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The effects of 0.025% hyoscine hydrobromide eyedrops on visual function in man
Author(s) -
Morrison J.D.,
Reilly J.
Publication year - 1989
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/j.1475-1313.1989.tb00803.x
Subject(s) - mydriasis , cycloplegia , contrast (vision) , hydrobromide , optics , grating , ophthalmology , chemistry , visual acuity , refractive error , physics , medicine
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 cydeg 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.