Relationship between interblink interval and dopamine

Dear Editor

An interesting study recently reported by Johnston et al¹ investigated the interblink interval between dry and normal eye subjects. The authors concluded that this interval was reduced in dry eyes in comparison with normal eyes, that there was a greater variability in interblink intervals in normal eyes, and that the parameters were useful for diagnosis of dry eye disease.¹

Using a method that measured the interblink interval achieved exactly what the authors expected, and enabled better discrimination between normal and dry eye subjects. As the authors state, monitor usage may have impaired their data slightly, and hence a comparative study of the same cohort but using a fixed visual stare would have been both interesting and relevant. The variability seen, as the authors discuss, could be related to an integral homeostatic mechanism. Taylor et al, who investigated and published an interesting paper relating to dopamine’s role in blink rate, suggested the ventromedial part of the caudate nucleus in particular is critically involved.²

We thank Johnston et al for reporting this enlightening study. Should it be repeated or augmented, a comparative study of fixed visual stare to monitor usage in the same participants and also comments on the relationship with dopamine levels would be interesting.