Strabismus - Fundamentals of Clinical Ophthalmology.pdf

ASSESSMENT OF STRABISMUS
(a)
Figure 6.9
The Worth 4-dot test for fusion
(b)
(c)
Figure 6.8 The 4 D base out prism test providing
supporting evidence of normal binocular vision.
When the prism is interposed to maintain binocular
vision, the eye subjected to the prism makes a
convergent movement while the other eye maintains
fixation
Bagolini striate glasses A test that comes
closest to the natural environment and testing in
free space is that using Bagolini lenses. The
lenses are striated with each eye at right angles to
the other, so a pinpoint of light will be seen as a
cross (Figure 6.10). As the test is done in free
space, the patient is aware of peripheral objects
surrounding the light which optimise the
association between the two eyes, allowing the
most natural environment for testing. In MFS,
the fovea of the non-dominant eye is suppressed
under non-binocular conditions. The cross is
seen because of peripheral fusion. The patient’s
interpretation of what is seen gives an indication
of the state of fusion. If the patients are mature
enough, they may be asked to draw what they
see and Figure 6.10 shows some of the more
common representations that the patient will
draw. In normal retinal correspondence, MFS
is a condition where there is suppression of one
fovea under binocular viewing. The condition
may be primary and without strabismus,
although it is more commonly associated with
a small angle strabismus which is usually
convergent but may be divergent.
Amblyoscope or synoptophore The use
of this instrument now figures less in orthoptic
practice than previously. It has value particularly
in large angle squint, giving some indication of
fusion and the capacity to build upon this.
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