The Interface Between Optometric Vision Therapy and Ophthalmology – Part 5

Much has changed since my serendipitous appearance on a panel organized by the Section on Ophthalmology of the American Academy of Pediatrics in 2001 detailed in Part 1.  The CITT and PEDIG studies are prime examples of movement in a positive direction regarding the interface between optometric vision therapy and ophthalmology.  More important, however, is what has not changed.  Neither the AAP nor AAPOS has had a conference similar to the one held in 2001 and were they to have one, it is highly unlikely that they would invite an optometrist to participate.  AAP and AAPOS have continued to publish policy statements intended to discredit optometric vision therapy.  And as much as these organizations claim that they support vision therapy for convergence insufficiency (CI), it has not changed the practice of ophthalmology which still relies primarily on home-based therapy reinforcing the double standard in their call for evidence-based medicine regarding optometric vision therapy for anything other than CI.

One could take an optimistic view and hold open the possibility that at some point ophthalmologists and pediatricians will publicly endorse the merits of optometric vision therapy.  There are signs that this may be the case, as promoted by COVD here, and as we’ve blogged about previously here.  Yet at every turn in the literature there is irony, and the short chapter by Poonyathalang et al regarding eye exercises to accelerate recovery from ocular motor nerve palsy is simply another example.  From their discussion:

“In our study, there were 5 patients in the non-exercise group for which the recovery time was more than six months; all of them occluded their paralytic eye most of the time either with an eye patch or by squeezing their eyelids shut.  Even though these patients eventually regained almost full range of eye movement, they had persistent difficulty adjusting to the spatial environment … A few patients reported that their double vision persisted in the paralytic direction, causing difficulties especially when driving, even though their eye movements range was near complete. In those patients we found that the speed of the paralytic muscle was slower than of the conjugate muscle.  Since single vision was present in central gaze, we advised using larger head movements, in conjunction with a larger car mirror, to permit driving.  The binocular fusion mechanism normally makes it possible to point both eyes at the same visual target.  Our exercises provide visual, somatosensory, and efference copy signals so that the brain can adapt to the peripheral motor weakness and induce ‘spread of con-comitance’.  Thus, our eye exercises may have sped up the spread of con-comitance, which is part of the natural course of recovery from ocular motor nerve palsy.”

Now the irony.  Let’s presume that following one’s finger toward the field of action of a nerve palsy or paretic muscle can help improve range of motion.  There may be visual and somatosensory feedback, but there isn’t much in the way of efference copy.  An article by Bruce Bridgeman calls that theory into serious question.  Does the name ring a bell?  You may have come across Dr. Bridgeman’s story before – he is a vision scientist who had an epiphany similar to what Stereo Sue experienced.  In Bridgeman’s case however the recovery of stereopsis was serendipity, brought about while immersed in a graduated stereoscopic 3D movie environment.  So Poonyathalang et al are on the right track, as was our pediatric ophthalmologist who suggested that a patient do repeated eye stretches.  But why not be more proactive about developing the fusion mechanism?

Richard W. Hertle, M.D., co-authored a chapter EOM surgery in the same text on Infantile Nystagmus as Poonyathalang et al.  You may have heard of Dr. Hertle before, as he is the ophthalmologic Vice-Chair of the CITT study.  Hertle’s chapter concludes with the following: “At any moment in time (the fourth dimension) the ocular-motor system abnormality of INS is clinically and electrophysiologically variably expressed.  The variability of the oscillation is due in part to a combination of complex visual system and developmental-neurological modifiers. The eye movement abnormality is not present in isolation; it continuously interacts with other ocular motor, vestibular, afferent-visual system, and cognitive factors on a minute-to-minute — as well as a year-to-year — basis.  The dynamic nature of this abnormality requires that clinicians and scientists evaluated and study this disease in that fourth dimension of time.  This conceptual approach will result in a more profound understanding of the disease and how our therapy changes the visual system of these patients.”

So where do you think we are, at the Interface Between Optometric Vision Therapy and Ophthalmology?  At the cusp of breakthrough, at the cusp of catastrophe, or mired somewhere in between?