Strabismus - Fundamentals of Clinical Ophthalmology.pdf

Preface
This book has been written for the general ophthalmologist, the trainee ophthalmologist, and the eye
health professional. It will also be of interest to the paediatrician and family physician.
An increased understanding of the organisation and development of the visual cortex in primates
and increased awareness of the interplay between sensory and motor development has resulted in a
major shift in the way that clinicians think about infant vision and the eye and child development.
The vulnerability of the visual system during development is critical to the understanding of
strabismus and amblyopia in childhood and to the presentation of adult strabismus that has its origins
in childhood.
There is now an emphasis on development of visual function in early infancy and away from
postinfantile development. This has led to concern for development of visual pathways in the cerebral
cortex in the central nervous system. Thirty to forty years ago, it was not uncommon for the family
doctor to reassure families that a child would grow out of a squint. Now the understanding is that no
child is too young to be assessed, managed and treated with the added assurance of safer modern
anaesthesia and surgical techniques for infants and children when strabismus surgery is indicated.
This goes hand in hand with the understanding that unless treatment is introduced early in the critical
periods of development, a good visual outcome will be frustrated. There is now a responsibility for
those entrusted with the care of children in the community to become their advocates and to ensure
early recognition of abnormality in development, appropriate intervention, and completion of care in
their first decade of life.
By contrast, adult onset of strabismus is more often associated with significant underlying
pathology in patients with potential for normal binocular vision. Surgical options are similar to those
in children except that adults can more often cooperate in surgery and procedures under local
anaesthesia. With the implementation of sophisticated treatment, success is often dependent on the
presence of a stable substrate of binocular vision and completion within a shorter timeframe.
The opportunity to author this text is welcome because of its challenge to present succinctly the
underlying neurophysiologic substrate of binocular vision and strabismus. This perspective provides
insights into the vulnerability of the visual system that is the basis for breakdown or failure to develop
normal binocular vision. As clinicians, we need to remind ourselves constantly that strabismus is the
recognition of a clinical sign, not a diagnosis. Rarely, the disturbed eye movement can be due to a
progressive pathological process, for example, neoplasm or inflammation. The primary diagnosis
could therefore be a cerebral tumour, threatening not only sight, but also life. The diagnosis of the
eye movement disorder would be a secondary diagnosis. The fact that the underlying cause is so
frequently static, or a developmental disorder, should not alter the principal of being alert to the
possibility of a progressive pathology as the underlying cause. Integration of visual science with
observations in clinical practice, and considering the causes and consequences of strabismus through
the decades of life should assist us in this.
Francis A Billson
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