High cognitive demand induces shifts in tonic accommodation of up to +1 D, which are predominantly parasympathetic-mediated but show sympathetic attenuation at initial values above 1.2 D.
Does cognitive demand and sympathetic blockade affect tonic accommodation in emmetropic men?
Cognitive-induced shifts in tonic accommodation appear to be predominantly parasympathetic-mediated, with sympathetic attenuation occurring at higher levels of tonic accommodation.
Absolute Event Rate: 0% vs 0%
ABSTRACT An infrared optometer was used to investigate the relation between cognitive induced shifts in tonic accommodation (TA) and ciliary muscle innervation. Twenty emmetropic men volunteers took part in a double‐masked protocol which involved high (a reverse counting task) and low levels of mental load and blocking of sympathetic innervation of the ciliary muscle with the nonselective β receptor antagonist timolol maleate (0.5%). The high level of cognitive demand induced shifts in TA of up to +1 D. There was no clear reason why large differences in intersubject susceptibility to these shifts occurred. The effect of β‐antagonism on these shifts was insignificant for subjects having initial TA values <1.2 D. However, sympathetic antagonism induced significant increases in cognitive shifts for the remaining subjects. The inference is that cognitive induced shifts in TA are predominantly parasympathetic mediated although a sympathetic attenuation may occur at higher levels of TA.
Bullimore et al. (Thu,) reported a other. High cognitive demand induces shifts in tonic accommodation of up to +1 D, which are predominantly parasympathetic-mediated but show sympathetic attenuation at initial values above 1.2 D.