Vergence control, and over-convergence associated with the extra accommodation required to overcome a hyperopic refractive error, play a role in the onset of accommodative esotropia. The classical explanation for the onset of accommodative esotropia is a compensation of far-sightedness by means of excessive accommodative convergence. It is an active area of research to understand the reasons why many infants with hyperopia develop accommodative esotropia whereas others do not, and which is the exact influence of the vergence system in this context.[14]