It was seven years ago following a meeting of the International Congress of Behavioral Optometry in Versailles that I was drawn to a bookstore in Paris bordering the River Seine. Optometry has a much greater presence in the United States than in France, but knowing the deep roots of vision therapy stemming from orthoptics there I was hoping to find some interesting reading on the subject in Science or Medicine. I was not disappointed.
In Gibert Jeune I found three phenomenal books: Guide pratique de reeducation des basses visions; Les surdites de perception; and Manuel de strabologie pratique: Aspects cliniques et therapeutiques. I was encouraged by how much practical information there was in these three books that bolstered what we know about vision therapy, yet saddened in a way that Ophthalmology at large remained so ignorant of these principles and of optometric literature.
It was therefore with much joy that while cleaning my desk this morning I came across a paper from Investigative Ophthalmology and Vision Science last year entitled Poor Postural Stability in Children with Vertigo and Vergence Anomalies. POSTURAL STABILITY – Vergence Abnormalities – IOVS 09
I recall putting the paper aside because I was impressed with not only its substance, but its references. Immediately after a reference to one of the books I purchased in Paris, five consecutive optometric references were listed. Of particular note was a reference to the Clinical Practice Guidelines on Care of the Patient with Accommodative and Vergence Dsyfunction, from the American Optometric Association.
As I re-read the paper its breadth once again took my breath away. The authors studied a population of children with vertigo who presented with vergence abnormalities, mostly convergence insufficiency, who lacked any clinical signs of vestibular disorder, the expected cause of vertigo. The vertigo under study wasn’t rip-roaring dizziness, but an imbalance of a milder variety that would occur in association with a sense of fatigue. A significant number of the children also experienced headaches. An earlier study had suggested that deficits of vergence can influence posutral control through proprioceptive signals. Postural stability in this study was documented through a posturography platform.
To treat these children the researchers prescribed orthoptic training to improve the range of vergence fusional amplitude in most cases, and in select cases prescribed low power plus lenses (0.50D). After training and/or wearing plus lenses, all children ceased having episodes of vertigo and headache.
Zoi Kapoula anchors this group of researchers at the Centre National de la Recherche Scientifique in Paris. They conclude that postural instability can be caused by impaired vergence inputs. The weighting of somatosensory, vestibular and visual inputs into dynamic postural control is a developmental phenomenon and children who have difficulty with postural control, particularly in the absence of vestibular anomalies, should be given the benefit of appropriate ophthalmic assessment and treatment.