Cyclopentolate

Abstract: Purpose. The purpose of this study was to examine the effect of cycloplegic agent on the measurement, of refractive error and the ocular components. Methods. We compared two commonly used topical cycloplegic agents, 1 % tropicamide and 1 % cyclopentolatc, for their effect on the measurement of refractive error (by Canon R-l autorefraction), accommodative response (by Canon R-l autorefraction and by the conventional, subjective "pushup" method), crystalline lens power (by video phakometry and by calculation), and axial ocular dimensions (by A-scan ultrasonography) in 20 emmetropic to moderately hyperopic children. Results. Comparison of refractive error at each drug's reported time of maximum cycloplegia (30 minutes for tropicamide and (50 minutes for cyclopentolate) showed that distance autorefraction in the vertical meridian differed by +0.20 ± 0.30 diopters (D) (P = 0.008). The average difference was +0.07 ±0.10 mm for anterior chamber depth (P = 0.004), —0.03 ± 0.05 mm for crystalline lens thickness (P = 0.025), —0.65 ± 0.(39 D for phakometrically measured crystalline lens power (P < 0.001), +0.03 ± 1.55 D for calculated crystalline lens power (P = 0.94), and -0.09 ± 0.19 mm for vitreous chamber depth (P = 0.062, all paired / tests; positive signs denote greater values with cyclopentolate). Residual accommodation was 0.4 7 and 0.67 D greater with tropicamide when measured by autorefraction and the pushup method (/-" = 0.013 and 0.08 respectively, paired / test). All significant differences were consistently in the direction of poorer cycloplegia with tropicamide. Conclusions. Although tropicamide, as expected, showed poorer cycloplegia compared to cyclopentolate, the degree of difference appeared to be small, with minimal effect on the measurement of distance refractive error and the ocular optical components. Invest Ophthalmol VisSci. 1994 ;35:515-527. v^linicians' use of cycloplegic agents to determine the "true" manifest refractive error is widespread, especially in infants and children. Pharmaceutical paralysis of accommodation is often necessary to relax the habitual accommodative posture in young hyperopes. However, the amount of cycloplegia required to accomplish this has been debated in the literature for many years. The belief that more cycloplegia is necessarily better has led to severe and inconvenient procedures,

Abstract: Literature on human plasma concentrations after instillation of ocular timolol, levobunolol, atropine, cyclopentolate, scopolamine, phenylephrine, betamethasone and technetium Tc 99m and theories of lacrimal drainage were reviewed. In all studies the eyedrops absorbed rapidly into the systemic circulation. Like the kinetics of the tracer substances in lacrimal scintigraphy, the plasma drug levels showed interindividual variations. Plasma levels of ocular drugs were lower when punctal occlusion was applied, the mechanism, however, could not be explained. Since an early and a late plasma peak was occasionally registered in some subjects in timolol and cyclopentolate studies, it is suggested that systemic absorption of ocular drugs is low during the nasolacrimal passage but occurs during conjunctival and nasal contact.

Abstract: In this prospective study, microdrops (mean drop volume 5.6 microl) and commercially available standard drops (mean drop volume 35.4 microl) of cyclopentolate, phenylephrine and tropicamide's clinical efficacy and systemic side effects were compared. Sixty-one infants requiring diagnostic pupil dilatation were studied for pupillary diameter, systemic blood pressure, heart rate and skin flushing changes related to the instillation of mydriatic drops. Both microdrops and standard drops of the drugs produced significant increase in pupillary diameter compared with the baseline (p 0.05). Mean blood pressure increased significantly in infants given standard drops. There was no significant change in the group that was given microdrops. In our opinion, reduced volume of mydriatics can prevent possible side effects.

Abstract: PURPOSE: Clinical aberrometry is commonly undertaken with the use of mydriatic agents, however there is no literature available on whether aberrometry results obtained under cycloplegia differ from those obtained without cycloplegia. METHODS: Higher order aberrations were measured over a 6-mm pupil with a Bausch and Lomb Technolas Zywave Aberrometer on the right eyes of 31 young subjects (average age 19.7 +/- 1.7 years; 5 females, 16 males). Two measurement conditions were used for each subject: 1) topical installation of 3 drops 1% cyclopentolate hydrochloride; and 2) topical installation of 1 drop 2.5% phenylephrine hydrochloride, prior to aberrometry measurements. RESULTS: For higher order aberrations (3rd to 5th order), average root mean square (RMS) after phenylephrine measurement (0.3852 microm) was significantly lower than after cyclopentolate (0.4259 microm). A small but statistically significant difference was found between the two conditions for average vertical and horizontal coma and, to a lesser extent, horizontal 5th order aberrations. Repeatability RMS, a measure of test-retest measurement repeatability, was similar for the two conditions at 0.15 microm, and significantly lower than the average RMS for the difference between the two conditions (residual RMS) of 0.22 microm. CONCLUSIONS: The difference between cycloplegic and non-cycloplegic aberration measurements has implications for surgical correction of higher order aberrations.