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At least 19 recordsLinked to original sources
PubMed1989

Blood pressure, intraocular pressure, and retinal vessels after high altitude mountain exposure.

Identical test protocols were used before and after 2 to 7 weeks of high altitude exposure in 23 climbers participating in 3 separate mountain expeditions in the Himalayas. The three groups reached altitudes of 4,000 m, 5,200, and 5,850 m, respectively. High altitude retinal hemorrhages (HARH) were found in three subjects (13%). Two weeks after the mountain exposure, reduced mean values of systolic (p less than 0.005) and diastolic (p less than 0.05) blood pressure and intraocular pressure (p less than 0.005) were found. Retinal veins were dilated 2.6% (p less than 0.001), and in both arteries (p less than 0.001) and veins (p less than 0.005) we observed a tendency for small vessels to dilate and large vessels to constrict. The intensity of reflection of light ("the central light reflex") from arteries was reduced (p = 0.003), indicating hemorrheology changes in the vessels. This study shows that significant changes in blood pressure, intraocular pressure and retinal vascularity follow hypoxic and physical strain of high altitude. The vascular conditioning of altitude acclimatization can be demonstrated in the retinal circulation 2 weeks after the exposure.

Adult↗
PubMed1991

Positive end-expiratory pressure increases intraocular pressure in cats.

BACKGROUND AND METHODS: The purpose of the present study was to examine the effect of various levels of positive end-expiratory pressure on intraocular pressure in cats. Fourteen healthy adult cats (2.6 to 3.7 kg) without evidence of ocular disease were anesthetized with pentobarbital, paralyzed, and placed on mechanical ventilation. Direct continuous measurements of heart rate (HR), mean arterial pressure (MAP), CVP, CSF pressure, and intraocular pressure were recorded at zero end-expiratory pressure, and at 5, 10, and 15 cm H2O positive end-expiratory pressure, applied in random order. MAIN RESULTS: There were no significant changes in pHa, Paco2, HR, MAP, hematocrit, and temperature. Intraocular pressure increased significantly from 17 (during zero end-expiratory pressure) to 20 mm Hg at 10 cm H2O positive end-expiratory pressure; at 15 cm H2O positive end-expiratory pressure, intraocular pressure increased significantly to 21 mm Hg. CVP and CSF pressure increased significantly in parallel with intraocular pressure at 5, 10, and 15 cm H2O positive end-expiratory pressure. CONCLUSIONS: We speculate that similar responses occur in man, and may be undesirable in patients with already increased intraocular pressure, when higher levels of positive end-expiratory pressure are used.

Animals↗
PubMed1990

Optic disc topography and short-term increase in intraocular pressure.

Intraocular pressure is intra- and interindividually inconstant. It is influenced by numerous ocular and general factors. We evaluated the question as to whether a short-term increase in intraocular pressure might change the two-dimensional topography of the optic nerve head. Optic disc photographs of 63 glaucomatous eyes in 33 Caucasian patients and 39 normal eyes in 22 subjects were taken at a baseline intraocular pressure of less than 20 mm Hg and at 1 and 8 s after pressure elevations of 10 and 20 mm Hg. No significant differences in the size and form of the optic disc, optic cup, neuroretinal rim, peripapillary scleral ring or parapapillary chorioretinal atrophy were found. The retinal vessels mostly reacted to the intraocular pressure elevation by an initial decrease and subsequent re-increase in their diameter; this change was significant (P less than 0.05) for the pressure elevation of 20 mm Hg. We conclude that the two-dimensional optic disc topography is not significantly changed by a short-term increase in intraocular pressure.

Adolescent↗
PubMed1983

Effects of moderate exercise on intraocular pressure.

Intraocular pressure measurements were made on human subjects using a noncontact tonometer before and at several time intervals after moderate exercise on a bicycle ergometer. One minute after exercise, intraocular pressures were significantly decreased (by 25%) but gradually returned toward pre-exercise values in 20 to 30 min. The results confirm findings by others that physical exertion results in a transient decrease in intraocular pressures and suggest that the magnitude of the reduction and the time required for recovery are related to the severity of the exertion.

Adult↗
PubMedDate not supplied

[Hemodynamic processes in eye models with different levels of intraocular pressure].

Intraocular pressure effects on blood flow volumic rate in an eye model were examined in various arterial pressure levels and perfused liquid viscosity values. The findings evidence an exponential relationship between intraocular pressure elevation and blood flow volumic rate reduction. Hypotensive drugs should be prescribed with care to glaucoma patients, with the blood viscosity values monitored.

Antihypertensive Agents↗
PubMed1979

The effect of thiopentone and fazadinium on intraocular pressure.

Intraocular pressure was measured in twenty-four patients using an applanation tonometer, after using thiopentone and fazadinium as induction agents. No significant rise in intraocular pressure above resting levels was noted before or after tracheal intubation, and it is suggested that this combination of induction agents should be satisfactory for general anaesthesia of a patient with a perforating eye injury who presents with a full stomach.

Adolescent↗
PubMed1986

The interrelationship between intraocular pressure and Honan Intraocular Pressure Reducer pressure.

The relationship between the pressure applied to the enucleated human eye using the Honan Intraocular Pressure Reducer (HIPR) and the peak intraocular pressure as a function of initial intraocular pressure has been examined. The peak intraocular pressure is linearly related to the applied HIPR pressure whether the latter is 30, 50, or 75 mm Hg. The slopes relating peak intraocular pressure to initial intraocular pressure at different HIPR settings are parallel. Use of the HIPR at settings greater than 30 mm Hg and an initial IOP of greater than 30 mm Hg could compromise ocular vascular perfusion.

Humans↗
PubMed1986

Effect of vecuronium on intraocular pressure.

Intraocular pressure decreased by 22.6% in association with neuromuscular blockade produced by vecuronium 0.1 mg kg-1. This appeared to be the result of an indirect action possibly via an effect on CVP. Vecuronium would be a suitable neuromuscular blocker for patients undergoing eye surgery in whom an increase in IOP would be undesirable.

Adult↗
PubMed1990

Comparison of the effects of isoflurane and halothane on intraocular pressure.

Intraocular pressure (IOP) was measured in four groups of patients receiving isoflurane or halothane in consecutively increasing or decreasing concentrations (1.0, 2.0 and 3.0 MAC in 70% nitrous oxide). IOP decreased significantly in all groups irrespective of whether the higher or the lower concentration of the volatile agent was used first. There were no further significant changes in IOP whether the concentrations were increased or decreased, suggesting no dose-relation. Maximum reductions in IOP were slightly greater in those receiving the higher concentrations of the volatile agents first (64 and 66% with isoflurane and halothane, respectively) in comparison to those receiving the lower concentrations first (54 and 46%, respectively).

Adult↗
PubMed1988

Effect of extracapsular cataract extraction on intraocular pressure.

Intraocular pressure (IOP) was measured in 27 normotensive patients scheduled to undergo uncomplicated extracapsular cataract extraction with insertion of a posterior chamber intraocular lens implant. The measurements were recorded the day before surgery, 3, 6 and 9 hours after surgery and the following morning. Fourteen of the patients had a substantial increase in IOP, to more than 30 mm Hg, on the evening of surgery. Most had normal IOP values the next morning. Ophthalmologists should be aware of this possible effect of extracapsular cataract extraction on IOP.

Cataract Extraction↗
PubMed1984

Effect of hemodialysis on intraocular pressure.

Intraocular pressure (IOP) was determined in 13 dialysis patients before, during, and after dialysis. The values were compared with those obtained in an age-, sex-, and time-matched normal control group. The IOP values obtained in dialysis patients were significantly lower than those in the control group. An insignificant decrease in IOP was noted during the first 2 h of dialysis. This was followed by a slight rise above the base line by the end of dialysis. Although the middialysis IOP was significantly lower than the postdialysis value, the latter was not significantly different from the predialysis value. Our results are at variance with several earlier studies demonstrating marked increase in IOP during dialysis. Lack of significant rise in IOP during dialysis in our study seems to be due to improved dialytic technique and better uremia control employed here as compared with the earlier studies.

Adult↗
PubMedDate not supplied

Thiopental and succinylcholine: Action on intraocular pressure.

Intraocular pressure (IOP) measurements were made in a series of 92 male surgical patients, to assess the effects of timing and dosage of succinylcholine given after a standardized sleep dose of thiopental (3 mg./kg.). The major findings of this study were as follows: (1) thiopental alone lowered IOP; (2) a small (0.5 mg./kg.) dose of succinylcholine, given immediately after thiopental, returned IOP to normal; (3) a large (1 mg./kg.) dose of succinylcholine immediately after thiopental maintained the IOP at a low value; (4) if 2 minutes elapsed between thiopental and 1 mg./kg. of succinylcholine, the relaxant raised the IOP to slightly above preanesthetic control values; (5) tracheal intubation caused a significant rise in IOP, more than any effect from succinylcholine itself; (6) succinylcholine drip (0.1 percent), begun after establishment of satisfactory endotracheal halothane-nitrous oxide anesthesia, caused significant IOP elevation in 4 of 11 patients.

Adult↗
PubMed1992

Corticosteroid treatment for inflammatory bowel disease in pediatric patients increases intraocular pressure.

Intraocular pressure (IOP) was measured in 54 pediatric patients (aged 7-21 years) with inflammatory bowel disease (IBD) who were treated with oral prednisone for 1-104 months. The difference in mean IOP between the treated patients (mean +/- SD, 15.62 +/- 4.11 mm Hg) and 55 age-matched controls (13.83 +/- 2.42 mm Hg) was statistically significant (P = 0.007). The IBD patients were classified as group I, IOP less than or equal to 19 mm Hg in both eyes, and group II, IOP greater than or equal to 20 mm Hg in either eye. Twelve of the 54 patients (22.2%) and none of the controls had IOP greater than or equal to 20 mm Hg (P less than 0.001). Seventeen of the 54 patients (31.5%) were characterized as "steroid responders" (IOP of greater than or equal to 20 mm Hg, change in IOP of greater than or equal to 6 mm Hg between visits, or difference in IOP of greater than or equal to 6 mm Hg between the two eyes). When the dose of prednisone was reduced to 0-10 mg/day 30 days or more before measurement, 9 steroid responders showed a decrease in IOP to within 2 SD of the mean control IOP; 7 of the 9 showed a decrease in IOP of greater than or equal to 6 mm Hg. These observations indicate that while prednisone is a causative factor in increasing the IOP, susceptibility to average doses of prednisone is highly variable, and patients need to be monitored on an individual basis. Because IBD is a chronic disorder that requires prolonged corticosteroid treatment, these children are at risk of developing steroid-induced glaucoma. Careful ophthalmologic monitoring of pediatric IBD patients, as well as of other pediatric patients who receive corticosteroid therapy, is recommended.

Adolescent↗
PubMed1988

Systemic blood pressure and intraocular pressure relationship.

The relationship between intraocular pressure (IOP) and arterial blood pressure (BP) was analyzed in response to two pressor agents (norepinephrine and angiotensin II) and two depressor agents (methacholine and isoproterenol) in pentobarbital anesthetized cats. Both IOP and BP were measured manometrically in the same animals. Intravenous norepinephrine and angiotensin II produced dose-dependent increases, whereas intravenous methacholine and isoproterenol produced dose-dependent decreases of both BP and IOP. The IOP response to methacholine was biphasic, with an initial decrease followed by an increase above the pre-drug level. In some experiments a cannula loop was inserted into a carotid artery in order to separate the direct ocular effect of drugs on IOP from that contributed by the changes in systemic BP. Intravenous administration of norepinephrine and angiotensin II produced a larger increase in IOP on the side where drugs were delayed by the loop. Conversely, methacholine produced a larger fall in IOP on the cannulated side while the effect of isoproterenol was essentially unchanged. In other experiments injections were made directly into the ocular arterial blood supply. Norepinephrine and angiotensin II produced a decrease in IOP, methacholine produced a rise of IOP and isoproterenol was not active by this route. The present findings indicate that IOP is largely influenced by arterial BP changes in the acute phase and that the IOP response to drugs is the algebraic sum of effects on systemic BP and their direct ocular effects.

Angiotensin II↗
PubMed1992

Neovascular glaucoma and intraocular pressure: II. Reduction of intraocular pressure--our 5-year experience.

The paper reports the results obtained with reduction of intraocular pressure in 38 eyes of 38 patients with acute neovascular glaucoma. Cyclocryocoagulation alone was made in 12 eyes, 26 eyes were treated by transscleral panretinal cryocoagulation combined with cyclocryocoagulation. In eyes treated by cyclocryocoagulation alone the intraocular pressure less than 26 mmHg was on 5th day after operation in 41.6%, on 10th day in 66.7%. However, this effect was transient in one-third of the patients, and no effect was found in one-third of eyes. In eyes treated by transscleral panretinal cryocoagulation combined with cyclocryocoagulation, the intraocular pressure less than 26 mmHg by 3 days after operation was recorded in 50%, by 10 days in 76.9%. Postoperative hypotension developed in 27%. It is concluded that intraocular pressure in neovascular glaucoma is better managed by transscleral panretinal cryocoagulation with concurrent cyclocryocoagulation than by cyclocryocoagulation alone.

Cryosurgery↗