The effect of topical beta-adrenoceptor antagonists on accommodation in emmetropia and myopia.
Using topical instillation of non-selective and selective beta-adrenoceptor antagonists we examine the proposal that a deficit in inhibitory sympathetic innervation of ciliary smooth muscle may be a specific precursor to the onset and development of late-onset myopia (LOM). Post-task accommodative hysteresis, a possible consequence of such a deficit, was assessed by measuring the time-course of regression of accommodation when open-loop (darkness) conditions were immediately imposed following far and near tasks. For the proposal to be feasible only LOMs should exhibit post-task responses which fail to differentiate the type of beta-antagonist employed. As the overall profile of responses to beta-adrenoceptor antagonism was equivalent for each of the three different refractive groups (emmetropes N = 6; early-onset myopes N = 5; LOMs N = 5) we conclude that a propensity to LOM is not associated with a deficit in sympathetic inhibition.
Gilmartin
B
B
Department of Vision Sciences, Aston University, Aston Triangle, Birmingham, UK.
Winfield
N R
NR
D000065:Accommodation, Ocular / Q000187:drug effects*; D000328:Adult; D015784:Betaxolol / Q000494:pharmacology*; D006801:Humans; D009216:Myopia / Q000503:physiopathology*; D013997:Time Factors; D013999:Timolol / Q000494:pharmacology
D013999:Timolol; D015784:Betaxolol