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Results for “INTRAOCULAR PRESSURE”

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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↗
PubMed2002

A rabbit model to study orbital venous pressure, intraocular pressure, and ocular hemodynamics simultaneously.

PURPOSE: To measure orbital venous pressure (OVP) and determine the effects of changes in mean arterial pressure (MAP) on OVP, intraocular pressure (IOP), episcleral venous pressure (EVP), and ciliary and choroidal blood flows. METHODS: The experiments were performed in anesthetized rabbits. In all animals, MAP, IOP, and OVP were measured by direct cannulation of the central ear artery, the vitreous, and the orbital venous sinus, respectively. Laser Doppler flowmetry was used to measure choroidal blood flow in one group, and ciliary blood flow in a second group. A servonull micropressure system was used to measure EVP in a third group. The protocol for all three groups entailed varying MAP mechanically with occluders on the aorta and vena cava. RESULTS: The OVP and IOP relationship correlated linearly (r = 0.99) during mechanical manipulation of MAP. EVP also correlated well with OVP (r = 0.9). Resistance calculations based on choroidal and ciliary blood flows and the pressure gradients indicate active adjustment of arterial resistance and passive changes in venous resistance in response to changing MAP in both circulations. CONCLUSIONS: The rabbit orbital venous sinus permits continuous measurements of OVP. The present findings show that OVP is not static and suggest that OVP may play an important role in IOP homeostasis and ocular hemodynamics.

Animals↗
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↗
PubMed1998

Effect of plasma colloid osmotic pressure on intraocular pressure during haemodialysis.

BACKGROUND: In a previous case report, it was shown that an increase in plasma colloid osmotic pressure induced by the removal of fluid during haemodialysis was instrumental in decreasing intraocular pressure. The relation between changes in intraocular pressure, plasma osmolarity, plasma colloid osmotic pressure, and body weight before and after haemodialysis is evaluated. METHODS: Intraocular pressure, plasma osmolarity, plasma colloid osmotic pressure, and body weight were evaluated before and after haemodialysis in 36 patients. RESULTS: Intraocular pressure and plasma osmolarity both decreased significantly after haemodialysis (p < 0.0001). Plasma colloid osmotic pressure increased significantly after haemodialysis (p < 0.0001). Body weight decreased significantly because of the removal of fluid during haemodialysis (p < 0.0001). No significant correlation was found between the change in intraocular pressure and that in plasma osmolarity (r = -0.206, p = 0.2297), whereas the change in intraocular pressure was correlated with the change in plasma colloid osmotic pressure (r = -0.510, p = 0.0012) and the change in body weight (r = 0.534, p = 0.0006). A significant correlation was found between the change in plasma colloid osmotic pressure and that in body weight (r = -0.756, p < 0.0001). CONCLUSION: The change in intraocular pressure was inversely correlated with the increase in plasma colloid osmotic pressure caused by the removal of fluid during haemodialysis.

Adult↗
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↗
PubMed1998

[Change in intraocular pressure after intraocular lens implant during a follow-up period of over 10 years].

Changes in intraocular pressure were studied in 141 eyes following intraocular lens implant. The average observational time was twelve years. We tried to fix both loops of the implant in the ciliary sulcus. The intraocular pressure increased over the ten year interval at 0.19 mmHg per year. Twenty-seven of the 141 eyes developed glaucoma. We studied the intraocular pressure of the cases with or without complications. Thirty-eight eyes had complications, fifteen eyes (39%) developed secondary glaucoma, and three eyes (8%) developed glaucomatous visual field defect. In twenty-three cases without secondary glaucoma, the intraocular pressure increased over a three-year interval after surgery and remained constant thereafter. 103 eyes had no complications to influence the intraocular pressure, twelve eyes (12%) developed secondary glaucoma, and four eyes (4%) developed glaucomatous visual field defect. In 91 cases without secondary glaucoma, the intraocular pressure increased over a five-year interval after surgery at 0.28 mmHg per year and remained constant thereafter. We recommend regular examination, especially during the initial five-year period when the intraocular pressure is apt to increase even if complications are not evident.

Adult↗
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↗