Eccentric fixation, Investigation
• A uniocular condition in which some part of
retina other than fovea is used for fixation, but
in which the fovea retains its normal straight
ahead projection (in most of the cases). It may
be associated with a defect of central vision
caused by a stuctural lesion of fovea.
• Eccentric fixation can be present during both
monocular and binocular viewing conditions, but
it is best diagnosed under monocular viewing
conditions. This is important to keep in mind to
avoid confusion with anomalous correspondence.
• Anomalous correspondence is relevant only
during binocular fusion and must be measured in
• It is only shown when the better eye is covered
(Exception = microtropia with identity)
• Why is it important to know about eccentric
• For a long time it has been known that there is a
class of amblyopic patients with eccentric
• Such patients do not assume central fixation
when the fellow eye is covered; the amblyopic
eye remains more or less deviated.
• This observation assumed great importance
when subtle modification of the fixation behavior
had to be carefully monitored to chart the
progress during active (pleoptic) treatment of
• Most patients are examined and treated
regardless of their fixation behavior and
before they reach an age at which a reliable
diagnosis of eccentric fixation becomes
possible and this pose many tantalizing
questions and clinical problems.
• In a study published 40 years ago we found
eccentric fixation in 44% of 433 amblyopic
patients with strabismus.
• In anisometropic amblyopia, eccentric fixation
was encountered only rarely except in patients
• Recent data on the prevalence of eccentric
fixation are lacking and as we are seeing and
treating amblyopic patients at a much younger
age than before it is our impression that eccentric
fixation has become less frequent.
• Bangerter’s classification of fixation patterns
in amblyopia is as follows:
I. Central fixation
II. Eccentricfixation (nonfoveolar)
III. No fixation
Nonfoveolar fixation may be divided into a
number of classes, depending on the retinal
area with which the eye appears to fixate-
Parafoveolar (adjacent to the foveolar reflex),
Parafoveal (outside but close to the foveal wall)
Peripherally eccentric (somewhere between the edge of the
fovea and the disk and occasionally even beyond the disk)
• The general term eccentric, though logically
applicable to all nonfoveolar patterns of fixation,
is often restricted to peripheral fixation.
• Nonfoveolar fixation occurs not only with
horizontal but also with vertical eccentricity.
• Nonfoveolar fixation is not as precise as foveolar
fixation. Nonfoveolar fixation always covers an
area that is larger the farther it is from the fovea
• Successively repeated ophthalmoscopic
observations or, better yet, successive fundus
photographs show this very clearly.
Fixation photographs of three
amblyopic patients with
C, peripheral eccentric
Each circle represents a fixation
during which a photograph was
taken. The different fixation
locations on 9 to 12 consecutive
photographs were superimposed on
the photographs shown in this
figure. Note the increasingly greater
scatter with increasingly greater
eccentricity. All three patients had a
visual acuity of 6/60 despite the
great difference infixation
pattern. (From Noorden GK von,
Mackensen G: Phenomenology of
eccentricfixation. Am J Ophthalmol
• Central as well as nonfoveolarfixation may be steady or
wandering. Wandering fixation, which occurs only
upon covering the sound eye, must be distinguished
from the monocular, spontaneous, pendular, and
vertical oscillations that are occasionally found in
deeply amblyopic eyes.
• This condition has been designated as the Heimann
Bielschowsky phenomenon. It is clinically similar to
other forms of monocular nystagmus that may occur in
connection with a posterior fossa or brain stem
• Generally patients with esotropia, one would expect a
nasal eccentricity, and in patients with exotropia, a
temporal eccentricity offixation.
• There are, however, esotropic patients with temporal
eccentric fixation and exotropic patients with nasal
eccentric fixation (paradoxical fixation behavior).
• This type offixation occurs most frequently in patients
who have consecutive deviations following surgery; for
example, a formerly esotropic patient with long-
standing amblyopia becomes exotropic, or vice versa.
• Paradoxicalfixation may also appear as a
• Oppel noted that 15 out of 50 untreated
esotropic patients (30%) fixated temporally,
whereas von Noorden and Mackensen found 6
of 40 esotropic patients (15%) who fixated
temporally, but only two of these had not
been treated surgically.
• Grossly eccentric fixation is readily established by
holding a small light source in front of the patient’s
eyes in the midline of his head; the fixating eye is
covered, and the patient is asked to fixate the light
with the amblyopic eye. If the eye has grossly
eccentric fixation, it will make no movement of
redress, or perhaps only a small one, but the
reflection of the light will not be centered in the
Temporally decentered light reflex OS. Visual acuity OS: 5/200.B,
Light reflex. OS remains decentered when OD is occluded. C, Series
of fixation photographs of OS reveal fixation with a retinal area one
disk diameter nasal to the optic disk
• Corneal Reflex Test:
• Assuming that the angle lambda is the same in
both eyes, eccentric fixation can be obtained
by comparing the position of corneal
reflection of pentorch in amblyopic eye with
that of the fellow eye.
• Relative displacement of reflex by 1mm would
indicate the eccentric fixation of
• Project the ophthalmoscopic target onto the patients retina so that
it can be seen by the practitioner and its position judged in relation
to the retinal details.
• Dilated pupil may be necessary, as the opthalmoscopic light causes
puplillary constriction, also young patients accommodate about 4D
looking at near targets causing examiner view blurred. Larger pupil
increases field of view of examiner.
• With the fixating eye occluded the examiner observes the
amblyopic eye noting the point or area of retina upon which the
star is projected when the patient is attempting to look at the star
straight at it.
• If the point or area is eccentric to the fovea the patient is
asked whether the star is straight ahead or to one side of the
• If the patient sees the star straight ahead it
indicates that the spatial value of retina has been
centered at the eccentric point of fixation.
• If however the patient sees the star to one or the
other side of the light, it must be then asertained
whether the fovea has retained its straight ahead
• To do this the patient is instructed to try and look
directly at the star and see it straight ahead.
• This will result in a movement of the eye in an attemt
to fix with the fovea often accompanied by the
statement that star has dissapeared.
• This indicates that the normal spatial value of the fovea
has been maintained (Eccentric viewing).
• The centre of projection of the amblyoscopic eye may
also be discovered visiscopically whilst the patient has
both eyes open.
• He is asked to look at the star and try to see it straight
ahead . In order to do this the amblyopic eye may:
(1) maintain fixation with an eccentric point or
area, but this may not be the point of eccentric retinal
fixation and only represent the point or area of retina
where the greatest visual acuity is obtained.
(2) make a movement to take up fixation with
another point or area of the retina other than the
fovea thet is with the point of eccentric retinal fixation.
This point may be found to nasal to the fovea, whereas
the point of greatest visual acuity is temporal to the
(3) makes a movement to take up fixation foveally
• After Image Transfer Method:
• This test assumes that an after image in one eye will be
transferred to the normally corresponding point in the
• Photographic flash gun, masked to provide a bright
strip of light, produce line after image in the non
amblyopic eye while the amblyopic eye is occluded.
• The occluder is then changed to the other eye and
patient made to read snellen chart or any other small
• After a few seconds the after image appears have been
transferred at a cortical level to the amblyopic eye.
• The patient is asked to indicate the position of
the after image in relation to the fixation point.
• In eccentric fixation the after image will appear
slightly to the side of fixation letter, few cases a
long way away(Indicates deeply ingrained ARC)
• It can often over come by encouraging the
patient to see the after image close to the
fixation letter or passing through it.
• Entopic phenomena:
• Haindinger’s brushes and maxwell’s spot are
entopic phenomena which occur due to
characteristics of central foveal area of retina.
• They can be seen only by the foveal area
under the right conditions.
• Haidinger’s brushes:
• In case of Haidinger’s brushes a brightly illuminated
blue polarized field is used when the direction of
polarization is rotated, two darkened and opposing
sectors of the central field can be seen to rotate: the
patient sees a dark blue rotating propeller.
• These circumstances are created by the use of specially
designed apparatus which comprises a disc of polarised
material rotating with a blue filter before a bright field.
• Haidinger’s brushes are yellowish, brushlike shapes
that seem to radiate from the point of fixation when
polarized, preferably blue light is viewed.
• With central fixation the center of the brushes is
superimposed on the fixation point; with eccentric
fixation the brushes appear peripheral to the fixation
• Its due to birefringence induced by the xanthophyll
which is radially polarizing.
• Some structure in can behave as radial analyzer of blue
filter- yellow macular pigment(xanthophyll) radial
• Vertical vibration falls on analyzer and horizontal on
the plane of transmission perpendicular to the plane of
• Vertical element travel more blue light so blue brush brush is
• Dichroism: The effect of absorption of light polarised in one
direction and transmission in plane at right angles.
• Maxwell’s spot:
• Maxwell’s spot is another entoptic phenomenon
whereby the macular region is represented by a
dark spot appearing in the blue region of the
visible spectrum. Its position, relative to that of a
fixation mark, should be a sensitive index of the
retinal area used for fixation.
• If a blue filter is quickly placed in front of your
eye as you view a bright uniform white or yellow
background a dark disc appears in the macular
• Why does this occur?????
• This is due to xanthophyll pigment (zeaxanthin) in
the macula, which acts as a yellow filter which
excludes more of blue light than the surrounding
retina does so that relatively dark spot appears in
the part of visual field that corresponding to the
• Can also be used to measure the density of
macular pigment. The darker maxwell spot the
denser the pigment.
• Perimetry Method:
• This method depends on the fact that the
physiological blind spot is same angular distance
from the fixation point in both eyes in normal
subjects; which is only true for isometric eyes and
similar axial length.
• The position of blind spot is plotted in the non-
amblyopic eye, and the position of its centre from
the fixation point horizantally and below the
horizontal are both carefully measured.
• The same measurements are repeated on the
• Any discrepancy between the position of the
blind spot relative to the fovea in the two eyes
indicates eccentric fixation.
• Amsler Charts:
• Can be used only in case of foveal scotoma’s.
• Patient with foveal scotoma reports an
interruption in the pattern of squares
corresponding to the scotoma.
• In amblyopia with central fixation(Eg-
anisometropic amblyopia) this distubence in the
lines will be at the point of fixation and extended
for about 1cm or more depending on the extent
• In eccentric fixation the scotoma will be to one
side of the point fixed by the patient- the
projection of fovea.
• Mallet called this lang’s one sided scotoma and
stated that it will only present in microtropia.
• Interestingly this scotoma is on the opposite to
that side which would expected from strabismus
(Eg- temporal in the esotropia, which is
charecteristic of microtropia)
• Past pointing test:
• This will give an indication if the localisation of objects
in space has been disturbed with the amblyopic eye.
• This procedure is first tried with the good eye so that
the practitioner can see the normal ability of the
patient to perform the test.
• The amblyopic eye is covered and the patient is asked
to place a finger on the forehead just above the eye.
• A pen torch is held just above the eye at a distance of
• The practitioner explains the word ‘Go’ the patient
moves the finger to touch the light.
• The occluder is then changed to the good eye and the
test is repeated with the amblyopic eye, the patient
being to touch the light with the tip of the finger.
• If this cannot be done the finger goes a few
centimeters to one side. Past pointing is demonstrated.
• This indicates that the eccentric area, upon which the
object of regard is imaged, is not being used to
estimate the principal visual direction.
• The innate association between the principal visual
direction and the fovea is maintained.
• RELATION TO VISUAL ACUITY:
• There is normal decrease in visual acuity as a function of the
distance of the object image from the foveola.
• While there is a general trend for eyes with low visual acuity
to have greater eccentricity of their fixation pattern.
• Since visual acuity decreases in the peripheral retina, the
magnitude of the eccentric fixation will determine the best
possible visual acuity that the patient may obtain in a case of
• EFFECT OF DARK ADAPTATION:
• The fixation movements were considerably larger
when the eyes were observed in bright light through
• Which result in improved functioning of the
amblyopic eye in low luminances
• CLINICAL SIGNIFICANCE:
• The attention directed to the fixation pattern of
amblyopic eyes is justified by the importance of
that pattern for the prognosis and selection of
• Peripheral eccentric fixation is an unfavorable
sign and unsteady and wandering fixation are
more favorable prognostic signs.
• It does not follow that standard vision can be
more readily and permanently restored to an eye
that already has central fixation.
• On the other hand, as it is often difficult to be
sure of the presence of central or eccentric
fixation at an early age, it is always appropriate to
start treatment with direct occlusion.
• Inverse occlusion is sometimes indicated at the
beginning of therapy in cases of steady eccentric
• Monitoring the fixation behavior in addition to
checking visual acuity may be helpful during the
treatment for amblyopia.
• Red filter:
• As the fovea contains only cones, a red filter placed before
the eye with non-central fixation while the dominant eye is
occluded, may have the effect of inducing central fixation
by preferential stimulation of the fovea.
• This is because under red illumination only the photopic
mechanism is active so that the cones of the fovea should
be preferentially stimulated.
• At other times when red filter was not being used, the
patient was required to use an occluder in front of the
amblyopic eye. The red filter was used for a period of two
months to eighteen months.
• Modified keeler opthalmoscope which may be used for diagnosis and
• The Nut Auto-disc is provided with three graticules.
• Stage 1: Localisation of the fovea
With the Auto-disc position 1
The linksz star in green light may be focused on the retina and
accurately placed on the patient’s fovea.
• Stage 2: Dazziling the extra macular retina
With the Auto-disc position 2
By pressing the trigger on the projectoscope the second graticule
consisting of a 3ᴼ or 5ᴼ black spot automatically rotates to occupy the
same position as the inner and the outer ring of linksz star.
At the same time a brilliant light of predetermined duration
and intensity dazzles the retina whilst the macular area is occluded
by the spot.
This technique inhibits the false fovea, and produses a
strong after image within few seconds.
• Stage 3: Foveal stimulation by flashing light
With the Auto-disc position 3
The 3ᴼ black spot is automatically replaced by a disc of
white light, whilst the extra macular retina is projected by a green
When the trigger is released to produce this effect, an
alternate is also automatically activated, produsing a flashing light.
The duration of the light and dark phases may be pre-set by
dails on the control unit.
• This can be used in treatment which involves only the
first two stages.
• The procedure is as follows-
1)The pupil of the amblyopic eye is dilated.
2)The patient is seated in such a way that the fixating eye
can observe a red spot light reflected in a mirror set at
a suitable angle of about 45ᴼ so that the amblyopic eye
is directed straight ahead or a slightly divergent
position. The amblyopic eye must be maintained
steadily in this position during the application of the
3)Stage 1 and 2 are carried out.
4)The mirror is then removed, the fixing eye then
occluded and the patient is instructed to look at a
white screen which is illuminated with a flashing white
light. The patient should then appreciate the after
image. His responces could be one among the
(і) Appreciation of correct negative after image- that is an
after image which is appreciated in the light and
consists of a colored circle with a clear centre.
All persons with normal vision will appreciate a
negative after image in the light and a positive after
image in the dark.
(іі) Appreciation of negative after image but with no
centre, i.e. no central spot- the after image being the
same color all over.
(ііі) Appreciation of negative after image with a black
(iv) No appreciation of after image
The aim of the treatment in the early stages, after the
patient is able to appreciate a after image is to obtain a
correct negative after image.
• This is done by repeated application of the stimulus
and also by regulating the dark and light phases of
alternoscope which illuminate the white screen.
• The patient should be taught how to project the
image straight ahead.
• Eg: In any case of convergent strabismus with
eccentric fixation the patient will project the after
image incorrectly in the direction of deviation.
• The patient is therefore taught to move his eye
outwards and attempt to place the after image
• This may be facilitated if there is an object within
which the patient may place the after image– i.e.
a cross with a gap in the centre.
• This is modified opthalmoscope by cuppers and is used
for diagnosis and treatment of eccentric fixation.
• The beam of light illuminates an area of approximately
30ᴼ at the posterior pole of the eye.
• A green filter is incorporated and also two black discs
of 5ᴼ and 3ᴼ diameter which can be placed in the
centre of the beam of the light.
• The pupli of amblyopic eye is dilated.
• The fovea is located with the green filter and then the
5ᴼ or 3ᴼ black disc is projected on to the macular area
and the light allowed to stimulate the circular
paramacular zone for 20 to 30 seconds.
• This produses an after image.
• Encourage the patient to appreceate correct after
• He is then instructed to look through one of the
instrument incorporating haidingers brushes and
encouraged to find the brushes within the clear centre
of the after image.
• Bilateral eccentric fixation:
• May occur in patients without strabismus and
with bilateral central scotomas caused by
Binocular Vision And Ocular Motility
Gunter K. von Noorden, MD
Emilio C. Campos, MD
Practical orthoptics in the treatment of squint
Pickwell’s binocular vision and anomalies
Bruce J. W. Evens
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