Thanks to our colleague in Kansas, Dr. Joe Sullivan, for pointing out this article in the current issue of Investigative Ophthalmology & Visual Science:
Binocular Coordination of Saccades During Reading In Strabismic Children. I haven’t read the entire paper yet, but the abstract is compelling. The results are described as follows: Saccade amplitude is similar in strabismic and in control children. In contrast, binocular coordination during and after the saccades is significantly poorer in strabismic children as opposed to control children; the duration of fixation is also significantly longer in strabismic children compared to controls. Binocular coordination in strabismic children who have binocular vision is better than those without binocular vision, but it is still worse than control subjects.
At first glance the statement about strabismic cihldren who have binocular vision seems almost like an oxymoron, but it’s referring to strabismic patients who have some level of sensory fusion. In ophthalmology this would be a monofixation syndrome, in which the patient has a very small amount of misalignment in terms of prism diopters (in this illustration between 4 and 5 prism diopters) and lacks bifoveal fixation, but has useful binocular vision in terms of stereopsis and vergence ranges The message here is that any intervention that can help the patient with strabismus to acquired greater interaction between the two eyes may also help to improve reading readiness skills in terms of the binocular yoking of saccades.
The authors conclude: In strabismic children binocular saccade coordination is deficient and could be responsible for impaired reading capabilities. Binocular vision plays an important role in improving binocular saccade yoking.
Thinking about the region of the parietal lobe responsible for attention, but also responsible for saccade and vergence, i.e. O.M., then training eye fixations, rotations, and saccades might improve attention. I say this because the monofixation syndrome patient might have attention problems causing reading problems. If the M pathway does not move the eyes to the next word then the P pathway might not be able to fixate on the words correctly. I like to also correct this with underlining words, highlighting words, using the reading finger to follow the words, and of course keeping the child motivated, top down type of wanting to do better.
August