Does it have a role in 21st century orthoptic practice? By Marie Cleary, PhD DBO Cert Ec

1. E&OE. Issue 1/September 2014
SYNOPTOPHORE
HAAG-STREIT UK
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Does it have a role in
21st century orthoptic
practice?
Marie Cleary Biography
References
1. Brodsky MC. Dissociated Horizontal Deviation: Clinical spectrum, pathogenesis, evolutionary
underpinnings, diagnosis, treatment and potential role in the development of infantile esotropia. (An
American Ophthalmological Society Thesis) Trans Am Ophthalmol Soc. 2007 December; 105: 272–293.
2. Hess RF, Mansouri B, & Thompson B. A binocular approach to treating amblyopia: antisuppression
therapy. Optometry & Vision Science 2010,87(9), 697-704.
3. Knox, P. J., Simmers, A. J., Gray, L. S., & Cleary, M. An exploratory study: prolonged periods of binocular
stimulation can provide an effective treatment for childhood amblyopia. Investigative ophthalmology &
visual science 2012; 53(2), 817-824.
4. Sydnor CF, Seaber JH, Buckley EG. Traumatic superior oblique palsies. Ophthalmology (Rochester)
1982; 89: 134-8.
5. Ellis FD, Helveston EM. Superior oblique palsy-diagnosis and classification. Int Ophthalmol Clin 1976;
16: 127-35.
6. Wong AMF. Understanding skew deviation and a new clinical test to differentiate it from trochlear
nerve palsy. Journal of American Association for Pediatric Ophthalmology and Strabismus 2010;
14(1),61–67
7. Scott WE, Mash AJ. (1973). Kappa angle measures of strabismic and nonstrabismic individuals.
Archives of Ophthalmology, 89(1), 18.
8. Basmak H, Sahin A, Yildirim N, Papakostas TD, Kanellopoulos AJ. Measurement of angle kappa with
synoptophore and Orbscan II in a normal population. Journal of Refractive Surgery 2007, 23(5), 456.
Dr Marie Cleary qualified as an
Orthoptist in 1981. She then
began working within the NHS,
where she was promoted
to teach on the Orthoptic
undergraduate programme
at the Glasgow Caledonian
University to in 1996.
In 2002, Dr Cleary completed a PHD in ‘Clinical Evaluation
of Fixation Characteristics and Visual Acuity Outcomes
in Human Amblyopia’ and is currently working as a Head
Orthoptist at the Gartnavel General Hospital Glasgow.
Dr Cleary is consistently involved in the development of
a shared-care ocular myasthenia Clinic, where she works
alongside a neurologist and specialist nurse to support
the introduction of an Orthoptist-led Idiopathic Intracranial
Hypertension clinic.
Dr Marie Cleary has continued to support collaborative
research between her department and the Department
of Vision Sciences at Glasgow Caledonian University, and
is an active practice placement educator for the Sheffield
Orthoptic Masters programme.

2. Why use the Synoptophore?
Does the synoptophore have
a role in 21st century orthoptic
practice? By Marie Cleary, PhD DBO Cert Ec
It is important to continually question our practice. Having
been trained using the Synoptophore on a daily-basis,
and being encouraged by my adult motility specialist to
measure torsion in 9 positions of gaze with it, I remain a
firm fan. In writing this, I have had to consider why I find it
valuable, and whether other tests could equally do the job.
While reflecting on my reasons for continued use of the
synoptophore on a regular basis, I came up with the
following list;
A unique means of assessment
The Orthoptist’s knowledge of projection and retinal
correspondence are fundamental to understanding and
treating cases presented to the orthoptic department. The
Synoptophore offers a unique means of assessing these,
while being able to manipulate the images presented to
both eyes by adjusting size, form and brightness. This is
distinct from other Binocular Vision (BV) tests. I use it as
an adjunct to free space tests where responses to Bagolini
glasses and Worth’s lights are ambiguous.
A clearer clinical picture
Assessment of fusion/area of Binocular Single Vision (BSV)
in manifest deviation can be more clear-cut than with
Bagolini glasses or Worth’s lights, because of the controls
within the slides.
It can help in differential diagnosis, including DHD versus
Intermittent exotropia.1 It may also influence management,
since the surgeon may opt to go straight to surgery rather
than using Botox, knowing BSV is achievable.
In rapidly alternating esotropia, BSV and alternating
suppression can be difficult to distinguish with Bagolini
glasses or Worth’s lights. The Synoptophore allows the
patient to be clear about which distinct image they are
seeing and when. Reducing image brightness/contrast to
the fixing eye can unmask BSV. This has become the
basis for some new computerised binocular amblyopia
treatments.2 3
Accurate assessment of suppression areas
Suppression area(s) can accurately be assessed. Unlike
with prisms, the image is moved in a continuous rather
than step-wise manner. With prisms, there are unequal
steps and the difficulty of prism distortion is removed in
larger deviations.
9 positions of gaze
Simultaneous assessment of horizontal, vertical and
torsional deviations, fixing either eye in 9 gaze positions,
is a unique selling point for the Synoptophore. Although
Maddox Wing provides this information for primary
position, it cannot be applied in other gaze positions. With
the use of a head and chin rest, the range of movements is
standardised for consecutive measurements.
The measurement of torsion is essential to differential
diagnosis of unilateral versus bilateral fourth nerve paresis,
where >10-154 5
degrees of excyclotorsion is indicative
of bilateral palsy, and fourth nerve paresis from skew
deviation/ocular tilt reaction, where the hypotropic eye is
extorted and the hypertropic eye is intorted.6
deviation/
ocular tilt reaction, where the hypotropic eye is extorted
and the hypertropic eye is intorted.6
Accurate assessment of torsion also informs the surgeon
when planning extra-ocular muscle surgery and retinal
macular surgery.
The Synoptophore can unmask torsion in patients who
cannot achieve fusion with prisms, and it is not clear why.
This can be achieved with other torsion tests, however,
the synoptophore allows correction for the torsion and the
assessment of the impact of this on BSV.
Angle Kappa; a valuable measurement
Assessing angle kappa, (the angle between the pupillary
axis and the line of sight) is key. This is important to
recognise in cases of pseudo-strabismus, but it is also
of value to measure in cases of strabismus where angle
kappa may enhance or mask the deviation.7
Relevance to research
The Synoptophore also retains relevance to current
research, with 48 citations in Google Scholar so far this
year, and more than 50 per annum over the past 5 years.
There are downsides to the Synoptophore which cannot
be ignored: it does induce convergence and create an
artificial visual environment. Updating slides and moving to
a computerised version seems the next logical step. The
latter has already been trialled in China and the US, but has
not yet become commercially available. I am convinced,
however, that it remains an important component of
orthoptic practice.
As a practice placement educator and manager, I am aware
that some students, new graduates (and older ones too)
shy away from using the synoptophore, as they consider it
too difficult or complicated. I would encourage all to
re-acquaint yourself with it.
This can influence the amount of surgery performed to
achieve an acceptable cosmetic appearance. It has also
been recognised that the measurement of angle kappa
is essential in cases of refractive procedures, especially
hypermetropes, to ensure accurate centration of the
ablation zone.8
Article by Marie Cleary. First published in November 2013 issue of BIOS ‘Parallel Vision’
Newsletter for Orthoptists.