VISION Flashcards
IN a snellen, The letter at the top of the chart subtends ________
at a distance of 200 ft
5 min of an arc
________ is reported as a nonmathematical fraction
that represents the patient’s ability compared to
that of a person with normal distance vision
Acuity
The clarity of these
media can be determined ophthalmoscopically, and a
complete examination requires that the pupil be dilated
to at least ________ in diameter. This is accomplished by
instilling two drops of _____________ in each eye after the
visual acuity has been measured,
6 mm
- 5 percent phenylephrine and/ or
- 5 to 1.0 percent tropicarnide
Rarely, an attack of __________
(manifesting itself by diminished vision, ocular pain,
nausea, and vomiting) may be precipitated by pharmacologic
pupillary dilatation
angle-closure glaucoma
The rod cells
contain ____________ a conjugated protein in which the
chromophore group is a carotenoid akin to vitamin A.
rhodopsin,
The rods function in the perception of visual stimuli in
subdued light___________ and the cones
are responsible for color discrimination and the perception
of stimuli in bright light ____________
(twilight or scotopic vision),
(photopic vision).
The fibers derived from macular cells
form a discrete bundle that first occupies the _________of the disc and optic nerve and then assumes a more
_____________within the nerve (papillomacular bundle).
temporal side
central position
Damage to the papillomacular
bundle produces the ____________(extending
from fixation to the blind spot).
“cecocentral” scotoma
Lesions at the junction of the
optic nerve and chiasm, 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
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”).
___________, there is an abnormality
of chiasmatic decussation, in which a majority of the fibers
cross to the other side
In albinism
Approximately __________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
80 percent
Three of these laminae (1, 4, 6), which constitute the large
dorsal nucleus, __________, and three (2, 3, 5) receive ___________
receive crossed (nasal) fibers from the contralateral eye
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
Other optic tract fibers terminate in the pretectum
and innervate both Edinger-Westphal nuclei, which subserve
__________
pupillary constriction and accommodation
A small group of fibers terminate in the ____________in animals and presumably also in
humans.
suprachiasmatic
nuclei
It supplies the inner retinal layers and issues
from the optic disc, where it divides into four branches,
each of which supplies a quadrant of the retina; it is these
vessels and their branches that are visible by ophthalmoscopy.
central
retinal artery
In up to a third of the population, a small cilioretinal artery may arise from
either the_________
and supply the macula
choroidal circulation or from the circle of ZinnHaller
It must be made clear, however, that an ophthalmoscopic appearance identical to that of papilledema can be
produced by____________ and by
___________
infarction of the optic nerve head (the “papillopathy” of anterior ischemic optic neuropathy).
inflammatory changes in the intraorbital portion of the
optic nerve ("papillitis", a form of optic neuritis).
In its mildest form, papilledema appears as slight
elevation of the disc and blurring of the disc margins,
especially of the________ and a mild
fullness of the veins in the disc.
superior and inferior aspects,
Because many normal individuals,
especially those with _______, have ill-defined disc margins, the early stage of papilledema may be difficult
to detect
hypermetropia
On the other hand, the presence of spontaneous venous pulsations is a reliable indicator of an
intracranial pressure below______and thus usually
excludes papilledema
200 mm H20,
More severe degrees of papilledema appear as further
elevation, or _______ of the entire disc and
surrounding retina
“mushrooming”
Purely unilateral edema of the optic disc
is indicative of a_________, but it can sometimes occur at
an early stage of increased intracranial pressure.
perioptic meningioma or other tumor
involving the optic nerve
______, while it may enlarge the blind
spot slightly, does not greatly affect visual acuity
Acute papilledema
Chronic or recurrent papilledema
may result in ________and cause a reduction
in visual acuity by that mechanism.
optic atrophy
_______
which occurs when papillitis in one eye occurs years after
an optic neuropathy of the opposite one.
“pseudo-Foster Kennedy syndrome,”
Papilledema caused by increased intracranial pressure
cannot be distinguished from combined edema of the optic
nerve and retina, which typifies _____
malignant hypertension.
Chronic papilledema, as occurs in ________ presents a special problem in diagnosis,
and represents a risk for permanent reduction in visual
acuity from secondary optic atrophy.
pseudotumor cerebri
The essential element in the pathogenesis of papilledema
is an_______
increase in pressure in the sheaths surrounding
the optic nerves, which communicate directly with
the subarachnoid space of the brain
Other causes of papilledema are cyanotic _______
congenital
heart disease, and other forms of polycythemia, hypocalcemia
though an obscure mechanism, and POEMS
The optic nerves, which constitute the axonic projections
of the retinal ganglion cells to the lateral geniculate bodies
and superior colliculi can be inspected in _________
the optic nerve
head.
This inflammatory process causes unilateral acute impairment
of vision that may appear in one or both eyes, either
simultaneously or successively.
O ptic N e u ritis ( P a p i l l itis; Retro b u l ba r N e u ritis)
papillitis is associated with marked impairment of
________ thus distinguishing it from the acute
papilledema of increased intracranial pressure
vision and a central scotoma that encompasses the blind
spot (cecocentral),
In optic neuritis, the patient may report an increase
in blurring of vision with exertion or with exposure to
heat (_________
Uhthoff phenomenon
steroids in optic neuritis
In one frequently cited study, the oral administration
of these drugs increased the frequency of a relapse
of optic neuritis so that intravenous agents are used
instead
As time progresses, more than half of adults with
optic neuritis will develop other symptoms and signs of
multiple sclerosis, ______
usually within 5 years,
Optic
neuritis is a main component of neuromyelitis optica
(Devic disease; see Chap. 36); the prognosis for recovery
is generally _______ than for optic neuritis
poorer
in ON, __________ as a
result, this test is a highly sensitive indicator of previous,
even asymptomatic, episodes of optic neuritis.
The pattern-
shift visual evoked potential becomes delayed;
__________, a maternally
inherited mitochondrial disorder, is an infrequent but
important cause of blindness in children and younger
adults because it may simulate the more common inflammatory
optic neuropathies, even at times causing a
relatively abrupt onset of visual loss followed by some
degree of recovery
Leber hereditary optic neuropathy
_______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.
Neuroretinitis
In persons older than 5 0 years o f age, ___________ is the most common cause of a persistent
monocular loss of vision
ischemic infarction
of the optic nerve head
In AION, The field defect is often ______
and involves the area of central fixation, accounting
for a severe loss of acuity.
altitudinal
arteritic
and non-arteritic forms of ischemic optic neuropathy
are distinguished, the former being the result of______
temporal
(giant cell) arteritis.
As to the pathogenesis of non-arteritic ischemic optic neuropathy, the usual (anterior) form has been
attributed by Hayreh to ischemia in the __________ and more specifically to occlusion of
the branches of the ___________
posterior ciliary artery circulation
peripapillary choroidal arterial system.
A relationship has been observed between ischemic
optic neuropathy and the use of _____
The visual loss
has occurred within__________h of taking the drug and is usually
unilatera
nitric oxide inhibitors,
such as sildenafil, for erectile dysfunction
24
________ may also produce visual
loss, and ischemic infarction of the retina and optic nerve.
Massive blood loss or intraoperative hypotension,
particularly in association with the use of cardiac
surgery with a bypass pump,
A remarkable unilateral or bilateral optic neuropathy,
which we have observed and which is also presumably
ischemic in nature, occurs after prolonged __________
operations that are performed with the patient in the
_______
laminectomy
prone position.
Similarly, optic and oculomotor disorders may rarely
complicate ethmoid or sphenoid sinus infections. Severe
__________ or
bacterial infection is the usual setting for these complications.
diabetes with mucormycosis or other invasive fungal
An otherwise ________
may cause a compressive optic neuropathy, usually with
accompanying ophthalmoparesis and slight proptosis
benign sphenoidal mucocele
it is caused by the toxic effects of
tobacco or alcohol or both.Impairment of visual acuity evolves over several days
or a week or two, and examination discloses bilateral,
roughly ____________, the
peripheral fields being intact
symmetrical central or centrocecal scotomas
Impairment of vision because of__________ is abrupt in onset and characterized by
____________as well as symptoms
of acidosis.
methyl alcohol intoxication methanol
large symmetrical central scotomas
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
Congenital cavitary defects because of defective closure
of the optic fissure may be a cause of impaired vision
because of failure of development ________
of the papillomacular
bundle
Of particular importance is the optic nerve glioma
that occurs in ________ with type I von
Recklinghausen neurofibromatosis
15 percent of patients
In RT induced damage of the ON, These complications followed the use of
more than _______of radiation (see Jiang et al) .
Radiation-induced optic neuropathy is typically delayed, occurring at an average of _____________
exposure, and is often accompanied by enhancement of
the nerve on MRI.
50 Gy (5,000 rad)
18 months after radiation
________ are more sensitive than white ones
in detecting defects of the visual pathways.
red-green test objects
moving targets are less useful than static
ones in _______
confrontational testing of visual fields
Similarly, a _________may be defined by asking the patient to report
changes in color or brightness of a red test object as it
is moved toward or away from the point of fixation
scotoma
Similarly, a ________may be identified by having
the patient fix with one eye on the examiner ‘s nose, on
which the examiner places the index finger of one hand
or a white-headed pin and has the patient compare it for
brightness, clarity, and color with a finger or pin held in
the periphery.
central scotoma
This may be a result
of severe papilledema, in which case it is usually accompanied
by an enlargement of the blind spot
concentric constriction
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
The cecocentral scotoma, which
tends to have an arcuate border, represents a lesion that
is predominantly in the distribution of the ___________
papillomacular
bundle.
_________ is characterized by unilateral or asymmetrical
bilateral scotomas.
Demyelinating
disease
Vascular lesions that take the form
of retinal hemorrhages or infarctions of the nerve-fiber
layer (cotton-wool patches) give rise to ______
unilateral scotomas;
Bitemporal hemianopia indicates a lesion of the
___________ and is caused most
often by the suprasellar extension of a tumor of the pituitary
gland
decussating fibers of the optic chiasm
Chiasmal syndromes from causes other than pituitary
adenoma are usually associated with _________
unilateral optic disc
atrophy, a relative afferent pupillary defect and a greater
defect in the inferior field
Incomplete homonymous
hemianopia has more localizing value. As a rule, if
the field defects in the two eyes are identical (congruous),
the lesion is likely to be in the ____________ if they are
incongruous, the visual fibers in the __________are more likely to be implicated
calcarine cortex and
subcortical white matter of the occipital lobe;
optic tract or in the
parietal or temporal lobe
The lower fibers of the geniculocalcarine pathway
(from the inferior retinas) swing in a wide arc over the
temporal hom of the lateral ventricle and then proceed
posteriorly to join the upper fibers of the pathway on their
way to the calcarine cortex.
This arc of fibers is
known variously as the ________
loop, and a lesion that interrupts these fibers will produce
a ____________
Flechsig, Meyer, or Archambault
superior homonymous quadrantanopia
if all the calcarine
cortex or all the subcortical geniculocalcarine fibers on
both sides are completely destroyed, the bilateral hemianopias
cause cerebral, _______
or “cortical, “ blindness
An __________is one that is confined by a
horizontal border and crosses the vertical meridian.
altitudinal defect
Herniation
of the occipital lobe over the tentorial margin can produce
a homonymous superior altitudinal defect by selectively
compressing the ______
inferior branches of the posterior
cerebral arteries.
Complete feigned blindness
is disproved by observing the normal ______________or strip,
or by noting that the patient’s eyes follow their own
image in a mirror that is moved in front of them.
ocular jerk movements
in response to a rotating optokinetic drum
Hysterical monocular loss may also
be revealed by the use of____________with red and green letters, where each eye can only
see letters with the color of its lens.
red-green glasses and an acuity
chart
Failure to understand the meaning of an entire picture
even though some of its parts are recognized is referred to
as simultanagnosia, and is found in bilateral lesions of the
____________
occipital-parietal junction
_________, a persistence
of repetitive afterimages, similar to the appearance of a
celluloid movie strip, occurs with right parietooccipital
lesions;
Palinopsia
Normal color vision depends on the integrity of cone
cells, which are most numerous in the _________
macular region
