near the nerve head, there is swelling of the disc (papillitis) The disc margins are then seen to be elevated, blurred, and, rarely, surrounded by hemorrhages. Inflammatory sheathing of the retinal veins, as described by Rucker, is known to occur but has been uncommon in our patients. In extreme cases, edema may suffuse from the disc to cause a rippling in the adjacent retina.
כרטיסיית מידע ללא שאלה
פלקווניל הוא היחד שלא רשום כעשוי להחמיר אופטיק נויריטיס.
In contrast, the subacute development of central field defects is attributable to toxins and other prescribed therapeutic agents, notably ethambutol, linezolid, isoniazid, streptomycin, chloramphenicol, methotrexate, and chlorpropamide. Infliximab and other TNF-alpha blocking medications can occasionally precipitate optic neuritis and other demyelinating syndromes of the central or peripheral nervous system.
איך עלולה להגרם פגיעה בראייה בעקבות תהליכים בקוורנוס סינוס?
בת 16 עם ירידה בראייה.
בפונדוס נראת התמונה הבאה:
מה האבחנה?
Neuroretinitis is a rare post- or parainfectious process seen mostly in children and young adults, sometimes in association with exposure to the Bartonella henselae bacteria
the cause of cat scratch fever. Papillitis is accompanied by macular edema and exudates situated radially in the Henle layer, producing a “macular star“ appearance.
מהו המסלול שמבצע המידע הויזואלי המתקבל ברשתית עד הגעתו לאונה האוקסיפיטלית?
The axons of ganglion cells are collected in the optic discs and then pass uninterruptedly through the optic nerves, optic chiasm, and optic tracts to synapse in the lateral geniculate
nuclei, the superior colliculi, the midbrain pretectum and the suprachiasmatic nucleus of the hypothalamus.
Approximately 80 percent of the fibers of the optic tract terminate in the lateral geniculate body, a thalamic nucleus, and synapse with the six laminae of its neurons.
Three of these laminae (1, 4, 6), which constitute the large dorsal nucleus, receive crossed (nasal) fibers from the contralateral eye, and three (2, 3, 5) receive uncrossed (temporal) fibers from the ipsilateral eye. Selective occlusion
of either component of the dual blood supply to the lateral geniculate, consisting of the anterior and posterior choroidal arteries, is infrequent but when it does occur, produces a characteristic “multiple sectoral field defect”; a quadruple sectoranopia, meaning homonymous sectoral defects in the upper and lower quadrants of both eyesdue to occlusion of the anterior choroidal artery, and two horizontal sectoranopias with occlusion of the posterior (lateral) choroidal artery.
Other optic tract fibers terminate in the pretectum and innervate both Edinger-Westphal nuclei, which subserve pupillary constriction and accommodation (see
Fig. 14-8). A small group of fibers terminate in the suprachiasmatic nuclei in animals and presumably also in humans. These anatomic details explain several useful clinical signs. If there is a lesion in one optic nerve, a light stimulus to the affected eye will have no effect on the pupil of either eye, although the ipsilateral pupil will still constrict consensually, i.e., in response to a light stimulus from the normal eye. (Tilis phenomenon is termed an afferent pupillary defect.)
In their course through the temporal lobes, the fibers from the lower and upper quadrants of each retina diverge. The lower ones arch around the anterior pole of the temporal horn of the lateral ventricle before turning Posteriorly; the upper ones follow a more direct path through the white matter of the uppermost part of the
temporal lobe (Fig. 13-4), and probably of the adjacent interior parietal lobe. Both groups of fibers merge posteriorly at the internal sagittal stratum. For these reasons incomplete lesions of the geniculocalcarine pathways (optic radiations) cause visual field defects that are partial and often not fully congruent.
מה תהיה ההפרעה הצפויה בשדה הראייה של מטופל עם פגיעה ב
anterior & posterior choroidal arteries?
Approximately 80 percent of the fibers of the optic
tract terminate in the lateral geniculate body, a thalamic nucleus, and synapse with the six laminae of its neurons.
Three of these laminae (1, 4, 6), which constitute the large dorsal nucleus, receive crossed (nasal) fibers from the contralateral eye, and three (2, 3, 5) receive uncrossed (temporal) fibers from the ipsilateral eye. Selective occlusion
of either component of the dual blood supply to the lateral geniculate, consisting of the anterior and posterior choroidal arteries, is infrequent but when it does occur, produces a characteristic “multiple sectoral field defect”; a quadruple sectoranopia, meaning homonymous sectoral defects in the upper and lower quadrants of both eyes
due to occlusion of the anterior choroidal artery, and two horizontal sectoranopias with occlusion of the posterior (lateral) choroidal artery
היכן מסתיימים האקסונים שיוצאים מהרטינה מתאי הגנגליון?
1. גרעין אדינגר-ווסטפהל ומדיאל ג’ניקולייט בודי
2. לטרל ג׳ניקולייט בודי וסופריור קוליקולוס
3. קורטקס calcarine
Lateral geniculate body and superior colliculus
The axons of ganglion cells are collected in the optic discs and then pass uninterruptedly through the optic nerves, optic chiasm, and optic tracts to synapse in the lateral geniculate
nuclei, the superior colliculi, the midbrain pretectum and the suprachiasmatic nucleus of the hypothalamus.
Approximately 80 percent of the fibers of the optic tract terminate in the lateral geniculate body, a thalamic nucleus, and synapse with the six laminae of its neurons.
Three of these laminae (1, 4, 6), which constitute the large dorsal nucleus, receive crossed (nasal) fibers from the contralateral eye, and three (2, 3, 5) receive uncrossed (temporal) fibers from the ipsilateral eye. Selective occlusion
of either component of the dual blood supply to the lateral geniculate, consisting of the anterior and posterior choroidal arteries, is infrequent but when it does occur, produces a characteristic “multiple sectoral field defect”; a quadruple sectoranopia, meaning homonymous sectoral defects in the upper and lower quadrants of both eyesdue to occlusion of the anterior choroidal artery, and two horizontal sectoranopias with occlusion of the posterior (lateral) choroidal artery.
Other optic tract fibers terminate in the pretectum and innervate both Edinger-Westphal nuclei, which subserve pupillary constriction and accommodation (see
Fig. 14-8). A small group of fibers terminate in the suprachiasmatic nuclei in animals and presumably also in humans. These anatomic details explain several useful clinical signs. If there is a lesion in one optic nerve, a light stimulus to the affected eye will have no effect on the pupil of either eye, although the ipsilateral pupil will still constrict consensually, i.e., in response to a light stimulus from the normal eye. (Tilis phenomenon is termed an afferent pupillary defect.)
In their course through the temporal lobes, the fibers from the lower and upper quadrants of each retina diverge. The lower ones arch around the anterior pole of the temporal horn of the lateral ventricle before turning Posteriorly; the upper ones follow a more direct path through the white matter of the uppermost part of the
temporal lobe (Fig. 13-4), and probably of the adjacent interior parietal lobe. Both groups of fibers merge posteriorly at the internal sagittal stratum. For these reasons incomplete lesions of the geniculocalcarine pathways (optic radiations) cause visual field defects that are partial and often not fully congruent.
Table 12-1
CAUSES OF EPISODIC VISUAL LOSS
Figure 12-1. A. Conventional Snellen chart and B. Jaeger card for the estimation of visual acuity. The Snellen chart is placed 20 ft from the subject.
The Jaeger card is used at 16 in from the subject’s eyes and approximates Snellen acuity if convergence and accommodation are normal.
Figure 12-2. Diagram showing the effects on the fields of vision produced by lesions at various points along the optic pathway.
A. Complete blindness in left eye from an optic nerve lesion.
B. A left “junctional scotoma” with vision loss in the left eye coupled with a superotemporal
defect in the right eye.
C. Chiasmatic lesion causing bitemporal hemianopia.
D. Right homonymous hemianopia from optic tract lesion.
E and F. Right superior and inferior quadrant hemianopia from interruption of visual radiations.
G. Right homonymous hemianopia caused by lesion of occipital striate cortex.
H. Hemianopia with macular sparing, typically from posterior cerebral artery infarction.
Figure 12-3. Diagram of the cellular elements of the retina. Light entering the eye anteriorly passes through the full thickness of the retina to reach the rods and cones (first system of retinal neurons). Impulses arising in these cells are transmitted by the bipolar cells (second system of retinal neurons) to the ganglion cell layer. The third system of visual neurons consists of the ganglion cells and their axons, which run uninterruptedly through the optic nerve, chiasm, and optic tracts, synapsing with cells in the lateral geniculate body.
Figure 12-4. The geniculocalcarine projection, showing the detour of lower fibers around the temporal horn. Note that a very small proportion of the pathway traverses the parietal lobe.
Figure 12-5. Diagrammatic depiction of the retinal projections, showing the disproportionately large representation of the macula in the lateral geniculate nucleus and visual (striate) cortex.
Figure 12-6. Hypertensive retinopathy, showing optic disc edema, cotton wool spots, hard exudates, and intraretinal hemorrhages.
Figure 12-7. Preretinal (subhyaloid) hemorrhage extending through
the macular of the left eye, precipitated by strong Valsalva maneuvering.
Figure 12-8. Appearance of the fundus in central retinal artery occlusion. In addition to the paucity of blood flow in retinal vessels, the retina has a creamy gray appearance, and there is a “cherry-red spot” at the fovea. (Courtesy of Dr. Shirley Wray.)
Figure 12-9. Glistening “Hollenhorst plaque” occlusion of a superior retinal artery branch (arrow). These occlusions represent atheromatous particles or, less often, platelet-fibrin emboli. Some are asymptomatic and others are associated with segmental visual loss or are seen after central retinal artery occlusion. (Courtesy of Dr. Shirley Wray.)
Figure 12-10. Occlusion of the central retinal vein with suffusion of the veins, swelling of the disc, and florid retinal hemorrhages. (Courtesy
of Dr. Shirley Wray.)
Figure 12-11. Mild papilledema with hyperemia of the disc and slight blurring of the disc margins. (Courtesy of Dr. Shirley Wray.)
Figure 12-13. Chronic papilledema with beginning optic atrophy, in which the disc stands out like a champagne cork. The hemorrhages and exudates have been absorbed, leaving a glistening residue around the disc. (Courtesy of Dr. Shirley Wray.)
Figure 12-12. Fully developed papilledema. The main characteristics are marked swelling and enlargement of the disc, vascular engorgement, obscuration of small vessels at the disc margin as a result of nerve-fiber edema, and white “cotton-wool spots” that represent superficial infarcts of the nerve-fiber layer. (Courtesy of Dr. Shirley Wray.)
Figure 12-14. Acute optic neuritis. Right, The disc is mildly swollen from an inflammatory process near the nerve head (papillitis). Left, MRI of the orbits with fat-saturation shows pathologic contrast enhancement of the right optic nerve.
Figure 12-15. Nonarteritic anterior ischemic optic neuropathy (NAION) related to hypertension and diabetes. There is diffuse disc swelling from infarction that extends into the retina as a milky edema. The veins are engorged. “Cotton-wool” infarcts can be seen to the left of the disc and a “flame” hemorrhage extends from the right disc margin.
