Optometric Terms 3 Flashcards
MFBF
monocular fixation in a binocular field: used frequently in amblyopia therapy, it is a created situation where both eyes receive the peripheral info, while the amblyopic eye is presented with a detailed, central task that it alone can perceive
MFBF is used as a “bridge” between
monocular and binocular activities and is used to override the tendency of the “good eye” to exert active cortical inhibition over the amblyopic eye
myopia
“nearsightedness” condition in which in the uncorrected eye, light rays come to point focus in front of the retina
myopia is compensated for by
minus lenses
nasal
towards the nose
NPC
near point convergence: closest point that an object of regard can be moved toward the nose without loss of fusion
neglect
(visual neglect, hemispatial agnosia, visual/spatial neglect, or semi-imperception)
caused by: injury from a stroke or other trauma, neglect is a passive unconscious decreased awareness of part of the field of view or other stimuli to one side of the body
usually occurs with a visual field defect, but may occur in absence of field loss
a person with field loss
would be aware of the area of loss and like to make compensations
a person with visual neglect and field loss
unconsciously neglect the area of the field loss and be less likely to compensate for the defect
damage to the right side of the brain may cause both
visual field loss and visual neglect to the left side
how does right brain injury neglect compare to left?
usually more severe
most common site for visual neglect is
parietal lobe, but damage to frontal lobe and even deeper structures (thalamus and basal ganglia) may cause it
noncomitant
(incomitant) in strabismus the condition in which the angle of deviation is not constant, but varies according to position of gaze
causes for noncomitant
this may be due to paralysis of one or more of the extra-ocular muscles, or from scar tissues after surgery
nystagmus
refers to rapid involuntary movements of the eyes that may be from side to side (Horizontal nystagmus), up and down (vertical nystagmus) or rotary
optic nerve
part of the nervous system that transmits the impulses of sight from the retina along the visual pathways
how many branches of the optic nerve are there
11 currently known
OKN
optokinetic nystagmus: based on the principle that the eyes tend to follow or track the motion of one element at a time in a steadily moving display
as the tracked element moves out of sight, the eyes will “snap back” to fixate and follow another one
OKN in infant
sub cortically-mediated function is present at about five days after birth
can be used as an objective measure of an infant’s ability to see detail in a moving stimulus, such as a bar grating or OKN drum
the absence of an OKN response suggests that the infant may not perceive the elements of the moving target as separate
organic
caused by a pathological or anatomical problem
orthophoria
condition in which the position of the eyes is not changed when binocularity is broken or interrupted as during an alternate cover test
the doctor will see no movement upon removing the occluder
paired cranial nerves
12 pairs of nerves emanate from the nervous tissue of the brain
ultimately exit/enter the cranium through openings in the skull
motor components of the cranial nerves are derived from what? and control what (3 examples)
cells located in the brain that send axons out of the cranium where they ultimately control:
1) muscle (e.g. eye movements)
2) glandular tissue (e.g. salivary glands)
3) specialized muscle (e.g., heart or stomach)
sensory components of cranial nerves originate from
collections of cells that are located outside the brain; these collections of nerve cells bodies are called sensory ganglia
cranial nerve I
olfactory
smell
cranial nerve II
optic
vision
cranial nerve III
oculomotor
eye movement and pupil dilation
cranial nerve IV
trochlear
innervates superior oblique, turns eye down and in
cranial nerve V
trigeminal
chewing
somatosensory info from the face & mouth
touch and pain
cranial nerve VI
abducens
moves eyes temporally
cranial nerve VII
facial
controls most facial expressions
secretion of tears & saliva
taste, somatosensory info from ear
cranial nerve VIII
vestibulocochlear (auditory)
hearing
equilibrium and balance
cranial nerve IX
glossopharyngeal
taste (posterior 1/3 of tongue)
somatosensory info from tongue, tonsils, pharynx;
controls some muscles used in swallowing
cranial nerve X
vagus
sensory motor, and autonomic functions of viscera (glands, digestion, heart)
cranial nerve XI
spinal accessory
controls trapezius & sternocleidomastoid
controls swallowing movements
controls muscles used in head movement