Strabismus - Fundamentals of Clinical Ophthalmology.pdf

STRABISMUS
Normal
R
L
Normal binocular
vision with bifoveal
fixation. Normal retinal
correspondence (NRC)
0° 15° 30° 45°
Monofixation
syndrome
R
L
Strabismus with
abnormal retinal
correspondence (ARC)
and suppression of left
macula when viewed
binocularly
45° 30°15° 0°
R
Exotropia with
diplopia
(normal retinal
correspondence)
Esotropia with
diplopia
(normal retinal
correspondence)
Suppression of
left eye
R
R
L
L
Strabismus with
normal macular
function and no
suppression
Strabismus and left
amblyopia without
ARC
Figure 6.11
The Hirschberg corneal light reflex test
Krimsky test
The Krimsky test uses a prism bar to equalise
the position of the light reflex from each eye; half
the number of prism dioptres of the deviation
equals magnitude of the deviation in degrees
(Figure 6.12).
Figure 6.10 Bagolini striated glasses consist of two
plano lenses (one for each eye) with parallel striations
for one eye set at right angles to the striations for the
other. The patient views a light at 6 m through the
glasses. If there is normal binocular vision the light is
perceived as two lines at right angles to each other
passing through the centre of each other. 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 binocular
conditions. The cross is seen because of peripheral
fusion
Motor evaluation – eye movements and
alignment
Hirschberg corneal light reflex test
Estimation of the corneal light reflex is one of
the simplest tests of ocular alignment. When
testing the corneal light reflex both the source of
light and the target should be held together. A
small nasal displacement of the corneal light
reflex is not uncommon in young children
(Figure 6.11).
Bruckner test
This test determines the presence of a
strabismus in the uncooperative child who may
not tolerate cover tests. A test light beam is held
at 1 m and the brightness of the red reflex in
each eye is compared. If the red reflex is brighter
in one eye than the other, then it is likely that
strabismus is present in the eye with the brighter
reflex. The disturbance of the accommodation
component of the near reflex raises a doubt that
the Bruckner test can be relied upon under
2 months of age. The reason lies in the smaller
pupil and poorer central vision in newborns who
have a greater depth of focus than adults, and as
accommodation does not need to be as exact,
this in turn affects the accuracy of the test. We
have found that it is useful after the age of 4
months but it has been argued that it is not
completely reliable until after 8 months. 9
15 D base out prism test
The 15 D base out prism test is a useful test
in infants. It stresses the binocular fusion by
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