The Wesson Fixation Disparity Card© can be used to
measure Fixation Disparity or Accommodative Lag. The Card yields clinically
accurate estimates of several key parameters involved in measurements of these
functions. Testing is quick and extensive use has shown the results to be
reliable over time.
Fixation disparity is a compensatory mechanism between
fusional or disparity vergence and its relationship with the underlying phoric
posture. Fixational disparity is sometimes called Retinal Slip and is measured
in minutes of arc. The associated phoria is measured in prism diopters.
Fixational disparity is not necessarily in the same direction as the phoric
posture and therefore should be measured independently of the dissociated
phoria. Fixation disparity cannot be measured using a prism to neutralize the
misalignment noted in an AO vectographic target or a Mallet unit. This neutral
point represents the associated phoria not the fixation disparity.
The Wesson Fixation Disparity Card© is used to measure
both horizontal and vertical disparity. With a set of loose prisms, the Card can
also be used to measure a forced vergence fixation disparity curve. Further, the
Card can be used for adults and pre-reader children to in the measurement of
Accommodative Lag using either the MEM method, the Nott method or the DOG
method. The reverse side provides a Gaussians waveform required for the DOG
method.
Kit includes polarized glasses. Hole are punched for
phoropter mounting. For use at 40 or 25 CM .
4624 Wesson Fixation Disparity Card
.......... $42.00
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