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At least 451 records · Page 25Linked to original sources
PubMed2005

Why patients with Alzheimer's disease may show increased sensitivity to tropicamide eye drops: role of locus coeruleus.

RATIONALE: Patients suffering from Alzheimer's disease (AD) may show increased sensitivity to tropicamide, a muscarinic cholinoceptor antagonist. AD is associated with a severe loss of noradrenergic neurones in the locus coeruleus (LC), which can be "switched off" experimentally by the alpha(2)-adrenoceptor agonist clonidine. The possibility arises that increased pupillary sensitivity to tropicamide in AD may be due to diminished LC activity. OBJECTIVE: To examine the hypothesis that clonidine may potentiate tropicamide-evoked mydriasis. MATERIALS AND METHODS: Sixteen healthy male volunteers participated in two experimental sessions (0.2 mg clonidine or placebo) conducted 1 week apart. In each session tropicamide (0.01% 10 microl x 2) was applied to the left eye and artificial tear (10 microl x 2) was applied to the right eye. Pupillary functions (resting pupil diameter and light and darkness reflexes), alertness and non-pupillary autonomic functions (blood pressure, heart rate, core temperature and salivary output) were measured. Data were analysed by ANOVA, with multiple comparisons. RESULTS: Tropicamide increased resting pupil diameter, velocity and amplitude of the darkness reflex response, and decreased recovery time of the light reflex response. Clonidine affected all these pupillary measures in the opposite direction with the exception of the recovery time. The mydriatic response to tropicamide was potentiated by pre-treatment with clonidine. Clonidine reduced critical flicker fusion frequency, subjective alertness, blood pressure, salivation and temperature. CONCLUSIONS: The potentiation of tropicamide-evoked pupil dilatation by clonidine may be due to the abolition of the increase in parasympathetically mediated pupil constriction due to reduced LC activity.

Adrenergic alpha-Agonists↗
PubMed2003

[Atypical tonic pupil as a complication of chickenpox infection].

BACKGROUND: Pupillary disorders following varicella infections are rare and few cases have been reported which were only partially pharmacologically tested. MATERIALS AND METHODS: A 5-year-old boy presented with a left-sided dilated and unreactive pupil, 3 months before he had suffered from chickenpox and in the course of the acute disease developed anterior uveitis which was treated with local prednisone and mydriatics. The pupil remained dilated despite discontinued medication, light reaction was absent and accommodation was impaired. Pilocarpine supersensitivity was an indication against a lesion of the sphincter muscle and reduced response to cholinesterase inhibitors (physostigmine) pointed towards a postganglionic lesion. CONCLUSIONS: It is probable that a varicella virus infection of the short ciliary nerves and the ciliary ganglion caused anterior uveitis and a postganglionic parasympathetic nerve lesion, clinically presenting as a tonic pupil. According to cases previously reported an irreversible nerve lesion has to be assumed.

Anti-Inflammatory Agents↗
PubMed1999

[Clinical use of mydriasis with 10% phenylephrine and its antagonism by 0.5% dapiprazole].

BACKGROUND: Dapiprazole hydrochloride is an alpha-1-adrenergic inhibitor that anticipates the mydriatic effect of phenylephrine in dilator muscle receptors in a competitive way. The aim of this study was to determine for which indications for mydriasis pupil dilation by phenylephrine alone is sufficient and if the reversal by dapiprazole is convenient and the practical. MATERIAL AND METHOD: In 286 eyes of 147 outpatients, the pupil was dilated for fluorescein angiography-FLA (100 eyes of 50 patients), examination of the fundus-Fd (99 eyes of 52 patients), central argon laser coagulation-cALC) (64 eyes of 32 patients), peripheral argon laser coagulation-pALC (16 eyes of 9 patients) and Nd:YAG capsulotomy (7 eyes of 4 patients) with phenylephrine 10% eyes drops, followed by reversal by dapiprazole 0.5%. The width and mobility of the pupil were tested at intervals of 10 min. When mydriasis by phenylephrine was insufficient, tropicamide was applied additionally. RESULTS: In 98% of FLA with scanning laser ophthalmoscope, 75% of cALC, 76% of Fd, 62% FLA with fundus camera and 38% of pALC, mydriasis could be reached that was sufficient for the indication. Diabetics showed significantly more sluggish pupil mobility (t1/2: P < 0.05 mydriasis, P < 0.005 reversal). The mean duration after using dapiprazole until reaching the starting value (+/- 1 mm) of the pupil was 44.3 +/- 26.3 min. In 86% of the examined eyes, the pupil reached its starting value within 1 h. The subjective degree of satisfaction with the application of dapiprazole was "satisfied" to "very satisfied" (5.4 +/- 1.4 points on a scale from 1 to 7 points). DISCUSSION AND CONCLUSION: In fundus examination, fluorescein angiography by a laser scanner, diagnostic retinal examination and central laser coagulation, the combination phenylephrine/dapiprazole was most suitable. In our opinion, the combination is less suitable for peripheral argon laser coagulation and fluorescein angiography using a fundus camera.

Adolescent↗
PubMed2004

The effects of pupil size on the multifocal electroretinogram.

This is an investigation of the effect of changing the pupil diameter on the P1 amplitude and latency of the multifocal electroretinogram (mfERG). MfERGs were recorded using a custom built wide field electrophysiological system. An array of 61 empirically scaled hexagons was used to stimulate the visual field. The duration of overall recording period was 8 min, segmented into 16 intervals each lasting 30 s. A combination of mydriatics and miotics were used to pharmacologically alter the pupil size and diameters between 1 and 10 mm were measured. There was a reduction in mfERG P1 amplitude in some cases greater than 50% (mfERG P1 amplitude 53 nV at 8 mm to 25 nV at 1 mm), with a change in pupil diameter of 7 mm. The mfERG P1 latency increased in some cases by as much as 8 ms in the central 40 degrees (mfERG P1 latency 39 ms at 8 mm to 47 ms at 1 mm). These results suggest that pupil size has significant effects on mfERG P1 amplitude and latency.

Electroretinography↗
PubMed1985

Comparison of the effects of detomidine and xylazine on some alpha 2-adrenoceptor-mediated responses in the central and peripheral nervous systems.

The effects of detomidine, a novel veterinary sedative analgesic, on some alpha 2-adrenoceptor-mediated responses in the central and peripheral nervous systems were studied. In pithed rats, detomidine was a very potent agonist at both pre- and postsynaptic alpha 2-adrenoceptors. Doses of 1.9 micrograms/kg and 6.5 micrograms/kg inhibited electrically induced tachycardia by 50% and increased mean blood pressure by 50 mmHg, respectively. In comparison, xylazine, though similar in specificity, was 40 times less potent than detomidine in this preparation. In unanaesthetized rats, detomidine both caused sedation and induced complex changes in body temperature. Low doses caused decreases in rectal temperature but these were reversed as the dose was increased. The decrease in rectal temperature could be blocked by yohimbine. Prazosin somewhat inhibited but did not eliminate the hyperthermia seen with the very high doses of detomidine. Xylazine caused much more severe falls in rectal temperature which could not be completely antagonized by alpha 2-adrenoceptor blockade. Both detomidine and xylazine caused dose-dependent mydriasis in anaesthetized rats, detomidine being about 10 times more potent than xylazine. The mydriatic effects of detomidine could be prevented by alpha 2- but not by alpha 1-adrenoceptor blockade. It is concluded that detomidine is a potent and rather specific alpha 2-adrenoceptor agonist in the central and peripheral nervous systems. In comparison with xylazine, detomidine has higher potency and greater specificity, especially at central alpha 2-adrenoceptors.

Animals↗
PubMed1995

Mediation of mydriasis in conscious rats by central postsynaptic alpha 2-adrenoceptors.

The alpha 2-adrenoceptor agonist, clonidine (0.001-1 mg/kg, IP), dose-dependently induced mydriasis in conscious rats (ED50 0.088 mg/kg). This response was maximal when measured 10 min after clonidine injection and was of about 30-min duration. The noradrenaline releasing agent, methamphetamine (0.75 mg/kg, IP), also increased pupil diameter. Clonidine (0.03 mg/kg, IP)-induced mydriasis was inhibited in a dose-related fashion by the alpha 2-adrenoceptor antagonists, idazoxan (0.03-3 mg/kg, IP) and yohimbine (0.03-3 mg/kg, IP), but was unaltered by the alpha 1- or beta-adrenergic antagonists, prazosin (1 and 3 mg/kg, IP) or pindolol (1 and 3 mg/kg, IP). Methamphetamine (0.75 mg/kg, IP)-induced mydriasis was similarly inhibited by idazoxan (1 mg/kg, IP) and yohimbine (1 mg/kg, IP). These data argued strongly that central alpha 2-adrenoceptors are involved in the mediation of mydriasis. The synaptic location of these receptors was determined using DSP-4 (50 mg/kg x 2, IP) to lesion noradrenergic neurones: this produced a 64% depletion of noradrenaline in the midbrain (containing the Edinger-Westphal nucleus responsible for mydriasis) and reduced the mydriatic effect of methamphetamine (0.75 mg/kg, IP) to a similar extent (72%), whereas clonidine mydriasis remained unaltered. Therefore, these results show that the mydriasis responses induced by either clonidine or methamphetamine are mediated by central postsynaptic alpha 2-adrenoceptors.

Adrenergic Agents↗
PubMed1986

Pupillary dilation as an index of central nervous system alpha 2-adrenoceptor activation.

In recent years there has been increasing evidence that some antihypertensive drugs like clonidine and alpha-methyldopa (after conversion in the brain to alpha-methylnorepinephrine) may decrease sympathetic tone by stimulating central nervous system (CNS) alpha 2-adrenoceptors. These same drugs also produce pupillary dilation in cats and rats. In this review, evidence is presented supporting the hypothesis that clonidinelike drugs act either directly or indirectly on CNS postsynaptic alpha 2-adrenoceptors to cause pupillary dilation by reduction of parasympathetic neural tone to the iris. It is further suggested that the underlying physiologic mechanism for this mydriatic action is activation of an ascending pathway that provides tonic inhibitory input by releasing norepinephrine on neurons in the Edinger-Westphal complex. Yohimbine-sensitive pupillary dilation in these species may provide a simple and effective model for quantitatively accessing CNS alpha 2-adrenoceptor activity.

Adrenergic alpha-Agonists↗
PubMed1992

The trigemino-pupillary reflex: a model of sensory-vegetative integration.

Trigeminal stimulation can induce pupillary changes. In vivo and in vitro studies have demonstrated that electrical impulses applied at the trigeminal level can provoke a miotic response, whose nature has been ascribed to the anti-dromic release of neuropeptides (substance P in particular). In order to better define the pupil response to trigeminal stimulation, we investigated the human pupil response to quantified (painless and painful) corneal stimuli by means of a combined (neurophysiological and pharmacological) technique. The response to corneal stimulation was bilateral, direct and consensual. It had a biphasic progression with an initial mydriasis (which directly correlated with the stimulus intensity), followed by a miotic phase. The mydriatic phase disappeared after thymoxamine application, while homatropine pre-treatment prevented occurrence of the miotic phase. The data obtained indicate that the pupillary response to corneal stimulation (trigemino-pupillary reflex) is a multisynaptic reflex with an afferent branch involving the trigeminal system, and an afferent branch involving both the sympathetic and the parasympathetic system. Other pathways, such as the SP-mediated release of acetylcholine, cannot be excluded. Thus the reflex appears to be a potentially useful tool for investigating pain/vegetative interactions in various clinical conditions. In turn, the description of its changes in pathologies characterized by a sympathetic/parasympathetic deficit or by a SP-ergic imbalance will allow us to better describe its inner mechanisms.

Adult↗
PubMed2003

Cataract surgery without preoperative eyedrops.

We present a technique that uses intracameral lidocaine to induce pupil dilation without using preoperative mydriatic eyedrops. After 1 or 2 drops of topical lidocaine hydrochloride 1% (Xylocaine-MPF 1%) are applied to the ocular surface, a 1.0 mm side-port incision is created through which Xylocaine-MPF 1% is injected into the anterior chamber. The lidocaine paralyzes the pupil sphincter, and adequate mydriasis occurs within 90 seconds. Epinephrine (0.3 cc of 1:1000) is added to the irrigation fluid comprising balanced salt solution (BSS), and standard phacoemulsification with intraocular lens implantation is performed. Pupil dilation is maintained or increased during the procedure. Postoperatively, the pupil returns more quickly to normal size and reaction. Using lidocaine for mydriasis instead of standard dilating drops eliminates the cardiac risk of topical sympathetic agents, decreases the time patients wait in the holding area before surgery, reduces the risk of superficial punctate keratopathy, and provides faster recovery of normal pupil function.

Anesthetics, Local↗
PubMed2005

Visualization of anterior chamber angle dynamics using optical coherence tomography.

PURPOSE: To describe the technology of optical coherence tomography (OCT) in imaging the anterior chamber angles and its impact on understanding the pathophysiology of angle-closure glaucoma (ACG). DESIGN: Observational case series. PARTICIPANTS: Three subjects with, respectively, impending angle-closure attack, plateau iris syndrome, and phacomorphic glaucoma were recruited. METHODS: The anterior chamber angle in each patient was imaged with a commercially available OCT unit. The angle configurations were assessed and compared before and after laser peripheral iridotomy (LPI) and argon laser peripheral iridoplasty (ALPI). MAIN OUTCOME MEASURES: Visualization of the changes in the anterior chamber angle configurations and normalization of the intraocular pressure (IOP). RESULTS: A patient with impending angle-closure attack precipitated by a topical mydriatic agent was treated with LPI. Optical coherence tomography imaging of the anterior chamber angles was performed before and after the laser procedure. Conversion of anterior iris bowing and angle crowding to iris straightening and angle opening after LPI was demonstrated. Intraocular pressure became normalized with the change in angle configuration. The second patient presented with symptoms of intermittent angle-closure attacks and was initially diagnosed with primary ACG. Despite successful LPI, the angles remained occludable, and the IOP continued to be elevated. Optical coherence tomography was used to review the anterior chamber angle configuration and demonstrated a typical pattern compatible with the diagnosis of plateau iris syndrome. Subsequent ALPI converted the plateau configuration to open angle, with normalization of IOP and disappearance of symptoms. The third patient presented with an acute angle-closure attack and was diagnosed with phacomorphic glaucoma. Argon laser peripheral iridoplasty was performed successfully to open the angle, as evident by the OCT images, and the IOP was brought under control, together with relief of symptoms. CONCLUSIONS: The commercially available OCT unit can be practically employed for anterior chamber angle imaging. The different patterns of angle configurations are correlated with the underlying pathophysiology in different forms of ACG.

Aged↗
PubMed2005

Evaluation of a new preoperative ophthalmic solution.

BACKGROUND: Maximum mydriasis and corneal clarity during intraocular surgery are important to ensure operational safety. However, repeated instillation of mydriatic and anti-inflammatory ophthalmic solutions during surgery may affect compliance and may damage the corneal epithelium. We developed an ophthalmic solution containing tropicamide, phenylephrine hydrochloride and diclofenac sodium, and compared the properties and effect on corneal epithelial barrier function and on mydriasis of the solution and of its individual components. METHODS: We developed the ophthalmic solution by mixing 10 mL of 0.5% tropicamide/0.5% phenylephrine, 10 mL of 5% phenylephrine and 10 mL of 0.1% diclofenac (TPD). We determined the stability of the chemicals in solution using high-performance liquid chromatography immediately, 1 week and 1 month after mixing. Corneal epithelial barrier function was assessed before and after instillation of the solutions in 26 eyes of 17 patients (5 with proliferative diabetic retinopathy or diabetic maculopathy, 8 with cataract and 4 with no eye disease). The fluorescent intensity was measured 10 times at the central cornea 30 minutes after instillation of 3 mL of 0.5% fluorescein solution and the average value calculated. Finally, the pupil diameter of 50 eyes of 38 patients undergoing cataract surgery was measured before and immediately after the operation. RESULTS: No remarkable changes in the pH or pharmacologic activity of the TPD solution were observed at any time after mixing. In the patients with diabetic retinopathy or cataract, the increase in mean fluorescent intensity was significantly greater with the individual solutions than with the TPD solution (p < 0.01); there was no significant difference in mean fluorescent intensity in the subjects with no eye disease. No statistically significant difference in pupil diameter was observed between the eyes that received the TPD solution and those that received the individual solutions. INTERPRETATION: TPD ophthalmic solution is simple to prepare and use. The TPD solution had a similar effect on mydriasis as the three individual solutions but was less destructive to the corneal epithelium.

Adult↗
PubMedDate not supplied

Effect of decreased retinal illumination on frequency doubling technology.

PURPOSE: To investigate the effect of changes in retinal illumination on Frequency Doubling Technology (FDT). METHODS: Five eyes, of 5 adults who were free from identifiable ocular pathology, were examined using the Snellen chart and the Pelli-Robson chart, conventional automated perimetry, and the full threshold N-30 program of FDT. Each test was performed with and without a 0.9, 1.5, or 2.4 log unit neutral-density (ND) filter placed before the eye. Furthermore, the influence of pupil diameter on FDT test results was compared after treatment with pilocarpine or cyclopentolate with the influence of ND filters. RESULTS: All tests showed a decrease in sensitivity with decreasing retinal illumination. Frequency Doubling Technology showed an especially pronounced and significant decrease in sensitivity. The maximum mean threshold difference in FDT results with ND filter was 31.2 dB while that with the Humphrey Field Analyzer and the Pelli-Robson chart were 13.3 dB and 0.66 log contrast, respectively. The mydriatic state of the pupil increased the sensitivity of FDT and the miotic state decreased it to about the same extent as the the 0.9 ND filter. CONCLUSION: The change in retinal illumination has more impact on FDT than on spatial contrast tests and conventional automated perimetry. It is important to take this into account in evaluating FDT results.

Adaptation, Ocular↗
PubMedDate not supplied

Recent advances in uveitis of juvenile idiopathic arthritis.

Chronic scarring-type uveitis is a frequent extra-articular manifestation of juvenile idiopathic arthritis. It occurs in about 20% of children with this disease, commencing typically within a few years from its onset. The risk of uveitis is greatest in antinuclear antibody-positive girls with early onset oligoarthritis. The classic clinical picture is chronic bilateral anterior uveitis, usually asymptomatic until substantial damage to intraocular structures occurs. In view of the asymptomatic nature of the condition, routine screening of juvenile idiopathic arthritis patients 2-4 times a year is crucial to prevent complications. The treatment consists of topical corticosteroids and mydriatics, in severe cases with immunosuppressive agents, and surgical management of complications. Although the prognosis of uveitis is improving, there are cases refractory to standard regimens. Patients in whom uveitis commences prior to the onset of arthritis present a special problem.

Anti-Inflammatory Agents↗
PubMed1980

A new low-concentration preparation for mydriasis and cycloplegia.

This study was designed to evaluate a low-concentration, cycloplegic-mydriatic mixture of phenylephrine and tropicamide in a routine office examination. No clinically significant difference in pupillary dilation was found between the usual instillation of the standard, commercially available phenylephrine 10% and tropicamide 1% drops and the prepared, low-concentration solution. Pupillary dilation was well maintained during direct and indirect ophthalmoscopy and retinoscopy. This solution is easily prepared from readily available drugs, and is simply delivered to the eye using a standard eye dropper. The safety and effectiveness of this low-concentration mixture of phenylephrine and tropicamide make it strongly recommended for routine use.

Administration, Topical↗
PubMed1999

Formulation and in vivo evaluation of ocular insert containing phenylephrine and tropicamide.

A Gelfoam based ocular device containing 1.7 mg of phenylephrine and 0.6 mg of tropicamide was formulated and evaluated for pupillary dilation in rabbits. The manufacturing procedure is fairly simple and the required excipients are inexpensive. The in vivo results show that the mydriatic response produced by the proposed device is larger and longer lasting than that produced by eyedrops with an equivalent amount of phenylephrine and tropicamide. The results reported in this study, along with those of previous studies, imply that Gelfoam(R) is a versatile drug carrier for either local or systemic drug delivery via the ophthalmic route.

Animals↗
PubMed1998

Systemic diclofenac sodium to maintain mydriasis during phacoemulsification.

PURPOSE: To determine whether systemic diclofenac sodium affects the maintenance of mydriasis during phacoemulsification and to compare pupil diameter regression rates with those in a control group. SETTING: An ophthalmic unit of a National Health Service Trust Hospital in the United Kingdom. METHOD: A prospective, randomized control study of 100 patients presenting for cataract surgery was undertaken. Both groups were administered an identical mydriatic regime commencing 1 hour before surgery. In addition, the diclofenac group (n = 48) received 50 mg of oral diclofenac sodium 1 hour before surgery. Both the control (n = 52) and diclofenac groups had phacoemulsification by one experienced surgeon using a standard technique. The surgeon was masked as to which group the patient belonged. The irrigating fluid in all cases contained adrenaline. Pupil diameter was measured at five stages during surgery and recorded along with the times relative to the start of the procedure. RESULTS: Mean pupil diameter in the diclofenac group was slightly larger than in the control group, but the difference was not significant. Although mean pupil diameter at the start of surgery was 0.4 mm greater in the diclofenac group, the slopes of regression in pupil diameters were virtually identical between the first three stages of surgery, after which a slight reversal occurred in both groups. The slope of regression of mydriasis was small in both groups. CONCLUSION: Systemic diclofenac sodium 50 mg given orally 1 hour before surgery did not significantly inhibit miosis when compared with a control group. Regression rates of pupil mydriasis were small in both groups.

Administration, Oral↗
PubMed1995

Corneal perforation as a complication of epidermolysis bullosa acquisita.

Epidermolysis bullosa acquisita (EBA) is now recognised as a histopathologically distinct condition. Ocular complications of hereditary epidermolysis bullosa (EB) have been well documented, but little has been reported with respect to the ocular manifestations associated with the acquired form. A patient with EBA and sarcoidosis--an association that does not appear to have been previously reported--developed spontaneous peripheral corneal melting and perforation. The defect healed with the use of a bandage contact lens, antibiotics, mydriatics and pulsed intravenous steroids, and resulted in a satisfactory visual outcome.

Adult↗
PubMed1999

The incidence of systemic side-effects following subconjunctival Mydricaine no. 1 injection.

PURPOSE: To investigate the cardiovascular response to the subconjunctival injection of 0.25 ml of Mydricaine No. 1 during vitrectomy surgery. METHODS: Pulse and blood pressure were recorded at 5 min intervals before and following the subconjunctival injection of Mydricaine No. 1 in a group of 49 sequential patients undergoing vitrectomy surgery under general anaesthetic during a 6 month period. These responses were compared with a sequential and similar group of 35 patients during the following 6 months. RESULTS: Ten patients in the group administered Mydricaine, but no patients in the control group, developed a sinus tachycardia of > 100 beats/min for more than 10 min which was attributable to the mydriatic regime used. The occurrence of this response was not predictable based on the patients' age, weight or the presence of conjunctival erythema. The magnitude and temporal course of the tachycardia observed were variable. Blood pressure recordings showed no clinically significant changes during the tachycardias. CONCLUSION: Twenty per cent of patients administered 0.25 ml of Mydricaine No. 1 subconjunctivally develop a significant sinus tachycardia following injection. This response is unpredictable and all patients given Mydricaine should be monitored carefully after injection.

Adolescent↗