The effects of 0.025% hyoscine hydrobromide eyedrops on visual function in man.
Instillation of three drops of 0.025% hyoscine hydrobromide into one eye at 5 min intervals caused a mydriasis and cycloplegia of rapid onset and of 4-6 days' duration; this was similar to the previously reported actions of concentrations of up to 0.5%. After refraction for the working distance of the experiments, contrast sensitivity to stationary oscilloscope-generated grating patterns of 10 and 20 c/deg was unaffected despite the mydriasis. Also, contrast sensitivity to laser interference fringes of 10 and 20 c/deg observed in the Maxwellian view, in which the effects of the ocular media are bypassed, was unaffected. Contrast sensitivity to a 3 c/deg phase-reversed grating pattern was, however, transiently reduced by 40% after hyoscine. A second series of experiments showed a deleterious effect of hyoscine on contrast sensitivity to both stationary and phase-reversed grating patterns of 2, 3 and 5 c/deg while contrast sensitivity at 10 c/deg was not consistently affected. These results were explained by a direct deleterious action of hyoscine at the level of the retina, specific to channels that detect low spatial frequencies.
Morrison
J D
JD
Institute of Physiology, University of Glasgow, UK.
Reilly
J
J
D000065:Accommodation, Ocular / Q000187:drug effects; D000293:Adolescent; D000328:Adult; D015350:Contrast Sensitivity / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual / Q000187:drug effects; D011680:Pupil / Q000187:drug effects; D012029:Refraction, Ocular; D012601:Scopolamine / Q000494:pharmacology*; D013997:Time Factors
D012601:Scopolamine