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Effects of muscarinic receptor modulators on ocular biometry of guinea pigs
Author(s) -
Fang Fang,
Huang Furong,
Xie Ruozhong,
Li Cheng,
Liu Yin,
Zhu Ying,
Qu Jia,
Zhou Xiangtian
Publication year - 2015
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/opo.12166
Subject(s) - pilocarpine , cyclopentolate , cycloplegia , repeated measures design , muscarinic acetylcholine receptor , medicine , guinea pig , ophthalmology , analysis of variance , anesthesia , agonist , endocrinology , eye disease , mathematics , refractive error , receptor , epilepsy , statistics , psychiatry
Purpose This study investigated whether pilocarpine and cyclopentolate induce changes in ocular biometry of guinea pigs, in order to understand if guinea pigs have a similar response to these two agents as humans do. Methods Under general anaesthesia, refraction, axial components and surface curvature in various optical interfaces of the eye were measured in 10 guinea pigs (age of 2 weeks) at baseline (0 min) and different time points (5, 10, 20, 30, 60, 90 min) after topical administration of pilocarpine or cyclopentolate. The interval between the two drug treatments for the same animals was at least 24 h. Results Eyes treated with pilocarpine developed approximately 6D myopia ( p < 0.001 from 0 to 90 min) with a decrease in anterior lens radius of curvature ( ALRC ) ( p < 0.001 from 0 to 90 min, repeated measures anova ). This myopic shift was moderately correlated to the decreased ALRC ( r 2 = 0.48, p < 0.001). Furthermore, a small but significant increase in the VCD ( p < 0.001 from 0 to 30 min, repeated measures anova ) with an unchanged AL ( p = 0.85 from 0 to 90 min, repeated measures anova ) after the drug treatment suggested a transient and mild forward movement of the lens. Cyclopentolate dilated the pupil in all eyes ( p < 0.001 from 0 to 90 min, repeated measures anova ) but did not change other ocular parameters. Conclusions The muscarinic agonist, pilocarpine induced a myopic shift mainly due to a decrease in ALRC , suggesting that guinea pigs have an accommodative mechanism similar to that in humans. The minimal changes produced by cyclopentolate could be due to the use of general anaesthesia, which may have reduced the susceptibility of the eye to topical cyclopentolate in the induction of cycloplegia.