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Results for “INTRAOCULAR PRESSURE”

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PubMed2001

Twenty-four hour intraocular pressure reduction with latanoprost compared with pilocarpine as third-line therapy in exfoliation glaucoma.

PURPOSE: To compare the 24 hour efficacy of latanoprost 0.005% given every evening with that of pilocarpine 4% given four times daily as third-line therapy in patients with exfoliation glaucoma receiving timolol 0.5% and dorzolamide 2% each given twice daily. METHOD: We enrolled 30 patients with exfoliation glaucoma not adequately controlled on timolol maleate 0.5% and dorzolamide 2%. Each patient underwent a baseline 24 hour intraocular pressure curve testing at 06:00, 10:00, 14:00, 18:00, 22:00 and 02:00 hours. Patients were randomised to receive either latanoprost 0.005% or pilocarpine 4% for a minimum of 8 weeks and were then crossed over to the opposite therapy. Diurnal curve testing was repeated at the end of each treatment. RESULTS: There was a significant decrease from baseline in intraocular pressure at each timepoint for both study medicines (p < 0.016). Latanoprost provided better intraocular pressure control than pilocarpine at daytime measuresments (17.4 vs 19.7 mmHg at 06:00 hours, p < 0.001; 17.8 vs 19.1 mmHg at 10:00 hours, p = 0.04). However, pilocarpine reduced the pressure more than latanoprost at 22:00 hours (18.4 vs 19.5 mmHg, p = 0.016). Overall, the diurnal intraocular pressure was reduced from a baseline of 21.5 +/- 3.7 mmHg to 18.8 +/- 3.1 mmHg on pilocarpine and to 18.0 +/- 3.0 mmHg on latanoprost (p = 0.06). In addition, mean peak pressure was similar between pilocarpine (21.0 +/- 2.9 mmHg) and latanoprost (20.5 +/- 3.8 mmHg) (p = 0.20). Side-effects were similar with the exception of blurred vision, which was only found with pilocarpine (10%). Compliance was more difficult with pilocarpine. CONCLUSION: In exfoliation glaucoma, as a third-line adjunctive therapy added to timolol and dorzolamide, latanoprost and pilocarpine have similar diurnal efficacy. However, latanoprost provides a greater morning pressure reduction.

Aged↗

PubMed1993

[New experimental model of central regulation of intraocular pressure].

We investigated the effect on the intraocular pressure (IOP) of microiontophoretic injection of oxytocin (OXT) into the cat hypothalamus, to elucidate the mechanisms of IOP regulation by the central nervous system (CNS). Under sodium pentobarbital anesthesia, the cat was fixed in a stereotaxic apparatus, immobilized, and ventilated artificially through a tracheal cannula. The IOP and blood pressure were continuously recorded with an electromanometer. A 3- to 5-barreled glass microelectrode was used; OXT and saline as a control were injected iontophoretically into the hypothalamus according to the stereotaxic coordinates. On completion of the experiment, the animal was deeply anesthetized and perfused transcardially. Frozen sections were cut and stained with neutral red, and the tracks of the electrodes were reconstructed. The IOP was elevated gradually without change in blood pressure, when OXT was injected into the supraoptic nucleus. The latency and the amplitude of this response were 171 +/- 25 sec and 0.99 +/- 0.46 mmHg (average +/- SD; n = 4), respectively. The IOP showed no change after saline application to the same site. We concluded that OXT-sensitive cells in the cat hypothalamus may play a role in regulating IOP. This model may be useful to study the mechanisms of IOP regulation by the CNS.

Animals↗

PubMed1998

Pulsatile ocular blood flow and intraocular pressure during retrobulbar injection of lignocaine: influence of additives.

PURPOSE: To assess the influence of adrenaline and hyaluronidase on pulsatile ocular blood flow and intraocular pressure changes during retrobulbar anesthesia. METHOD: Patients undergoing cataract surgery under local anesthesia received a 5-mL retrobulbar injection of lignocaine with either adrenaline, hyaluronidase, or no addition. Continuous pneumotonometry was performed using the OBF tonograph (OBF Labs, Chippenham, UK), which automatically derives pulsatile ocular blood flow values. Measurements were taken before and one minute after injection, and changes were compared between groups to evaluate the effects of changing the constituents of the injection. RESULTS: There was a marked decrease in pulsatile ocular blood flow during injection in all groups. In the group receiving lignocaine with hyaluronidase, the decrease in pulsatile ocular blood flow (mean -141 microL/min) was significantly less than in either the group receiving lignocaine and adrenaline (mean -249 microL/min) or the group receiving lignocaine alone (mean -245 microL/min). There was no significant change in intraocular pressure in any group. CONCLUSION: Hyaluronidase appears to lessen the reduction in pulsatile ocular blood flow. Injection volumes of 5 mL need not cause significant intraocular pressure change.

Anesthesia, Local↗

PubMed2004

Cluster headache: interictal asymmetric increment in intraocular pressure elicited by Valsalva manoeuvre.

Changes in intraocular pressure (IOP) elicited by a Valsalva manoeuvre were studied in 11 male patients (mean age 39.8 years) suffering from episodic cluster headache (CH), and 12 healthy male controls (mean age 39.9 years). The tests were performed at rest and while exhaling hard through a mouthpiece connected to a mercury manometer. In the CH group, during symptomatic periods, between attacks, Valsalva manoeuvre elicited an asymmetric increase in IOP with significantly higher values on the symptomatic side (P = 0011), whereas no asymmetric increments in IOP were found during asymptomatic periods. Outside the cluster period the IOP values both baseline and with Valsalva manoeuvre did not differ from controls. The increment in IOP took place within a few seconds, as in spontaneous CH attacks, thus pointing to a rapid increase in intraocular blood volume or vasodilatation. These findings may reflect a latent increased vascular reactivity of the symptomatic orbit during CH period.

Adult↗

PubMedDate not supplied

A new electromechanical method for measuring intraocular pressure.

A new electromechanical method to measure intraocular pressure is presented. A light probe was made to collide with an eye (cornea or sclera) and to bounce back. The impact was registered by an acceleration sensor or the duration of contact with the eye was measured using the phenomenon of the electrical conductivity of biological objects. Laboratory experiments were carried out using pig eyes pressurized with water leveled to different heights. Preliminary clinical trials were carried out comparing the values obtained with those of the Goldmann applanation tonometer. The time of contact and the deceleration time decreases and the deceleration maximum increases in proportion with IOP. A new kind of tonometer can be constructed based on this principle. Measurement can be performed to cornea or sclera without an anesthetic drop. Further study is required to evaluate the accuracy and usefulness of this method.

Animals↗

PubMed1979

Effect of beta-phenylethylamine on intraocular pressure.

Upon injection of beta-phenylethylamine (PEA) into the subconjunctival space of rabbit, intraocular pressure increased. This effect went parallel with the amount of PEA transferred into the anterior chamber, which indicates that intraocular pressure was elevated by direct action of PEA.

Animals↗

PubMed1987

Diurnal variation of intraocular pressure and the overriding effects of sleep.

Intraocular pressure (IOP) was recorded regularly over a 24-h period in 13 normal subjects. All subjects showed a dramatic rise in IOP after sleep, ranging from 37 to 248%. In a second experiment, IOP decreased when 15 subjects remained upright and awake throughout the night. When sleep was not permitted IOP was lowest at 3:00 a.m. (0300); when six of these subjects were permitted to sleep from 0600 to 0800, they showed a rapid and significant increase in IOP of up to 150%, whereas the remaining nine subjects showed (posturally induced) increases of up to 38%.

Adolescent↗

PubMed1980

Influence of morphine and naltrexone on the intraocular pressure of conscious cynomolgus monkeys (Macaca fascicularis).

Intraocular pressure (IOP) was measured by applanation tonometry in four trained conscious monkeys (Macaca fascicularis) which were treated with morphine (5 mg/kg), naltrexone (1 mg/kg) and a mixture of both drugs (in the same doses as given separately). Morphine lowered IOP in all animals at both 20 and 40 min after drug administration. The inter-individual scatter was 1.8--11 mm Hg. Mydriasis was noted in three monkeys. Behaviour was characteristically affected. The morphine antagonist naltrexone one and the mixture of morphine and naltrexone had no effect on IOP or pupil. Behaviour, however, differed from the normal as well as the morphine-induced behaviour. The results indicate that the morphine effect on IOP must be mediated by a specific agonistic action on the morphine receptor.

Animals↗

PubMed1997

Experimental glaucoma: perimetric field defects and intraocular pressure.

PURPOSE: To investigate the relationship between intraocular pressure (IOP) and the progression of visual field defects caused by experimental glaucoma in Macaca mulatta monkeys. METHODS: Perimetric fields were measured by behavioral methods in 18 rhesus monkeys during the course of unilateral glaucoma produced by argon laser treatment of the trabecular meshwork. The monkeys' IOPs were measured by applanation tonometry. Visual field defects were quantified by the mean deviation perimetric index from Humphrey Field Analyzer C24-2, model 630 (Humphrey Allergan, San Leandro, CA, U.S.A.), full-threshold data. RESULTS: The monkeys' eyes demonstrated considerable variability in their susceptibility to pressure-induced neural damage. For 10 of the monkeys, significant field defects were correlated with the increases in their IOPs and the defects progressed monotonically to end-state glaucoma. For the other monkeys, the mean deviation index was not well correlated with IOP; some eyes withstood pressures in excess of 35 mm Hg for several months before significant reduction in visual sensitivity. However, once they began, the rate of progression of field defects was similar across subjects. CONCLUSIONS: Laser ablation of the trabecular meshwork in monkeys provides a model for investigations of the effects of IOP that are not confounded by other ocular or visual disorders. Behavioral perimetry showed the same intersubject variability in the effects of elevated IOP on visual field sensitivities of monkeys that are common with high-tension glaucoma or ocular hypertension in patients. Thus, these investigations provide additional support for the use of the model for a wide variety of clinical investigations on glaucoma.

Animals↗

PubMed1997

Intraocular pressure and aqueous humor dynamics in patients with AIDS treated with intravitreal cidofovir (HPMPC) for cytomegalovirus retinitis.

PURPOSE: To evaluate the decrease in intraocular pressure associated with cidofovir (1-[(S)-3-hydroxy-2-(phosphonomethoxy)propyl]cytosine dihydrate; HPMPC) intravitreal injections. METHODS: We followed up 97 eyes of 63 patients with acquired immunodeficiency syndrome (AIDS) who had cytomegalovirus retinitis and had been treated with up to nine 20-microgram intravitreal cidofovir injections. Measurements were taken at baseline, between 2 and 3 weeks, and at 5 to 6 weeks after injections. Anterior chamber fluorophotometry was studied in seven eyes (four patients) before and after injections. Ciliary body anatomy was evaluated in two patients. RESULTS: After the first intravitreal injection, mean intraocular pressure was 2.2 mm Hg lower than that at baseline at 2 to 3 weeks (P < .001) and 1.3 mm Hg lower than at baseline at 5 to 6 weeks (P = .0025). After the second injection, mean pressure was 2.6 mm Hg lower at 2 to 3 weeks (P = .0013) and 1.5 mm Hg lower at 5 to 6 weeks (P = .043). After subsequent injections, however, the decrease was less than 1 mm Hg, suggesting that a plateau had been reached. Pressure in eyes with anterior uveitis after the first injection was lower than that in eyes without anterior uveitis (P < .0001). The mean rate of aqueous flow decreased from 2.8 to 1.9 microliters per minute 2 to 4 weeks after injection (P < .015). Ultrasound biomicroscopy disclosed that severe hypotony after cidofovir injections is associated with ciliary body atrophy. CONCLUSIONS: Intraocular pressure decreases after the initial 20-microgram cidofovir intravitreal injection. However, eyes stabilize (pressure plateaus) after three injections. Effects on the ciliary body are the main cause of the decrease after cidofovir injections.

Acquired Immunodeficiency Syndrome↗

PubMed1989

Silicone tubes in glaucoma surgery: the effect of technical modifications on early postoperative intraocular pressures and complications.

One hundred and nineteen eyes with glaucoma were treated by implantation of silicone rubber tubes draining either to encircling inverted gutters (92 eyes) or to integral plates sutured at the equator of the globe. The occurrence of persistent choroidal effusion was related significantly (S less than 0.01) to post-operative hypotony and choroidal haemorrhage appeared to occur during periods of ocular hypotony. This paper describes our surgical modifications to overcome these problems. A one-piece integral tube and plate with a slit-valve mechanism designed to regulate post-operative intraocular pressure had a very variable response in 27 eyes, with mean pressures similar to those after unligated tube and gutters. Ligation of the tube in 34 eyes caused significantly higher mean intraocular pressures on the first two days after surgery than that in 43 eyes without ligation and the incidence of ocular hypotony (less than 7 mmHg) was significantly lower after ligation. However, five eyes with ligated tubes required operative release of the suture because of uncontrollably raised intraocular pressures. Venting of the drainage tube on the anterior chamber side of the occlusive ligation in 15 eyes caused fewer cases of raised post-operative intraocular pressures, but also a moderate increase in the frequency of ocular hypotony. At present a combination of occlusive ligation and a venting stab into the drainage tube in a one-piece tube and plate system appears to be the best design for avoiding short-term ocular hypotony whilst achieving long-term pressure control.

Adolescent↗

PubMed1991

Long-term outcome following trabeculectomy: I Retrospective analysis of intraocular pressure regulation and cataract formation.

Decrease of intraocular pressure (IOP) and the occurrence of cataract were analysed in 75 patients of a community-based material followed for 6-12 years after trabeculectomy. IOP was controlled (less than or equal to 21 mmHg) with or without additional treatment in approximately 90% of the eyes, both at 5 years and at the last visit. The share of eyes requiring no medication for IOP control decreased linearly with time from approximately 90 to 60% between one and 10 years postoperatively. Thirty-eight per cent of the patients without cataract at the time of operation suffered from cataract development during follow-up. The prevalence of dense cataract producing severe visual loss at the last visit was 47%. The occurrence of cataract was correlated with the age of patients at operation. Cataract formation showed no relationship of statistical significance with preoperative treatment, with time since surgery, the magnitude of preoperative IOP and the reduction of postoperative IOP.

Aged↗

PubMed1985

Intraocular pressure, ocular toxicity and neurotoxicity in response to 11-hydroxy-delta 9-tetrahydrocannabinol and 1-nantradol.

Both acute and chronic effects on intraocular pressure of 11-hydroxy- delta 9-tetrahydrocannabinol (11-OH-delta 9-THC; a metabolite of delta 9-THC) and 1-nantradol (a synthetic cannabinoid) have been examined in the cat. Acute effects of these cannabinoids on ocular tension have also been determined in the monkey. Single dose effects of several other hydroxylated delta 9-THC metabolites have been evaluated in either the cat or the monkey. Results indicated that 11-OH-delta 9-THC and 1-nantradol produced similar acute effects in both species, with 1-nantradol significantly lowering intraocular pressure and 11-OH- delta 9-THC producing no change. Neither 11-OH- delta 9-THC nor 1-nantradol lowered ocular tension chronically when delivered for nine days to cats eyes via osmotic minipumps and connecting extraocular cannulas. Neither cannabinoid likewise produced ocular toxicity, although both produced neurotoxicity, as assessed by evaluation of electroencephalograms recorded from rats. Both 8-beta-OH- delta 9-THC and 8-beta-11-diOH- delta 9-THC were inactive with regard to acute effects on ocular tension. These results support previous findings suggesting that hydroxylation of the terpene portion of the delta 9-THC molecule significantly reduces intraocular pressure lowering activity. In addition, results from these and earlier studies suggest that structural requirements for tension lowering effects, ocular toxicity, and neurotoxicity, may well be distinctively different.

Animals↗

PubMed1990

Influence of intraocular pressure on axial elongation.

The role of intraocular pressure (IOP) on axial elongation was studied by the following three experiments. 1) Thickness of the sclera in the lid-sutured-myopia of three monkeys was examined by light microscopy. The sclera of the experimental eye in the posterior pole was thinner than that of the control eye, but no differences were found in the equatorial and limbal parts of the sclera. 2) By increasing IOP, the scleral wall extensibility in 8 normal, enucleated rabbit eyes was measured by placing the foil strain gauges on the sclera. Extensibility of the sclera in the posterior pole showed a different response from that at the equator and in the limbus. 3) IOPs of the 184 human myopic eyes were measured by a Mackay-Marg tonometer in various postures. IOP elevations in high myopia and postural variations of IOP were obtained. From these experiments, it was suggested that IOP seemed to be one of the main factors in increasing the axis to the posterior pole.

Adolescent↗

PubMed1995

[Effect of severing trigeminal nerve on intraocular pressure and pupil in rabbits].

Changes of intraocular pressure (IOP) and pupil were observed through severing trigeminal nerve (TN), and the possible effect on TN on regulation of IOP was investigated in 5 rabbits. When TN was severed, the mean IOP at the same side was sharply and significantly elevated, being almost 2-fold of that before the procedure (P < 0.01). After the procedure, the mean elevated IOP decreased rapidly. The mean IOP at the end of the procedure was 0.28kPa higher than that before the procedure, and the IOP difference between pre- and post-procedure was not significant (P > 0.05). There was no significant difference in the comparison between the mean IOP after the procedure for 2 weeks and that before the procedure (P > 0.05). On the other hand, the mean diameter of pupils during and at the end of the procedure was significantly decreased (P < 0.01), when compared with that before the procedure, and afterward it gradually recovered. The above findings show that the rapid and significant reactions of IOP and pupil during the procedure are possibly affected by the actions of some neuropeptides in the TN5 suggesting that TN, participate in the regulation of IOP.

Animals↗

PubMed1999

A randomized trial of the effect of midazolam on intraocular pressure.

PURPOSE: The effect of midazolam on intraocular pressure (IOP) in adults was studied as an initial step in determining whether it can be used as a preoperative anxiolytic or sedative agent in children with glaucoma who are undergoing examination for IOP measurements. METHODS: This study followed a prospective, placebo controlled, randomized, double masked design. Fifty-five participants were enrolled after informed consent was obtained. Each enrolled patient underwent a brief history and eye examination. Measurements of IOP were taken at baseline and 5, 10, and 15 minutes after intravenous administration of 1 mg midazolam or placebo. IOP was the primary outcome measured. RESULTS: There was no difference in IOP fluctuation from baseline between patients who received midazolam and those who received placebo. CONCLUSION: Early results indicate that because midazolam does not lower IOP, it may be a useful adjunct to ketamine anesthesia in children with glaucoma undergoing ophthalmologic examination under anesthesia. However, studies of midazolam must be conducted in children and patients with glaucoma before its use in these populations can be recommended.

Anesthesia, Intravenous↗

PubMed2006

Relationship between central corneal thickness and changes of optic nerve head topography and blood flow after intraocular pressure reduction in open-angle glaucoma and ocular hypertension.

OBJECTIVES: To investigate changes in optic nerve head topography and blood flow after therapeutic intraocular pressure reduction and to correlate them with central corneal thickness. METHODS: Sixteen patients with open-angle glaucoma and 16 patients with ocular hypertension underwent Heidelberg retina tomography and scanning laser Doppler flowmetry in 1 eye before and at least 2 months after a mean 35% sustained therapeutic reduction in intraocular pressure. Patients were assigned to a thin or thick group based on their median central corneal thickness. RESULTS: Compared with 16 patients with thick corneas (mean +/- SD central corneal thickness, 587 +/- 31 microm), the 16 patients with thin corneas (518 +/- 32 microm) had greater reductions in mean (36 +/- 32 vs 4 +/- 36 microm, P = .003) and in maximum cup depth (73 +/- 107 vs 4 +/- 89 microm, P = .02). These changes were not statistically significantly different between the patients with open-angle glaucoma and those with ocular hypertension. Smaller mean +/- SD improvements in neuroretinal rim blood flow were seen in patients with thinner corneas compared with those with thicker corneas (35 +/- 80 vs 110 +/- 111 arbitrary units, P = .04). CONCLUSION: Patients with open-angle glaucoma and ocular hypertension with thinner corneas show significantly greater shallowing of the cup, a surrogate marker for lamina cribrosa displacement (compliance), and smaller improvements of neuroretinal rim blood flow after intraocular pressure reduction.

Antihypertensive Agents↗

PubMed1998

[Intraocular pressure values in intubation anesthesia in patients with and without chronic open angle glaucoma].

BACKGROUND: A number of clinical studies have investigated the influence of hypnotics and relaxants on intraocular pressure. All of them referred to the normal eye. Our goal was to show if there is a difference in intraocular pressure profile during general anesthesia between eyes with and without primary open angle glaucoma. PATIENTS AND METHODS: We prospectively examined two groups of 20 patients with and without primary open angle glaucoma. Intraocular pressure (IOP) readings were taken using a Perkins hand held applanation tonometer during routine surgery on cataract or glaucoma on the fellow eye. Balanced anesthesia was carried out using Etomidate, Vecuronium, Fentanyl, N2O and Enflurane. RESULTS: In the glaucoma group IOP fell from 20.3 +/- 4.1 mm Hg before induction of anesthesia (baseline) to 13.2 +/- 3.8 mm Hg (65% of baseline) after induction and 12.6 +/- 4.2 mm Hg (62%) 5 minutes after induction. In the non-glaucoma group IOP was 16.3 +/- 3.5, 9.7 +/- 3.0 (62%) und 9.6 +/- 3.0 (59%) respectively. Directly after placement of endotracheal tube we read 17.8 +/- 7.6 mm Hg (87%) in the glaucoma and 13.0 +/- 5.9 mm Hg (82%) in the non-glaucoma group. Shortly before removal of endotracheal tube we found IOP to be 21.3 +/- 4.5 mm Hg (107%) in the glaucoma and 17.8 +/- 6.8 mm Hg (106%) in the non-glaucoma group. Back on the ward we measured 19.8 +/- 4.1 mm Hg (94%) and 15.4 +/- 3.5 (93%) respectively. Pressure changes relative to baseline values show no statistically significant differences between the two groups. CONCLUSIONS: General anesthesia lowers IOP to the advantage of intraocular surgery. There is no statistically significant difference in pressure change relative to baseline value in eyes with and without primary open angle glaucoma.

Aged↗