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Tropicamide
Published in Anton C. de Groot, Monographs in Contact Allergy, 2021
Tropicamide is a synthetic muscarinic antagonist with actions similar to atropine and with an anticholinergic property. Upon ocular administration, tropicamide binds to and blocks the muscarinic receptors in the sphincter and ciliary muscle in the eye. This inhibits the responses from cholinergic stimulation, producing dilation of the pupil and paralysis of the ciliary muscle. Tropicamide in eye drops is indicated to induce mydriasis and cycloplegia in diagnostic procedures, such as measurement of refractive errors and examination of the fund us of the eye (1).
Pathological Processes of the Eye Related to Chemical Exposure
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
For adequate broad visualization of the fundus, particularly in the case of the small rodent species, mydriatics are necessary. A variety of mydriatics are available for use, but the one most commonly used is a parasympatholytic agent, tropicamide (0.1 ml of a 0.5% solution), because of its rapid onset and rapid recovery. In the small rodents, tropicamide produces maximum effect in approximately 5 min following instillation, and recovery occurs in about 1 h. In the dog, cat, and monkey, maximum effect occurs 20 to 30 min after instillation, and recovery does not occur until 2 h in the monkey and 12 to 18 h in the dog and cat.3
Cholinergic Antagonists
Published in Sahab Uddin, Rashid Mamunur, Advances in Neuropharmacology, 2020
Vishal S. Gulecha, Manoj S. Mahajan, Aman Upaganlawar, Abdulla Sherikar, Chandrashekhar Upasani
For carrying out an ophthalmoscopic examination, antimuscarinic agents are applied topically as eye drops or ointment, which proved advantageous (Sharma and Sharma, 2017). The shorter-acting antimuscarinics, such as tropicamide, eucatropine, or cyclopentolate, are preferred drugs used in adults and older children. Sometimes, greater efficacy of atropine is needed for children that at same time imposes more risk of antimuscarinic poisoning (McBrien et al., 2013). Antimuscarinics from tertiary amino group show enhanced penetration after conjunctival application. Preclinical evaluations indicate that a quaternary agent, glycopyrrolate which is analogous to atropine in onset and duration of action (McBrien et al., 2013).
Diurnal Variation and Effects of Dilation and Sedation on Intraocular Pressure in Infant Rhesus Monkeys
Published in Current Eye Research, 2023
Krista M. Beach, Li-Fang Hung, Linjiang Lou, Lisa A. Ostrin
In addition to sedation, many protocols in animal models require instillation of topical mydriatic agents. For example, measurement of refraction, biometry, and retinal imaging requires pupil dilation and cycloplegia. In our lab, we typically use tropicamide because it provides sufficient pupil dilation and cycloplegia while being relatively short acting. However, administration of tropicamide has also been shown to affect IOP in some species. While tropicamide was shown not to affect IOP in sheep or humans,28,29 tropicamide elevated IOP in cats and dogs.30–34 Additionally, in cats, the effects of tropicamide on IOP were shown to decrease with age.33 The effects of tropicamide on IOP and interactions with age in rhesus monkeys are unknown.
The prophylactic effect of betaxolol 0.5% versus brimonidine 0.2% on IOP elevation after Nd:YAG laser posterior capsulotomy
Published in Clinical and Experimental Optometry, 2022
Navid Elmi Sadr, Elnaz Saber, Fatemeh Paknazar
In this study, IOP was measured 1 hour before performing laser posterior capsulotomy and 4 hours after it. The age of the patients, number of laser shots, total laser energy, and baseline mean IOP were not significantly different between the study groups. Tropicamide 1%, which is a cycloplegic drug, was used to dilate the pupil before laser treatment. It is shown that cycloplegics can temporarily increase IOP by decreasing trabecular outflow. Tropicamide has a duration of action approximately 4–6 hours.25 On the other hand, brimonidine and betaxolol have peak IOP reduction 2 hours after instillation.22 The time needed to reach peak effect of brimonidine and betaxolol, in addition to the time needed for effects of tropicamide to wear off, are not as the same in every patient. By measuring IOP at different time intervals after laser application, the confounding effect of inter-individual variations can be minimised. COVID-19 pandemic was the main limitation for the researchers to do multiple ocular examination. In accordance with health and safety protocols, keeping the patients in the clinic for an extended time of observation and examination was not allowed. For this reason, IOP was measured at one time point (4 hours after laser application). There were three reasons to choose this time point. First, the maximum increase in IOP occurs within 3–4 hours after the laser treatment.3–6,12,15,20 Second, the maximum IOP lowering effect of the drugs has appeared, and third, the mydriatic effect of tropicamide has diminished considerably at this time point.
Effect of Cycloplegia on Refractive Error Measure in Chinese School Students
Published in Ophthalmic Epidemiology, 2022
Fang Gu, Hans M. Gao, Xin Zheng, Lei Gu, Jianyao Huang, Jia Meng, Juanjuan Li, Lei Gao, Jianyong Wang, Ronghua Zhang, Jianqin Shen, Gui-Shuang Ying, Hongguang Cui
Unlike previous studies that used the 1% cyclopentolate or atropine as cycloplegic agent (Table 5), our study used 0.5% tropicamide as the cycloplegic agent. Although 1% cyclopentolate is a well-accepted cycloplegic agent in children, tropicamide is an alternative agent for cycloplegic refraction, having less toxicity and side effects than cyclopentolate in children.24 Several studies have compared the cycloplegic effect between cyclopentolate and tropicamide in children and adults, and reported mean refractive error difference ranging from −0.08 D to 0.54 D.25–30 The meta-analysis of these six studies suggested that cycloplegic effect of cyclopentolate was stronger than that of tropicamide with an insignificant mean refractive error difference of 0.175 D, however, their cycloplegic effect difference was statistically significant in children with mean refractive error 0.215 D (95% confidence interval: 0.082 to 0.348 D) more plus from cyclopentolate than from tropicamide.31 Thus, our study may under-estimate cycloplegic effect on refractive error of school students.