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PubMed1996

Effect of locally applied prazosin on the kinetics of the pupillary light reflex.

The effect of locally applied prazosin on pupillometric measures was studied in healthy volunteers, in an attempt to identify the role of alpha 1-adrenoceptors in the recovery time of the light reflex. Prazosin antagonized the mydriatic effect of phenylephrine, but did not alter that of tropicamide. Miotic responses to a range of light stimuli were measured under ambient temperature conditions of 22 degrees C and 40 degrees C. The 40 degrees C condition was associated with shorter recovery times of the light reflex; prazosin increased the recovery time under both temperature conditions. Response amplitude was not affected by the temperature condition or prazosin. The results are consistent with the hypothesis that sympathetic neuromuscular transmission is involved in the redilatation of the pupil following a miotic response to light stimulation.

Adolescent↗
PubMed2003

Effect of pupil size on multifocal pattern visual evoked potentials.

The purpose of this study was to investigate the influence of pupil diameter on the amplitude and latency of multifocal visual evoked potentials (mfVEP). The multifocal objective perimeter (Accumap; Objectivision) was used to stimulate the visual field at 56 sites extending to 32 degrees using a pseudo-random pattern stimulus. The mfVEP were recorded using bipolar occipital electrodes, 7 min/eye. Ten normal subjects were recruited from the community and one eye was randomly selected for testing. The mfVEP were recorded at four different pupil diameters (2 mm, 4 mm, 6 mm, 8 mm), obtained by applying tropicamide (0.5%) or pilocarpine (2%) in different dilutions. Appropriate refractive correction was provided to overcome cycloplegia and achieve a visual acuity of 6/7.5 or better. Analysis revealed that at most pupil diameters the normalized full field amplitude did not show significant variation, except at the most miotic pupil diameter (2 mm), where the amplitude became reduced, based on 2-way anova and Tukey's T method. There was, however, significant correlation between latency and pupil area (correlation coefficient: upper field -0.63, lower field -0.76). The results suggest that even in the presence of mydriatics or miotics, the mfVEP test can be used to assess diseases that affect amplitude, provided near correction is used. The interpretation of latency, however, must be made with caution, as a borderline conduction defect with a dilated pupil may appear normal.

Adult↗
PubMed2002

Effects of topical 0.5% tropicamide on intraocular pressure in normal cats.

The objective of the study was to determine the effect of topical 0.5% tropicamide on intraocular pressure (IOP) in normotensive feline eyes. IOP was measured bilaterally in 70 clinically healthy cats and gonioscopy (and goniophotography) was performed. Thereafter, 50 cats were treated unilaterally with one drop of 0.5% tropicamide. The contralateral, left eye served as a control. In the placebo group consisting of 20 cats, one drop of physiologic saline solution was administered to the right eye. In all cats, IOP of both eyes was measured 30, 60 and 90 min after topical administration. After unilateral tropicamide application, IOP increased significantly both in the right and in the left eye. Maximum average IOP increase was observed at the control measurement performed 90 min after treatment, with an elevation of 3.8 +/- 4.2 mmHg in the right eye and 3.5 +/- 3.6 mmHg in the left eye. Maximum IOP increase after treatment was 18.0 mmHg in the treated eye and 17.0 mmHg in the left eye. Measurements made at 60 min after treatment revealed a significantly higher increase in IOP in the right eye as compared to the left eye (P60 < 0.05), whereas the differences between right and left eye in IOP increase were not significant at 30 and 90 min after mydriatic application (P30 = 0.123; P90 = 0.305). Although tropicamide-induced mydriasis was observed in the treated eye, the contralateral eye did not show any changes in pupillary function at any time. With increasing age of the cats, IOP increase was found to be more moderate, whereas the gender of the cats did not have any significant influence on IOP changes. In the 20 cats in the placebo group, no significant changes in IOP were observed. We conclude that topical 0.5% tropicamide causes a significant elevation of IOP in the treated and untreated eye in normal cats.

Administration, Topical↗
PubMed2000

Effectiveness of screening and monitoring tests for diabetic retinopathy--a systematic review.

AIMS: To determine which screening and monitoring tests for diabetic retinopathy are most effective and under what circumstances. METHODS: A systematic review of the English language literature, published from 1983 to April 1999. RESULTS: Available studies are generally limited in their ability to answer the important questions on the effectiveness of tests for early detection of diabetic retinopathy. No randomized controlled trials were identified although primary studies exist for two screening tests: ophthalmoscopy, either direct or indirect, and retinal photography, using either mydriasis or non-mydriasis. Retinal photography under mydriasis appears to be the most effective test, with the majority reporting levels of sensitivity in excess of 80%. However effectiveness is compromised when photographs are ungradable. Ophthalmoscopy can also reach acceptable standards of sensitivity and specificity. CONCLUSION: Based on an assessment of available cohort studies, the most effective strategy for testing is the use of mydriatic retinal photography with the additional use of ophthalmoscopy for cases where photographs are ungradable. This does not exclude the use of ophthalmoscopy alone for opportunistic case finding but there is evidence of considerable variation in effectiveness of this test.

Diabetic Retinopathy↗
PubMed2000

[Driving ability after reversal of phenylephrine 10% induced mydriasis by dapiprazole 0.5%; a prospective study on 65 eyes].

BACKGROUND: Particularly outpatients want to reach the ability for driving a car as soon as possible after pupillary dilatation. Dapiprazole is an alpha-1 adrenergic inhibitor that antagonizes the mydriatic effect of phenylephrine in a direct competitive way. The aim of this study was to determine restoration of traffic related functions after dapiprazole application in accordance with the guidelines of the German Society of Ophthalmology (DOG). SUBJECTS: 65 eyes of 33 subjects were tested (17 females, 16 males). All had driving licenses without restrictions. Before mydriasis and after reversal with dapiprazole traffic-related functions were evaluated (photopic visual acuity, mesopic vision, sensitivity to glare, colour vision, accommodation, visual field). RESULTS: No relevant changes of the parameter responsible for the ability to drive a motor vehicle could be shown after reaching premydriatic pupil diameters. CONCLUSIONS: There is evidence that reaching normal pupil diameters after reversal of mydriasis by dapiprazole is a valid sign of restoration of traffic related functions.

Adolescent↗
PubMed2006

[Treatment of uveitis-associated refractory ocular hypotony with topical ibopamine].

BACKGROUND: Ibopamine is a non-selective dopamine- and adrenalin-receptor agonist that has been shown to cause pupillary dilation and an increase in aqueous humour secretion. This novel drug can be used as a mydriatic agent, as a provocative test in open-angle glaucoma, and for the treatment of persisting ocular hypotony. HISTORY AND SIGNS: This 47-year-old man had a history of uveitis associated with Crohn's disease. Six years after deep sclerectomy for uveitic secondary glaucoma, he developed severe hypotony in his left eye with drop of visual acuity (VA). The hypotony did not respond to topical steroid treatment. 2 % Ibopamine solution was ordered t. i. d. concomitant to 1 % prednisolone acetate. THERAPY AND OUTCOME: Intraocular pressure (IOP) began to rise after 3 weeks of Ibopamine treatment and returned to normal (12 mmHg) with continuous recovery of VA after 8 weeks. Ibopamine was discontinued at an IOP of 16 mmHg after a course of 12 weeks. IOP and VA remained stable during the 12-month follow-up period. CONCLUSIONS: Ibopamine 2 % eye drops in combination with topical steroids are a therapeutic option in uveitis-associated ocular hypotony.

Administration, Topical↗
PubMed1975

Pediatric ophthalmic mythology.

Headaches in children are virtually never the result of eye problems. If a child needs glasses, young age is almost never a contraindication to their use. Any child in whom strabismus is recognized or suspected should be referred to an ophthalmologist. The strabismus may be a presenting sign of a serious disease. Even if it is not, spontaneous cure almost never occurs. Furthermore, the younger the child, the easier and more successful will be the treatment of both the strabismus and the amblyopia that often accompanies it. Dyslexia is not the result of abnormalities of the eyes and is unaffected by eye exercises. There are no significant ocular hazards in the use of standard mydriatic (dilating) eye drops in children.

Adolescent↗
PubMed2005

Post-cycloplegia myopic shift in an older population.

PURPOSE: To demonstrate that use of a mydriatic agent remains a significant confounder in autorefraction of the presbyopic population. METHODS: The pre- and post-cycloplegic autorefraction results of 37 subjects over 50 years of age were measured using a Humphrey-598 autorefractor. The results of both eyes were included in a multivariate regression analysis. RESULTS: The average age of the patient sample was 63.4 years. The mean spherical equivalent (SEQ) shifts for the hyperopic, myopic, pseudophakic, and emmetropic eyes were -0.53 D (95% CI -0.77 D to -0.39 D; p < 0.001), -0.38 D (95%CI -0.81 D to +0.04 D; p = 0.077), -0.49 D (95% CI -0.78 D to -0.20 D; p = 0.001), and -0.35 D (95% CI -0.59 D to -0.11 D; p = 0.004), respectively. CONCLUSION: Cyclopleged autorefraction in the presbyopic population is associated with a myopic shift that can potentially lead to overestimation of myopic prevalence. This is an important factor in comparing population studies where cyclogleged autorefraction is used in contrast to non-cyclopleged autorefraction and subjective refraction.

Accommodation, Ocular↗
PubMed1999

Chemical delivery systems: evaluation of physicochemical properties and enzymatic stability of phenylephrone derivatives.

The physicochemical properties and enzymatic stability of esters of phenylephrone, synthesized on the basis of the chemical delivery system (CDS) concept, were studied as a new class of mydriatic agents. Potentiometrically determined ionization constants (pKa) of the novel compounds were in the range 7.19-7.21. The three esters of phenylephrone (isovaleryl, phenylacetyl, and pivalyl) were more lipophilic than phenylephrone as indicated by n-octanol/pH 7.4 buffer partition coefficients (log Papp) and the chromatographic capacity factors (log k'). The chemical stability of the esters of phenylephrone was evaluated in hydrochloric acid, citrate, and phosphate buffers (with pH ranging between 2.0 and 8.0), and the enzymatic hydrolysis in rat and human plasma. The samples were analyzed using HPLC assay procedures. The phenylephrone esters were found to undergo comparatively slow hydrolytic degradation in buffer with pH 3.0 and 4.0, with half-lives ranging from 1136 to 1980 hr at 37 degrees C. The novel esters were readily hydrolyzed in human plasma with half-lives ranging between 16.2 and 47.8 min. The hydrolytic degradation rates were higher in rat plasma than in human plasma, in which the half-lives were in the range of 9.8-38.3 min. In the present investigations, only phenylephrone, not the active species phenylephrine, was detected. Among the esters studied, isovaleryl ester was the most labile. Pivalyl ester, having a tertiary carbon, showed relatively high resistance to chemical and enzymatic hydrolysis because of the steric hindrance, followed by phenyl and isovaleryl esters. The results suggest that the duration of action of the phenylephrone CDS can be controlled with proper chemical manipulations.

Animals↗
PubMed2001

Maintenance of mydriasis with one bolus of epinephrine injection during phacoemulsification.

Surgically-induced miosis commonly occurs during cataract extraction surgery, complicating removal of lens cortex and placement of a posterior chamber intraocular lens. To maintain intraoperative mydriasis, one bolus of epinephrine injection was used in our study. The pupillary response to various doses of intracameral epinephrine (0.1 ml of 1:25,000, 1:50,000, 1:100,000, 1:200,000, 1:400,000) was assessed in 60 consecutive patients. The pupil size was measured just prior to the incision, one min after epinephrine injection, after phacoemulsification and after irrigation/aspiration. There was no significant difference among the mean mydriatic responses to the epinephrine concentrations we tested. The 1:400,000 concentration appeared to be as effective as 1:25,000, but two cases of the 1:400,000 group failed to maintain the pupil diameter after irrigation/aspiration. In addition, we found that blood pressure did not elevate after injection of any concentration of epinephrine. We concluded that one bolus of an extremely dilute concentration of epinephrine (i.e., 1:400,000) injection might be effective in maintaining mydriasis during cataract surgery without systemic side effects.

Aged↗
PubMed1987

The specificity of the pupillary actions of morphine and naloxone.

Like many other opiates, morphine has a specific dose dependent mydriatic effect in mice which is antagonized by naloxone. In the present work we have studied the pupillary effects of the dextrorotatory isomers of morphine and naloxone, in comparison with the levorotatory active isomers. The dextrorotatory isomers lacked agonist and antagonist action, respectively. These results confirm that the pupillary effects of opiates are mediated through specific opiate receptors.

Animals↗
PubMed1998

The effect of intracameral adrenaline infusion on pupil size, pulse rate, and blood pressure during phacoemulsification.

Pupillary constriction during phacoemulsification (phaco) and irrigation/aspiration (I/A) is found to be the major cause of iris damage, incomplete cortex removal, posterior capsule rupture, vitreous loss and even posterior lens material dislocation. Cataract surgery is performed more easily if mydriasis can be maintained. Irrigation fluid containing adrenaline is thought to be of benefit in this respect. We designed a prospective study assessing the efficacy and safety of using perioperative adrenaline during phacoemulsification, as an adjunct to preoperative topical mydriatics. Forty-two cases were randomized to receive intraocular irrigation fluid with or without 1:1,000,000 adrenaline, as a study or control group. Diameter of the pupil, pulse rate, systolic and diastolic pressure before-phaco, after-phaco-before-I/A and after-I/A were measured. All of the operations were performed by the same surgeon with the same technique. The pupil size after-phaco-before-I/A was 8.00 mm in the study group and 5.96 mm in the control group. The mydriasis maintained during phacoemulsification was significantly greater in the study group, p < 0.00001. The pupil size after-I/A was 8.03 mm in the study group, and 5.54 mm in the control group. The mydriasis maintained during I/A was significantly greater in the study group, p < 0.00001. Pulse rate and blood pressure in patients of the study group, even those with hypertension, showed no significant fluctuation during the surgery. We concluded that intraocular irrigation with 1:1,000,000 adrenaline was a safe and effective way of maintaining mydriasis during cataract surgery.

Blood Pressure↗
PubMed1996

Pupil dilatation assay by tropicamide is modulated by apolipoprotein E epsilon 4 allele dosage in Alzheimer's disease.

The mydriatic response to dilute tropicamide was studied in 25 Japanese patients with Alzheimer's disease (AD), 13 patients with non-AD neurological diseases (non-AD) and 11 normal elderly subjects (control). Although the changes in resting pupil diameter and area over baseline were significantly greater (p < 0.05) in AD patients than in non-AD patients and controls, there was considerable overlap between the three groups. The change in resting pupil area was significantly greater (p < 0.05) in AD patients homozygous for ApoE epsilon 4 than in AD patients heterozygous for or without this allele. Despite a limited sample size in the present study, our results indicate that the pupil dilation assay by tropicamide is not an effective diagnostic tool for AD, and it may be modulated by different gene dosage of ApoE epsilon 4.

Aged↗
PubMed1988

Does anisocoria by clonidine reflect a central sympathetic dysfunction in cluster headache?

Local pharmacological manipulations of both pupils in persons with cluster headache (CH) have shown a reduced pain-side sympathetic activity. It is difficult to determine if this sympathetic defect is localized in the nuclei of the CNS and/or in peripheral neurons that innervate the pupil. This study demonstrates that in a CH group 2% tyramine (an intraneuronal norepinephrine releaser) instillation into both eyes induces an asymmetric and bilateral mydriasis with the onset of anisocoria characterized by a pupillary diameter being less on the pain-side eye. In addition, intravenous administration of 0.10 mg clonidine, an inhibitor of central sympathetic activity, causes a bilateral miotic response, which is more marked on the pain-side eye. In a healthy control group, clonidine induces a symmetric and bilateral miosis but less intense than that observed in both eyes of CH sufferers. In CH patients, pretreatment with clonidine augments the degree of anisocoria induced by tyramine instillation, increasing the mydriatic response only in the pain-free-side pupil. The hypothesis of a permanent sympathetic defect of the pain-side pupil expressing itself as a reduced sympathetic tone of CNS nuclei and peripheral neurons that innervate the pupil is proposed.

Adult↗
PubMed1977

Effects of topical anesthetics on phenylephrine-induced mydriasis.

Pupil responses to phenylephrine alone and to phenylephrine preceded by a topical anesthetic were recorded by means of an infrared pupillometer. In response to phenylephrine, pupils dilated more in eyes with pale irides. Dilation was greater if a topical anesthetic was applied before the mydriatic. Benoxinate, proparacaine, and tetracaine produced approximately equal degrees of enhancement of the mydriasis. One drop of 1% phenylephrine had only a small dilating effect on an eye when the fellow eye received the phenylephrine preceded by 0.5% proparacaine.

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↗
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↗
PubMed1990

Effects of dapiprazole on the reversal of pharmacologically induced mydriasis.

The ability of a new alpha-adrenergic antagonist, dapiprazole, to reverse mydriasis produced by phenylephrine 2.5% or 10%, tropicamide 0.5%, and the combination of phenylephrine 2.5% and tropicamide 0.5% was investigated. A double masked crossover design was used to study both efficacy of mydriatic reversal and time course. The safety of administration was evaluated as well. Subjects were optometry students and their spouses. The results demonstrate that dapiprazole is safe and effective for reversing mydriasis produced by both concentrations of phenylephrine, and partially effective in reversing mydriasis in eyes treated with tropicamide 0.5%, alone, or in combination with 2.5% phenylephrine.

Accommodation, Ocular↗