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Results for “Tropicamide”

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At least 19 recordsLinked to original sources

PubMed1990

Time course of cycloplegia induced by a new phenylephrine-tropicamide combination drug.

A motorized and computer-interfaced phoropter was used to track the development of cycloplegia and recovery of accommodation over a 60-min period, after the topical application of a phenylephrine 5%-tropicamide 0.8% drug combination (Phenyltrope). Phenyltrope was introduced into the Canadian market about 2 years ago (Compendium of Pharmaceuticals and Specialties, 1987), and advertised as a fast acting cycloplegic and mydriatic drug. Here we report the results of our investigation of the depth of action and the temporal aspects of cycloplegia for this drug combination as a function of iris color. We also compare the action spectrum of Phenyltrope to that of tropicamide 1% under similar test conditions. Our results indicate that the latency for cycloplegia was shorter for tropicamide, the maximum rate of accommodative loss similar for both drugs, and the resultant cycloplegia at 20 min deeper for Phenyltrope. Recovery from induced cycloplegia was greater for tropicamide 60 min after drug administration. For both Phenyltrope and tropicamide, no significant differences in any of the parameters investigated were observed as a function of iris color. We conclude that even though Phenyltrope induced a measurably deeper cycloplegia than did tropicamide, the amount of residual accommodation present at 20 min (about 38%) is insufficient for most refractive purposes.

Accommodation, Ocular↗

PubMed1982

Mydriatic effectiveness of dilute combinations of phenylephrine and tropicamide.

The effects of two solutions, each consisting of a combination of tropicamide and phenylephrine at lower than conventional concentrations, were studied in 79 students at Pacific University College of Optometry. Clinically effective diameters (CED's), measured when the eye was illuminated for direct ophthalmoscopy, were followed for 90 min after mydriatic instillation. Intraocular pressure (IOP), systolic arterial blood pressure (sBP), and the systolic BP/IOP ratio were also monitored for 90 min. Both combination A (0.25% tropicamide + 1.25% phenylephrine) and combination B (0.125% tropicamide + 2.0% phenylephrine) produced CED's as large as produced by 0.5% tropicamide in the opposite eye. By combining a low concentration of a sympathomimetic with a parasympatholytic agent, it is possible to achieve mydriasis superior to that produced by 0.5% tropicamide or 2.5% phenylephrine while reducing the risk of systemic or ocular side effects.

Adult↗

PubMed1990

Reduced mydriasis from repeated doses of tropicamide and cyclopentolate.

Pupils are often dilated for examination the day before surgery and again on the day of surgery. The following experiment was performed to determine the effect of serial doses of two commonly used mydriatic agents: on two consecutive days the pupil of one of the eyes of 28 subjects was dilated with tropicamide 1%, and the pupil of one of the eyes of 30 subjects was dilated with cyclopentolate hydrochloride 1%. The other eyes in both groups were dilated only on the second day, and thus served as controls. Pupil sizes were measured from photographs before and after dilation. The pupils of the eyes treated twice with either drug did not dilate as well after the second dose as those of the control eyes (P less than .005 for tropicamide, P less than .001 for cyclopentolate). The pupils of the eyes twice-treated with tropicamide were an average of 0.15 mm smaller than the control pupils; those twice-treated with cyclopentolate were 0.36 mm smaller. For subjects treated with cyclopentolate, this decreased mydriasis was related to age (P less than .05) and to eye color (P less than .025): the younger and blue-eyed subjects dilated less on the second day than the older and brown-eyed subjects. If full mydriasis is required at surgery, pupils should probably not be dilated with either tropicamide or cyclopentolate the day before surgery.

Adult↗

PubMed1989

A pupillographic evaluation of a phenylephrine HCl 5%-tropicamide 0.8% combination mydriatic.

A continuously recording high-resolution pupillometer was used to measure changes in pupil size and pupil reactivity to temporally modulated light, following topical application of a phenylephrine HCl 5%-tropicamide 0.8% combination mydriatic (Phenyltrope). A controlled light stimulus induced pupillary changes in the left eye while changes in the consensual pupillary responses were measured in the mydriatic-treated right eye. The effects on pupil light reactivity of a single drop of the combination mydriatic were also compared to those caused by one drop of tropicamide 1% alone. Phenyltrope was introduced onto the ophthalmic market ostensibly offering faster mydriasis because of its combined effect of both the parasympathetic and sympathetic innervation to the pupil. In the present study, we looked for any differences in the pupil reaction times and amplitudes as a function of time after drug administration, iris coloration and type of mydriatic instilled. Our results show that while the combination is a fast acting mydriatic providing a large and stable pupillary dilation in subjects with either blue or brown irides, it does not differ appreciably in efficacy from the mydriatic effect of tropicamide 1% alone in healthy subjects between 20 to 36 years of age. Applications of our findings to the clinical environment are presented.

Administration, Topical↗

PubMed1983

Tropicamide-induced mydriasis in densely pigmented eyes.

Clinically effective diameters (CED's) corresponding to illumination intensities used in direct ophthalmoscopy were determined in 30 young adults with densely pigmented irides after instillation of 1 drop of 0.5% tropicamide. All subjects were of Asian, Pacific Island, or Hispanic origin. The maximum CED was attained by 30 min and was maintained without significant change for the next 60 min. Ninety percent of the subjects had maximum CED's of 6.0 mm or more, and 57% had CED's of 7.0 mm or more. These figures correspond to the entrance pupil diameters and are free from the effects of corneal magnification. The average CED's for these densely pigmented eyes did not differ in a statistically significant manner from corresponding mean CED's for 97 less densely pigmented Caucasian eyes during the interval of 30 to 90 min after instillation of tropicamide. Tropicamide at 0.5% concentration appears to be an effective mydriatic for use in these densely pigmented eyes with procedures requiring intensities of illumination similar to those used in direct ophthalmoscopy.

Adult↗

PubMed1985

Sector pupil dilation with phenylephrine and tropicamide.

A comparison of sector pupil dilation produced with 2.5% phenylephrine and 1.0% tropicamide was carried out on nine subjects. We found that 2.5% phenylephrine produced a significant increase in the vertical as compared to the horizontal diameter at 10, 20, 30, 40, and 50 min after instillation of the drug with the maximum vertical diameter occurring at 40 min. The pupil diameter in the vertical and horizontal meridians before drug instillation was 3.7 mm +/- 0.2 (mean +/- SE) whereas at 40 min the vertical and horizontal diameters were 6.7 mm +/- 0.4 and 5.2 mm +/- 0.3, respectively. Instillation of 1% tropicamide produced equal dilation of the vertical and horizontal diameters, which was maximum at 40 min. Before drug instillation, the pupils were 3.7 mm +/- 0.2 (mean +/- SE) in both the horizontal and vertical meridians. At 50 min the pupil diameter was 7.0 mm +/- 0.2 in both meridians in the eye that received tropicamide.

Adult↗

PubMed1989

Influence of thymoxamine eye-drops on the mydriatic effect of tropicamide and phenylephrine alone and in combination.

In a preliminary experiment in 12 healthy volunteers, one drop of thymoxamine 0.5% instilled into the conjunctival sac completely reversed the mydriasis produced by phenylephrine 2.5%, 5% and 10% after 20 minutes. In a second study in eight volunteers, thymoxamine 0.5% completely prevented the mydriasis produced by phenylephrine 2.5% and produced a miosis. It also completely reversed the mydriasis produced by tropicamide 0.5%. The mydriatic effect of tropicamide 0.5% plus phenylephrine 2.5%, however, was not completely reversed by thymoxamine 0.5% over a period of 180 minutes. Phenylephrine, tropicamide and thymoxamine are freely available for use by registered optometrists.

Adolescent↗

PubMed1992

Influence of ocular tropicamide on exercise testing.

This study was aimed to evaluate the effects of tropicamide 0.5% eye drops on cardiovascular parameters during exercise testing. The study group included 154 healthy subjects (mean age: 44.7 +/- 8 years). The subjects were divided into three groups according to the size of the pupils at the onset of exercise: A: pupils not dilated (n = 27), B: pupils partially dilated (n = 90) and C: pupils widely dilated (n = 37). They were compared to 66 healthy controls (age 43.8 +/- 8) who did not receive the drops. Rest and exercise parameters were affected in groups A and B, while the results of group C resembled those of the controls: (a) resting heart rate -66.7, 66.6, 70.9 and 69.3, respectively (p = 0.03); (b) heart rate at 50 and 100 W - 104, 107, 110 and 111 (p = 0.01) and 131, 131, 137, 139, respectively (p = 0.01); and (c) peak systolic blood pressure - 192, 186, 183, 175; respectively (p = 0.004). Reanalyzing the data by scoring of visual impairment gave identical results. As a whole, the study group achieved higher work loads than the controls (126 vs. 119 W; p = 0.03). We conclude that the instillation of ocular tropicamide has definite effects on cardiovascular parameters, both at rest and during exercise. Mainly, patients showed a lower heart rate at the initial levels of exercise. However, at symptom-limited level, tropicamide does not influence a patient's ability to achieve the target heart rate, and stress testing results are not altered by the drug.

Adult↗

PubMed1992

Effects of pilocarpine and tropicamide on blood-aqueous barrier permeability in man.

The time courses of changes in the effects of topical pilocarpine and tropicamide on the index of the blood-aqueous barrier permeability to plasma protein (Pin) were determined in normal volunteers. Before and after drug instillation in one eye, protein concentration in the anterior chamber (Ca) was determined from aqueous flare intensity with a laser flare-cell meter and from aqueous flow by fluorophotometry. The Pin was calculated from the Ca, plasma protein concentration, and aqueous flow. One percent pilocarpine produced a maximum increase of 21 +/- 10% in the Ca (mean +/- SEM, n = 10), no significant change in the aqueous flow (n = 5), and a maximum increase of 29 +/- 10% in the Pin (n = 10). Three percent pilocarpine produced a maximum increase of 55 +/- 11% in the Ca (n = 8), a maximum increase of 34 +/- 13% in the aqueous flow (n = 5), and a maximum increase of 74 +/- 18% in the Pin (n = 8). Tropicamide (0.4%) produced a maximum decrease of 17 +/- 7% in the Ca (n = 8), a maximum decrease of 15 +/- 11% in the aqueous flow (n = 8), and a maximum decrease of 24 +/- 13% in the Pin (n = 8). The results indicated that pilocarpine increased the blood-aqueous barrier permeability to plasma protein in a dose-dependent manner and that tropicamide reduced it.

Adult↗

PubMed1989

Ideal concentration of tropicamide with hydroxyamphetamine 1% for routine pupillary dilation.

In this double-masked clinical study, we evaluated four concentrations of tropicamide (0.05%, 0.1%, 0.25%, and 0.5%) combined with hydroxyamphetamine 1% to find the combination that gives maximal pupillary dilation and inhibition of responsiveness to light and minimal paralysis of accommodation. With all concentrations, pupil size was maximal at 60 minutes, and there was no significant difference between the groups in mean pupillary diameter. Inhibition of the pupillary responses to light and loss of accommodation were directly related to the concentration of tropicamide. Tropicamide 0.25% combined with hydroxyamphetamine 1% was considered ideal for dilation and inhibition of the light response without inhibiting accommodation for near vision.

Accommodation, Ocular↗

PubMed1978

Antimuscarinic effects of stereoisomers of tropicamide on rabbit iris sphincter.

The antimuscarinic activity of optical isomers of tropicamide were compared on the isolated rabbit iris sphincter. The increasing concentrations of both the (--)- and (+)-isomer shifted the dose-response curve of carbachol to the right in a parallel fashion. The competitive reversible muscarinic blocking effects of both isomers were confirmed by pA2 plots. The pA2 values from the nonpigmented irides for (--)- and (+)-tropicamide were 7.88 and 6.18, respectively. Thus the (+)-isomer has only 1/50 the blocking activity of the (--)-isomer. Although both isomers are slightly less active in the pigmented iris, the activity difference between the isomers was high. From the nonpigmented iris, the blocking effect of the active (--)-tropicamide was readily reversed by washing, whereas reversal of this isomer's effect from the pigmented iris was relatively slow.

Animals↗

PubMed1989

Pupil dilatation with tropicamide. The effects on acuity, accommodation and refraction.

The effect of pupil dilatation with tropicamide 1% on visual acuity and accommodation was assessed in 100 eyes of 52 consecutive patients attending the general ophthalmic outpatient clinic. Snellen visual acuity remained unchanged in 55 eyes and deteriorated by one line in 41 eyes. The remaining four eyes deteriorated by two lines. Tropicamide gave rise to a reduction in the amplitude of accommodation which tended to vary inversely with the age of the patient. However, all patients who wore reading glasses for presbyopia were still able to read when their pupils had been dilated.

Accommodation, Ocular↗

PubMed1992

[The cycloplegic effect of atropine in comparison with the cyclopentolate-tropicamide-phenylephrine combination].

Atropine is thought to produce the most effective cycloplegia in early childhood. Cyclopentolate and Tropicamide are the best known short acting cycloplegic agents. Phenylephrine is an adrenergic agent and has also a cycloplegic effect. In this study we compared a combination of Cyclopentolate, Tropicamide and Phenylephrine with Atropine and observed no difference between them.

Accommodation, Ocular↗

PubMed1981

Dose-response effects of tropicamide HCl.

Using double-masking procedures, the mydriatic and cycloplegic effects of 0.25, 0.5, 0.75, and 1.0% tropicamide were studied. All doses produced clinically useful mydriasis of at least 6-mm pupils. Using testing conditions of both normal (35 ft-c) and bright (150 ft-c) illumination, no mydriatic dose-response differences for the four concentrations were found. Cycloplegic effects were dose related. A single drop of either 0.75 or 1.0% tropicamide reduced the amplitude of accommodation to about 1.5 D, which is adequate for a cycloplegic refraction.

Adult↗

PubMed1982

Effect of tropicamide on ocular blood flow in the rabbit.

Intracardiac injection of 15 microspheres labeled with 85Sr (strontium) and 141CE (cerium) were used to determine ocular blood flow in seven rabbits before and 25 min after bilateral application of tropicamide to the cornea. By using two different isotopes distinguishable under gammaspectrometry, each animal served as its own control. After administration of two drops of 1% tropicamide, no significant difference in blood flow between treated and untreated eyes was observed.

Administration, Topical↗

PubMed1986

Does prior instillation of a topical anesthetic enhance the effect of tropicamide?

Preinstillation of a topical anesthetic has been reported to increase the effect of subsequently applied mydriatics. We examined the effect of instilling 1 drop of proparacaine hydrochloride (0.5%) before applying 1 drop of tropicamide (1%). The results show that preanesthesia prolongs the mydriatic and the cycloplegic effects of tropicamide in eyes with either lightly or more heavily pigmented irides.

Accommodation, Ocular↗

PubMed1986

Pharmacokinetics of topically applied cyclopentolate HCl and tropicamide.

The time course of accommodative loss after the topical application of 0.5% and 1.0% concentrations of cyclopentolate HCl and tropicamide was measured over a 20-min interval in 50 age- and sex-matched subjects between 20 and 30 years of age. Computer-assisted measures of residual accommodation provided detailed data on the temporal aspects of the cycloplegia induced by these commonly utilized drugs when used alone or with the topical anesthetic proparacaine HCl. The pattern of recovery of ocular accommodation from cycloplegia was also measured over a 5-h period, starting 2 h after drug application. The results show that latency, depth of cycloplegia, and rate of accommodative loss are regulated to drug type and concentration, and are influenced by the iris coloration of the test eye. The rate of onset of cycloplegia was not accelerated in blue or brown irides by the preadministration of proparacaine. Regardless of iris pigmentation, recovery from tropicamide cycloplegia was much faster than recovery from cyclopentolate cycloplegia. In contrast, the depth of cyclopentolate cycloplegia present in brown irides during the recovery phase was much greater than in blue irides. Mechanisms to explain these observations are proposed and clinical implications of these findings are presented.

Accommodation, Ocular↗

PubMed1986

Effects of decreasing concentrations of tropicamide on sector pupil dilation.

We compared the effects of decreasing concentrations of tropicamide on sector pupil dilation. The concentrations of 0.25, 0.125, 0.03125, and 0.0156% tropicamide were instilled on 10 subjects and the horizontal and vertical pupil diameters measured at 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, and 90 min after drug instillation. We obtained significant pupil dilation with the 0.25% concentration but with progressively decreasing concentrations we obtained a concomitant decrease in pupil dilation, suggesting that it is the inherent action of the constrictor muscle to respond differently than the dilator muscle (no sector dilation), and this effect is not concentration dependent.

Adolescent↗