Strabismus - Fundamentals of Clinical Ophthalmology.pdf

Glossary
AC:A ratio The ratio of accommodation
produced by convergence to the accommodation
measured in prism dioptres.
Amblyopia An acquired defect in monocular
vision due to disturbed binocular vision without
an underlying organic cause.
Angle kappa The angle between the line joining
the visual axis (the line between the fovea and
object of interest) and the mid-pupillary line.
Anomalous retinal correspondence Where
the fovea of one eye is paired with a non-foveal
part of the fellow deviated eye to acquire a
common visual direction.
Binocular single vision Using two eyes
simultaneously with bifoveal fixation to form a
common single precept.
Consecutive strabismus Refers to reversal of
direction of strabismus usually as a result of
surgery.
Diplopia and confusion Diplopia is the
simultaneous perception of two images of a
single object. Confusion is the simultaneous
appreciation of two superimposed images that
cannot be fused into a single precept.
Fusion Involves a sensory and a motor
component. There is integration of the two
dissimilar images from each eye into a single
precept, which is maintained through motor
responses involving the ocular muscles.
Head thrusting A feature of clinical motor
apraxia. The child unable to initiate saccade
maintains fixation on initial object of regard. To
break fixation the head is turned and the eyes are
dragged from object of regard to fresh object of
regard. To centre the gaze the head is turned
back in the opposite direction, completing the
appearance of head thrusting.
Monofixation syndrome A sensory monocular
status where there is an absence of bifoveal
central binocular fusion in the presence of
peripheral binocular fusion. The absence of
central fusion is associated with a central
scotoma in one eye during the act of binocular
viewing.
Near reflex A reflex where there is pupil
constriction and convergence linked to
accommodation.
Optokinetic mechanism Where the image of
the object of regard is held steady on the retina
during sustained head rotation.
Primary position of gaze The position of both
eyes looking straight ahead with the body and
head erect.
Saccade A refixation movement, bringing the
object of regard onto the fovea.
Smooth pursuit Holding the image of a
moving object on the fovea.
Stereopsis The binocular perception of depth.
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